[bitcoin-dev] User Activated Soft Fork Split Protection

[bitcoin-dev] User Activated Soft Fork Split Protection

[James Hilliard]

Due to the proposed calendar(https://segwit2x.github.io/) for the
SegWit2x agreement being too slow to activate SegWit mandatory
signalling ahead of BIP148 using BIP91 I would like to propose another
option that miners can use to prevent a chain split ahead of the Aug
1st BIP148 activation date.

The splitprotection soft fork is essentially BIP91 but using BIP8
instead of BIP9 with a lower activation threshold and immediate
mandatory signalling lock-in. This allows for a majority of miners to
activate mandatory SegWit signalling and prevent a potential chain
split ahead of BIP148 activation.

This BIP allows for miners to respond to market forces quickly ahead
of BIP148 activation by signalling for splitprotection. Any miners
already running BIP148 should be encouraged to use splitprotection.

<pre>
  BIP: splitprotection
  Layer: Consensus (soft fork)
  Title: User Activated Soft Fork Split Protection
  Author: James Hilliard <james.hilliard1@gmail.com>
  Comments-Summary: No comments yet.
  Comments-URI:
  Status: Draft
  Type: Standards Track
  Created: 2017-05-22
  License: BSD-3-Clause
           CC0-1.0
</pre>

==Abstract==

This document specifies a coordination mechanism for a simple majority
of miners to prevent a chain split ahead of BIP148 activation.

==Definitions==

"existing segwit deployment" refer to the BIP9 "segwit" deployment
using bit 1, between November 15th 2016 and November 15th 2017 to
activate BIP141, BIP143 and BIP147.

==Motivation==

The biggest risk of BIP148 is an extended chain split, this BIP
provides a way for a simple majority of miners to eliminate that risk.

This BIP provides a way for a simple majority of miners to coordinate
activation of the existing segwit deployment with less than 95%
hashpower before BIP148 activation. Due to time constraints unless
immediately deployed BIP91 will likely not be able to enforce
mandatory signalling of segwit before the Aug 1st activation of
BIP148. This BIP provides a method for rapid miner activation of
SegWit mandatory signalling ahead of the BIP148 activation date. Since
the primary goal of this BIP is to reduce the chance of an extended
chain split as much as possible we activate using a simple miner
majority of 65% over a 504 block interval rather than a higher
percentage. This BIP also allows miners to signal their intention to
run BIP148 in order to prevent a chain split.

==Specification==

While this BIP is active, all blocks must set the nVersion header top
3 bits to 001 together with bit field (1<<1) (according to the
existing segwit deployment). Blocks that do not signal as required
will be rejected.

==Deployment==

This BIP will be deployed by "version bits" with a 65%(this can be
adjusted if desired) activation threshold BIP9 with the name
"splitprotecion" and using bit 2.

This BIP starts immediately and is a BIP8 style soft fork since
mandatory signalling will start on midnight August 1st 2017 (epoch
time 1501545600) regardless of whether or not this BIP has reached its
own signalling threshold. This BIP will cease to be active when segwit
is locked-in.

=== Reference implementation ===

<pre>
// Check if Segregated Witness is Locked In
bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
Consensus::Params& params)
{
    LOCK(cs_main);
    return (VersionBitsState(pindexPrev, params,
Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
THRESHOLD_LOCKED_IN);
}

// SPLITPROTECTION mandatory segwit signalling.
if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
THRESHOLD_LOCKED_IN &&
     !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
// Segwit is not locked in
     !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
and is not active.
{
    bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
VERSIONBITS_TOP_BITS;
    bool fSegbit = (pindex->nVersion &
VersionBitsMask(chainparams.GetConsensus(),
Consensus::DEPLOYMENT_SEGWIT)) != 0;
    if (!(fVersionBits && fSegbit)) {
        return state.DoS(0, error("ConnectBlock(): relayed block must
signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
    }
}

// BIP148 mandatory segwit signalling.
int64_t nMedianTimePast = pindex->GetMedianTimePast();
if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00 UTC
     (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
     (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
 // Segwit is not locked in
      !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
 // and is not active.
{
    bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
VERSIONBITS_TOP_BITS;
    bool fSegbit = (pindex->nVersion &
VersionBitsMask(chainparams.GetConsensus(),
Consensus::DEPLOYMENT_SEGWIT)) != 0;
    if (!(fVersionBits && fSegbit)) {
        return state.DoS(0, error("ConnectBlock(): relayed block must
signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
    }
}
</pre>

https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1

==Backwards Compatibility==

This deployment is compatible with the existing "segwit" bit 1
deployment scheduled between midnight November 15th, 2016 and midnight
November 15th, 2017. This deployment is also compatible with the
existing BIP148 deployment. This BIP is compatible with BIP91 only if
BIP91 activates before it and before BIP148. Miners will need to
upgrade their nodes to support splitprotection otherwise they may
build on top of an invalid block. While this bip is active users
should either upgrade to splitprotection or wait for additional
confirmations when accepting payments.

==Rationale==

Historically we have used IsSuperMajority() to activate soft forks
such as BIP66 which has a mandatory signalling requirement for miners
once activated, this ensures that miners are aware of new rules being
enforced. This technique can be leveraged to lower the signalling
threshold of a soft fork while it is in the process of being deployed
in a backwards compatible way. We also use a BIP8 style timeout to
ensure that this BIP is compatible with BIP148 and that BIP148
compatible mandatory signalling activates regardless of miner
signalling levels.

By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
deployment, this BIP can cause the existing "segwit" deployment to
activate without needing to release a new deployment. As we approach
BIP148 activation it may be desirable for a majority of miners to have
a method that will ensure that there is no chain split.

==References==

*[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html
Mailing list discussion]
*[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283
P2SH flag day activation]
*[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
*[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
*[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
*[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
*[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
Version 0 Witness Program]]
*[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element malleability]]
*[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment]]
*[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
*[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit benefits]

==Copyright==

This document is dual licensed as BSD 3-clause, and Creative Commons
CC0 1.0 Universal.

Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[Karl Johan Alm]

One thing about BIP148 activation that may be affected by this is the
fact that segwit signalling non-BIP148 miners + BIP148 miners may hold
majority hash power and prevent a chain split. With this SF, that will
no longer be the case, right? Or am I completely confused on the
subject?

On Wed, Jun 7, 2017 at 9:56 AM, James Hilliard via bitcoin-dev
<bitcoin-dev@lists.linuxfoundation.org> wrote:
> Due to the proposed calendar(https://segwit2x.github.io/) for the
> SegWit2x agreement being too slow to activate SegWit mandatory
> signalling ahead of BIP148 using BIP91 I would like to propose another
> option that miners can use to prevent a chain split ahead of the Aug
> 1st BIP148 activation date.
>
> The splitprotection soft fork is essentially BIP91 but using BIP8
> instead of BIP9 with a lower activation threshold and immediate
> mandatory signalling lock-in. This allows for a majority of miners to
> activate mandatory SegWit signalling and prevent a potential chain
> split ahead of BIP148 activation.
>
> This BIP allows for miners to respond to market forces quickly ahead
> of BIP148 activation by signalling for splitprotection. Any miners
> already running BIP148 should be encouraged to use splitprotection.
>
> <pre>
>   BIP: splitprotection
>   Layer: Consensus (soft fork)
>   Title: User Activated Soft Fork Split Protection
>   Author: James Hilliard <james.hilliard1@gmail.com>
>   Comments-Summary: No comments yet.
>   Comments-URI:
>   Status: Draft
>   Type: Standards Track
>   Created: 2017-05-22
>   License: BSD-3-Clause
>            CC0-1.0
> </pre>
>
> ==Abstract==
>
> This document specifies a coordination mechanism for a simple majority
> of miners to prevent a chain split ahead of BIP148 activation.
>
> ==Definitions==
>
> "existing segwit deployment" refer to the BIP9 "segwit" deployment
> using bit 1, between November 15th 2016 and November 15th 2017 to
> activate BIP141, BIP143 and BIP147.
>
> ==Motivation==
>
> The biggest risk of BIP148 is an extended chain split, this BIP
> provides a way for a simple majority of miners to eliminate that risk.
>
> This BIP provides a way for a simple majority of miners to coordinate
> activation of the existing segwit deployment with less than 95%
> hashpower before BIP148 activation. Due to time constraints unless
> immediately deployed BIP91 will likely not be able to enforce
> mandatory signalling of segwit before the Aug 1st activation of
> BIP148. This BIP provides a method for rapid miner activation of
> SegWit mandatory signalling ahead of the BIP148 activation date. Since
> the primary goal of this BIP is to reduce the chance of an extended
> chain split as much as possible we activate using a simple miner
> majority of 65% over a 504 block interval rather than a higher
> percentage. This BIP also allows miners to signal their intention to
> run BIP148 in order to prevent a chain split.
>
> ==Specification==
>
> While this BIP is active, all blocks must set the nVersion header top
> 3 bits to 001 together with bit field (1<<1) (according to the
> existing segwit deployment). Blocks that do not signal as required
> will be rejected.
>
> ==Deployment==
>
> This BIP will be deployed by "version bits" with a 65%(this can be
> adjusted if desired) activation threshold BIP9 with the name
> "splitprotecion" and using bit 2.
>
> This BIP starts immediately and is a BIP8 style soft fork since
> mandatory signalling will start on midnight August 1st 2017 (epoch
> time 1501545600) regardless of whether or not this BIP has reached its
> own signalling threshold. This BIP will cease to be active when segwit
> is locked-in.
>
> === Reference implementation ===
>
> <pre>
> // Check if Segregated Witness is Locked In
> bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
> Consensus::Params& params)
> {
>     LOCK(cs_main);
>     return (VersionBitsState(pindexPrev, params,
> Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
> THRESHOLD_LOCKED_IN);
> }
>
> // SPLITPROTECTION mandatory segwit signalling.
> if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
> Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
> THRESHOLD_LOCKED_IN &&
>      !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
> // Segwit is not locked in
>      !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
> and is not active.
> {
>     bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
> VERSIONBITS_TOP_BITS;
>     bool fSegbit = (pindex->nVersion &
> VersionBitsMask(chainparams.GetConsensus(),
> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>     if (!(fVersionBits && fSegbit)) {
>         return state.DoS(0, error("ConnectBlock(): relayed block must
> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>     }
> }
>
> // BIP148 mandatory segwit signalling.
> int64_t nMedianTimePast = pindex->GetMedianTimePast();
> if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00 UTC
>      (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
>      (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>  // Segwit is not locked in
>       !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
>  // and is not active.
> {
>     bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
> VERSIONBITS_TOP_BITS;
>     bool fSegbit = (pindex->nVersion &
> VersionBitsMask(chainparams.GetConsensus(),
> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>     if (!(fVersionBits && fSegbit)) {
>         return state.DoS(0, error("ConnectBlock(): relayed block must
> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>     }
> }
> </pre>
>
> https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1
>
> ==Backwards Compatibility==
>
> This deployment is compatible with the existing "segwit" bit 1
> deployment scheduled between midnight November 15th, 2016 and midnight
> November 15th, 2017. This deployment is also compatible with the
> existing BIP148 deployment. This BIP is compatible with BIP91 only if
> BIP91 activates before it and before BIP148. Miners will need to
> upgrade their nodes to support splitprotection otherwise they may
> build on top of an invalid block. While this bip is active users
> should either upgrade to splitprotection or wait for additional
> confirmations when accepting payments.
>
> ==Rationale==
>
> Historically we have used IsSuperMajority() to activate soft forks
> such as BIP66 which has a mandatory signalling requirement for miners
> once activated, this ensures that miners are aware of new rules being
> enforced. This technique can be leveraged to lower the signalling
> threshold of a soft fork while it is in the process of being deployed
> in a backwards compatible way. We also use a BIP8 style timeout to
> ensure that this BIP is compatible with BIP148 and that BIP148
> compatible mandatory signalling activates regardless of miner
> signalling levels.
>
> By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
> deployment, this BIP can cause the existing "segwit" deployment to
> activate without needing to release a new deployment. As we approach
> BIP148 activation it may be desirable for a majority of miners to have
> a method that will ensure that there is no chain split.
>
> ==References==
>
> *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html
> Mailing list discussion]
> *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283
> P2SH flag day activation]
> *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
> *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
> *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
> *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
> *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
> Version 0 Witness Program]]
> *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element malleability]]
> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment]]
> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
> *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit benefits]
>
> ==Copyright==
>
> This document is dual licensed as BSD 3-clause, and Creative Commons
> CC0 1.0 Universal.
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev

Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[James Hilliard]

You need a majority of miners enforcing BIP148 upon BIP148 activation
to prevent a split, not just a majority signalling segwit. This
provides a miner coordination mechanism for BIP148 mandatory
signalling enforcement.

On Tue, Jun 6, 2017 at 8:11 PM, Karl Johan Alm
<karljohan-alm@garage.co.jp> wrote:
> One thing about BIP148 activation that may be affected by this is the
> fact that segwit signalling non-BIP148 miners + BIP148 miners may hold
> majority hash power and prevent a chain split. With this SF, that will
> no longer be the case, right? Or am I completely confused on the
> subject?
>
> On Wed, Jun 7, 2017 at 9:56 AM, James Hilliard via bitcoin-dev
> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>> Due to the proposed calendar(https://segwit2x.github.io/) for the
>> SegWit2x agreement being too slow to activate SegWit mandatory
>> signalling ahead of BIP148 using BIP91 I would like to propose another
>> option that miners can use to prevent a chain split ahead of the Aug
>> 1st BIP148 activation date.
>>
>> The splitprotection soft fork is essentially BIP91 but using BIP8
>> instead of BIP9 with a lower activation threshold and immediate
>> mandatory signalling lock-in. This allows for a majority of miners to
>> activate mandatory SegWit signalling and prevent a potential chain
>> split ahead of BIP148 activation.
>>
>> This BIP allows for miners to respond to market forces quickly ahead
>> of BIP148 activation by signalling for splitprotection. Any miners
>> already running BIP148 should be encouraged to use splitprotection.
>>
>> <pre>
>>   BIP: splitprotection
>>   Layer: Consensus (soft fork)
>>   Title: User Activated Soft Fork Split Protection
>>   Author: James Hilliard <james.hilliard1@gmail.com>
>>   Comments-Summary: No comments yet.
>>   Comments-URI:
>>   Status: Draft
>>   Type: Standards Track
>>   Created: 2017-05-22
>>   License: BSD-3-Clause
>>            CC0-1.0
>> </pre>
>>
>> ==Abstract==
>>
>> This document specifies a coordination mechanism for a simple majority
>> of miners to prevent a chain split ahead of BIP148 activation.
>>
>> ==Definitions==
>>
>> "existing segwit deployment" refer to the BIP9 "segwit" deployment
>> using bit 1, between November 15th 2016 and November 15th 2017 to
>> activate BIP141, BIP143 and BIP147.
>>
>> ==Motivation==
>>
>> The biggest risk of BIP148 is an extended chain split, this BIP
>> provides a way for a simple majority of miners to eliminate that risk.
>>
>> This BIP provides a way for a simple majority of miners to coordinate
>> activation of the existing segwit deployment with less than 95%
>> hashpower before BIP148 activation. Due to time constraints unless
>> immediately deployed BIP91 will likely not be able to enforce
>> mandatory signalling of segwit before the Aug 1st activation of
>> BIP148. This BIP provides a method for rapid miner activation of
>> SegWit mandatory signalling ahead of the BIP148 activation date. Since
>> the primary goal of this BIP is to reduce the chance of an extended
>> chain split as much as possible we activate using a simple miner
>> majority of 65% over a 504 block interval rather than a higher
>> percentage. This BIP also allows miners to signal their intention to
>> run BIP148 in order to prevent a chain split.
>>
>> ==Specification==
>>
>> While this BIP is active, all blocks must set the nVersion header top
>> 3 bits to 001 together with bit field (1<<1) (according to the
>> existing segwit deployment). Blocks that do not signal as required
>> will be rejected.
>>
>> ==Deployment==
>>
>> This BIP will be deployed by "version bits" with a 65%(this can be
>> adjusted if desired) activation threshold BIP9 with the name
>> "splitprotecion" and using bit 2.
>>
>> This BIP starts immediately and is a BIP8 style soft fork since
>> mandatory signalling will start on midnight August 1st 2017 (epoch
>> time 1501545600) regardless of whether or not this BIP has reached its
>> own signalling threshold. This BIP will cease to be active when segwit
>> is locked-in.
>>
>> === Reference implementation ===
>>
>> <pre>
>> // Check if Segregated Witness is Locked In
>> bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
>> Consensus::Params& params)
>> {
>>     LOCK(cs_main);
>>     return (VersionBitsState(pindexPrev, params,
>> Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
>> THRESHOLD_LOCKED_IN);
>> }
>>
>> // SPLITPROTECTION mandatory segwit signalling.
>> if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
>> Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
>> THRESHOLD_LOCKED_IN &&
>>      !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>> // Segwit is not locked in
>>      !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
>> and is not active.
>> {
>>     bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>> VERSIONBITS_TOP_BITS;
>>     bool fSegbit = (pindex->nVersion &
>> VersionBitsMask(chainparams.GetConsensus(),
>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>     if (!(fVersionBits && fSegbit)) {
>>         return state.DoS(0, error("ConnectBlock(): relayed block must
>> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>     }
>> }
>>
>> // BIP148 mandatory segwit signalling.
>> int64_t nMedianTimePast = pindex->GetMedianTimePast();
>> if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00 UTC
>>      (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
>>      (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>>  // Segwit is not locked in
>>       !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
>>  // and is not active.
>> {
>>     bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>> VERSIONBITS_TOP_BITS;
>>     bool fSegbit = (pindex->nVersion &
>> VersionBitsMask(chainparams.GetConsensus(),
>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>     if (!(fVersionBits && fSegbit)) {
>>         return state.DoS(0, error("ConnectBlock(): relayed block must
>> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>     }
>> }
>> </pre>
>>
>> https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1
>>
>> ==Backwards Compatibility==
>>
>> This deployment is compatible with the existing "segwit" bit 1
>> deployment scheduled between midnight November 15th, 2016 and midnight
>> November 15th, 2017. This deployment is also compatible with the
>> existing BIP148 deployment. This BIP is compatible with BIP91 only if
>> BIP91 activates before it and before BIP148. Miners will need to
>> upgrade their nodes to support splitprotection otherwise they may
>> build on top of an invalid block. While this bip is active users
>> should either upgrade to splitprotection or wait for additional
>> confirmations when accepting payments.
>>
>> ==Rationale==
>>
>> Historically we have used IsSuperMajority() to activate soft forks
>> such as BIP66 which has a mandatory signalling requirement for miners
>> once activated, this ensures that miners are aware of new rules being
>> enforced. This technique can be leveraged to lower the signalling
>> threshold of a soft fork while it is in the process of being deployed
>> in a backwards compatible way. We also use a BIP8 style timeout to
>> ensure that this BIP is compatible with BIP148 and that BIP148
>> compatible mandatory signalling activates regardless of miner
>> signalling levels.
>>
>> By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
>> deployment, this BIP can cause the existing "segwit" deployment to
>> activate without needing to release a new deployment. As we approach
>> BIP148 activation it may be desirable for a majority of miners to have
>> a method that will ensure that there is no chain split.
>>
>> ==References==
>>
>> *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html
>> Mailing list discussion]
>> *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283
>> P2SH flag day activation]
>> *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
>> *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
>> *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
>> *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
>> *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
>> Version 0 Witness Program]]
>> *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element malleability]]
>> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment]]
>> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
>> *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit benefits]
>>
>> ==Copyright==
>>
>> This document is dual licensed as BSD 3-clause, and Creative Commons
>> CC0 1.0 Universal.
>> _______________________________________________
>> bitcoin-dev mailing list
>> bitcoin-dev@lists.linuxfoundation.org
>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev

Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[Tao Effect]

[-- Attachment #1.1: Type: text/plain, Size: 9373 bytes --]

What is the probability that a 65% threshold is too low and can allow a "surprise miner attack", whereby miners are kept offline before the deadline, and brought online immediately after, creating potential havoc?

(Nit: "simple majority" usually refers to >50%, I think, might cause confusion.)

-Greg Slepak

--
Please do not email me anything that you are not comfortable also sharing with the NSA.

> On Jun 6, 2017, at 5:56 PM, James Hilliard via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org <mailto:bitcoin-dev@lists.linuxfoundation.org>> wrote:
> 
> Due to the proposed calendar(https://segwit2x.github.io/ <https://segwit2x.github.io/>) for the
> SegWit2x agreement being too slow to activate SegWit mandatory
> signalling ahead of BIP148 using BIP91 I would like to propose another
> option that miners can use to prevent a chain split ahead of the Aug
> 1st BIP148 activation date.
> 
> The splitprotection soft fork is essentially BIP91 but using BIP8
> instead of BIP9 with a lower activation threshold and immediate
> mandatory signalling lock-in. This allows for a majority of miners to
> activate mandatory SegWit signalling and prevent a potential chain
> split ahead of BIP148 activation.
> 
> This BIP allows for miners to respond to market forces quickly ahead
> of BIP148 activation by signalling for splitprotection. Any miners
> already running BIP148 should be encouraged to use splitprotection.
> 
> <pre>
>  BIP: splitprotection
>  Layer: Consensus (soft fork)
>  Title: User Activated Soft Fork Split Protection
>  Author: James Hilliard <james.hilliard1@gmail.com <mailto:james.hilliard1@gmail.com>>
>  Comments-Summary: No comments yet.
>  Comments-URI:
>  Status: Draft
>  Type: Standards Track
>  Created: 2017-05-22
>  License: BSD-3-Clause
>           CC0-1.0
> </pre>
> 
> ==Abstract==
> 
> This document specifies a coordination mechanism for a simple majority
> of miners to prevent a chain split ahead of BIP148 activation.
> 
> ==Definitions==
> 
> "existing segwit deployment" refer to the BIP9 "segwit" deployment
> using bit 1, between November 15th 2016 and November 15th 2017 to
> activate BIP141, BIP143 and BIP147.
> 
> ==Motivation==
> 
> The biggest risk of BIP148 is an extended chain split, this BIP
> provides a way for a simple majority of miners to eliminate that risk.
> 
> This BIP provides a way for a simple majority of miners to coordinate
> activation of the existing segwit deployment with less than 95%
> hashpower before BIP148 activation. Due to time constraints unless
> immediately deployed BIP91 will likely not be able to enforce
> mandatory signalling of segwit before the Aug 1st activation of
> BIP148. This BIP provides a method for rapid miner activation of
> SegWit mandatory signalling ahead of the BIP148 activation date. Since
> the primary goal of this BIP is to reduce the chance of an extended
> chain split as much as possible we activate using a simple miner
> majority of 65% over a 504 block interval rather than a higher
> percentage. This BIP also allows miners to signal their intention to
> run BIP148 in order to prevent a chain split.
> 
> ==Specification==
> 
> While this BIP is active, all blocks must set the nVersion header top
> 3 bits to 001 together with bit field (1<<1) (according to the
> existing segwit deployment). Blocks that do not signal as required
> will be rejected.
> 
> ==Deployment==
> 
> This BIP will be deployed by "version bits" with a 65%(this can be
> adjusted if desired) activation threshold BIP9 with the name
> "splitprotecion" and using bit 2.
> 
> This BIP starts immediately and is a BIP8 style soft fork since
> mandatory signalling will start on midnight August 1st 2017 (epoch
> time 1501545600) regardless of whether or not this BIP has reached its
> own signalling threshold. This BIP will cease to be active when segwit
> is locked-in.
> 
> === Reference implementation ===
> 
> <pre>
> // Check if Segregated Witness is Locked In
> bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
> Consensus::Params& params)
> {
>    LOCK(cs_main);
>    return (VersionBitsState(pindexPrev, params,
> Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
> THRESHOLD_LOCKED_IN);
> }
> 
> // SPLITPROTECTION mandatory segwit signalling.
> if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
> Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
> THRESHOLD_LOCKED_IN &&
>     !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
> // Segwit is not locked in
>     !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
> and is not active.
> {
>    bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
> VERSIONBITS_TOP_BITS;
>    bool fSegbit = (pindex->nVersion &
> VersionBitsMask(chainparams.GetConsensus(),
> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>    if (!(fVersionBits && fSegbit)) {
>        return state.DoS(0, error("ConnectBlock(): relayed block must
> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>    }
> }
> 
> // BIP148 mandatory segwit signalling.
> int64_t nMedianTimePast = pindex->GetMedianTimePast();
> if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00 UTC
>     (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
>     (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
> // Segwit is not locked in
>      !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
> // and is not active.
> {
>    bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
> VERSIONBITS_TOP_BITS;
>    bool fSegbit = (pindex->nVersion &
> VersionBitsMask(chainparams.GetConsensus(),
> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>    if (!(fVersionBits && fSegbit)) {
>        return state.DoS(0, error("ConnectBlock(): relayed block must
> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>    }
> }
> </pre>
> 
> https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1 <https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1>
> 
> ==Backwards Compatibility==
> 
> This deployment is compatible with the existing "segwit" bit 1
> deployment scheduled between midnight November 15th, 2016 and midnight
> November 15th, 2017. This deployment is also compatible with the
> existing BIP148 deployment. This BIP is compatible with BIP91 only if
> BIP91 activates before it and before BIP148. Miners will need to
> upgrade their nodes to support splitprotection otherwise they may
> build on top of an invalid block. While this bip is active users
> should either upgrade to splitprotection or wait for additional
> confirmations when accepting payments.
> 
> ==Rationale==
> 
> Historically we have used IsSuperMajority() to activate soft forks
> such as BIP66 which has a mandatory signalling requirement for miners
> once activated, this ensures that miners are aware of new rules being
> enforced. This technique can be leveraged to lower the signalling
> threshold of a soft fork while it is in the process of being deployed
> in a backwards compatible way. We also use a BIP8 style timeout to
> ensure that this BIP is compatible with BIP148 and that BIP148
> compatible mandatory signalling activates regardless of miner
> signalling levels.
> 
> By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
> deployment, this BIP can cause the existing "segwit" deployment to
> activate without needing to release a new deployment. As we approach
> BIP148 activation it may be desirable for a majority of miners to have
> a method that will ensure that there is no chain split.
> 
> ==References==
> 
> *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html <https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html>
> Mailing list discussion]
> *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283 <https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283>
> P2SH flag day activation]
> *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
> *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
> *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
> *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
> *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
> Version 0 Witness Program]]
> *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element malleability]]
> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment]]
> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
> *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit benefits <https://bitcoincore.org/en/2016/01/26/segwit-benefits/%20Segwit%20benefits>]
> 
> ==Copyright==
> 
> This document is dual licensed as BSD 3-clause, and Creative Commons
> CC0 1.0 Universal.
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org <mailto:bitcoin-dev@lists.linuxfoundation.org>
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev <https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev>


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Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[James Hilliard]

This is a BIP8 style soft fork so mandatory signalling will be active
after Aug 1st regardless.

On Tue, Jun 6, 2017 at 8:51 PM, Tao Effect <contact@taoeffect.com> wrote:
> What is the probability that a 65% threshold is too low and can allow a
> "surprise miner attack", whereby miners are kept offline before the
> deadline, and brought online immediately after, creating potential havoc?
>
> (Nit: "simple majority" usually refers to >50%, I think, might cause
> confusion.)
>
> -Greg Slepak
>
> --
> Please do not email me anything that you are not comfortable also sharing
> with the NSA.
>
> On Jun 6, 2017, at 5:56 PM, James Hilliard via bitcoin-dev
> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>
> Due to the proposed calendar(https://segwit2x.github.io/) for the
> SegWit2x agreement being too slow to activate SegWit mandatory
> signalling ahead of BIP148 using BIP91 I would like to propose another
> option that miners can use to prevent a chain split ahead of the Aug
> 1st BIP148 activation date.
>
> The splitprotection soft fork is essentially BIP91 but using BIP8
> instead of BIP9 with a lower activation threshold and immediate
> mandatory signalling lock-in. This allows for a majority of miners to
> activate mandatory SegWit signalling and prevent a potential chain
> split ahead of BIP148 activation.
>
> This BIP allows for miners to respond to market forces quickly ahead
> of BIP148 activation by signalling for splitprotection. Any miners
> already running BIP148 should be encouraged to use splitprotection.
>
> <pre>
>  BIP: splitprotection
>  Layer: Consensus (soft fork)
>  Title: User Activated Soft Fork Split Protection
>  Author: James Hilliard <james.hilliard1@gmail.com>
>  Comments-Summary: No comments yet.
>  Comments-URI:
>  Status: Draft
>  Type: Standards Track
>  Created: 2017-05-22
>  License: BSD-3-Clause
>           CC0-1.0
> </pre>
>
> ==Abstract==
>
> This document specifies a coordination mechanism for a simple majority
> of miners to prevent a chain split ahead of BIP148 activation.
>
> ==Definitions==
>
> "existing segwit deployment" refer to the BIP9 "segwit" deployment
> using bit 1, between November 15th 2016 and November 15th 2017 to
> activate BIP141, BIP143 and BIP147.
>
> ==Motivation==
>
> The biggest risk of BIP148 is an extended chain split, this BIP
> provides a way for a simple majority of miners to eliminate that risk.
>
> This BIP provides a way for a simple majority of miners to coordinate
> activation of the existing segwit deployment with less than 95%
> hashpower before BIP148 activation. Due to time constraints unless
> immediately deployed BIP91 will likely not be able to enforce
> mandatory signalling of segwit before the Aug 1st activation of
> BIP148. This BIP provides a method for rapid miner activation of
> SegWit mandatory signalling ahead of the BIP148 activation date. Since
> the primary goal of this BIP is to reduce the chance of an extended
> chain split as much as possible we activate using a simple miner
> majority of 65% over a 504 block interval rather than a higher
> percentage. This BIP also allows miners to signal their intention to
> run BIP148 in order to prevent a chain split.
>
> ==Specification==
>
> While this BIP is active, all blocks must set the nVersion header top
> 3 bits to 001 together with bit field (1<<1) (according to the
> existing segwit deployment). Blocks that do not signal as required
> will be rejected.
>
> ==Deployment==
>
> This BIP will be deployed by "version bits" with a 65%(this can be
> adjusted if desired) activation threshold BIP9 with the name
> "splitprotecion" and using bit 2.
>
> This BIP starts immediately and is a BIP8 style soft fork since
> mandatory signalling will start on midnight August 1st 2017 (epoch
> time 1501545600) regardless of whether or not this BIP has reached its
> own signalling threshold. This BIP will cease to be active when segwit
> is locked-in.
>
> === Reference implementation ===
>
> <pre>
> // Check if Segregated Witness is Locked In
> bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
> Consensus::Params& params)
> {
>    LOCK(cs_main);
>    return (VersionBitsState(pindexPrev, params,
> Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
> THRESHOLD_LOCKED_IN);
> }
>
> // SPLITPROTECTION mandatory segwit signalling.
> if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
> Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
> THRESHOLD_LOCKED_IN &&
>     !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
> // Segwit is not locked in
>     !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
> and is not active.
> {
>    bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
> VERSIONBITS_TOP_BITS;
>    bool fSegbit = (pindex->nVersion &
> VersionBitsMask(chainparams.GetConsensus(),
> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>    if (!(fVersionBits && fSegbit)) {
>        return state.DoS(0, error("ConnectBlock(): relayed block must
> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>    }
> }
>
> // BIP148 mandatory segwit signalling.
> int64_t nMedianTimePast = pindex->GetMedianTimePast();
> if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00 UTC
>     (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
>     (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
> // Segwit is not locked in
>      !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
> // and is not active.
> {
>    bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
> VERSIONBITS_TOP_BITS;
>    bool fSegbit = (pindex->nVersion &
> VersionBitsMask(chainparams.GetConsensus(),
> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>    if (!(fVersionBits && fSegbit)) {
>        return state.DoS(0, error("ConnectBlock(): relayed block must
> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>    }
> }
> </pre>
>
> https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1
>
> ==Backwards Compatibility==
>
> This deployment is compatible with the existing "segwit" bit 1
> deployment scheduled between midnight November 15th, 2016 and midnight
> November 15th, 2017. This deployment is also compatible with the
> existing BIP148 deployment. This BIP is compatible with BIP91 only if
> BIP91 activates before it and before BIP148. Miners will need to
> upgrade their nodes to support splitprotection otherwise they may
> build on top of an invalid block. While this bip is active users
> should either upgrade to splitprotection or wait for additional
> confirmations when accepting payments.
>
> ==Rationale==
>
> Historically we have used IsSuperMajority() to activate soft forks
> such as BIP66 which has a mandatory signalling requirement for miners
> once activated, this ensures that miners are aware of new rules being
> enforced. This technique can be leveraged to lower the signalling
> threshold of a soft fork while it is in the process of being deployed
> in a backwards compatible way. We also use a BIP8 style timeout to
> ensure that this BIP is compatible with BIP148 and that BIP148
> compatible mandatory signalling activates regardless of miner
> signalling levels.
>
> By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
> deployment, this BIP can cause the existing "segwit" deployment to
> activate without needing to release a new deployment. As we approach
> BIP148 activation it may be desirable for a majority of miners to have
> a method that will ensure that there is no chain split.
>
> ==References==
>
> *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html
> Mailing list discussion]
> *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283
> P2SH flag day activation]
> *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
> *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
> *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
> *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
> *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
> Version 0 Witness Program]]
> *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element malleability]]
> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment]]
> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
> *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit benefits]
>
> ==Copyright==
>
> This document is dual licensed as BSD 3-clause, and Creative Commons
> CC0 1.0 Universal.
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>
>

Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[Jacob Eliosoff]

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While this isn't an unreasonable proposal, it will orphan blocks from any
miner who isn't running it (or BIP148) by Aug 1, right?  That seems rather
rushed for a non-backwards-compatible SF, especially since in practice,
miners are unlikely to deploy it until it comes bundled with some version
of the Segwit2x HF code.

I realize this is a touchy topic but - how much hard evidence is there that
there *will* be significant disruption if miners simply ignore both this
and BIP148?  Correct me but afaict, BIP148 has ~0% hashrate support.

Unless the HF code is ready and agree on soon (say by Jul 1), my vote is to
keep the main chain backwards-compatible, especially if evidence of miner
support for BIP148 doesn't materialize soon.  It seems less disruptive for
recently-deployed BIP148 nodes to revert than to ask every miner in the
system to quickly upgrade or get orphaned.

Just my view, I respect that others will differ.


On Tue, Jun 6, 2017 at 9:54 PM, James Hilliard via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> This is a BIP8 style soft fork so mandatory signalling will be active
> after Aug 1st regardless.
>
> On Tue, Jun 6, 2017 at 8:51 PM, Tao Effect <contact@taoeffect.com> wrote:
> > What is the probability that a 65% threshold is too low and can allow a
> > "surprise miner attack", whereby miners are kept offline before the
> > deadline, and brought online immediately after, creating potential havoc?
> >
> > (Nit: "simple majority" usually refers to >50%, I think, might cause
> > confusion.)
> >
> > -Greg Slepak
> >
> > --
> > Please do not email me anything that you are not comfortable also sharing
> > with the NSA.
> >
> > On Jun 6, 2017, at 5:56 PM, James Hilliard via bitcoin-dev
> > <bitcoin-dev@lists.linuxfoundation.org> wrote:
> >
> > Due to the proposed calendar(https://segwit2x.github.io/) for the
> > SegWit2x agreement being too slow to activate SegWit mandatory
> > signalling ahead of BIP148 using BIP91 I would like to propose another
> > option that miners can use to prevent a chain split ahead of the Aug
> > 1st BIP148 activation date.
> >
> > The splitprotection soft fork is essentially BIP91 but using BIP8
> > instead of BIP9 with a lower activation threshold and immediate
> > mandatory signalling lock-in. This allows for a majority of miners to
> > activate mandatory SegWit signalling and prevent a potential chain
> > split ahead of BIP148 activation.
> >
> > This BIP allows for miners to respond to market forces quickly ahead
> > of BIP148 activation by signalling for splitprotection. Any miners
> > already running BIP148 should be encouraged to use splitprotection.
> >
> > <pre>
> >  BIP: splitprotection
> >  Layer: Consensus (soft fork)
> >  Title: User Activated Soft Fork Split Protection
> >  Author: James Hilliard <james.hilliard1@gmail.com>
> >  Comments-Summary: No comments yet.
> >  Comments-URI:
> >  Status: Draft
> >  Type: Standards Track
> >  Created: 2017-05-22
> >  License: BSD-3-Clause
> >           CC0-1.0
> > </pre>
> >
> > ==Abstract==
> >
> > This document specifies a coordination mechanism for a simple majority
> > of miners to prevent a chain split ahead of BIP148 activation.
> >
> > ==Definitions==
> >
> > "existing segwit deployment" refer to the BIP9 "segwit" deployment
> > using bit 1, between November 15th 2016 and November 15th 2017 to
> > activate BIP141, BIP143 and BIP147.
> >
> > ==Motivation==
> >
> > The biggest risk of BIP148 is an extended chain split, this BIP
> > provides a way for a simple majority of miners to eliminate that risk.
> >
> > This BIP provides a way for a simple majority of miners to coordinate
> > activation of the existing segwit deployment with less than 95%
> > hashpower before BIP148 activation. Due to time constraints unless
> > immediately deployed BIP91 will likely not be able to enforce
> > mandatory signalling of segwit before the Aug 1st activation of
> > BIP148. This BIP provides a method for rapid miner activation of
> > SegWit mandatory signalling ahead of the BIP148 activation date. Since
> > the primary goal of this BIP is to reduce the chance of an extended
> > chain split as much as possible we activate using a simple miner
> > majority of 65% over a 504 block interval rather than a higher
> > percentage. This BIP also allows miners to signal their intention to
> > run BIP148 in order to prevent a chain split.
> >
> > ==Specification==
> >
> > While this BIP is active, all blocks must set the nVersion header top
> > 3 bits to 001 together with bit field (1<<1) (according to the
> > existing segwit deployment). Blocks that do not signal as required
> > will be rejected.
> >
> > ==Deployment==
> >
> > This BIP will be deployed by "version bits" with a 65%(this can be
> > adjusted if desired) activation threshold BIP9 with the name
> > "splitprotecion" and using bit 2.
> >
> > This BIP starts immediately and is a BIP8 style soft fork since
> > mandatory signalling will start on midnight August 1st 2017 (epoch
> > time 1501545600) regardless of whether or not this BIP has reached its
> > own signalling threshold. This BIP will cease to be active when segwit
> > is locked-in.
> >
> > === Reference implementation ===
> >
> > <pre>
> > // Check if Segregated Witness is Locked In
> > bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
> > Consensus::Params& params)
> > {
> >    LOCK(cs_main);
> >    return (VersionBitsState(pindexPrev, params,
> > Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
> > THRESHOLD_LOCKED_IN);
> > }
> >
> > // SPLITPROTECTION mandatory segwit signalling.
> > if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
> > Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
> > THRESHOLD_LOCKED_IN &&
> >     !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
> > // Segwit is not locked in
> >     !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
> > and is not active.
> > {
> >    bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
> > VERSIONBITS_TOP_BITS;
> >    bool fSegbit = (pindex->nVersion &
> > VersionBitsMask(chainparams.GetConsensus(),
> > Consensus::DEPLOYMENT_SEGWIT)) != 0;
> >    if (!(fVersionBits && fSegbit)) {
> >        return state.DoS(0, error("ConnectBlock(): relayed block must
> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
> >    }
> > }
> >
> > // BIP148 mandatory segwit signalling.
> > int64_t nMedianTimePast = pindex->GetMedianTimePast();
> > if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00 UTC
> >     (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
> >     (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
> > // Segwit is not locked in
> >      !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
> > // and is not active.
> > {
> >    bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
> > VERSIONBITS_TOP_BITS;
> >    bool fSegbit = (pindex->nVersion &
> > VersionBitsMask(chainparams.GetConsensus(),
> > Consensus::DEPLOYMENT_SEGWIT)) != 0;
> >    if (!(fVersionBits && fSegbit)) {
> >        return state.DoS(0, error("ConnectBlock(): relayed block must
> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
> >    }
> > }
> > </pre>
> >
> > https://github.com/bitcoin/bitcoin/compare/0.14...
> jameshilliard:splitprotection-v0.14.1
> >
> > ==Backwards Compatibility==
> >
> > This deployment is compatible with the existing "segwit" bit 1
> > deployment scheduled between midnight November 15th, 2016 and midnight
> > November 15th, 2017. This deployment is also compatible with the
> > existing BIP148 deployment. This BIP is compatible with BIP91 only if
> > BIP91 activates before it and before BIP148. Miners will need to
> > upgrade their nodes to support splitprotection otherwise they may
> > build on top of an invalid block. While this bip is active users
> > should either upgrade to splitprotection or wait for additional
> > confirmations when accepting payments.
> >
> > ==Rationale==
> >
> > Historically we have used IsSuperMajority() to activate soft forks
> > such as BIP66 which has a mandatory signalling requirement for miners
> > once activated, this ensures that miners are aware of new rules being
> > enforced. This technique can be leveraged to lower the signalling
> > threshold of a soft fork while it is in the process of being deployed
> > in a backwards compatible way. We also use a BIP8 style timeout to
> > ensure that this BIP is compatible with BIP148 and that BIP148
> > compatible mandatory signalling activates regardless of miner
> > signalling levels.
> >
> > By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
> > deployment, this BIP can cause the existing "segwit" deployment to
> > activate without needing to release a new deployment. As we approach
> > BIP148 activation it may be desirable for a majority of miners to have
> > a method that will ensure that there is no chain split.
> >
> > ==References==
> >
> > *[https://lists.linuxfoundation.org/pipermail/
> bitcoin-dev/2017-March/013714.html
> > Mailing list discussion]
> > *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.
> cpp#L1281-L1283
> > P2SH flag day activation]
> > *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
> > *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
> > *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
> > *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
> > *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
> > Version 0 Witness Program]]
> > *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element
> malleability]]
> > *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment]]
> > *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
> > *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit
> benefits]
> >
> > ==Copyright==
> >
> > This document is dual licensed as BSD 3-clause, and Creative Commons
> > CC0 1.0 Universal.
> > _______________________________________________
> > bitcoin-dev mailing list
> > bitcoin-dev@lists.linuxfoundation.org
> > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
> >
> >
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>

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Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[Tao Effect]

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See thread on replay attacks for why activating regardless of threshold is a bad idea [1].

BIP91 OTOH seems perfectly reasonable. 80% instead of 95% makes it more difficult for miners to hold together in opposition to Core. It gives Core more leverage in negotiations.

If they don't activate with 80%, Core can release another BIP to reduce it to 75%.

Each threshold reduction makes it both more likely to succeed, but also increases the likelihood of harm to the ecosystem.

Cheers,
Greg

[1] https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-June/014497.html <https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-June/014497.html>

--
Please do not email me anything that you are not comfortable also sharing with the NSA.

> On Jun 6, 2017, at 6:54 PM, James Hilliard <james.hilliard1@gmail.com <mailto:james.hilliard1@gmail.com>> wrote:
> 
> This is a BIP8 style soft fork so mandatory signalling will be active
> after Aug 1st regardless.
> 
> On Tue, Jun 6, 2017 at 8:51 PM, Tao Effect <contact@taoeffect.com <mailto:contact@taoeffect.com>> wrote:
>> What is the probability that a 65% threshold is too low and can allow a
>> "surprise miner attack", whereby miners are kept offline before the
>> deadline, and brought online immediately after, creating potential havoc?
>> 
>> (Nit: "simple majority" usually refers to >50%, I think, might cause
>> confusion.)
>> 
>> -Greg Slepak
>> 
>> --
>> Please do not email me anything that you are not comfortable also sharing
>> with the NSA.
>> 
>> On Jun 6, 2017, at 5:56 PM, James Hilliard via bitcoin-dev
>> <bitcoin-dev@lists.linuxfoundation.org <mailto:bitcoin-dev@lists.linuxfoundation.org>> wrote:
>> 
>> Due to the proposed calendar(https://segwit2x.github.io/ <https://segwit2x.github.io/>) for the
>> SegWit2x agreement being too slow to activate SegWit mandatory
>> signalling ahead of BIP148 using BIP91 I would like to propose another
>> option that miners can use to prevent a chain split ahead of the Aug
>> 1st BIP148 activation date.
>> 
>> The splitprotection soft fork is essentially BIP91 but using BIP8
>> instead of BIP9 with a lower activation threshold and immediate
>> mandatory signalling lock-in. This allows for a majority of miners to
>> activate mandatory SegWit signalling and prevent a potential chain
>> split ahead of BIP148 activation.
>> 
>> This BIP allows for miners to respond to market forces quickly ahead
>> of BIP148 activation by signalling for splitprotection. Any miners
>> already running BIP148 should be encouraged to use splitprotection.
>> 
>> <pre>
>> BIP: splitprotection
>> Layer: Consensus (soft fork)
>> Title: User Activated Soft Fork Split Protection
>> Author: James Hilliard <james.hilliard1@gmail.com <mailto:james.hilliard1@gmail.com>>
>> Comments-Summary: No comments yet.
>> Comments-URI:
>> Status: Draft
>> Type: Standards Track
>> Created: 2017-05-22
>> License: BSD-3-Clause
>>          CC0-1.0
>> </pre>
>> 
>> ==Abstract==
>> 
>> This document specifies a coordination mechanism for a simple majority
>> of miners to prevent a chain split ahead of BIP148 activation.
>> 
>> ==Definitions==
>> 
>> "existing segwit deployment" refer to the BIP9 "segwit" deployment
>> using bit 1, between November 15th 2016 and November 15th 2017 to
>> activate BIP141, BIP143 and BIP147.
>> 
>> ==Motivation==
>> 
>> The biggest risk of BIP148 is an extended chain split, this BIP
>> provides a way for a simple majority of miners to eliminate that risk.
>> 
>> This BIP provides a way for a simple majority of miners to coordinate
>> activation of the existing segwit deployment with less than 95%
>> hashpower before BIP148 activation. Due to time constraints unless
>> immediately deployed BIP91 will likely not be able to enforce
>> mandatory signalling of segwit before the Aug 1st activation of
>> BIP148. This BIP provides a method for rapid miner activation of
>> SegWit mandatory signalling ahead of the BIP148 activation date. Since
>> the primary goal of this BIP is to reduce the chance of an extended
>> chain split as much as possible we activate using a simple miner
>> majority of 65% over a 504 block interval rather than a higher
>> percentage. This BIP also allows miners to signal their intention to
>> run BIP148 in order to prevent a chain split.
>> 
>> ==Specification==
>> 
>> While this BIP is active, all blocks must set the nVersion header top
>> 3 bits to 001 together with bit field (1<<1) (according to the
>> existing segwit deployment). Blocks that do not signal as required
>> will be rejected.
>> 
>> ==Deployment==
>> 
>> This BIP will be deployed by "version bits" with a 65%(this can be
>> adjusted if desired) activation threshold BIP9 with the name
>> "splitprotecion" and using bit 2.
>> 
>> This BIP starts immediately and is a BIP8 style soft fork since
>> mandatory signalling will start on midnight August 1st 2017 (epoch
>> time 1501545600) regardless of whether or not this BIP has reached its
>> own signalling threshold. This BIP will cease to be active when segwit
>> is locked-in.
>> 
>> === Reference implementation ===
>> 
>> <pre>
>> // Check if Segregated Witness is Locked In
>> bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
>> Consensus::Params& params)
>> {
>>   LOCK(cs_main);
>>   return (VersionBitsState(pindexPrev, params,
>> Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
>> THRESHOLD_LOCKED_IN);
>> }
>> 
>> // SPLITPROTECTION mandatory segwit signalling.
>> if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
>> Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
>> THRESHOLD_LOCKED_IN &&
>>    !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>> // Segwit is not locked in
>>    !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
>> and is not active.
>> {
>>   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>> VERSIONBITS_TOP_BITS;
>>   bool fSegbit = (pindex->nVersion &
>> VersionBitsMask(chainparams.GetConsensus(),
>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>   if (!(fVersionBits && fSegbit)) {
>>       return state.DoS(0, error("ConnectBlock(): relayed block must
>> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>   }
>> }
>> 
>> // BIP148 mandatory segwit signalling.
>> int64_t nMedianTimePast = pindex->GetMedianTimePast();
>> if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00 UTC
>>    (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
>>    (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>> // Segwit is not locked in
>>     !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
>> // and is not active.
>> {
>>   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>> VERSIONBITS_TOP_BITS;
>>   bool fSegbit = (pindex->nVersion &
>> VersionBitsMask(chainparams.GetConsensus(),
>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>   if (!(fVersionBits && fSegbit)) {
>>       return state.DoS(0, error("ConnectBlock(): relayed block must
>> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>   }
>> }
>> </pre>
>> 
>> https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1 <https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1>
>> 
>> ==Backwards Compatibility==
>> 
>> This deployment is compatible with the existing "segwit" bit 1
>> deployment scheduled between midnight November 15th, 2016 and midnight
>> November 15th, 2017. This deployment is also compatible with the
>> existing BIP148 deployment. This BIP is compatible with BIP91 only if
>> BIP91 activates before it and before BIP148. Miners will need to
>> upgrade their nodes to support splitprotection otherwise they may
>> build on top of an invalid block. While this bip is active users
>> should either upgrade to splitprotection or wait for additional
>> confirmations when accepting payments.
>> 
>> ==Rationale==
>> 
>> Historically we have used IsSuperMajority() to activate soft forks
>> such as BIP66 which has a mandatory signalling requirement for miners
>> once activated, this ensures that miners are aware of new rules being
>> enforced. This technique can be leveraged to lower the signalling
>> threshold of a soft fork while it is in the process of being deployed
>> in a backwards compatible way. We also use a BIP8 style timeout to
>> ensure that this BIP is compatible with BIP148 and that BIP148
>> compatible mandatory signalling activates regardless of miner
>> signalling levels.
>> 
>> By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
>> deployment, this BIP can cause the existing "segwit" deployment to
>> activate without needing to release a new deployment. As we approach
>> BIP148 activation it may be desirable for a majority of miners to have
>> a method that will ensure that there is no chain split.
>> 
>> ==References==
>> 
>> *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html
>> Mailing list discussion]
>> *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283
>> P2SH flag day activation]
>> *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
>> *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
>> *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
>> *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
>> *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
>> Version 0 Witness Program]]
>> *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element malleability]]
>> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment]]
>> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
>> *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit benefits]
>> 
>> ==Copyright==
>> 
>> This document is dual licensed as BSD 3-clause, and Creative Commons
>> CC0 1.0 Universal.
>> _______________________________________________
>> bitcoin-dev mailing list
>> bitcoin-dev@lists.linuxfoundation.org
>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>> 
>> 


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Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[James Hilliard]

I think even 55% would probably work out fine simply due to incentive
structures, once signalling is over 51% it's then clear to miners that
non-signalling blocks will be orphaned and the rest will rapidly
update to splitprotection/BIP148. The purpose of this BIP is to reduce
chain split risk for BIP148 since it's looking like BIP148 is going to
be run by a non-insignificant percentage of the economy at a minimum.

On Wed, Jun 7, 2017 at 12:20 AM, Tao Effect <contact@taoeffect.com> wrote:
> See thread on replay attacks for why activating regardless of threshold is a
> bad idea [1].
>
> BIP91 OTOH seems perfectly reasonable. 80% instead of 95% makes it more
> difficult for miners to hold together in opposition to Core. It gives Core
> more leverage in negotiations.
>
> If they don't activate with 80%, Core can release another BIP to reduce it
> to 75%.
>
> Each threshold reduction makes it both more likely to succeed, but also
> increases the likelihood of harm to the ecosystem.
>
> Cheers,
> Greg
>
> [1]
> https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-June/014497.html
>
> --
> Please do not email me anything that you are not comfortable also sharing
> with the NSA.
>
> On Jun 6, 2017, at 6:54 PM, James Hilliard <james.hilliard1@gmail.com>
> wrote:
>
> This is a BIP8 style soft fork so mandatory signalling will be active
> after Aug 1st regardless.
>
> On Tue, Jun 6, 2017 at 8:51 PM, Tao Effect <contact@taoeffect.com> wrote:
>
> What is the probability that a 65% threshold is too low and can allow a
> "surprise miner attack", whereby miners are kept offline before the
> deadline, and brought online immediately after, creating potential havoc?
>
> (Nit: "simple majority" usually refers to >50%, I think, might cause
> confusion.)
>
> -Greg Slepak
>
> --
> Please do not email me anything that you are not comfortable also sharing
> with the NSA.
>
> On Jun 6, 2017, at 5:56 PM, James Hilliard via bitcoin-dev
> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>
> Due to the proposed calendar(https://segwit2x.github.io/) for the
> SegWit2x agreement being too slow to activate SegWit mandatory
> signalling ahead of BIP148 using BIP91 I would like to propose another
> option that miners can use to prevent a chain split ahead of the Aug
> 1st BIP148 activation date.
>
> The splitprotection soft fork is essentially BIP91 but using BIP8
> instead of BIP9 with a lower activation threshold and immediate
> mandatory signalling lock-in. This allows for a majority of miners to
> activate mandatory SegWit signalling and prevent a potential chain
> split ahead of BIP148 activation.
>
> This BIP allows for miners to respond to market forces quickly ahead
> of BIP148 activation by signalling for splitprotection. Any miners
> already running BIP148 should be encouraged to use splitprotection.
>
> <pre>
> BIP: splitprotection
> Layer: Consensus (soft fork)
> Title: User Activated Soft Fork Split Protection
> Author: James Hilliard <james.hilliard1@gmail.com>
> Comments-Summary: No comments yet.
> Comments-URI:
> Status: Draft
> Type: Standards Track
> Created: 2017-05-22
> License: BSD-3-Clause
>          CC0-1.0
> </pre>
>
> ==Abstract==
>
> This document specifies a coordination mechanism for a simple majority
> of miners to prevent a chain split ahead of BIP148 activation.
>
> ==Definitions==
>
> "existing segwit deployment" refer to the BIP9 "segwit" deployment
> using bit 1, between November 15th 2016 and November 15th 2017 to
> activate BIP141, BIP143 and BIP147.
>
> ==Motivation==
>
> The biggest risk of BIP148 is an extended chain split, this BIP
> provides a way for a simple majority of miners to eliminate that risk.
>
> This BIP provides a way for a simple majority of miners to coordinate
> activation of the existing segwit deployment with less than 95%
> hashpower before BIP148 activation. Due to time constraints unless
> immediately deployed BIP91 will likely not be able to enforce
> mandatory signalling of segwit before the Aug 1st activation of
> BIP148. This BIP provides a method for rapid miner activation of
> SegWit mandatory signalling ahead of the BIP148 activation date. Since
> the primary goal of this BIP is to reduce the chance of an extended
> chain split as much as possible we activate using a simple miner
> majority of 65% over a 504 block interval rather than a higher
> percentage. This BIP also allows miners to signal their intention to
> run BIP148 in order to prevent a chain split.
>
> ==Specification==
>
> While this BIP is active, all blocks must set the nVersion header top
> 3 bits to 001 together with bit field (1<<1) (according to the
> existing segwit deployment). Blocks that do not signal as required
> will be rejected.
>
> ==Deployment==
>
> This BIP will be deployed by "version bits" with a 65%(this can be
> adjusted if desired) activation threshold BIP9 with the name
> "splitprotecion" and using bit 2.
>
> This BIP starts immediately and is a BIP8 style soft fork since
> mandatory signalling will start on midnight August 1st 2017 (epoch
> time 1501545600) regardless of whether or not this BIP has reached its
> own signalling threshold. This BIP will cease to be active when segwit
> is locked-in.
>
> === Reference implementation ===
>
> <pre>
> // Check if Segregated Witness is Locked In
> bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
> Consensus::Params& params)
> {
>   LOCK(cs_main);
>   return (VersionBitsState(pindexPrev, params,
> Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
> THRESHOLD_LOCKED_IN);
> }
>
> // SPLITPROTECTION mandatory segwit signalling.
> if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
> Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
> THRESHOLD_LOCKED_IN &&
>    !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
> // Segwit is not locked in
>    !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
> and is not active.
> {
>   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
> VERSIONBITS_TOP_BITS;
>   bool fSegbit = (pindex->nVersion &
> VersionBitsMask(chainparams.GetConsensus(),
> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>   if (!(fVersionBits && fSegbit)) {
>       return state.DoS(0, error("ConnectBlock(): relayed block must
> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>   }
> }
>
> // BIP148 mandatory segwit signalling.
> int64_t nMedianTimePast = pindex->GetMedianTimePast();
> if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00 UTC
>    (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
>    (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
> // Segwit is not locked in
>     !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
> // and is not active.
> {
>   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
> VERSIONBITS_TOP_BITS;
>   bool fSegbit = (pindex->nVersion &
> VersionBitsMask(chainparams.GetConsensus(),
> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>   if (!(fVersionBits && fSegbit)) {
>       return state.DoS(0, error("ConnectBlock(): relayed block must
> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>   }
> }
> </pre>
>
> https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1
>
> ==Backwards Compatibility==
>
> This deployment is compatible with the existing "segwit" bit 1
> deployment scheduled between midnight November 15th, 2016 and midnight
> November 15th, 2017. This deployment is also compatible with the
> existing BIP148 deployment. This BIP is compatible with BIP91 only if
> BIP91 activates before it and before BIP148. Miners will need to
> upgrade their nodes to support splitprotection otherwise they may
> build on top of an invalid block. While this bip is active users
> should either upgrade to splitprotection or wait for additional
> confirmations when accepting payments.
>
> ==Rationale==
>
> Historically we have used IsSuperMajority() to activate soft forks
> such as BIP66 which has a mandatory signalling requirement for miners
> once activated, this ensures that miners are aware of new rules being
> enforced. This technique can be leveraged to lower the signalling
> threshold of a soft fork while it is in the process of being deployed
> in a backwards compatible way. We also use a BIP8 style timeout to
> ensure that this BIP is compatible with BIP148 and that BIP148
> compatible mandatory signalling activates regardless of miner
> signalling levels.
>
> By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
> deployment, this BIP can cause the existing "segwit" deployment to
> activate without needing to release a new deployment. As we approach
> BIP148 activation it may be desirable for a majority of miners to have
> a method that will ensure that there is no chain split.
>
> ==References==
>
> *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html
> Mailing list discussion]
> *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283
> P2SH flag day activation]
> *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
> *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
> *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
> *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
> *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
> Version 0 Witness Program]]
> *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element malleability]]
> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment]]
> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
> *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit benefits]
>
> ==Copyright==
>
> This document is dual licensed as BSD 3-clause, and Creative Commons
> CC0 1.0 Universal.
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>
>
>

Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[Erik Aronesty]

[-- Attachment #1: Type: text/plain, Size: 11281 bytes --]

This is, by far, the safest way for miners to quickly defend against a
chain split, much better than a -bip148 option.   This allows miners to
defend themselves, with very little risk, since the defense is only
activated if the majority of miners do so. I would move for a very rapid
deployment.   Only miners would need to upgrade.   Regular users would not
have to concern themselves with this release.

On Wed, Jun 7, 2017 at 6:13 AM, James Hilliard via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> I think even 55% would probably work out fine simply due to incentive
> structures, once signalling is over 51% it's then clear to miners that
> non-signalling blocks will be orphaned and the rest will rapidly
> update to splitprotection/BIP148. The purpose of this BIP is to reduce
> chain split risk for BIP148 since it's looking like BIP148 is going to
> be run by a non-insignificant percentage of the economy at a minimum.
>
> On Wed, Jun 7, 2017 at 12:20 AM, Tao Effect <contact@taoeffect.com> wrote:
> > See thread on replay attacks for why activating regardless of threshold
> is a
> > bad idea [1].
> >
> > BIP91 OTOH seems perfectly reasonable. 80% instead of 95% makes it more
> > difficult for miners to hold together in opposition to Core. It gives
> Core
> > more leverage in negotiations.
> >
> > If they don't activate with 80%, Core can release another BIP to reduce
> it
> > to 75%.
> >
> > Each threshold reduction makes it both more likely to succeed, but also
> > increases the likelihood of harm to the ecosystem.
> >
> > Cheers,
> > Greg
> >
> > [1]
> > https://lists.linuxfoundation.org/pipermail/bitcoin-dev/
> 2017-June/014497.html
> >
> > --
> > Please do not email me anything that you are not comfortable also sharing
> > with the NSA.
> >
> > On Jun 6, 2017, at 6:54 PM, James Hilliard <james.hilliard1@gmail.com>
> > wrote:
> >
> > This is a BIP8 style soft fork so mandatory signalling will be active
> > after Aug 1st regardless.
> >
> > On Tue, Jun 6, 2017 at 8:51 PM, Tao Effect <contact@taoeffect.com>
> wrote:
> >
> > What is the probability that a 65% threshold is too low and can allow a
> > "surprise miner attack", whereby miners are kept offline before the
> > deadline, and brought online immediately after, creating potential havoc?
> >
> > (Nit: "simple majority" usually refers to >50%, I think, might cause
> > confusion.)
> >
> > -Greg Slepak
> >
> > --
> > Please do not email me anything that you are not comfortable also sharing
> > with the NSA.
> >
> > On Jun 6, 2017, at 5:56 PM, James Hilliard via bitcoin-dev
> > <bitcoin-dev@lists.linuxfoundation.org> wrote:
> >
> > Due to the proposed calendar(https://segwit2x.github.io/) for the
> > SegWit2x agreement being too slow to activate SegWit mandatory
> > signalling ahead of BIP148 using BIP91 I would like to propose another
> > option that miners can use to prevent a chain split ahead of the Aug
> > 1st BIP148 activation date.
> >
> > The splitprotection soft fork is essentially BIP91 but using BIP8
> > instead of BIP9 with a lower activation threshold and immediate
> > mandatory signalling lock-in. This allows for a majority of miners to
> > activate mandatory SegWit signalling and prevent a potential chain
> > split ahead of BIP148 activation.
> >
> > This BIP allows for miners to respond to market forces quickly ahead
> > of BIP148 activation by signalling for splitprotection. Any miners
> > already running BIP148 should be encouraged to use splitprotection.
> >
> > <pre>
> > BIP: splitprotection
> > Layer: Consensus (soft fork)
> > Title: User Activated Soft Fork Split Protection
> > Author: James Hilliard <james.hilliard1@gmail.com>
> > Comments-Summary: No comments yet.
> > Comments-URI:
> > Status: Draft
> > Type: Standards Track
> > Created: 2017-05-22
> > License: BSD-3-Clause
> >          CC0-1.0
> > </pre>
> >
> > ==Abstract==
> >
> > This document specifies a coordination mechanism for a simple majority
> > of miners to prevent a chain split ahead of BIP148 activation.
> >
> > ==Definitions==
> >
> > "existing segwit deployment" refer to the BIP9 "segwit" deployment
> > using bit 1, between November 15th 2016 and November 15th 2017 to
> > activate BIP141, BIP143 and BIP147.
> >
> > ==Motivation==
> >
> > The biggest risk of BIP148 is an extended chain split, this BIP
> > provides a way for a simple majority of miners to eliminate that risk.
> >
> > This BIP provides a way for a simple majority of miners to coordinate
> > activation of the existing segwit deployment with less than 95%
> > hashpower before BIP148 activation. Due to time constraints unless
> > immediately deployed BIP91 will likely not be able to enforce
> > mandatory signalling of segwit before the Aug 1st activation of
> > BIP148. This BIP provides a method for rapid miner activation of
> > SegWit mandatory signalling ahead of the BIP148 activation date. Since
> > the primary goal of this BIP is to reduce the chance of an extended
> > chain split as much as possible we activate using a simple miner
> > majority of 65% over a 504 block interval rather than a higher
> > percentage. This BIP also allows miners to signal their intention to
> > run BIP148 in order to prevent a chain split.
> >
> > ==Specification==
> >
> > While this BIP is active, all blocks must set the nVersion header top
> > 3 bits to 001 together with bit field (1<<1) (according to the
> > existing segwit deployment). Blocks that do not signal as required
> > will be rejected.
> >
> > ==Deployment==
> >
> > This BIP will be deployed by "version bits" with a 65%(this can be
> > adjusted if desired) activation threshold BIP9 with the name
> > "splitprotecion" and using bit 2.
> >
> > This BIP starts immediately and is a BIP8 style soft fork since
> > mandatory signalling will start on midnight August 1st 2017 (epoch
> > time 1501545600) regardless of whether or not this BIP has reached its
> > own signalling threshold. This BIP will cease to be active when segwit
> > is locked-in.
> >
> > === Reference implementation ===
> >
> > <pre>
> > // Check if Segregated Witness is Locked In
> > bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
> > Consensus::Params& params)
> > {
> >   LOCK(cs_main);
> >   return (VersionBitsState(pindexPrev, params,
> > Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
> > THRESHOLD_LOCKED_IN);
> > }
> >
> > // SPLITPROTECTION mandatory segwit signalling.
> > if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
> > Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
> > THRESHOLD_LOCKED_IN &&
> >    !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
> > // Segwit is not locked in
> >    !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
> > and is not active.
> > {
> >   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
> > VERSIONBITS_TOP_BITS;
> >   bool fSegbit = (pindex->nVersion &
> > VersionBitsMask(chainparams.GetConsensus(),
> > Consensus::DEPLOYMENT_SEGWIT)) != 0;
> >   if (!(fVersionBits && fSegbit)) {
> >       return state.DoS(0, error("ConnectBlock(): relayed block must
> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
> >   }
> > }
> >
> > // BIP148 mandatory segwit signalling.
> > int64_t nMedianTimePast = pindex->GetMedianTimePast();
> > if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00 UTC
> >    (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
> >    (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
> > // Segwit is not locked in
> >     !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
> > // and is not active.
> > {
> >   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
> > VERSIONBITS_TOP_BITS;
> >   bool fSegbit = (pindex->nVersion &
> > VersionBitsMask(chainparams.GetConsensus(),
> > Consensus::DEPLOYMENT_SEGWIT)) != 0;
> >   if (!(fVersionBits && fSegbit)) {
> >       return state.DoS(0, error("ConnectBlock(): relayed block must
> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
> >   }
> > }
> > </pre>
> >
> > https://github.com/bitcoin/bitcoin/compare/0.14...
> jameshilliard:splitprotection-v0.14.1
> >
> > ==Backwards Compatibility==
> >
> > This deployment is compatible with the existing "segwit" bit 1
> > deployment scheduled between midnight November 15th, 2016 and midnight
> > November 15th, 2017. This deployment is also compatible with the
> > existing BIP148 deployment. This BIP is compatible with BIP91 only if
> > BIP91 activates before it and before BIP148. Miners will need to
> > upgrade their nodes to support splitprotection otherwise they may
> > build on top of an invalid block. While this bip is active users
> > should either upgrade to splitprotection or wait for additional
> > confirmations when accepting payments.
> >
> > ==Rationale==
> >
> > Historically we have used IsSuperMajority() to activate soft forks
> > such as BIP66 which has a mandatory signalling requirement for miners
> > once activated, this ensures that miners are aware of new rules being
> > enforced. This technique can be leveraged to lower the signalling
> > threshold of a soft fork while it is in the process of being deployed
> > in a backwards compatible way. We also use a BIP8 style timeout to
> > ensure that this BIP is compatible with BIP148 and that BIP148
> > compatible mandatory signalling activates regardless of miner
> > signalling levels.
> >
> > By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
> > deployment, this BIP can cause the existing "segwit" deployment to
> > activate without needing to release a new deployment. As we approach
> > BIP148 activation it may be desirable for a majority of miners to have
> > a method that will ensure that there is no chain split.
> >
> > ==References==
> >
> > *[https://lists.linuxfoundation.org/pipermail/
> bitcoin-dev/2017-March/013714.html
> > Mailing list discussion]
> > *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.
> cpp#L1281-L1283
> > P2SH flag day activation]
> > *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
> > *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
> > *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
> > *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
> > *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
> > Version 0 Witness Program]]
> > *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element
> malleability]]
> > *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment]]
> > *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
> > *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit
> benefits]
> >
> > ==Copyright==
> >
> > This document is dual licensed as BSD 3-clause, and Creative Commons
> > CC0 1.0 Universal.
> > _______________________________________________
> > bitcoin-dev mailing list
> > bitcoin-dev@lists.linuxfoundation.org
> > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
> >
> >
> >
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>

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Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[Jacob Eliosoff]

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This is not the safest defense against a split.  If 70% of miners run
"splitprotection", and 0.1% run BIP148, there's no "safety"/"defense"
reason for splitprotection to activate segwit.  It should only do so if
*BIP148* support (NB: not just segwit support!) >50%.

The truly defensive logic is "If the majority supports orphaning non-segwit
blocks starting Aug 1, I'll join them."

If the real goal of this BIP is to induce miners to run segwit, then fair
enough.  But passing it off as the safest defense is bad faith.


On Wed, Jun 7, 2017 at 10:10 AM, Erik Aronesty via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> This is, by far, the safest way for miners to quickly defend against a
> chain split, much better than a -bip148 option.   This allows miners to
> defend themselves, with very little risk, since the defense is only
> activated if the majority of miners do so. I would move for a very rapid
> deployment.   Only miners would need to upgrade.   Regular users would not
> have to concern themselves with this release.
>
> On Wed, Jun 7, 2017 at 6:13 AM, James Hilliard via bitcoin-dev <
> bitcoin-dev@lists.linuxfoundation.org> wrote:
>
>> I think even 55% would probably work out fine simply due to incentive
>> structures, once signalling is over 51% it's then clear to miners that
>> non-signalling blocks will be orphaned and the rest will rapidly
>> update to splitprotection/BIP148. The purpose of this BIP is to reduce
>> chain split risk for BIP148 since it's looking like BIP148 is going to
>> be run by a non-insignificant percentage of the economy at a minimum.
>>
>> On Wed, Jun 7, 2017 at 12:20 AM, Tao Effect <contact@taoeffect.com>
>> wrote:
>> > See thread on replay attacks for why activating regardless of threshold
>> is a
>> > bad idea [1].
>> >
>> > BIP91 OTOH seems perfectly reasonable. 80% instead of 95% makes it more
>> > difficult for miners to hold together in opposition to Core. It gives
>> Core
>> > more leverage in negotiations.
>> >
>> > If they don't activate with 80%, Core can release another BIP to reduce
>> it
>> > to 75%.
>> >
>> > Each threshold reduction makes it both more likely to succeed, but also
>> > increases the likelihood of harm to the ecosystem.
>> >
>> > Cheers,
>> > Greg
>> >
>> > [1]
>> > https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017
>> -June/014497.html
>> >
>> > --
>> > Please do not email me anything that you are not comfortable also
>> sharing
>> > with the NSA.
>> >
>> > On Jun 6, 2017, at 6:54 PM, James Hilliard <james.hilliard1@gmail.com>
>> > wrote:
>> >
>> > This is a BIP8 style soft fork so mandatory signalling will be active
>> > after Aug 1st regardless.
>> >
>> > On Tue, Jun 6, 2017 at 8:51 PM, Tao Effect <contact@taoeffect.com>
>> wrote:
>> >
>> > What is the probability that a 65% threshold is too low and can allow a
>> > "surprise miner attack", whereby miners are kept offline before the
>> > deadline, and brought online immediately after, creating potential
>> havoc?
>> >
>> > (Nit: "simple majority" usually refers to >50%, I think, might cause
>> > confusion.)
>> >
>> > -Greg Slepak
>> >
>> > --
>> > Please do not email me anything that you are not comfortable also
>> sharing
>> > with the NSA.
>> >
>> > On Jun 6, 2017, at 5:56 PM, James Hilliard via bitcoin-dev
>> > <bitcoin-dev@lists.linuxfoundation.org> wrote:
>> >
>> > Due to the proposed calendar(https://segwit2x.github.io/) for the
>> > SegWit2x agreement being too slow to activate SegWit mandatory
>> > signalling ahead of BIP148 using BIP91 I would like to propose another
>> > option that miners can use to prevent a chain split ahead of the Aug
>> > 1st BIP148 activation date.
>> >
>> > The splitprotection soft fork is essentially BIP91 but using BIP8
>> > instead of BIP9 with a lower activation threshold and immediate
>> > mandatory signalling lock-in. This allows for a majority of miners to
>> > activate mandatory SegWit signalling and prevent a potential chain
>> > split ahead of BIP148 activation.
>> >
>> > This BIP allows for miners to respond to market forces quickly ahead
>> > of BIP148 activation by signalling for splitprotection. Any miners
>> > already running BIP148 should be encouraged to use splitprotection.
>> >
>> > <pre>
>> > BIP: splitprotection
>> > Layer: Consensus (soft fork)
>> > Title: User Activated Soft Fork Split Protection
>> > Author: James Hilliard <james.hilliard1@gmail.com>
>> > Comments-Summary: No comments yet.
>> > Comments-URI:
>> > Status: Draft
>> > Type: Standards Track
>> > Created: 2017-05-22
>> > License: BSD-3-Clause
>> >          CC0-1.0
>> > </pre>
>> >
>> > ==Abstract==
>> >
>> > This document specifies a coordination mechanism for a simple majority
>> > of miners to prevent a chain split ahead of BIP148 activation.
>> >
>> > ==Definitions==
>> >
>> > "existing segwit deployment" refer to the BIP9 "segwit" deployment
>> > using bit 1, between November 15th 2016 and November 15th 2017 to
>> > activate BIP141, BIP143 and BIP147.
>> >
>> > ==Motivation==
>> >
>> > The biggest risk of BIP148 is an extended chain split, this BIP
>> > provides a way for a simple majority of miners to eliminate that risk.
>> >
>> > This BIP provides a way for a simple majority of miners to coordinate
>> > activation of the existing segwit deployment with less than 95%
>> > hashpower before BIP148 activation. Due to time constraints unless
>> > immediately deployed BIP91 will likely not be able to enforce
>> > mandatory signalling of segwit before the Aug 1st activation of
>> > BIP148. This BIP provides a method for rapid miner activation of
>> > SegWit mandatory signalling ahead of the BIP148 activation date. Since
>> > the primary goal of this BIP is to reduce the chance of an extended
>> > chain split as much as possible we activate using a simple miner
>> > majority of 65% over a 504 block interval rather than a higher
>> > percentage. This BIP also allows miners to signal their intention to
>> > run BIP148 in order to prevent a chain split.
>> >
>> > ==Specification==
>> >
>> > While this BIP is active, all blocks must set the nVersion header top
>> > 3 bits to 001 together with bit field (1<<1) (according to the
>> > existing segwit deployment). Blocks that do not signal as required
>> > will be rejected.
>> >
>> > ==Deployment==
>> >
>> > This BIP will be deployed by "version bits" with a 65%(this can be
>> > adjusted if desired) activation threshold BIP9 with the name
>> > "splitprotecion" and using bit 2.
>> >
>> > This BIP starts immediately and is a BIP8 style soft fork since
>> > mandatory signalling will start on midnight August 1st 2017 (epoch
>> > time 1501545600) regardless of whether or not this BIP has reached its
>> > own signalling threshold. This BIP will cease to be active when segwit
>> > is locked-in.
>> >
>> > === Reference implementation ===
>> >
>> > <pre>
>> > // Check if Segregated Witness is Locked In
>> > bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
>> > Consensus::Params& params)
>> > {
>> >   LOCK(cs_main);
>> >   return (VersionBitsState(pindexPrev, params,
>> > Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
>> > THRESHOLD_LOCKED_IN);
>> > }
>> >
>> > // SPLITPROTECTION mandatory segwit signalling.
>> > if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
>> > Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
>> > THRESHOLD_LOCKED_IN &&
>> >    !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>> > // Segwit is not locked in
>> >    !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
>> > and is not active.
>> > {
>> >   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>> > VERSIONBITS_TOP_BITS;
>> >   bool fSegbit = (pindex->nVersion &
>> > VersionBitsMask(chainparams.GetConsensus(),
>> > Consensus::DEPLOYMENT_SEGWIT)) != 0;
>> >   if (!(fVersionBits && fSegbit)) {
>> >       return state.DoS(0, error("ConnectBlock(): relayed block must
>> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>> >   }
>> > }
>> >
>> > // BIP148 mandatory segwit signalling.
>> > int64_t nMedianTimePast = pindex->GetMedianTimePast();
>> > if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00 UTC
>> >    (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
>> >    (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>> > // Segwit is not locked in
>> >     !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
>> > // and is not active.
>> > {
>> >   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>> > VERSIONBITS_TOP_BITS;
>> >   bool fSegbit = (pindex->nVersion &
>> > VersionBitsMask(chainparams.GetConsensus(),
>> > Consensus::DEPLOYMENT_SEGWIT)) != 0;
>> >   if (!(fVersionBits && fSegbit)) {
>> >       return state.DoS(0, error("ConnectBlock(): relayed block must
>> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>> >   }
>> > }
>> > </pre>
>> >
>> > https://github.com/bitcoin/bitcoin/compare/0.14...jameshilli
>> ard:splitprotection-v0.14.1
>> >
>> > ==Backwards Compatibility==
>> >
>> > This deployment is compatible with the existing "segwit" bit 1
>> > deployment scheduled between midnight November 15th, 2016 and midnight
>> > November 15th, 2017. This deployment is also compatible with the
>> > existing BIP148 deployment. This BIP is compatible with BIP91 only if
>> > BIP91 activates before it and before BIP148. Miners will need to
>> > upgrade their nodes to support splitprotection otherwise they may
>> > build on top of an invalid block. While this bip is active users
>> > should either upgrade to splitprotection or wait for additional
>> > confirmations when accepting payments.
>> >
>> > ==Rationale==
>> >
>> > Historically we have used IsSuperMajority() to activate soft forks
>> > such as BIP66 which has a mandatory signalling requirement for miners
>> > once activated, this ensures that miners are aware of new rules being
>> > enforced. This technique can be leveraged to lower the signalling
>> > threshold of a soft fork while it is in the process of being deployed
>> > in a backwards compatible way. We also use a BIP8 style timeout to
>> > ensure that this BIP is compatible with BIP148 and that BIP148
>> > compatible mandatory signalling activates regardless of miner
>> > signalling levels.
>> >
>> > By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
>> > deployment, this BIP can cause the existing "segwit" deployment to
>> > activate without needing to release a new deployment. As we approach
>> > BIP148 activation it may be desirable for a majority of miners to have
>> > a method that will ensure that there is no chain split.
>> >
>> > ==References==
>> >
>> > *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/
>> 2017-March/013714.html
>> > Mailing list discussion]
>> > *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cp
>> p#L1281-L1283
>> > P2SH flag day activation]
>> > *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
>> > *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
>> > *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
>> > *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
>> > *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
>> > Version 0 Witness Program]]
>> > *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element
>> malleability]]
>> > *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment]]
>> > *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
>> > *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit
>> benefits]
>> >
>> > ==Copyright==
>> >
>> > This document is dual licensed as BSD 3-clause, and Creative Commons
>> > CC0 1.0 Universal.
>> > _______________________________________________
>> > bitcoin-dev mailing list
>> > bitcoin-dev@lists.linuxfoundation.org
>> > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>> >
>> >
>> >
>> _______________________________________________
>> bitcoin-dev mailing list
>> bitcoin-dev@lists.linuxfoundation.org
>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>
>
>
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>
>

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Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[Erik Aronesty]

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> But passing it off as the safest defense is bad faith.

Without this option, a miner has to guess whether a split will be
economically impacting.   With this option, his miner will automatically
switch to the chain least likely to get wiped out... as soon as a simple
majority of miners supports it.


On Wed, Jun 7, 2017 at 12:44 PM, Jacob Eliosoff <jacob.eliosoff@gmail.com>
wrote:

> This is not the safest defense against a split.  If 70% of miners run
> "splitprotection", and 0.1% run BIP148, there's no "safety"/"defense"
> reason for splitprotection to activate segwit.  It should only do so if
> *BIP148* support (NB: not just segwit support!) >50%.
>
> The truly defensive logic is "If the majority supports orphaning
> non-segwit blocks starting Aug 1, I'll join them."
>
> If the real goal of this BIP is to induce miners to run segwit, then fair
> enough.  But passing it off as the safest defense is bad faith.
>
>
> On Wed, Jun 7, 2017 at 10:10 AM, Erik Aronesty via bitcoin-dev <
> bitcoin-dev@lists.linuxfoundation.org> wrote:
>
>> This is, by far, the safest way for miners to quickly defend against a
>> chain split, much better than a -bip148 option.   This allows miners to
>> defend themselves, with very little risk, since the defense is only
>> activated if the majority of miners do so. I would move for a very rapid
>> deployment.   Only miners would need to upgrade.   Regular users would not
>> have to concern themselves with this release.
>>
>> On Wed, Jun 7, 2017 at 6:13 AM, James Hilliard via bitcoin-dev <
>> bitcoin-dev@lists.linuxfoundation.org> wrote:
>>
>>> I think even 55% would probably work out fine simply due to incentive
>>> structures, once signalling is over 51% it's then clear to miners that
>>> non-signalling blocks will be orphaned and the rest will rapidly
>>> update to splitprotection/BIP148. The purpose of this BIP is to reduce
>>> chain split risk for BIP148 since it's looking like BIP148 is going to
>>> be run by a non-insignificant percentage of the economy at a minimum.
>>>
>>> On Wed, Jun 7, 2017 at 12:20 AM, Tao Effect <contact@taoeffect.com>
>>> wrote:
>>> > See thread on replay attacks for why activating regardless of
>>> threshold is a
>>> > bad idea [1].
>>> >
>>> > BIP91 OTOH seems perfectly reasonable. 80% instead of 95% makes it more
>>> > difficult for miners to hold together in opposition to Core. It gives
>>> Core
>>> > more leverage in negotiations.
>>> >
>>> > If they don't activate with 80%, Core can release another BIP to
>>> reduce it
>>> > to 75%.
>>> >
>>> > Each threshold reduction makes it both more likely to succeed, but also
>>> > increases the likelihood of harm to the ecosystem.
>>> >
>>> > Cheers,
>>> > Greg
>>> >
>>> > [1]
>>> > https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017
>>> -June/014497.html
>>> >
>>> > --
>>> > Please do not email me anything that you are not comfortable also
>>> sharing
>>> > with the NSA.
>>> >
>>> > On Jun 6, 2017, at 6:54 PM, James Hilliard <james.hilliard1@gmail.com>
>>> > wrote:
>>> >
>>> > This is a BIP8 style soft fork so mandatory signalling will be active
>>> > after Aug 1st regardless.
>>> >
>>> > On Tue, Jun 6, 2017 at 8:51 PM, Tao Effect <contact@taoeffect.com>
>>> wrote:
>>> >
>>> > What is the probability that a 65% threshold is too low and can allow a
>>> > "surprise miner attack", whereby miners are kept offline before the
>>> > deadline, and brought online immediately after, creating potential
>>> havoc?
>>> >
>>> > (Nit: "simple majority" usually refers to >50%, I think, might cause
>>> > confusion.)
>>> >
>>> > -Greg Slepak
>>> >
>>> > --
>>> > Please do not email me anything that you are not comfortable also
>>> sharing
>>> > with the NSA.
>>> >
>>> > On Jun 6, 2017, at 5:56 PM, James Hilliard via bitcoin-dev
>>> > <bitcoin-dev@lists.linuxfoundation.org> wrote:
>>> >
>>> > Due to the proposed calendar(https://segwit2x.github.io/) for the
>>> > SegWit2x agreement being too slow to activate SegWit mandatory
>>> > signalling ahead of BIP148 using BIP91 I would like to propose another
>>> > option that miners can use to prevent a chain split ahead of the Aug
>>> > 1st BIP148 activation date.
>>> >
>>> > The splitprotection soft fork is essentially BIP91 but using BIP8
>>> > instead of BIP9 with a lower activation threshold and immediate
>>> > mandatory signalling lock-in. This allows for a majority of miners to
>>> > activate mandatory SegWit signalling and prevent a potential chain
>>> > split ahead of BIP148 activation.
>>> >
>>> > This BIP allows for miners to respond to market forces quickly ahead
>>> > of BIP148 activation by signalling for splitprotection. Any miners
>>> > already running BIP148 should be encouraged to use splitprotection.
>>> >
>>> > <pre>
>>> > BIP: splitprotection
>>> > Layer: Consensus (soft fork)
>>> > Title: User Activated Soft Fork Split Protection
>>> > Author: James Hilliard <james.hilliard1@gmail.com>
>>> > Comments-Summary: No comments yet.
>>> > Comments-URI:
>>> > Status: Draft
>>> > Type: Standards Track
>>> > Created: 2017-05-22
>>> > License: BSD-3-Clause
>>> >          CC0-1.0
>>> > </pre>
>>> >
>>> > ==Abstract==
>>> >
>>> > This document specifies a coordination mechanism for a simple majority
>>> > of miners to prevent a chain split ahead of BIP148 activation.
>>> >
>>> > ==Definitions==
>>> >
>>> > "existing segwit deployment" refer to the BIP9 "segwit" deployment
>>> > using bit 1, between November 15th 2016 and November 15th 2017 to
>>> > activate BIP141, BIP143 and BIP147.
>>> >
>>> > ==Motivation==
>>> >
>>> > The biggest risk of BIP148 is an extended chain split, this BIP
>>> > provides a way for a simple majority of miners to eliminate that risk.
>>> >
>>> > This BIP provides a way for a simple majority of miners to coordinate
>>> > activation of the existing segwit deployment with less than 95%
>>> > hashpower before BIP148 activation. Due to time constraints unless
>>> > immediately deployed BIP91 will likely not be able to enforce
>>> > mandatory signalling of segwit before the Aug 1st activation of
>>> > BIP148. This BIP provides a method for rapid miner activation of
>>> > SegWit mandatory signalling ahead of the BIP148 activation date. Since
>>> > the primary goal of this BIP is to reduce the chance of an extended
>>> > chain split as much as possible we activate using a simple miner
>>> > majority of 65% over a 504 block interval rather than a higher
>>> > percentage. This BIP also allows miners to signal their intention to
>>> > run BIP148 in order to prevent a chain split.
>>> >
>>> > ==Specification==
>>> >
>>> > While this BIP is active, all blocks must set the nVersion header top
>>> > 3 bits to 001 together with bit field (1<<1) (according to the
>>> > existing segwit deployment). Blocks that do not signal as required
>>> > will be rejected.
>>> >
>>> > ==Deployment==
>>> >
>>> > This BIP will be deployed by "version bits" with a 65%(this can be
>>> > adjusted if desired) activation threshold BIP9 with the name
>>> > "splitprotecion" and using bit 2.
>>> >
>>> > This BIP starts immediately and is a BIP8 style soft fork since
>>> > mandatory signalling will start on midnight August 1st 2017 (epoch
>>> > time 1501545600) regardless of whether or not this BIP has reached its
>>> > own signalling threshold. This BIP will cease to be active when segwit
>>> > is locked-in.
>>> >
>>> > === Reference implementation ===
>>> >
>>> > <pre>
>>> > // Check if Segregated Witness is Locked In
>>> > bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
>>> > Consensus::Params& params)
>>> > {
>>> >   LOCK(cs_main);
>>> >   return (VersionBitsState(pindexPrev, params,
>>> > Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
>>> > THRESHOLD_LOCKED_IN);
>>> > }
>>> >
>>> > // SPLITPROTECTION mandatory segwit signalling.
>>> > if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
>>> > Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
>>> > THRESHOLD_LOCKED_IN &&
>>> >    !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>>> > // Segwit is not locked in
>>> >    !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
>>> > and is not active.
>>> > {
>>> >   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>>> > VERSIONBITS_TOP_BITS;
>>> >   bool fSegbit = (pindex->nVersion &
>>> > VersionBitsMask(chainparams.GetConsensus(),
>>> > Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>> >   if (!(fVersionBits && fSegbit)) {
>>> >       return state.DoS(0, error("ConnectBlock(): relayed block must
>>> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>> >   }
>>> > }
>>> >
>>> > // BIP148 mandatory segwit signalling.
>>> > int64_t nMedianTimePast = pindex->GetMedianTimePast();
>>> > if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00
>>> UTC
>>> >    (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
>>> >    (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>>> > // Segwit is not locked in
>>> >     !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
>>> > // and is not active.
>>> > {
>>> >   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>>> > VERSIONBITS_TOP_BITS;
>>> >   bool fSegbit = (pindex->nVersion &
>>> > VersionBitsMask(chainparams.GetConsensus(),
>>> > Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>> >   if (!(fVersionBits && fSegbit)) {
>>> >       return state.DoS(0, error("ConnectBlock(): relayed block must
>>> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>> >   }
>>> > }
>>> > </pre>
>>> >
>>> > https://github.com/bitcoin/bitcoin/compare/0.14...jameshilli
>>> ard:splitprotection-v0.14.1
>>> >
>>> > ==Backwards Compatibility==
>>> >
>>> > This deployment is compatible with the existing "segwit" bit 1
>>> > deployment scheduled between midnight November 15th, 2016 and midnight
>>> > November 15th, 2017. This deployment is also compatible with the
>>> > existing BIP148 deployment. This BIP is compatible with BIP91 only if
>>> > BIP91 activates before it and before BIP148. Miners will need to
>>> > upgrade their nodes to support splitprotection otherwise they may
>>> > build on top of an invalid block. While this bip is active users
>>> > should either upgrade to splitprotection or wait for additional
>>> > confirmations when accepting payments.
>>> >
>>> > ==Rationale==
>>> >
>>> > Historically we have used IsSuperMajority() to activate soft forks
>>> > such as BIP66 which has a mandatory signalling requirement for miners
>>> > once activated, this ensures that miners are aware of new rules being
>>> > enforced. This technique can be leveraged to lower the signalling
>>> > threshold of a soft fork while it is in the process of being deployed
>>> > in a backwards compatible way. We also use a BIP8 style timeout to
>>> > ensure that this BIP is compatible with BIP148 and that BIP148
>>> > compatible mandatory signalling activates regardless of miner
>>> > signalling levels.
>>> >
>>> > By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
>>> > deployment, this BIP can cause the existing "segwit" deployment to
>>> > activate without needing to release a new deployment. As we approach
>>> > BIP148 activation it may be desirable for a majority of miners to have
>>> > a method that will ensure that there is no chain split.
>>> >
>>> > ==References==
>>> >
>>> > *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/20
>>> 17-March/013714.html
>>> > Mailing list discussion]
>>> > *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cp
>>> p#L1281-L1283
>>> > P2SH flag day activation]
>>> > *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
>>> > *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
>>> > *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
>>> > *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
>>> > *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
>>> > Version 0 Witness Program]]
>>> > *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element
>>> malleability]]
>>> > *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit
>>> deployment]]
>>> > *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
>>> > *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit
>>> benefits]
>>> >
>>> > ==Copyright==
>>> >
>>> > This document is dual licensed as BSD 3-clause, and Creative Commons
>>> > CC0 1.0 Universal.
>>> > _______________________________________________
>>> > bitcoin-dev mailing list
>>> > bitcoin-dev@lists.linuxfoundation.org
>>> > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>> >
>>> >
>>> >
>>> _______________________________________________
>>> bitcoin-dev mailing list
>>> bitcoin-dev@lists.linuxfoundation.org
>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>>
>>
>>
>> _______________________________________________
>> bitcoin-dev mailing list
>> bitcoin-dev@lists.linuxfoundation.org
>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>
>>
>

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Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[Jacob Eliosoff]

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You're missing my point.  "As soon as a simple majority supports it" - what
is "it"?  BIP148?  Or "deferring to the miner consensus on BIP148"?  It's
the difference between supporting one side of a vote, vs supporting
deferral to the outcome of the vote.

Or if you mean, the safe thing for miners is to orphan non-segwit blocks
Aug 1 *regardless* of the miner consensus (since the economic consensus
might differ), then there's zero need for this BIP: they should just run
BIP148.

As I said: this BIP should be corrected to only orphan if >50% signal for
BIP148.  Or, define two bits, one meaning "I support BIP148," the other "I
will go w/ the miner majority on BIP148."  Fudging them this way is
deceptive.


On Jun 7, 2017 2:05 PM, "Erik Aronesty" <erik@q32.com> wrote:

> But passing it off as the safest defense is bad faith.

Without this option, a miner has to guess whether a split will be
economically impacting.   With this option, his miner will automatically
switch to the chain least likely to get wiped out... as soon as a simple
majority of miners supports it.


On Wed, Jun 7, 2017 at 12:44 PM, Jacob Eliosoff <jacob.eliosoff@gmail.com>
wrote:

> This is not the safest defense against a split.  If 70% of miners run
> "splitprotection", and 0.1% run BIP148, there's no "safety"/"defense"
> reason for splitprotection to activate segwit.  It should only do so if
> *BIP148* support (NB: not just segwit support!) >50%.
>
> The truly defensive logic is "If the majority supports orphaning
> non-segwit blocks starting Aug 1, I'll join them."
>
> If the real goal of this BIP is to induce miners to run segwit, then fair
> enough.  But passing it off as the safest defense is bad faith.
>
>
> On Wed, Jun 7, 2017 at 10:10 AM, Erik Aronesty via bitcoin-dev <
> bitcoin-dev@lists.linuxfoundation.org> wrote:
>
>> This is, by far, the safest way for miners to quickly defend against a
>> chain split, much better than a -bip148 option.   This allows miners to
>> defend themselves, with very little risk, since the defense is only
>> activated if the majority of miners do so. I would move for a very rapid
>> deployment.   Only miners would need to upgrade.   Regular users would not
>> have to concern themselves with this release.
>>
>> On Wed, Jun 7, 2017 at 6:13 AM, James Hilliard via bitcoin-dev <
>> bitcoin-dev@lists.linuxfoundation.org> wrote:
>>
>>> I think even 55% would probably work out fine simply due to incentive
>>> structures, once signalling is over 51% it's then clear to miners that
>>> non-signalling blocks will be orphaned and the rest will rapidly
>>> update to splitprotection/BIP148. The purpose of this BIP is to reduce
>>> chain split risk for BIP148 since it's looking like BIP148 is going to
>>> be run by a non-insignificant percentage of the economy at a minimum.
>>>
>>> On Wed, Jun 7, 2017 at 12:20 AM, Tao Effect <contact@taoeffect.com>
>>> wrote:
>>> > See thread on replay attacks for why activating regardless of
>>> threshold is a
>>> > bad idea [1].
>>> >
>>> > BIP91 OTOH seems perfectly reasonable. 80% instead of 95% makes it more
>>> > difficult for miners to hold together in opposition to Core. It gives
>>> Core
>>> > more leverage in negotiations.
>>> >
>>> > If they don't activate with 80%, Core can release another BIP to
>>> reduce it
>>> > to 75%.
>>> >
>>> > Each threshold reduction makes it both more likely to succeed, but also
>>> > increases the likelihood of harm to the ecosystem.
>>> >
>>> > Cheers,
>>> > Greg
>>> >
>>> > [1]
>>> > https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017
>>> -June/014497.html
>>> >
>>> > --
>>> > Please do not email me anything that you are not comfortable also
>>> sharing
>>> > with the NSA.
>>> >
>>> > On Jun 6, 2017, at 6:54 PM, James Hilliard <james.hilliard1@gmail.com>
>>> > wrote:
>>> >
>>> > This is a BIP8 style soft fork so mandatory signalling will be active
>>> > after Aug 1st regardless.
>>> >
>>> > On Tue, Jun 6, 2017 at 8:51 PM, Tao Effect <contact@taoeffect.com>
>>> wrote:
>>> >
>>> > What is the probability that a 65% threshold is too low and can allow a
>>> > "surprise miner attack", whereby miners are kept offline before the
>>> > deadline, and brought online immediately after, creating potential
>>> havoc?
>>> >
>>> > (Nit: "simple majority" usually refers to >50%, I think, might cause
>>> > confusion.)
>>> >
>>> > -Greg Slepak
>>> >
>>> > --
>>> > Please do not email me anything that you are not comfortable also
>>> sharing
>>> > with the NSA.
>>> >
>>> > On Jun 6, 2017, at 5:56 PM, James Hilliard via bitcoin-dev
>>> > <bitcoin-dev@lists.linuxfoundation.org> wrote:
>>> >
>>> > Due to the proposed calendar(https://segwit2x.github.io/) for the
>>> > SegWit2x agreement being too slow to activate SegWit mandatory
>>> > signalling ahead of BIP148 using BIP91 I would like to propose another
>>> > option that miners can use to prevent a chain split ahead of the Aug
>>> > 1st BIP148 activation date.
>>> >
>>> > The splitprotection soft fork is essentially BIP91 but using BIP8
>>> > instead of BIP9 with a lower activation threshold and immediate
>>> > mandatory signalling lock-in. This allows for a majority of miners to
>>> > activate mandatory SegWit signalling and prevent a potential chain
>>> > split ahead of BIP148 activation.
>>> >
>>> > This BIP allows for miners to respond to market forces quickly ahead
>>> > of BIP148 activation by signalling for splitprotection. Any miners
>>> > already running BIP148 should be encouraged to use splitprotection.
>>> >
>>> > <pre>
>>> > BIP: splitprotection
>>> > Layer: Consensus (soft fork)
>>> > Title: User Activated Soft Fork Split Protection
>>> > Author: James Hilliard <james.hilliard1@gmail.com>
>>> > Comments-Summary: No comments yet.
>>> > Comments-URI:
>>> > Status: Draft
>>> > Type: Standards Track
>>> > Created: 2017-05-22
>>> > License: BSD-3-Clause
>>> >          CC0-1.0
>>> > </pre>
>>> >
>>> > ==Abstract==
>>> >
>>> > This document specifies a coordination mechanism for a simple majority
>>> > of miners to prevent a chain split ahead of BIP148 activation.
>>> >
>>> > ==Definitions==
>>> >
>>> > "existing segwit deployment" refer to the BIP9 "segwit" deployment
>>> > using bit 1, between November 15th 2016 and November 15th 2017 to
>>> > activate BIP141, BIP143 and BIP147.
>>> >
>>> > ==Motivation==
>>> >
>>> > The biggest risk of BIP148 is an extended chain split, this BIP
>>> > provides a way for a simple majority of miners to eliminate that risk.
>>> >
>>> > This BIP provides a way for a simple majority of miners to coordinate
>>> > activation of the existing segwit deployment with less than 95%
>>> > hashpower before BIP148 activation. Due to time constraints unless
>>> > immediately deployed BIP91 will likely not be able to enforce
>>> > mandatory signalling of segwit before the Aug 1st activation of
>>> > BIP148. This BIP provides a method for rapid miner activation of
>>> > SegWit mandatory signalling ahead of the BIP148 activation date. Since
>>> > the primary goal of this BIP is to reduce the chance of an extended
>>> > chain split as much as possible we activate using a simple miner
>>> > majority of 65% over a 504 block interval rather than a higher
>>> > percentage. This BIP also allows miners to signal their intention to
>>> > run BIP148 in order to prevent a chain split.
>>> >
>>> > ==Specification==
>>> >
>>> > While this BIP is active, all blocks must set the nVersion header top
>>> > 3 bits to 001 together with bit field (1<<1) (according to the
>>> > existing segwit deployment). Blocks that do not signal as required
>>> > will be rejected.
>>> >
>>> > ==Deployment==
>>> >
>>> > This BIP will be deployed by "version bits" with a 65%(this can be
>>> > adjusted if desired) activation threshold BIP9 with the name
>>> > "splitprotecion" and using bit 2.
>>> >
>>> > This BIP starts immediately and is a BIP8 style soft fork since
>>> > mandatory signalling will start on midnight August 1st 2017 (epoch
>>> > time 1501545600) regardless of whether or not this BIP has reached its
>>> > own signalling threshold. This BIP will cease to be active when segwit
>>> > is locked-in.
>>> >
>>> > === Reference implementation ===
>>> >
>>> > <pre>
>>> > // Check if Segregated Witness is Locked In
>>> > bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
>>> > Consensus::Params& params)
>>> > {
>>> >   LOCK(cs_main);
>>> >   return (VersionBitsState(pindexPrev, params,
>>> > Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
>>> > THRESHOLD_LOCKED_IN);
>>> > }
>>> >
>>> > // SPLITPROTECTION mandatory segwit signalling.
>>> > if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
>>> > Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
>>> > THRESHOLD_LOCKED_IN &&
>>> >    !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>>> > // Segwit is not locked in
>>> >    !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
>>> > and is not active.
>>> > {
>>> >   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>>> > VERSIONBITS_TOP_BITS;
>>> >   bool fSegbit = (pindex->nVersion &
>>> > VersionBitsMask(chainparams.GetConsensus(),
>>> > Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>> >   if (!(fVersionBits && fSegbit)) {
>>> >       return state.DoS(0, error("ConnectBlock(): relayed block must
>>> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>> >   }
>>> > }
>>> >
>>> > // BIP148 mandatory segwit signalling.
>>> > int64_t nMedianTimePast = pindex->GetMedianTimePast();
>>> > if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00
>>> UTC
>>> >    (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
>>> >    (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>>> > // Segwit is not locked in
>>> >     !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
>>> > // and is not active.
>>> > {
>>> >   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>>> > VERSIONBITS_TOP_BITS;
>>> >   bool fSegbit = (pindex->nVersion &
>>> > VersionBitsMask(chainparams.GetConsensus(),
>>> > Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>> >   if (!(fVersionBits && fSegbit)) {
>>> >       return state.DoS(0, error("ConnectBlock(): relayed block must
>>> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>> >   }
>>> > }
>>> > </pre>
>>> >
>>> > https://github.com/bitcoin/bitcoin/compare/0.14...jameshilli
>>> ard:splitprotection-v0.14.1
>>> >
>>> > ==Backwards Compatibility==
>>> >
>>> > This deployment is compatible with the existing "segwit" bit 1
>>> > deployment scheduled between midnight November 15th, 2016 and midnight
>>> > November 15th, 2017. This deployment is also compatible with the
>>> > existing BIP148 deployment. This BIP is compatible with BIP91 only if
>>> > BIP91 activates before it and before BIP148. Miners will need to
>>> > upgrade their nodes to support splitprotection otherwise they may
>>> > build on top of an invalid block. While this bip is active users
>>> > should either upgrade to splitprotection or wait for additional
>>> > confirmations when accepting payments.
>>> >
>>> > ==Rationale==
>>> >
>>> > Historically we have used IsSuperMajority() to activate soft forks
>>> > such as BIP66 which has a mandatory signalling requirement for miners
>>> > once activated, this ensures that miners are aware of new rules being
>>> > enforced. This technique can be leveraged to lower the signalling
>>> > threshold of a soft fork while it is in the process of being deployed
>>> > in a backwards compatible way. We also use a BIP8 style timeout to
>>> > ensure that this BIP is compatible with BIP148 and that BIP148
>>> > compatible mandatory signalling activates regardless of miner
>>> > signalling levels.
>>> >
>>> > By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
>>> > deployment, this BIP can cause the existing "segwit" deployment to
>>> > activate without needing to release a new deployment. As we approach
>>> > BIP148 activation it may be desirable for a majority of miners to have
>>> > a method that will ensure that there is no chain split.
>>> >
>>> > ==References==
>>> >
>>> > *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/20
>>> 17-March/013714.html
>>> > Mailing list discussion]
>>> > *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cp
>>> p#L1281-L1283
>>> > P2SH flag day activation]
>>> > *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
>>> > *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
>>> > *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
>>> > *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
>>> > *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
>>> > Version 0 Witness Program]]
>>> > *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element
>>> malleability]]
>>> > *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit
>>> deployment]]
>>> > *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
>>> > *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit
>>> benefits]
>>> >
>>> > ==Copyright==
>>> >
>>> > This document is dual licensed as BSD 3-clause, and Creative Commons
>>> > CC0 1.0 Universal.
>>> > _______________________________________________
>>> > bitcoin-dev mailing list
>>> > bitcoin-dev@lists.linuxfoundation.org
>>> > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>> >
>>> >
>>> >
>>> _______________________________________________
>>> bitcoin-dev mailing list
>>> bitcoin-dev@lists.linuxfoundation.org
>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>>
>>
>>
>> _______________________________________________
>> bitcoin-dev mailing list
>> bitcoin-dev@lists.linuxfoundation.org
>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>
>>
>

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Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[Erik Aronesty]

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I get it, a threshold could be put in place, but something like 33% would
more accurately reflect the risks miners run.

I'm not aware of a good signal to indicates someone is planning to run
BIP148 and orphan a miner's blocks.



On Wed, Jun 7, 2017 at 3:39 PM, Jacob Eliosoff <jacob.eliosoff@gmail.com>
wrote:

> You're missing my point.  "As soon as a simple majority supports it" -
> what is "it"?  BIP148?  Or "deferring to the miner consensus on BIP148"?
> It's the difference between supporting one side of a vote, vs supporting
> deferral to the outcome of the vote.
>
> Or if you mean, the safe thing for miners is to orphan non-segwit blocks
> Aug 1 *regardless* of the miner consensus (since the economic consensus
> might differ), then there's zero need for this BIP: they should just run
> BIP148.
>
> As I said: this BIP should be corrected to only orphan if >50% signal for
> BIP148.  Or, define two bits, one meaning "I support BIP148," the other "I
> will go w/ the miner majority on BIP148."  Fudging them this way is
> deceptive.
>
>
> On Jun 7, 2017 2:05 PM, "Erik Aronesty" <erik@q32.com> wrote:
>
> > But passing it off as the safest defense is bad faith.
>
> Without this option, a miner has to guess whether a split will be
> economically impacting.   With this option, his miner will automatically
> switch to the chain least likely to get wiped out... as soon as a simple
> majority of miners supports it.
>
>
> On Wed, Jun 7, 2017 at 12:44 PM, Jacob Eliosoff <jacob.eliosoff@gmail.com>
> wrote:
>
>> This is not the safest defense against a split.  If 70% of miners run
>> "splitprotection", and 0.1% run BIP148, there's no "safety"/"defense"
>> reason for splitprotection to activate segwit.  It should only do so if
>> *BIP148* support (NB: not just segwit support!) >50%.
>>
>> The truly defensive logic is "If the majority supports orphaning
>> non-segwit blocks starting Aug 1, I'll join them."
>>
>> If the real goal of this BIP is to induce miners to run segwit, then fair
>> enough.  But passing it off as the safest defense is bad faith.
>>
>>
>> On Wed, Jun 7, 2017 at 10:10 AM, Erik Aronesty via bitcoin-dev <
>> bitcoin-dev@lists.linuxfoundation.org> wrote:
>>
>>> This is, by far, the safest way for miners to quickly defend against a
>>> chain split, much better than a -bip148 option.   This allows miners to
>>> defend themselves, with very little risk, since the defense is only
>>> activated if the majority of miners do so. I would move for a very rapid
>>> deployment.   Only miners would need to upgrade.   Regular users would not
>>> have to concern themselves with this release.
>>>
>>> On Wed, Jun 7, 2017 at 6:13 AM, James Hilliard via bitcoin-dev <
>>> bitcoin-dev@lists.linuxfoundation.org> wrote:
>>>
>>>> I think even 55% would probably work out fine simply due to incentive
>>>> structures, once signalling is over 51% it's then clear to miners that
>>>> non-signalling blocks will be orphaned and the rest will rapidly
>>>> update to splitprotection/BIP148. The purpose of this BIP is to reduce
>>>> chain split risk for BIP148 since it's looking like BIP148 is going to
>>>> be run by a non-insignificant percentage of the economy at a minimum.
>>>>
>>>> On Wed, Jun 7, 2017 at 12:20 AM, Tao Effect <contact@taoeffect.com>
>>>> wrote:
>>>> > See thread on replay attacks for why activating regardless of
>>>> threshold is a
>>>> > bad idea [1].
>>>> >
>>>> > BIP91 OTOH seems perfectly reasonable. 80% instead of 95% makes it
>>>> more
>>>> > difficult for miners to hold together in opposition to Core. It gives
>>>> Core
>>>> > more leverage in negotiations.
>>>> >
>>>> > If they don't activate with 80%, Core can release another BIP to
>>>> reduce it
>>>> > to 75%.
>>>> >
>>>> > Each threshold reduction makes it both more likely to succeed, but
>>>> also
>>>> > increases the likelihood of harm to the ecosystem.
>>>> >
>>>> > Cheers,
>>>> > Greg
>>>> >
>>>> > [1]
>>>> > https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017
>>>> -June/014497.html
>>>> >
>>>> > --
>>>> > Please do not email me anything that you are not comfortable also
>>>> sharing
>>>> > with the NSA.
>>>> >
>>>> > On Jun 6, 2017, at 6:54 PM, James Hilliard <james.hilliard1@gmail.com
>>>> >
>>>> > wrote:
>>>> >
>>>> > This is a BIP8 style soft fork so mandatory signalling will be active
>>>> > after Aug 1st regardless.
>>>> >
>>>> > On Tue, Jun 6, 2017 at 8:51 PM, Tao Effect <contact@taoeffect.com>
>>>> wrote:
>>>> >
>>>> > What is the probability that a 65% threshold is too low and can allow
>>>> a
>>>> > "surprise miner attack", whereby miners are kept offline before the
>>>> > deadline, and brought online immediately after, creating potential
>>>> havoc?
>>>> >
>>>> > (Nit: "simple majority" usually refers to >50%, I think, might cause
>>>> > confusion.)
>>>> >
>>>> > -Greg Slepak
>>>> >
>>>> > --
>>>> > Please do not email me anything that you are not comfortable also
>>>> sharing
>>>> > with the NSA.
>>>> >
>>>> > On Jun 6, 2017, at 5:56 PM, James Hilliard via bitcoin-dev
>>>> > <bitcoin-dev@lists.linuxfoundation.org> wrote:
>>>> >
>>>> > Due to the proposed calendar(https://segwit2x.github.io/) for the
>>>> > SegWit2x agreement being too slow to activate SegWit mandatory
>>>> > signalling ahead of BIP148 using BIP91 I would like to propose another
>>>> > option that miners can use to prevent a chain split ahead of the Aug
>>>> > 1st BIP148 activation date.
>>>> >
>>>> > The splitprotection soft fork is essentially BIP91 but using BIP8
>>>> > instead of BIP9 with a lower activation threshold and immediate
>>>> > mandatory signalling lock-in. This allows for a majority of miners to
>>>> > activate mandatory SegWit signalling and prevent a potential chain
>>>> > split ahead of BIP148 activation.
>>>> >
>>>> > This BIP allows for miners to respond to market forces quickly ahead
>>>> > of BIP148 activation by signalling for splitprotection. Any miners
>>>> > already running BIP148 should be encouraged to use splitprotection.
>>>> >
>>>> > <pre>
>>>> > BIP: splitprotection
>>>> > Layer: Consensus (soft fork)
>>>> > Title: User Activated Soft Fork Split Protection
>>>> > Author: James Hilliard <james.hilliard1@gmail.com>
>>>> > Comments-Summary: No comments yet.
>>>> > Comments-URI:
>>>> > Status: Draft
>>>> > Type: Standards Track
>>>> > Created: 2017-05-22
>>>> > License: BSD-3-Clause
>>>> >          CC0-1.0
>>>> > </pre>
>>>> >
>>>> > ==Abstract==
>>>> >
>>>> > This document specifies a coordination mechanism for a simple majority
>>>> > of miners to prevent a chain split ahead of BIP148 activation.
>>>> >
>>>> > ==Definitions==
>>>> >
>>>> > "existing segwit deployment" refer to the BIP9 "segwit" deployment
>>>> > using bit 1, between November 15th 2016 and November 15th 2017 to
>>>> > activate BIP141, BIP143 and BIP147.
>>>> >
>>>> > ==Motivation==
>>>> >
>>>> > The biggest risk of BIP148 is an extended chain split, this BIP
>>>> > provides a way for a simple majority of miners to eliminate that risk.
>>>> >
>>>> > This BIP provides a way for a simple majority of miners to coordinate
>>>> > activation of the existing segwit deployment with less than 95%
>>>> > hashpower before BIP148 activation. Due to time constraints unless
>>>> > immediately deployed BIP91 will likely not be able to enforce
>>>> > mandatory signalling of segwit before the Aug 1st activation of
>>>> > BIP148. This BIP provides a method for rapid miner activation of
>>>> > SegWit mandatory signalling ahead of the BIP148 activation date. Since
>>>> > the primary goal of this BIP is to reduce the chance of an extended
>>>> > chain split as much as possible we activate using a simple miner
>>>> > majority of 65% over a 504 block interval rather than a higher
>>>> > percentage. This BIP also allows miners to signal their intention to
>>>> > run BIP148 in order to prevent a chain split.
>>>> >
>>>> > ==Specification==
>>>> >
>>>> > While this BIP is active, all blocks must set the nVersion header top
>>>> > 3 bits to 001 together with bit field (1<<1) (according to the
>>>> > existing segwit deployment). Blocks that do not signal as required
>>>> > will be rejected.
>>>> >
>>>> > ==Deployment==
>>>> >
>>>> > This BIP will be deployed by "version bits" with a 65%(this can be
>>>> > adjusted if desired) activation threshold BIP9 with the name
>>>> > "splitprotecion" and using bit 2.
>>>> >
>>>> > This BIP starts immediately and is a BIP8 style soft fork since
>>>> > mandatory signalling will start on midnight August 1st 2017 (epoch
>>>> > time 1501545600) regardless of whether or not this BIP has reached its
>>>> > own signalling threshold. This BIP will cease to be active when segwit
>>>> > is locked-in.
>>>> >
>>>> > === Reference implementation ===
>>>> >
>>>> > <pre>
>>>> > // Check if Segregated Witness is Locked In
>>>> > bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
>>>> > Consensus::Params& params)
>>>> > {
>>>> >   LOCK(cs_main);
>>>> >   return (VersionBitsState(pindexPrev, params,
>>>> > Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
>>>> > THRESHOLD_LOCKED_IN);
>>>> > }
>>>> >
>>>> > // SPLITPROTECTION mandatory segwit signalling.
>>>> > if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
>>>> > Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
>>>> > THRESHOLD_LOCKED_IN &&
>>>> >    !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>>>> > // Segwit is not locked in
>>>> >    !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
>>>> > and is not active.
>>>> > {
>>>> >   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>>>> > VERSIONBITS_TOP_BITS;
>>>> >   bool fSegbit = (pindex->nVersion &
>>>> > VersionBitsMask(chainparams.GetConsensus(),
>>>> > Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>>> >   if (!(fVersionBits && fSegbit)) {
>>>> >       return state.DoS(0, error("ConnectBlock(): relayed block must
>>>> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>>> >   }
>>>> > }
>>>> >
>>>> > // BIP148 mandatory segwit signalling.
>>>> > int64_t nMedianTimePast = pindex->GetMedianTimePast();
>>>> > if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00
>>>> UTC
>>>> >    (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
>>>> >    (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>>>> > // Segwit is not locked in
>>>> >     !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
>>>> > // and is not active.
>>>> > {
>>>> >   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>>>> > VERSIONBITS_TOP_BITS;
>>>> >   bool fSegbit = (pindex->nVersion &
>>>> > VersionBitsMask(chainparams.GetConsensus(),
>>>> > Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>>> >   if (!(fVersionBits && fSegbit)) {
>>>> >       return state.DoS(0, error("ConnectBlock(): relayed block must
>>>> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>>> >   }
>>>> > }
>>>> > </pre>
>>>> >
>>>> > https://github.com/bitcoin/bitcoin/compare/0.14...jameshilli
>>>> ard:splitprotection-v0.14.1
>>>> >
>>>> > ==Backwards Compatibility==
>>>> >
>>>> > This deployment is compatible with the existing "segwit" bit 1
>>>> > deployment scheduled between midnight November 15th, 2016 and midnight
>>>> > November 15th, 2017. This deployment is also compatible with the
>>>> > existing BIP148 deployment. This BIP is compatible with BIP91 only if
>>>> > BIP91 activates before it and before BIP148. Miners will need to
>>>> > upgrade their nodes to support splitprotection otherwise they may
>>>> > build on top of an invalid block. While this bip is active users
>>>> > should either upgrade to splitprotection or wait for additional
>>>> > confirmations when accepting payments.
>>>> >
>>>> > ==Rationale==
>>>> >
>>>> > Historically we have used IsSuperMajority() to activate soft forks
>>>> > such as BIP66 which has a mandatory signalling requirement for miners
>>>> > once activated, this ensures that miners are aware of new rules being
>>>> > enforced. This technique can be leveraged to lower the signalling
>>>> > threshold of a soft fork while it is in the process of being deployed
>>>> > in a backwards compatible way. We also use a BIP8 style timeout to
>>>> > ensure that this BIP is compatible with BIP148 and that BIP148
>>>> > compatible mandatory signalling activates regardless of miner
>>>> > signalling levels.
>>>> >
>>>> > By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
>>>> > deployment, this BIP can cause the existing "segwit" deployment to
>>>> > activate without needing to release a new deployment. As we approach
>>>> > BIP148 activation it may be desirable for a majority of miners to have
>>>> > a method that will ensure that there is no chain split.
>>>> >
>>>> > ==References==
>>>> >
>>>> > *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/20
>>>> 17-March/013714.html
>>>> > Mailing list discussion]
>>>> > *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cp
>>>> p#L1281-L1283
>>>> > P2SH flag day activation]
>>>> > *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
>>>> > *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
>>>> > *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
>>>> > *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
>>>> > *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
>>>> > Version 0 Witness Program]]
>>>> > *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element
>>>> malleability]]
>>>> > *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit
>>>> deployment]]
>>>> > *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
>>>> > *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit
>>>> benefits]
>>>> >
>>>> > ==Copyright==
>>>> >
>>>> > This document is dual licensed as BSD 3-clause, and Creative Commons
>>>> > CC0 1.0 Universal.
>>>> > _______________________________________________
>>>> > bitcoin-dev mailing list
>>>> > bitcoin-dev@lists.linuxfoundation.org
>>>> > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>>> >
>>>> >
>>>> >
>>>> _______________________________________________
>>>> bitcoin-dev mailing list
>>>> bitcoin-dev@lists.linuxfoundation.org
>>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>>>
>>>
>>>
>>> _______________________________________________
>>> bitcoin-dev mailing list
>>> bitcoin-dev@lists.linuxfoundation.org
>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>>
>>>
>>
>
>

[-- Attachment #2: Type: text/html, Size: 19753 bytes --]

Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[Jared Lee Richardson]

> This is, by far, the safest way for miners to quickly defend against a chain split, much better than a -bip148 option.   This allows miners to defend themselves, with very little risk, since the defense is only activated if the majority of miners do so. I would move for a very rapid deployment.   Only miners would need to upgrade.   Regular users would not have to concern themselves with this release.

FYI, even if very successful, this deployment and change may have a
severe negative impact on a small group of miners.  Any miners/pools
who are not actively following the forums, news, or these discussions
may be difficult to reach and communicate with in time, particularly
with language barriers.  Of those, any who are also either not
signaling segwit currently or are running an older software version
will have their blocks continuously and constantly orphaned, but may
not have any alarms or notifications set up for such an unexpected
failure.  That may or may not be a worthy consideration, but it is
definitely brusque and a harsh price to pay.  Considering the
opposition mentioned against transaction limits for the rare cases
where a very large transaction has already been signed, it seems that
this would be worthy of consideration.  For the few miners in that
situation, it does turn segwit from an optional softfork into a
punishing hardfork.

I don't think that's a sufficient reason alone to kill the idea, but
it should be a concern.

Jared

On Wed, Jun 7, 2017 at 7:10 AM, Erik Aronesty via bitcoin-dev
<bitcoin-dev@lists.linuxfoundation.org> wrote:
> This is, by far, the safest way for miners to quickly defend against a chain
> split, much better than a -bip148 option.   This allows miners to defend
> themselves, with very little risk, since the defense is only activated if
> the majority of miners do so. I would move for a very rapid deployment.
> Only miners would need to upgrade.   Regular users would not have to concern
> themselves with this release.
>
> On Wed, Jun 7, 2017 at 6:13 AM, James Hilliard via bitcoin-dev
> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>>
>> I think even 55% would probably work out fine simply due to incentive
>> structures, once signalling is over 51% it's then clear to miners that
>> non-signalling blocks will be orphaned and the rest will rapidly
>> update to splitprotection/BIP148. The purpose of this BIP is to reduce
>> chain split risk for BIP148 since it's looking like BIP148 is going to
>> be run by a non-insignificant percentage of the economy at a minimum.
>>
>> On Wed, Jun 7, 2017 at 12:20 AM, Tao Effect <contact@taoeffect.com> wrote:
>> > See thread on replay attacks for why activating regardless of threshold
>> > is a
>> > bad idea [1].
>> >
>> > BIP91 OTOH seems perfectly reasonable. 80% instead of 95% makes it more
>> > difficult for miners to hold together in opposition to Core. It gives
>> > Core
>> > more leverage in negotiations.
>> >
>> > If they don't activate with 80%, Core can release another BIP to reduce
>> > it
>> > to 75%.
>> >
>> > Each threshold reduction makes it both more likely to succeed, but also
>> > increases the likelihood of harm to the ecosystem.
>> >
>> > Cheers,
>> > Greg
>> >
>> > [1]
>> >
>> > https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-June/014497.html
>> >
>> > --
>> > Please do not email me anything that you are not comfortable also
>> > sharing
>> > with the NSA.
>> >
>> > On Jun 6, 2017, at 6:54 PM, James Hilliard <james.hilliard1@gmail.com>
>> > wrote:
>> >
>> > This is a BIP8 style soft fork so mandatory signalling will be active
>> > after Aug 1st regardless.
>> >
>> > On Tue, Jun 6, 2017 at 8:51 PM, Tao Effect <contact@taoeffect.com>
>> > wrote:
>> >
>> > What is the probability that a 65% threshold is too low and can allow a
>> > "surprise miner attack", whereby miners are kept offline before the
>> > deadline, and brought online immediately after, creating potential
>> > havoc?
>> >
>> > (Nit: "simple majority" usually refers to >50%, I think, might cause
>> > confusion.)
>> >
>> > -Greg Slepak
>> >
>> > --
>> > Please do not email me anything that you are not comfortable also
>> > sharing
>> > with the NSA.
>> >
>> > On Jun 6, 2017, at 5:56 PM, James Hilliard via bitcoin-dev
>> > <bitcoin-dev@lists.linuxfoundation.org> wrote:
>> >
>> > Due to the proposed calendar(https://segwit2x.github.io/) for the
>> > SegWit2x agreement being too slow to activate SegWit mandatory
>> > signalling ahead of BIP148 using BIP91 I would like to propose another
>> > option that miners can use to prevent a chain split ahead of the Aug
>> > 1st BIP148 activation date.
>> >
>> > The splitprotection soft fork is essentially BIP91 but using BIP8
>> > instead of BIP9 with a lower activation threshold and immediate
>> > mandatory signalling lock-in. This allows for a majority of miners to
>> > activate mandatory SegWit signalling and prevent a potential chain
>> > split ahead of BIP148 activation.
>> >
>> > This BIP allows for miners to respond to market forces quickly ahead
>> > of BIP148 activation by signalling for splitprotection. Any miners
>> > already running BIP148 should be encouraged to use splitprotection.
>> >
>> > <pre>
>> > BIP: splitprotection
>> > Layer: Consensus (soft fork)
>> > Title: User Activated Soft Fork Split Protection
>> > Author: James Hilliard <james.hilliard1@gmail.com>
>> > Comments-Summary: No comments yet.
>> > Comments-URI:
>> > Status: Draft
>> > Type: Standards Track
>> > Created: 2017-05-22
>> > License: BSD-3-Clause
>> >          CC0-1.0
>> > </pre>
>> >
>> > ==Abstract==
>> >
>> > This document specifies a coordination mechanism for a simple majority
>> > of miners to prevent a chain split ahead of BIP148 activation.
>> >
>> > ==Definitions==
>> >
>> > "existing segwit deployment" refer to the BIP9 "segwit" deployment
>> > using bit 1, between November 15th 2016 and November 15th 2017 to
>> > activate BIP141, BIP143 and BIP147.
>> >
>> > ==Motivation==
>> >
>> > The biggest risk of BIP148 is an extended chain split, this BIP
>> > provides a way for a simple majority of miners to eliminate that risk.
>> >
>> > This BIP provides a way for a simple majority of miners to coordinate
>> > activation of the existing segwit deployment with less than 95%
>> > hashpower before BIP148 activation. Due to time constraints unless
>> > immediately deployed BIP91 will likely not be able to enforce
>> > mandatory signalling of segwit before the Aug 1st activation of
>> > BIP148. This BIP provides a method for rapid miner activation of
>> > SegWit mandatory signalling ahead of the BIP148 activation date. Since
>> > the primary goal of this BIP is to reduce the chance of an extended
>> > chain split as much as possible we activate using a simple miner
>> > majority of 65% over a 504 block interval rather than a higher
>> > percentage. This BIP also allows miners to signal their intention to
>> > run BIP148 in order to prevent a chain split.
>> >
>> > ==Specification==
>> >
>> > While this BIP is active, all blocks must set the nVersion header top
>> > 3 bits to 001 together with bit field (1<<1) (according to the
>> > existing segwit deployment). Blocks that do not signal as required
>> > will be rejected.
>> >
>> > ==Deployment==
>> >
>> > This BIP will be deployed by "version bits" with a 65%(this can be
>> > adjusted if desired) activation threshold BIP9 with the name
>> > "splitprotecion" and using bit 2.
>> >
>> > This BIP starts immediately and is a BIP8 style soft fork since
>> > mandatory signalling will start on midnight August 1st 2017 (epoch
>> > time 1501545600) regardless of whether or not this BIP has reached its
>> > own signalling threshold. This BIP will cease to be active when segwit
>> > is locked-in.
>> >
>> > === Reference implementation ===
>> >
>> > <pre>
>> > // Check if Segregated Witness is Locked In
>> > bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
>> > Consensus::Params& params)
>> > {
>> >   LOCK(cs_main);
>> >   return (VersionBitsState(pindexPrev, params,
>> > Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
>> > THRESHOLD_LOCKED_IN);
>> > }
>> >
>> > // SPLITPROTECTION mandatory segwit signalling.
>> > if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
>> > Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
>> > THRESHOLD_LOCKED_IN &&
>> >    !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>> > // Segwit is not locked in
>> >    !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
>> > and is not active.
>> > {
>> >   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>> > VERSIONBITS_TOP_BITS;
>> >   bool fSegbit = (pindex->nVersion &
>> > VersionBitsMask(chainparams.GetConsensus(),
>> > Consensus::DEPLOYMENT_SEGWIT)) != 0;
>> >   if (!(fVersionBits && fSegbit)) {
>> >       return state.DoS(0, error("ConnectBlock(): relayed block must
>> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>> >   }
>> > }
>> >
>> > // BIP148 mandatory segwit signalling.
>> > int64_t nMedianTimePast = pindex->GetMedianTimePast();
>> > if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00 UTC
>> >    (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
>> >    (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>> > // Segwit is not locked in
>> >     !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
>> > // and is not active.
>> > {
>> >   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>> > VERSIONBITS_TOP_BITS;
>> >   bool fSegbit = (pindex->nVersion &
>> > VersionBitsMask(chainparams.GetConsensus(),
>> > Consensus::DEPLOYMENT_SEGWIT)) != 0;
>> >   if (!(fVersionBits && fSegbit)) {
>> >       return state.DoS(0, error("ConnectBlock(): relayed block must
>> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>> >   }
>> > }
>> > </pre>
>> >
>> >
>> > https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1
>> >
>> > ==Backwards Compatibility==
>> >
>> > This deployment is compatible with the existing "segwit" bit 1
>> > deployment scheduled between midnight November 15th, 2016 and midnight
>> > November 15th, 2017. This deployment is also compatible with the
>> > existing BIP148 deployment. This BIP is compatible with BIP91 only if
>> > BIP91 activates before it and before BIP148. Miners will need to
>> > upgrade their nodes to support splitprotection otherwise they may
>> > build on top of an invalid block. While this bip is active users
>> > should either upgrade to splitprotection or wait for additional
>> > confirmations when accepting payments.
>> >
>> > ==Rationale==
>> >
>> > Historically we have used IsSuperMajority() to activate soft forks
>> > such as BIP66 which has a mandatory signalling requirement for miners
>> > once activated, this ensures that miners are aware of new rules being
>> > enforced. This technique can be leveraged to lower the signalling
>> > threshold of a soft fork while it is in the process of being deployed
>> > in a backwards compatible way. We also use a BIP8 style timeout to
>> > ensure that this BIP is compatible with BIP148 and that BIP148
>> > compatible mandatory signalling activates regardless of miner
>> > signalling levels.
>> >
>> > By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
>> > deployment, this BIP can cause the existing "segwit" deployment to
>> > activate without needing to release a new deployment. As we approach
>> > BIP148 activation it may be desirable for a majority of miners to have
>> > a method that will ensure that there is no chain split.
>> >
>> > ==References==
>> >
>> >
>> > *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html
>> > Mailing list discussion]
>> >
>> > *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283
>> > P2SH flag day activation]
>> > *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
>> > *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
>> > *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
>> > *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
>> > *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
>> > Version 0 Witness Program]]
>> > *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element
>> > malleability]]
>> > *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment]]
>> > *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
>> > *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit
>> > benefits]
>> >
>> > ==Copyright==
>> >
>> > This document is dual licensed as BSD 3-clause, and Creative Commons
>> > CC0 1.0 Universal.
>> > _______________________________________________
>> > bitcoin-dev mailing list
>> > bitcoin-dev@lists.linuxfoundation.org
>> > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>> >
>> >
>> >
>> _______________________________________________
>> bitcoin-dev mailing list
>> bitcoin-dev@lists.linuxfoundation.org
>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>
>
>
> _______________________________________________
> bitcoin-dev mailing list
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Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[James Hilliard]

Keep in mind that this is only temporary until segwit has locked in,
after that happens it becomes optional for miners again.

On Wed, Jun 7, 2017 at 4:09 PM, Jared Lee Richardson <jaredr26@gmail.com> wrote:
>> This is, by far, the safest way for miners to quickly defend against a chain split, much better than a -bip148 option.   This allows miners to defend themselves, with very little risk, since the defense is only activated if the majority of miners do so. I would move for a very rapid deployment.   Only miners would need to upgrade.   Regular users would not have to concern themselves with this release.
>
> FYI, even if very successful, this deployment and change may have a
> severe negative impact on a small group of miners.  Any miners/pools
> who are not actively following the forums, news, or these discussions
> may be difficult to reach and communicate with in time, particularly
> with language barriers.  Of those, any who are also either not
> signaling segwit currently or are running an older software version
> will have their blocks continuously and constantly orphaned, but may
> not have any alarms or notifications set up for such an unexpected
> failure.  That may or may not be a worthy consideration, but it is
> definitely brusque and a harsh price to pay.  Considering the
> opposition mentioned against transaction limits for the rare cases
> where a very large transaction has already been signed, it seems that
> this would be worthy of consideration.  For the few miners in that
> situation, it does turn segwit from an optional softfork into a
> punishing hardfork.
>
> I don't think that's a sufficient reason alone to kill the idea, but
> it should be a concern.
>
> Jared
>
> On Wed, Jun 7, 2017 at 7:10 AM, Erik Aronesty via bitcoin-dev
> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>> This is, by far, the safest way for miners to quickly defend against a chain
>> split, much better than a -bip148 option.   This allows miners to defend
>> themselves, with very little risk, since the defense is only activated if
>> the majority of miners do so. I would move for a very rapid deployment.
>> Only miners would need to upgrade.   Regular users would not have to concern
>> themselves with this release.
>>
>> On Wed, Jun 7, 2017 at 6:13 AM, James Hilliard via bitcoin-dev
>> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>>>
>>> I think even 55% would probably work out fine simply due to incentive
>>> structures, once signalling is over 51% it's then clear to miners that
>>> non-signalling blocks will be orphaned and the rest will rapidly
>>> update to splitprotection/BIP148. The purpose of this BIP is to reduce
>>> chain split risk for BIP148 since it's looking like BIP148 is going to
>>> be run by a non-insignificant percentage of the economy at a minimum.
>>>
>>> On Wed, Jun 7, 2017 at 12:20 AM, Tao Effect <contact@taoeffect.com> wrote:
>>> > See thread on replay attacks for why activating regardless of threshold
>>> > is a
>>> > bad idea [1].
>>> >
>>> > BIP91 OTOH seems perfectly reasonable. 80% instead of 95% makes it more
>>> > difficult for miners to hold together in opposition to Core. It gives
>>> > Core
>>> > more leverage in negotiations.
>>> >
>>> > If they don't activate with 80%, Core can release another BIP to reduce
>>> > it
>>> > to 75%.
>>> >
>>> > Each threshold reduction makes it both more likely to succeed, but also
>>> > increases the likelihood of harm to the ecosystem.
>>> >
>>> > Cheers,
>>> > Greg
>>> >
>>> > [1]
>>> >
>>> > https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-June/014497.html
>>> >
>>> > --
>>> > Please do not email me anything that you are not comfortable also
>>> > sharing
>>> > with the NSA.
>>> >
>>> > On Jun 6, 2017, at 6:54 PM, James Hilliard <james.hilliard1@gmail.com>
>>> > wrote:
>>> >
>>> > This is a BIP8 style soft fork so mandatory signalling will be active
>>> > after Aug 1st regardless.
>>> >
>>> > On Tue, Jun 6, 2017 at 8:51 PM, Tao Effect <contact@taoeffect.com>
>>> > wrote:
>>> >
>>> > What is the probability that a 65% threshold is too low and can allow a
>>> > "surprise miner attack", whereby miners are kept offline before the
>>> > deadline, and brought online immediately after, creating potential
>>> > havoc?
>>> >
>>> > (Nit: "simple majority" usually refers to >50%, I think, might cause
>>> > confusion.)
>>> >
>>> > -Greg Slepak
>>> >
>>> > --
>>> > Please do not email me anything that you are not comfortable also
>>> > sharing
>>> > with the NSA.
>>> >
>>> > On Jun 6, 2017, at 5:56 PM, James Hilliard via bitcoin-dev
>>> > <bitcoin-dev@lists.linuxfoundation.org> wrote:
>>> >
>>> > Due to the proposed calendar(https://segwit2x.github.io/) for the
>>> > SegWit2x agreement being too slow to activate SegWit mandatory
>>> > signalling ahead of BIP148 using BIP91 I would like to propose another
>>> > option that miners can use to prevent a chain split ahead of the Aug
>>> > 1st BIP148 activation date.
>>> >
>>> > The splitprotection soft fork is essentially BIP91 but using BIP8
>>> > instead of BIP9 with a lower activation threshold and immediate
>>> > mandatory signalling lock-in. This allows for a majority of miners to
>>> > activate mandatory SegWit signalling and prevent a potential chain
>>> > split ahead of BIP148 activation.
>>> >
>>> > This BIP allows for miners to respond to market forces quickly ahead
>>> > of BIP148 activation by signalling for splitprotection. Any miners
>>> > already running BIP148 should be encouraged to use splitprotection.
>>> >
>>> > <pre>
>>> > BIP: splitprotection
>>> > Layer: Consensus (soft fork)
>>> > Title: User Activated Soft Fork Split Protection
>>> > Author: James Hilliard <james.hilliard1@gmail.com>
>>> > Comments-Summary: No comments yet.
>>> > Comments-URI:
>>> > Status: Draft
>>> > Type: Standards Track
>>> > Created: 2017-05-22
>>> > License: BSD-3-Clause
>>> >          CC0-1.0
>>> > </pre>
>>> >
>>> > ==Abstract==
>>> >
>>> > This document specifies a coordination mechanism for a simple majority
>>> > of miners to prevent a chain split ahead of BIP148 activation.
>>> >
>>> > ==Definitions==
>>> >
>>> > "existing segwit deployment" refer to the BIP9 "segwit" deployment
>>> > using bit 1, between November 15th 2016 and November 15th 2017 to
>>> > activate BIP141, BIP143 and BIP147.
>>> >
>>> > ==Motivation==
>>> >
>>> > The biggest risk of BIP148 is an extended chain split, this BIP
>>> > provides a way for a simple majority of miners to eliminate that risk.
>>> >
>>> > This BIP provides a way for a simple majority of miners to coordinate
>>> > activation of the existing segwit deployment with less than 95%
>>> > hashpower before BIP148 activation. Due to time constraints unless
>>> > immediately deployed BIP91 will likely not be able to enforce
>>> > mandatory signalling of segwit before the Aug 1st activation of
>>> > BIP148. This BIP provides a method for rapid miner activation of
>>> > SegWit mandatory signalling ahead of the BIP148 activation date. Since
>>> > the primary goal of this BIP is to reduce the chance of an extended
>>> > chain split as much as possible we activate using a simple miner
>>> > majority of 65% over a 504 block interval rather than a higher
>>> > percentage. This BIP also allows miners to signal their intention to
>>> > run BIP148 in order to prevent a chain split.
>>> >
>>> > ==Specification==
>>> >
>>> > While this BIP is active, all blocks must set the nVersion header top
>>> > 3 bits to 001 together with bit field (1<<1) (according to the
>>> > existing segwit deployment). Blocks that do not signal as required
>>> > will be rejected.
>>> >
>>> > ==Deployment==
>>> >
>>> > This BIP will be deployed by "version bits" with a 65%(this can be
>>> > adjusted if desired) activation threshold BIP9 with the name
>>> > "splitprotecion" and using bit 2.
>>> >
>>> > This BIP starts immediately and is a BIP8 style soft fork since
>>> > mandatory signalling will start on midnight August 1st 2017 (epoch
>>> > time 1501545600) regardless of whether or not this BIP has reached its
>>> > own signalling threshold. This BIP will cease to be active when segwit
>>> > is locked-in.
>>> >
>>> > === Reference implementation ===
>>> >
>>> > <pre>
>>> > // Check if Segregated Witness is Locked In
>>> > bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
>>> > Consensus::Params& params)
>>> > {
>>> >   LOCK(cs_main);
>>> >   return (VersionBitsState(pindexPrev, params,
>>> > Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
>>> > THRESHOLD_LOCKED_IN);
>>> > }
>>> >
>>> > // SPLITPROTECTION mandatory segwit signalling.
>>> > if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
>>> > Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
>>> > THRESHOLD_LOCKED_IN &&
>>> >    !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>>> > // Segwit is not locked in
>>> >    !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
>>> > and is not active.
>>> > {
>>> >   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>>> > VERSIONBITS_TOP_BITS;
>>> >   bool fSegbit = (pindex->nVersion &
>>> > VersionBitsMask(chainparams.GetConsensus(),
>>> > Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>> >   if (!(fVersionBits && fSegbit)) {
>>> >       return state.DoS(0, error("ConnectBlock(): relayed block must
>>> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>> >   }
>>> > }
>>> >
>>> > // BIP148 mandatory segwit signalling.
>>> > int64_t nMedianTimePast = pindex->GetMedianTimePast();
>>> > if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00 UTC
>>> >    (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
>>> >    (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>>> > // Segwit is not locked in
>>> >     !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
>>> > // and is not active.
>>> > {
>>> >   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>>> > VERSIONBITS_TOP_BITS;
>>> >   bool fSegbit = (pindex->nVersion &
>>> > VersionBitsMask(chainparams.GetConsensus(),
>>> > Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>> >   if (!(fVersionBits && fSegbit)) {
>>> >       return state.DoS(0, error("ConnectBlock(): relayed block must
>>> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>> >   }
>>> > }
>>> > </pre>
>>> >
>>> >
>>> > https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1
>>> >
>>> > ==Backwards Compatibility==
>>> >
>>> > This deployment is compatible with the existing "segwit" bit 1
>>> > deployment scheduled between midnight November 15th, 2016 and midnight
>>> > November 15th, 2017. This deployment is also compatible with the
>>> > existing BIP148 deployment. This BIP is compatible with BIP91 only if
>>> > BIP91 activates before it and before BIP148. Miners will need to
>>> > upgrade their nodes to support splitprotection otherwise they may
>>> > build on top of an invalid block. While this bip is active users
>>> > should either upgrade to splitprotection or wait for additional
>>> > confirmations when accepting payments.
>>> >
>>> > ==Rationale==
>>> >
>>> > Historically we have used IsSuperMajority() to activate soft forks
>>> > such as BIP66 which has a mandatory signalling requirement for miners
>>> > once activated, this ensures that miners are aware of new rules being
>>> > enforced. This technique can be leveraged to lower the signalling
>>> > threshold of a soft fork while it is in the process of being deployed
>>> > in a backwards compatible way. We also use a BIP8 style timeout to
>>> > ensure that this BIP is compatible with BIP148 and that BIP148
>>> > compatible mandatory signalling activates regardless of miner
>>> > signalling levels.
>>> >
>>> > By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
>>> > deployment, this BIP can cause the existing "segwit" deployment to
>>> > activate without needing to release a new deployment. As we approach
>>> > BIP148 activation it may be desirable for a majority of miners to have
>>> > a method that will ensure that there is no chain split.
>>> >
>>> > ==References==
>>> >
>>> >
>>> > *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html
>>> > Mailing list discussion]
>>> >
>>> > *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283
>>> > P2SH flag day activation]
>>> > *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
>>> > *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
>>> > *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
>>> > *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
>>> > *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
>>> > Version 0 Witness Program]]
>>> > *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element
>>> > malleability]]
>>> > *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment]]
>>> > *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
>>> > *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit
>>> > benefits]
>>> >
>>> > ==Copyright==
>>> >
>>> > This document is dual licensed as BSD 3-clause, and Creative Commons
>>> > CC0 1.0 Universal.
>>> > _______________________________________________
>>> > bitcoin-dev mailing list
>>> > bitcoin-dev@lists.linuxfoundation.org
>>> > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>> >
>>> >
>>> >
>>> _______________________________________________
>>> bitcoin-dev mailing list
>>> bitcoin-dev@lists.linuxfoundation.org
>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>
>>
>>
>> _______________________________________________
>> bitcoin-dev mailing list
>> bitcoin-dev@lists.linuxfoundation.org
>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>

Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[Jared Lee Richardson]

I think this BIP represents a gamble, and the gamble may not be a good
one.  The gamble here is that if the segwit2x changes are rolled out
on time, and if the signatories accept the bit4 + bit1 signaling
proposals within BIP91, the launch will go smoother, as intended.  But
conversely, if either the segwit2x signatories balk about the Bit1
signaling OR if the timelines for segwit2mb are missed even by a bit,
it may cause the BIP148 chainsplit to be worse than it would be
without.  Given the frequent concerns raised in multiple places about
the aggressiveness of the segwit2x timelines, including the
non-hardfork timelines, this does not seem like a great gamble to be
making.

The reason I say it may make the chainsplit be worse than it would
otherwise be is that it may provide a false sense of safety for BIP148
that currently does not currently exist(and should not, as it is a
chainsplit).  That sense of safety would only be legitimate if the
segwit2x signatories were on board, and the segwit2x code effectively
enforced BIP148 simultaneously, neither of which are guaranteed.  If
users and more miners had a false sense that BIP148 was *not* going to
chainsplit from default / segwit2x, they might not follow the news if
suddenly the segwit2x plan were delayed for a few days.  While any
additional support would definitely be cheered on by BIP148
supporters, the practical reality might be that this proposal would
take BIP148 from the "unlikely to have any viable chain after flag day
without segwit2x" category into the "small but viable minority chain"
category, and even worse, it might strengthen the chainsplit just days
before segwit is activated on BOTH chains, putting the BIP148
supporters on the wrong pro-segwit, but still-viable chain.

If Core had taken a strong stance to include BIP148 into the client,
and if BIP148 support were much much broader, I would feel differently
as the gamble would be more likely to discourage a chainsplit (By
forcing the acceleration of segwit2x) rather than encourage it (by
strengthening an extreme minority chainsplit that may wind up on the
wrong side of two segwit-activated chains).  As it stands now, this
seems like a very dangerous attempt to compromise with a small but
vocal group that are the ones creating the threat to begin with.

Jared

On Tue, Jun 6, 2017 at 5:56 PM, James Hilliard via bitcoin-dev
<bitcoin-dev@lists.linuxfoundation.org> wrote:
> Due to the proposed calendar(https://segwit2x.github.io/) for the
> SegWit2x agreement being too slow to activate SegWit mandatory
> signalling ahead of BIP148 using BIP91 I would like to propose another
> option that miners can use to prevent a chain split ahead of the Aug
> 1st BIP148 activation date.
>
> The splitprotection soft fork is essentially BIP91 but using BIP8
> instead of BIP9 with a lower activation threshold and immediate
> mandatory signalling lock-in. This allows for a majority of miners to
> activate mandatory SegWit signalling and prevent a potential chain
> split ahead of BIP148 activation.
>
> This BIP allows for miners to respond to market forces quickly ahead
> of BIP148 activation by signalling for splitprotection. Any miners
> already running BIP148 should be encouraged to use splitprotection.
>
> <pre>
>   BIP: splitprotection
>   Layer: Consensus (soft fork)
>   Title: User Activated Soft Fork Split Protection
>   Author: James Hilliard <james.hilliard1@gmail.com>
>   Comments-Summary: No comments yet.
>   Comments-URI:
>   Status: Draft
>   Type: Standards Track
>   Created: 2017-05-22
>   License: BSD-3-Clause
>            CC0-1.0
> </pre>
>
> ==Abstract==
>
> This document specifies a coordination mechanism for a simple majority
> of miners to prevent a chain split ahead of BIP148 activation.
>
> ==Definitions==
>
> "existing segwit deployment" refer to the BIP9 "segwit" deployment
> using bit 1, between November 15th 2016 and November 15th 2017 to
> activate BIP141, BIP143 and BIP147.
>
> ==Motivation==
>
> The biggest risk of BIP148 is an extended chain split, this BIP
> provides a way for a simple majority of miners to eliminate that risk.
>
> This BIP provides a way for a simple majority of miners to coordinate
> activation of the existing segwit deployment with less than 95%
> hashpower before BIP148 activation. Due to time constraints unless
> immediately deployed BIP91 will likely not be able to enforce
> mandatory signalling of segwit before the Aug 1st activation of
> BIP148. This BIP provides a method for rapid miner activation of
> SegWit mandatory signalling ahead of the BIP148 activation date. Since
> the primary goal of this BIP is to reduce the chance of an extended
> chain split as much as possible we activate using a simple miner
> majority of 65% over a 504 block interval rather than a higher
> percentage. This BIP also allows miners to signal their intention to
> run BIP148 in order to prevent a chain split.
>
> ==Specification==
>
> While this BIP is active, all blocks must set the nVersion header top
> 3 bits to 001 together with bit field (1<<1) (according to the
> existing segwit deployment). Blocks that do not signal as required
> will be rejected.
>
> ==Deployment==
>
> This BIP will be deployed by "version bits" with a 65%(this can be
> adjusted if desired) activation threshold BIP9 with the name
> "splitprotecion" and using bit 2.
>
> This BIP starts immediately and is a BIP8 style soft fork since
> mandatory signalling will start on midnight August 1st 2017 (epoch
> time 1501545600) regardless of whether or not this BIP has reached its
> own signalling threshold. This BIP will cease to be active when segwit
> is locked-in.
>
> === Reference implementation ===
>
> <pre>
> // Check if Segregated Witness is Locked In
> bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
> Consensus::Params& params)
> {
>     LOCK(cs_main);
>     return (VersionBitsState(pindexPrev, params,
> Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
> THRESHOLD_LOCKED_IN);
> }
>
> // SPLITPROTECTION mandatory segwit signalling.
> if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
> Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
> THRESHOLD_LOCKED_IN &&
>      !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
> // Segwit is not locked in
>      !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
> and is not active.
> {
>     bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
> VERSIONBITS_TOP_BITS;
>     bool fSegbit = (pindex->nVersion &
> VersionBitsMask(chainparams.GetConsensus(),
> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>     if (!(fVersionBits && fSegbit)) {
>         return state.DoS(0, error("ConnectBlock(): relayed block must
> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>     }
> }
>
> // BIP148 mandatory segwit signalling.
> int64_t nMedianTimePast = pindex->GetMedianTimePast();
> if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00 UTC
>      (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
>      (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>  // Segwit is not locked in
>       !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
>  // and is not active.
> {
>     bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
> VERSIONBITS_TOP_BITS;
>     bool fSegbit = (pindex->nVersion &
> VersionBitsMask(chainparams.GetConsensus(),
> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>     if (!(fVersionBits && fSegbit)) {
>         return state.DoS(0, error("ConnectBlock(): relayed block must
> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>     }
> }
> </pre>
>
> https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1
>
> ==Backwards Compatibility==
>
> This deployment is compatible with the existing "segwit" bit 1
> deployment scheduled between midnight November 15th, 2016 and midnight
> November 15th, 2017. This deployment is also compatible with the
> existing BIP148 deployment. This BIP is compatible with BIP91 only if
> BIP91 activates before it and before BIP148. Miners will need to
> upgrade their nodes to support splitprotection otherwise they may
> build on top of an invalid block. While this bip is active users
> should either upgrade to splitprotection or wait for additional
> confirmations when accepting payments.
>
> ==Rationale==
>
> Historically we have used IsSuperMajority() to activate soft forks
> such as BIP66 which has a mandatory signalling requirement for miners
> once activated, this ensures that miners are aware of new rules being
> enforced. This technique can be leveraged to lower the signalling
> threshold of a soft fork while it is in the process of being deployed
> in a backwards compatible way. We also use a BIP8 style timeout to
> ensure that this BIP is compatible with BIP148 and that BIP148
> compatible mandatory signalling activates regardless of miner
> signalling levels.
>
> By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
> deployment, this BIP can cause the existing "segwit" deployment to
> activate without needing to release a new deployment. As we approach
> BIP148 activation it may be desirable for a majority of miners to have
> a method that will ensure that there is no chain split.
>
> ==References==
>
> *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html
> Mailing list discussion]
> *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283
> P2SH flag day activation]
> *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
> *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
> *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
> *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
> *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
> Version 0 Witness Program]]
> *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element malleability]]
> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment]]
> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
> *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit benefits]
>
> ==Copyright==
>
> This document is dual licensed as BSD 3-clause, and Creative Commons
> CC0 1.0 Universal.
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev

Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[James Hilliard]

I don't really see how this would increase the likelihood of an
extended chain split assuming BIP148 is going to have
non-insignificant economic backing. This BIP is designed to provide a
risk mitigation measure that miners can safely deploy. Since this BIP
only activates with a clear miner majority it should not increase the
risk of an extended chain split. At this point it is not completely
clear how much economic support there is for BIP148 but support
certainly seems to be growing and we have nearly 2 months until BIP148
activation. I intentionally used a shorter activation period here so
that decisions by miners can be made close to the BIP148 activation
date.

On Wed, Jun 7, 2017 at 4:29 PM, Jared Lee Richardson <jaredr26@gmail.com> wrote:
> I think this BIP represents a gamble, and the gamble may not be a good
> one.  The gamble here is that if the segwit2x changes are rolled out
> on time, and if the signatories accept the bit4 + bit1 signaling
> proposals within BIP91, the launch will go smoother, as intended.  But
> conversely, if either the segwit2x signatories balk about the Bit1
> signaling OR if the timelines for segwit2mb are missed even by a bit,
> it may cause the BIP148 chainsplit to be worse than it would be
> without.  Given the frequent concerns raised in multiple places about
> the aggressiveness of the segwit2x timelines, including the
> non-hardfork timelines, this does not seem like a great gamble to be
> making.
>
> The reason I say it may make the chainsplit be worse than it would
> otherwise be is that it may provide a false sense of safety for BIP148
> that currently does not currently exist(and should not, as it is a
> chainsplit).  That sense of safety would only be legitimate if the
> segwit2x signatories were on board, and the segwit2x code effectively
> enforced BIP148 simultaneously, neither of which are guaranteed.  If
> users and more miners had a false sense that BIP148 was *not* going to
> chainsplit from default / segwit2x, they might not follow the news if
> suddenly the segwit2x plan were delayed for a few days.  While any
> additional support would definitely be cheered on by BIP148
> supporters, the practical reality might be that this proposal would
> take BIP148 from the "unlikely to have any viable chain after flag day
> without segwit2x" category into the "small but viable minority chain"
> category, and even worse, it might strengthen the chainsplit just days
> before segwit is activated on BOTH chains, putting the BIP148
> supporters on the wrong pro-segwit, but still-viable chain.
>
> If Core had taken a strong stance to include BIP148 into the client,
> and if BIP148 support were much much broader, I would feel differently
> as the gamble would be more likely to discourage a chainsplit (By
> forcing the acceleration of segwit2x) rather than encourage it (by
> strengthening an extreme minority chainsplit that may wind up on the
> wrong side of two segwit-activated chains).  As it stands now, this
> seems like a very dangerous attempt to compromise with a small but
> vocal group that are the ones creating the threat to begin with.
>
> Jared
>
> On Tue, Jun 6, 2017 at 5:56 PM, James Hilliard via bitcoin-dev
> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>> Due to the proposed calendar(https://segwit2x.github.io/) for the
>> SegWit2x agreement being too slow to activate SegWit mandatory
>> signalling ahead of BIP148 using BIP91 I would like to propose another
>> option that miners can use to prevent a chain split ahead of the Aug
>> 1st BIP148 activation date.
>>
>> The splitprotection soft fork is essentially BIP91 but using BIP8
>> instead of BIP9 with a lower activation threshold and immediate
>> mandatory signalling lock-in. This allows for a majority of miners to
>> activate mandatory SegWit signalling and prevent a potential chain
>> split ahead of BIP148 activation.
>>
>> This BIP allows for miners to respond to market forces quickly ahead
>> of BIP148 activation by signalling for splitprotection. Any miners
>> already running BIP148 should be encouraged to use splitprotection.
>>
>> <pre>
>>   BIP: splitprotection
>>   Layer: Consensus (soft fork)
>>   Title: User Activated Soft Fork Split Protection
>>   Author: James Hilliard <james.hilliard1@gmail.com>
>>   Comments-Summary: No comments yet.
>>   Comments-URI:
>>   Status: Draft
>>   Type: Standards Track
>>   Created: 2017-05-22
>>   License: BSD-3-Clause
>>            CC0-1.0
>> </pre>
>>
>> ==Abstract==
>>
>> This document specifies a coordination mechanism for a simple majority
>> of miners to prevent a chain split ahead of BIP148 activation.
>>
>> ==Definitions==
>>
>> "existing segwit deployment" refer to the BIP9 "segwit" deployment
>> using bit 1, between November 15th 2016 and November 15th 2017 to
>> activate BIP141, BIP143 and BIP147.
>>
>> ==Motivation==
>>
>> The biggest risk of BIP148 is an extended chain split, this BIP
>> provides a way for a simple majority of miners to eliminate that risk.
>>
>> This BIP provides a way for a simple majority of miners to coordinate
>> activation of the existing segwit deployment with less than 95%
>> hashpower before BIP148 activation. Due to time constraints unless
>> immediately deployed BIP91 will likely not be able to enforce
>> mandatory signalling of segwit before the Aug 1st activation of
>> BIP148. This BIP provides a method for rapid miner activation of
>> SegWit mandatory signalling ahead of the BIP148 activation date. Since
>> the primary goal of this BIP is to reduce the chance of an extended
>> chain split as much as possible we activate using a simple miner
>> majority of 65% over a 504 block interval rather than a higher
>> percentage. This BIP also allows miners to signal their intention to
>> run BIP148 in order to prevent a chain split.
>>
>> ==Specification==
>>
>> While this BIP is active, all blocks must set the nVersion header top
>> 3 bits to 001 together with bit field (1<<1) (according to the
>> existing segwit deployment). Blocks that do not signal as required
>> will be rejected.
>>
>> ==Deployment==
>>
>> This BIP will be deployed by "version bits" with a 65%(this can be
>> adjusted if desired) activation threshold BIP9 with the name
>> "splitprotecion" and using bit 2.
>>
>> This BIP starts immediately and is a BIP8 style soft fork since
>> mandatory signalling will start on midnight August 1st 2017 (epoch
>> time 1501545600) regardless of whether or not this BIP has reached its
>> own signalling threshold. This BIP will cease to be active when segwit
>> is locked-in.
>>
>> === Reference implementation ===
>>
>> <pre>
>> // Check if Segregated Witness is Locked In
>> bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
>> Consensus::Params& params)
>> {
>>     LOCK(cs_main);
>>     return (VersionBitsState(pindexPrev, params,
>> Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
>> THRESHOLD_LOCKED_IN);
>> }
>>
>> // SPLITPROTECTION mandatory segwit signalling.
>> if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
>> Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
>> THRESHOLD_LOCKED_IN &&
>>      !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>> // Segwit is not locked in
>>      !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
>> and is not active.
>> {
>>     bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>> VERSIONBITS_TOP_BITS;
>>     bool fSegbit = (pindex->nVersion &
>> VersionBitsMask(chainparams.GetConsensus(),
>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>     if (!(fVersionBits && fSegbit)) {
>>         return state.DoS(0, error("ConnectBlock(): relayed block must
>> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>     }
>> }
>>
>> // BIP148 mandatory segwit signalling.
>> int64_t nMedianTimePast = pindex->GetMedianTimePast();
>> if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00 UTC
>>      (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
>>      (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>>  // Segwit is not locked in
>>       !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
>>  // and is not active.
>> {
>>     bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>> VERSIONBITS_TOP_BITS;
>>     bool fSegbit = (pindex->nVersion &
>> VersionBitsMask(chainparams.GetConsensus(),
>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>     if (!(fVersionBits && fSegbit)) {
>>         return state.DoS(0, error("ConnectBlock(): relayed block must
>> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>     }
>> }
>> </pre>
>>
>> https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1
>>
>> ==Backwards Compatibility==
>>
>> This deployment is compatible with the existing "segwit" bit 1
>> deployment scheduled between midnight November 15th, 2016 and midnight
>> November 15th, 2017. This deployment is also compatible with the
>> existing BIP148 deployment. This BIP is compatible with BIP91 only if
>> BIP91 activates before it and before BIP148. Miners will need to
>> upgrade their nodes to support splitprotection otherwise they may
>> build on top of an invalid block. While this bip is active users
>> should either upgrade to splitprotection or wait for additional
>> confirmations when accepting payments.
>>
>> ==Rationale==
>>
>> Historically we have used IsSuperMajority() to activate soft forks
>> such as BIP66 which has a mandatory signalling requirement for miners
>> once activated, this ensures that miners are aware of new rules being
>> enforced. This technique can be leveraged to lower the signalling
>> threshold of a soft fork while it is in the process of being deployed
>> in a backwards compatible way. We also use a BIP8 style timeout to
>> ensure that this BIP is compatible with BIP148 and that BIP148
>> compatible mandatory signalling activates regardless of miner
>> signalling levels.
>>
>> By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
>> deployment, this BIP can cause the existing "segwit" deployment to
>> activate without needing to release a new deployment. As we approach
>> BIP148 activation it may be desirable for a majority of miners to have
>> a method that will ensure that there is no chain split.
>>
>> ==References==
>>
>> *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html
>> Mailing list discussion]
>> *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283
>> P2SH flag day activation]
>> *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
>> *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
>> *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
>> *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
>> *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
>> Version 0 Witness Program]]
>> *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element malleability]]
>> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment]]
>> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
>> *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit benefits]
>>
>> ==Copyright==
>>
>> This document is dual licensed as BSD 3-clause, and Creative Commons
>> CC0 1.0 Universal.
>> _______________________________________________
>> bitcoin-dev mailing list
>> bitcoin-dev@lists.linuxfoundation.org
>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev

Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[Jared Lee Richardson]

> Keep in mind that this is only temporary until segwit has locked in,
after that happens it becomes optional for miners again.

I missed that, that does effectively address that concern.  It appears
that BIP148 implements the same rule as would be required to prevent a
later chainsplit as well, no?

This comment did bring to mind another concern about BIP148/91 though,
which I'll raise in the pull request discussion.  Feel free to respond
to it there.

Jared

On Wed, Jun 7, 2017 at 2:21 PM, James Hilliard
<james.hilliard1@gmail.com> wrote:
> Keep in mind that this is only temporary until segwit has locked in,
> after that happens it becomes optional for miners again.
>
> On Wed, Jun 7, 2017 at 4:09 PM, Jared Lee Richardson <jaredr26@gmail.com> wrote:
>>> This is, by far, the safest way for miners to quickly defend against a chain split, much better than a -bip148 option.   This allows miners to defend themselves, with very little risk, since the defense is only activated if the majority of miners do so. I would move for a very rapid deployment.   Only miners would need to upgrade.   Regular users would not have to concern themselves with this release.
>>
>> FYI, even if very successful, this deployment and change may have a
>> severe negative impact on a small group of miners.  Any miners/pools
>> who are not actively following the forums, news, or these discussions
>> may be difficult to reach and communicate with in time, particularly
>> with language barriers.  Of those, any who are also either not
>> signaling segwit currently or are running an older software version
>> will have their blocks continuously and constantly orphaned, but may
>> not have any alarms or notifications set up for such an unexpected
>> failure.  That may or may not be a worthy consideration, but it is
>> definitely brusque and a harsh price to pay.  Considering the
>> opposition mentioned against transaction limits for the rare cases
>> where a very large transaction has already been signed, it seems that
>> this would be worthy of consideration.  For the few miners in that
>> situation, it does turn segwit from an optional softfork into a
>> punishing hardfork.
>>
>> I don't think that's a sufficient reason alone to kill the idea, but
>> it should be a concern.
>>
>> Jared
>>
>> On Wed, Jun 7, 2017 at 7:10 AM, Erik Aronesty via bitcoin-dev
>> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>>> This is, by far, the safest way for miners to quickly defend against a chain
>>> split, much better than a -bip148 option.   This allows miners to defend
>>> themselves, with very little risk, since the defense is only activated if
>>> the majority of miners do so. I would move for a very rapid deployment.
>>> Only miners would need to upgrade.   Regular users would not have to concern
>>> themselves with this release.
>>>
>>> On Wed, Jun 7, 2017 at 6:13 AM, James Hilliard via bitcoin-dev
>>> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>>>>
>>>> I think even 55% would probably work out fine simply due to incentive
>>>> structures, once signalling is over 51% it's then clear to miners that
>>>> non-signalling blocks will be orphaned and the rest will rapidly
>>>> update to splitprotection/BIP148. The purpose of this BIP is to reduce
>>>> chain split risk for BIP148 since it's looking like BIP148 is going to
>>>> be run by a non-insignificant percentage of the economy at a minimum.
>>>>
>>>> On Wed, Jun 7, 2017 at 12:20 AM, Tao Effect <contact@taoeffect.com> wrote:
>>>> > See thread on replay attacks for why activating regardless of threshold
>>>> > is a
>>>> > bad idea [1].
>>>> >
>>>> > BIP91 OTOH seems perfectly reasonable. 80% instead of 95% makes it more
>>>> > difficult for miners to hold together in opposition to Core. It gives
>>>> > Core
>>>> > more leverage in negotiations.
>>>> >
>>>> > If they don't activate with 80%, Core can release another BIP to reduce
>>>> > it
>>>> > to 75%.
>>>> >
>>>> > Each threshold reduction makes it both more likely to succeed, but also
>>>> > increases the likelihood of harm to the ecosystem.
>>>> >
>>>> > Cheers,
>>>> > Greg
>>>> >
>>>> > [1]
>>>> >
>>>> > https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-June/014497.html
>>>> >
>>>> > --
>>>> > Please do not email me anything that you are not comfortable also
>>>> > sharing
>>>> > with the NSA.
>>>> >
>>>> > On Jun 6, 2017, at 6:54 PM, James Hilliard <james.hilliard1@gmail.com>
>>>> > wrote:
>>>> >
>>>> > This is a BIP8 style soft fork so mandatory signalling will be active
>>>> > after Aug 1st regardless.
>>>> >
>>>> > On Tue, Jun 6, 2017 at 8:51 PM, Tao Effect <contact@taoeffect.com>
>>>> > wrote:
>>>> >
>>>> > What is the probability that a 65% threshold is too low and can allow a
>>>> > "surprise miner attack", whereby miners are kept offline before the
>>>> > deadline, and brought online immediately after, creating potential
>>>> > havoc?
>>>> >
>>>> > (Nit: "simple majority" usually refers to >50%, I think, might cause
>>>> > confusion.)
>>>> >
>>>> > -Greg Slepak
>>>> >
>>>> > --
>>>> > Please do not email me anything that you are not comfortable also
>>>> > sharing
>>>> > with the NSA.
>>>> >
>>>> > On Jun 6, 2017, at 5:56 PM, James Hilliard via bitcoin-dev
>>>> > <bitcoin-dev@lists.linuxfoundation.org> wrote:
>>>> >
>>>> > Due to the proposed calendar(https://segwit2x.github.io/) for the
>>>> > SegWit2x agreement being too slow to activate SegWit mandatory
>>>> > signalling ahead of BIP148 using BIP91 I would like to propose another
>>>> > option that miners can use to prevent a chain split ahead of the Aug
>>>> > 1st BIP148 activation date.
>>>> >
>>>> > The splitprotection soft fork is essentially BIP91 but using BIP8
>>>> > instead of BIP9 with a lower activation threshold and immediate
>>>> > mandatory signalling lock-in. This allows for a majority of miners to
>>>> > activate mandatory SegWit signalling and prevent a potential chain
>>>> > split ahead of BIP148 activation.
>>>> >
>>>> > This BIP allows for miners to respond to market forces quickly ahead
>>>> > of BIP148 activation by signalling for splitprotection. Any miners
>>>> > already running BIP148 should be encouraged to use splitprotection.
>>>> >
>>>> > <pre>
>>>> > BIP: splitprotection
>>>> > Layer: Consensus (soft fork)
>>>> > Title: User Activated Soft Fork Split Protection
>>>> > Author: James Hilliard <james.hilliard1@gmail.com>
>>>> > Comments-Summary: No comments yet.
>>>> > Comments-URI:
>>>> > Status: Draft
>>>> > Type: Standards Track
>>>> > Created: 2017-05-22
>>>> > License: BSD-3-Clause
>>>> >          CC0-1.0
>>>> > </pre>
>>>> >
>>>> > ==Abstract==
>>>> >
>>>> > This document specifies a coordination mechanism for a simple majority
>>>> > of miners to prevent a chain split ahead of BIP148 activation.
>>>> >
>>>> > ==Definitions==
>>>> >
>>>> > "existing segwit deployment" refer to the BIP9 "segwit" deployment
>>>> > using bit 1, between November 15th 2016 and November 15th 2017 to
>>>> > activate BIP141, BIP143 and BIP147.
>>>> >
>>>> > ==Motivation==
>>>> >
>>>> > The biggest risk of BIP148 is an extended chain split, this BIP
>>>> > provides a way for a simple majority of miners to eliminate that risk.
>>>> >
>>>> > This BIP provides a way for a simple majority of miners to coordinate
>>>> > activation of the existing segwit deployment with less than 95%
>>>> > hashpower before BIP148 activation. Due to time constraints unless
>>>> > immediately deployed BIP91 will likely not be able to enforce
>>>> > mandatory signalling of segwit before the Aug 1st activation of
>>>> > BIP148. This BIP provides a method for rapid miner activation of
>>>> > SegWit mandatory signalling ahead of the BIP148 activation date. Since
>>>> > the primary goal of this BIP is to reduce the chance of an extended
>>>> > chain split as much as possible we activate using a simple miner
>>>> > majority of 65% over a 504 block interval rather than a higher
>>>> > percentage. This BIP also allows miners to signal their intention to
>>>> > run BIP148 in order to prevent a chain split.
>>>> >
>>>> > ==Specification==
>>>> >
>>>> > While this BIP is active, all blocks must set the nVersion header top
>>>> > 3 bits to 001 together with bit field (1<<1) (according to the
>>>> > existing segwit deployment). Blocks that do not signal as required
>>>> > will be rejected.
>>>> >
>>>> > ==Deployment==
>>>> >
>>>> > This BIP will be deployed by "version bits" with a 65%(this can be
>>>> > adjusted if desired) activation threshold BIP9 with the name
>>>> > "splitprotecion" and using bit 2.
>>>> >
>>>> > This BIP starts immediately and is a BIP8 style soft fork since
>>>> > mandatory signalling will start on midnight August 1st 2017 (epoch
>>>> > time 1501545600) regardless of whether or not this BIP has reached its
>>>> > own signalling threshold. This BIP will cease to be active when segwit
>>>> > is locked-in.
>>>> >
>>>> > === Reference implementation ===
>>>> >
>>>> > <pre>
>>>> > // Check if Segregated Witness is Locked In
>>>> > bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
>>>> > Consensus::Params& params)
>>>> > {
>>>> >   LOCK(cs_main);
>>>> >   return (VersionBitsState(pindexPrev, params,
>>>> > Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
>>>> > THRESHOLD_LOCKED_IN);
>>>> > }
>>>> >
>>>> > // SPLITPROTECTION mandatory segwit signalling.
>>>> > if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
>>>> > Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
>>>> > THRESHOLD_LOCKED_IN &&
>>>> >    !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>>>> > // Segwit is not locked in
>>>> >    !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
>>>> > and is not active.
>>>> > {
>>>> >   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>>>> > VERSIONBITS_TOP_BITS;
>>>> >   bool fSegbit = (pindex->nVersion &
>>>> > VersionBitsMask(chainparams.GetConsensus(),
>>>> > Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>>> >   if (!(fVersionBits && fSegbit)) {
>>>> >       return state.DoS(0, error("ConnectBlock(): relayed block must
>>>> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>>> >   }
>>>> > }
>>>> >
>>>> > // BIP148 mandatory segwit signalling.
>>>> > int64_t nMedianTimePast = pindex->GetMedianTimePast();
>>>> > if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00 UTC
>>>> >    (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
>>>> >    (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>>>> > // Segwit is not locked in
>>>> >     !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
>>>> > // and is not active.
>>>> > {
>>>> >   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>>>> > VERSIONBITS_TOP_BITS;
>>>> >   bool fSegbit = (pindex->nVersion &
>>>> > VersionBitsMask(chainparams.GetConsensus(),
>>>> > Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>>> >   if (!(fVersionBits && fSegbit)) {
>>>> >       return state.DoS(0, error("ConnectBlock(): relayed block must
>>>> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>>> >   }
>>>> > }
>>>> > </pre>
>>>> >
>>>> >
>>>> > https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1
>>>> >
>>>> > ==Backwards Compatibility==
>>>> >
>>>> > This deployment is compatible with the existing "segwit" bit 1
>>>> > deployment scheduled between midnight November 15th, 2016 and midnight
>>>> > November 15th, 2017. This deployment is also compatible with the
>>>> > existing BIP148 deployment. This BIP is compatible with BIP91 only if
>>>> > BIP91 activates before it and before BIP148. Miners will need to
>>>> > upgrade their nodes to support splitprotection otherwise they may
>>>> > build on top of an invalid block. While this bip is active users
>>>> > should either upgrade to splitprotection or wait for additional
>>>> > confirmations when accepting payments.
>>>> >
>>>> > ==Rationale==
>>>> >
>>>> > Historically we have used IsSuperMajority() to activate soft forks
>>>> > such as BIP66 which has a mandatory signalling requirement for miners
>>>> > once activated, this ensures that miners are aware of new rules being
>>>> > enforced. This technique can be leveraged to lower the signalling
>>>> > threshold of a soft fork while it is in the process of being deployed
>>>> > in a backwards compatible way. We also use a BIP8 style timeout to
>>>> > ensure that this BIP is compatible with BIP148 and that BIP148
>>>> > compatible mandatory signalling activates regardless of miner
>>>> > signalling levels.
>>>> >
>>>> > By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
>>>> > deployment, this BIP can cause the existing "segwit" deployment to
>>>> > activate without needing to release a new deployment. As we approach
>>>> > BIP148 activation it may be desirable for a majority of miners to have
>>>> > a method that will ensure that there is no chain split.
>>>> >
>>>> > ==References==
>>>> >
>>>> >
>>>> > *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html
>>>> > Mailing list discussion]
>>>> >
>>>> > *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283
>>>> > P2SH flag day activation]
>>>> > *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
>>>> > *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
>>>> > *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
>>>> > *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
>>>> > *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
>>>> > Version 0 Witness Program]]
>>>> > *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element
>>>> > malleability]]
>>>> > *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment]]
>>>> > *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
>>>> > *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit
>>>> > benefits]
>>>> >
>>>> > ==Copyright==
>>>> >
>>>> > This document is dual licensed as BSD 3-clause, and Creative Commons
>>>> > CC0 1.0 Universal.
>>>> > _______________________________________________
>>>> > bitcoin-dev mailing list
>>>> > bitcoin-dev@lists.linuxfoundation.org
>>>> > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>>> >
>>>> >
>>>> >
>>>> _______________________________________________
>>>> bitcoin-dev mailing list
>>>> bitcoin-dev@lists.linuxfoundation.org
>>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>>
>>>
>>>
>>> _______________________________________________
>>> bitcoin-dev mailing list
>>> bitcoin-dev@lists.linuxfoundation.org
>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>>

Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[James Hilliard]

Yes, this is the same as BIP148, there is no mandatory signalling
after segwit is locked in.

On Wed, Jun 7, 2017 at 4:43 PM, Jared Lee Richardson <jaredr26@gmail.com> wrote:
>> Keep in mind that this is only temporary until segwit has locked in,
> after that happens it becomes optional for miners again.
>
> I missed that, that does effectively address that concern.  It appears
> that BIP148 implements the same rule as would be required to prevent a
> later chainsplit as well, no?
>
> This comment did bring to mind another concern about BIP148/91 though,
> which I'll raise in the pull request discussion.  Feel free to respond
> to it there.
>
> Jared
>
> On Wed, Jun 7, 2017 at 2:21 PM, James Hilliard
> <james.hilliard1@gmail.com> wrote:
>> Keep in mind that this is only temporary until segwit has locked in,
>> after that happens it becomes optional for miners again.
>>
>> On Wed, Jun 7, 2017 at 4:09 PM, Jared Lee Richardson <jaredr26@gmail.com> wrote:
>>>> This is, by far, the safest way for miners to quickly defend against a chain split, much better than a -bip148 option.   This allows miners to defend themselves, with very little risk, since the defense is only activated if the majority of miners do so. I would move for a very rapid deployment.   Only miners would need to upgrade.   Regular users would not have to concern themselves with this release.
>>>
>>> FYI, even if very successful, this deployment and change may have a
>>> severe negative impact on a small group of miners.  Any miners/pools
>>> who are not actively following the forums, news, or these discussions
>>> may be difficult to reach and communicate with in time, particularly
>>> with language barriers.  Of those, any who are also either not
>>> signaling segwit currently or are running an older software version
>>> will have their blocks continuously and constantly orphaned, but may
>>> not have any alarms or notifications set up for such an unexpected
>>> failure.  That may or may not be a worthy consideration, but it is
>>> definitely brusque and a harsh price to pay.  Considering the
>>> opposition mentioned against transaction limits for the rare cases
>>> where a very large transaction has already been signed, it seems that
>>> this would be worthy of consideration.  For the few miners in that
>>> situation, it does turn segwit from an optional softfork into a
>>> punishing hardfork.
>>>
>>> I don't think that's a sufficient reason alone to kill the idea, but
>>> it should be a concern.
>>>
>>> Jared
>>>
>>> On Wed, Jun 7, 2017 at 7:10 AM, Erik Aronesty via bitcoin-dev
>>> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>>>> This is, by far, the safest way for miners to quickly defend against a chain
>>>> split, much better than a -bip148 option.   This allows miners to defend
>>>> themselves, with very little risk, since the defense is only activated if
>>>> the majority of miners do so. I would move for a very rapid deployment.
>>>> Only miners would need to upgrade.   Regular users would not have to concern
>>>> themselves with this release.
>>>>
>>>> On Wed, Jun 7, 2017 at 6:13 AM, James Hilliard via bitcoin-dev
>>>> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>>>>>
>>>>> I think even 55% would probably work out fine simply due to incentive
>>>>> structures, once signalling is over 51% it's then clear to miners that
>>>>> non-signalling blocks will be orphaned and the rest will rapidly
>>>>> update to splitprotection/BIP148. The purpose of this BIP is to reduce
>>>>> chain split risk for BIP148 since it's looking like BIP148 is going to
>>>>> be run by a non-insignificant percentage of the economy at a minimum.
>>>>>
>>>>> On Wed, Jun 7, 2017 at 12:20 AM, Tao Effect <contact@taoeffect.com> wrote:
>>>>> > See thread on replay attacks for why activating regardless of threshold
>>>>> > is a
>>>>> > bad idea [1].
>>>>> >
>>>>> > BIP91 OTOH seems perfectly reasonable. 80% instead of 95% makes it more
>>>>> > difficult for miners to hold together in opposition to Core. It gives
>>>>> > Core
>>>>> > more leverage in negotiations.
>>>>> >
>>>>> > If they don't activate with 80%, Core can release another BIP to reduce
>>>>> > it
>>>>> > to 75%.
>>>>> >
>>>>> > Each threshold reduction makes it both more likely to succeed, but also
>>>>> > increases the likelihood of harm to the ecosystem.
>>>>> >
>>>>> > Cheers,
>>>>> > Greg
>>>>> >
>>>>> > [1]
>>>>> >
>>>>> > https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-June/014497.html
>>>>> >
>>>>> > --
>>>>> > Please do not email me anything that you are not comfortable also
>>>>> > sharing
>>>>> > with the NSA.
>>>>> >
>>>>> > On Jun 6, 2017, at 6:54 PM, James Hilliard <james.hilliard1@gmail.com>
>>>>> > wrote:
>>>>> >
>>>>> > This is a BIP8 style soft fork so mandatory signalling will be active
>>>>> > after Aug 1st regardless.
>>>>> >
>>>>> > On Tue, Jun 6, 2017 at 8:51 PM, Tao Effect <contact@taoeffect.com>
>>>>> > wrote:
>>>>> >
>>>>> > What is the probability that a 65% threshold is too low and can allow a
>>>>> > "surprise miner attack", whereby miners are kept offline before the
>>>>> > deadline, and brought online immediately after, creating potential
>>>>> > havoc?
>>>>> >
>>>>> > (Nit: "simple majority" usually refers to >50%, I think, might cause
>>>>> > confusion.)
>>>>> >
>>>>> > -Greg Slepak
>>>>> >
>>>>> > --
>>>>> > Please do not email me anything that you are not comfortable also
>>>>> > sharing
>>>>> > with the NSA.
>>>>> >
>>>>> > On Jun 6, 2017, at 5:56 PM, James Hilliard via bitcoin-dev
>>>>> > <bitcoin-dev@lists.linuxfoundation.org> wrote:
>>>>> >
>>>>> > Due to the proposed calendar(https://segwit2x.github.io/) for the
>>>>> > SegWit2x agreement being too slow to activate SegWit mandatory
>>>>> > signalling ahead of BIP148 using BIP91 I would like to propose another
>>>>> > option that miners can use to prevent a chain split ahead of the Aug
>>>>> > 1st BIP148 activation date.
>>>>> >
>>>>> > The splitprotection soft fork is essentially BIP91 but using BIP8
>>>>> > instead of BIP9 with a lower activation threshold and immediate
>>>>> > mandatory signalling lock-in. This allows for a majority of miners to
>>>>> > activate mandatory SegWit signalling and prevent a potential chain
>>>>> > split ahead of BIP148 activation.
>>>>> >
>>>>> > This BIP allows for miners to respond to market forces quickly ahead
>>>>> > of BIP148 activation by signalling for splitprotection. Any miners
>>>>> > already running BIP148 should be encouraged to use splitprotection.
>>>>> >
>>>>> > <pre>
>>>>> > BIP: splitprotection
>>>>> > Layer: Consensus (soft fork)
>>>>> > Title: User Activated Soft Fork Split Protection
>>>>> > Author: James Hilliard <james.hilliard1@gmail.com>
>>>>> > Comments-Summary: No comments yet.
>>>>> > Comments-URI:
>>>>> > Status: Draft
>>>>> > Type: Standards Track
>>>>> > Created: 2017-05-22
>>>>> > License: BSD-3-Clause
>>>>> >          CC0-1.0
>>>>> > </pre>
>>>>> >
>>>>> > ==Abstract==
>>>>> >
>>>>> > This document specifies a coordination mechanism for a simple majority
>>>>> > of miners to prevent a chain split ahead of BIP148 activation.
>>>>> >
>>>>> > ==Definitions==
>>>>> >
>>>>> > "existing segwit deployment" refer to the BIP9 "segwit" deployment
>>>>> > using bit 1, between November 15th 2016 and November 15th 2017 to
>>>>> > activate BIP141, BIP143 and BIP147.
>>>>> >
>>>>> > ==Motivation==
>>>>> >
>>>>> > The biggest risk of BIP148 is an extended chain split, this BIP
>>>>> > provides a way for a simple majority of miners to eliminate that risk.
>>>>> >
>>>>> > This BIP provides a way for a simple majority of miners to coordinate
>>>>> > activation of the existing segwit deployment with less than 95%
>>>>> > hashpower before BIP148 activation. Due to time constraints unless
>>>>> > immediately deployed BIP91 will likely not be able to enforce
>>>>> > mandatory signalling of segwit before the Aug 1st activation of
>>>>> > BIP148. This BIP provides a method for rapid miner activation of
>>>>> > SegWit mandatory signalling ahead of the BIP148 activation date. Since
>>>>> > the primary goal of this BIP is to reduce the chance of an extended
>>>>> > chain split as much as possible we activate using a simple miner
>>>>> > majority of 65% over a 504 block interval rather than a higher
>>>>> > percentage. This BIP also allows miners to signal their intention to
>>>>> > run BIP148 in order to prevent a chain split.
>>>>> >
>>>>> > ==Specification==
>>>>> >
>>>>> > While this BIP is active, all blocks must set the nVersion header top
>>>>> > 3 bits to 001 together with bit field (1<<1) (according to the
>>>>> > existing segwit deployment). Blocks that do not signal as required
>>>>> > will be rejected.
>>>>> >
>>>>> > ==Deployment==
>>>>> >
>>>>> > This BIP will be deployed by "version bits" with a 65%(this can be
>>>>> > adjusted if desired) activation threshold BIP9 with the name
>>>>> > "splitprotecion" and using bit 2.
>>>>> >
>>>>> > This BIP starts immediately and is a BIP8 style soft fork since
>>>>> > mandatory signalling will start on midnight August 1st 2017 (epoch
>>>>> > time 1501545600) regardless of whether or not this BIP has reached its
>>>>> > own signalling threshold. This BIP will cease to be active when segwit
>>>>> > is locked-in.
>>>>> >
>>>>> > === Reference implementation ===
>>>>> >
>>>>> > <pre>
>>>>> > // Check if Segregated Witness is Locked In
>>>>> > bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
>>>>> > Consensus::Params& params)
>>>>> > {
>>>>> >   LOCK(cs_main);
>>>>> >   return (VersionBitsState(pindexPrev, params,
>>>>> > Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
>>>>> > THRESHOLD_LOCKED_IN);
>>>>> > }
>>>>> >
>>>>> > // SPLITPROTECTION mandatory segwit signalling.
>>>>> > if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
>>>>> > Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
>>>>> > THRESHOLD_LOCKED_IN &&
>>>>> >    !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>>>>> > // Segwit is not locked in
>>>>> >    !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
>>>>> > and is not active.
>>>>> > {
>>>>> >   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>>>>> > VERSIONBITS_TOP_BITS;
>>>>> >   bool fSegbit = (pindex->nVersion &
>>>>> > VersionBitsMask(chainparams.GetConsensus(),
>>>>> > Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>>>> >   if (!(fVersionBits && fSegbit)) {
>>>>> >       return state.DoS(0, error("ConnectBlock(): relayed block must
>>>>> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>>>> >   }
>>>>> > }
>>>>> >
>>>>> > // BIP148 mandatory segwit signalling.
>>>>> > int64_t nMedianTimePast = pindex->GetMedianTimePast();
>>>>> > if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00 UTC
>>>>> >    (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
>>>>> >    (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>>>>> > // Segwit is not locked in
>>>>> >     !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
>>>>> > // and is not active.
>>>>> > {
>>>>> >   bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>>>>> > VERSIONBITS_TOP_BITS;
>>>>> >   bool fSegbit = (pindex->nVersion &
>>>>> > VersionBitsMask(chainparams.GetConsensus(),
>>>>> > Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>>>> >   if (!(fVersionBits && fSegbit)) {
>>>>> >       return state.DoS(0, error("ConnectBlock(): relayed block must
>>>>> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>>>> >   }
>>>>> > }
>>>>> > </pre>
>>>>> >
>>>>> >
>>>>> > https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1
>>>>> >
>>>>> > ==Backwards Compatibility==
>>>>> >
>>>>> > This deployment is compatible with the existing "segwit" bit 1
>>>>> > deployment scheduled between midnight November 15th, 2016 and midnight
>>>>> > November 15th, 2017. This deployment is also compatible with the
>>>>> > existing BIP148 deployment. This BIP is compatible with BIP91 only if
>>>>> > BIP91 activates before it and before BIP148. Miners will need to
>>>>> > upgrade their nodes to support splitprotection otherwise they may
>>>>> > build on top of an invalid block. While this bip is active users
>>>>> > should either upgrade to splitprotection or wait for additional
>>>>> > confirmations when accepting payments.
>>>>> >
>>>>> > ==Rationale==
>>>>> >
>>>>> > Historically we have used IsSuperMajority() to activate soft forks
>>>>> > such as BIP66 which has a mandatory signalling requirement for miners
>>>>> > once activated, this ensures that miners are aware of new rules being
>>>>> > enforced. This technique can be leveraged to lower the signalling
>>>>> > threshold of a soft fork while it is in the process of being deployed
>>>>> > in a backwards compatible way. We also use a BIP8 style timeout to
>>>>> > ensure that this BIP is compatible with BIP148 and that BIP148
>>>>> > compatible mandatory signalling activates regardless of miner
>>>>> > signalling levels.
>>>>> >
>>>>> > By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
>>>>> > deployment, this BIP can cause the existing "segwit" deployment to
>>>>> > activate without needing to release a new deployment. As we approach
>>>>> > BIP148 activation it may be desirable for a majority of miners to have
>>>>> > a method that will ensure that there is no chain split.
>>>>> >
>>>>> > ==References==
>>>>> >
>>>>> >
>>>>> > *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html
>>>>> > Mailing list discussion]
>>>>> >
>>>>> > *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283
>>>>> > P2SH flag day activation]
>>>>> > *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
>>>>> > *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
>>>>> > *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
>>>>> > *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
>>>>> > *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
>>>>> > Version 0 Witness Program]]
>>>>> > *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element
>>>>> > malleability]]
>>>>> > *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment]]
>>>>> > *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
>>>>> > *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit
>>>>> > benefits]
>>>>> >
>>>>> > ==Copyright==
>>>>> >
>>>>> > This document is dual licensed as BSD 3-clause, and Creative Commons
>>>>> > CC0 1.0 Universal.
>>>>> > _______________________________________________
>>>>> > bitcoin-dev mailing list
>>>>> > bitcoin-dev@lists.linuxfoundation.org
>>>>> > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>>>> >
>>>>> >
>>>>> >
>>>>> _______________________________________________
>>>>> bitcoin-dev mailing list
>>>>> bitcoin-dev@lists.linuxfoundation.org
>>>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> bitcoin-dev mailing list
>>>> bitcoin-dev@lists.linuxfoundation.org
>>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>>>

Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[Jared Lee Richardson]

Could this risk mitigation measure be an optional flag?  And if so,
could it+BIP91 signal on a different bit than bit4?

The reason being, if for some reason the segwit2x activation cannot
take place in time, it would be preferable for miners to have a more
standard approach to activation that requires stronger consensus and
may be more forgiving than BIP148.  If the segwit2x activation is on
time to cooperate with BIP148, it could be signaled through the
non-bit4 approach and everything could go smoothly.  Thoughts on that
idea?  It may add more complexity and more developer time, but may
also address your concerns among others.

> Since this BIP
> only activates with a clear miner majority it should not increase the
> risk of an extended chain split.

The concern I'm raising is more about the psychology of giving BIP148
a sense of safety that may not be valid.  Without several more steps,
BIP148 is definitely on track to be a risky chainsplit, and without
segwit2x it will almost certainly be a small minority chain. (Unless
the segwit2x compromise falls apart before then, and even in that case
it is likely to be a minority chain)

Jared


On Wed, Jun 7, 2017 at 2:42 PM, James Hilliard
<james.hilliard1@gmail.com> wrote:
> I don't really see how this would increase the likelihood of an
> extended chain split assuming BIP148 is going to have
> non-insignificant economic backing. This BIP is designed to provide a
> risk mitigation measure that miners can safely deploy. Since this BIP
> only activates with a clear miner majority it should not increase the
> risk of an extended chain split. At this point it is not completely
> clear how much economic support there is for BIP148 but support
> certainly seems to be growing and we have nearly 2 months until BIP148
> activation. I intentionally used a shorter activation period here so
> that decisions by miners can be made close to the BIP148 activation
> date.
>
> On Wed, Jun 7, 2017 at 4:29 PM, Jared Lee Richardson <jaredr26@gmail.com> wrote:
>> I think this BIP represents a gamble, and the gamble may not be a good
>> one.  The gamble here is that if the segwit2x changes are rolled out
>> on time, and if the signatories accept the bit4 + bit1 signaling
>> proposals within BIP91, the launch will go smoother, as intended.  But
>> conversely, if either the segwit2x signatories balk about the Bit1
>> signaling OR if the timelines for segwit2mb are missed even by a bit,
>> it may cause the BIP148 chainsplit to be worse than it would be
>> without.  Given the frequent concerns raised in multiple places about
>> the aggressiveness of the segwit2x timelines, including the
>> non-hardfork timelines, this does not seem like a great gamble to be
>> making.
>>
>> The reason I say it may make the chainsplit be worse than it would
>> otherwise be is that it may provide a false sense of safety for BIP148
>> that currently does not currently exist(and should not, as it is a
>> chainsplit).  That sense of safety would only be legitimate if the
>> segwit2x signatories were on board, and the segwit2x code effectively
>> enforced BIP148 simultaneously, neither of which are guaranteed.  If
>> users and more miners had a false sense that BIP148 was *not* going to
>> chainsplit from default / segwit2x, they might not follow the news if
>> suddenly the segwit2x plan were delayed for a few days.  While any
>> additional support would definitely be cheered on by BIP148
>> supporters, the practical reality might be that this proposal would
>> take BIP148 from the "unlikely to have any viable chain after flag day
>> without segwit2x" category into the "small but viable minority chain"
>> category, and even worse, it might strengthen the chainsplit just days
>> before segwit is activated on BOTH chains, putting the BIP148
>> supporters on the wrong pro-segwit, but still-viable chain.
>>
>> If Core had taken a strong stance to include BIP148 into the client,
>> and if BIP148 support were much much broader, I would feel differently
>> as the gamble would be more likely to discourage a chainsplit (By
>> forcing the acceleration of segwit2x) rather than encourage it (by
>> strengthening an extreme minority chainsplit that may wind up on the
>> wrong side of two segwit-activated chains).  As it stands now, this
>> seems like a very dangerous attempt to compromise with a small but
>> vocal group that are the ones creating the threat to begin with.
>>
>> Jared
>>
>> On Tue, Jun 6, 2017 at 5:56 PM, James Hilliard via bitcoin-dev
>> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>>> Due to the proposed calendar(https://segwit2x.github.io/) for the
>>> SegWit2x agreement being too slow to activate SegWit mandatory
>>> signalling ahead of BIP148 using BIP91 I would like to propose another
>>> option that miners can use to prevent a chain split ahead of the Aug
>>> 1st BIP148 activation date.
>>>
>>> The splitprotection soft fork is essentially BIP91 but using BIP8
>>> instead of BIP9 with a lower activation threshold and immediate
>>> mandatory signalling lock-in. This allows for a majority of miners to
>>> activate mandatory SegWit signalling and prevent a potential chain
>>> split ahead of BIP148 activation.
>>>
>>> This BIP allows for miners to respond to market forces quickly ahead
>>> of BIP148 activation by signalling for splitprotection. Any miners
>>> already running BIP148 should be encouraged to use splitprotection.
>>>
>>> <pre>
>>>   BIP: splitprotection
>>>   Layer: Consensus (soft fork)
>>>   Title: User Activated Soft Fork Split Protection
>>>   Author: James Hilliard <james.hilliard1@gmail.com>
>>>   Comments-Summary: No comments yet.
>>>   Comments-URI:
>>>   Status: Draft
>>>   Type: Standards Track
>>>   Created: 2017-05-22
>>>   License: BSD-3-Clause
>>>            CC0-1.0
>>> </pre>
>>>
>>> ==Abstract==
>>>
>>> This document specifies a coordination mechanism for a simple majority
>>> of miners to prevent a chain split ahead of BIP148 activation.
>>>
>>> ==Definitions==
>>>
>>> "existing segwit deployment" refer to the BIP9 "segwit" deployment
>>> using bit 1, between November 15th 2016 and November 15th 2017 to
>>> activate BIP141, BIP143 and BIP147.
>>>
>>> ==Motivation==
>>>
>>> The biggest risk of BIP148 is an extended chain split, this BIP
>>> provides a way for a simple majority of miners to eliminate that risk.
>>>
>>> This BIP provides a way for a simple majority of miners to coordinate
>>> activation of the existing segwit deployment with less than 95%
>>> hashpower before BIP148 activation. Due to time constraints unless
>>> immediately deployed BIP91 will likely not be able to enforce
>>> mandatory signalling of segwit before the Aug 1st activation of
>>> BIP148. This BIP provides a method for rapid miner activation of
>>> SegWit mandatory signalling ahead of the BIP148 activation date. Since
>>> the primary goal of this BIP is to reduce the chance of an extended
>>> chain split as much as possible we activate using a simple miner
>>> majority of 65% over a 504 block interval rather than a higher
>>> percentage. This BIP also allows miners to signal their intention to
>>> run BIP148 in order to prevent a chain split.
>>>
>>> ==Specification==
>>>
>>> While this BIP is active, all blocks must set the nVersion header top
>>> 3 bits to 001 together with bit field (1<<1) (according to the
>>> existing segwit deployment). Blocks that do not signal as required
>>> will be rejected.
>>>
>>> ==Deployment==
>>>
>>> This BIP will be deployed by "version bits" with a 65%(this can be
>>> adjusted if desired) activation threshold BIP9 with the name
>>> "splitprotecion" and using bit 2.
>>>
>>> This BIP starts immediately and is a BIP8 style soft fork since
>>> mandatory signalling will start on midnight August 1st 2017 (epoch
>>> time 1501545600) regardless of whether or not this BIP has reached its
>>> own signalling threshold. This BIP will cease to be active when segwit
>>> is locked-in.
>>>
>>> === Reference implementation ===
>>>
>>> <pre>
>>> // Check if Segregated Witness is Locked In
>>> bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
>>> Consensus::Params& params)
>>> {
>>>     LOCK(cs_main);
>>>     return (VersionBitsState(pindexPrev, params,
>>> Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
>>> THRESHOLD_LOCKED_IN);
>>> }
>>>
>>> // SPLITPROTECTION mandatory segwit signalling.
>>> if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
>>> Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
>>> THRESHOLD_LOCKED_IN &&
>>>      !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>>> // Segwit is not locked in
>>>      !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
>>> and is not active.
>>> {
>>>     bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>>> VERSIONBITS_TOP_BITS;
>>>     bool fSegbit = (pindex->nVersion &
>>> VersionBitsMask(chainparams.GetConsensus(),
>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>>     if (!(fVersionBits && fSegbit)) {
>>>         return state.DoS(0, error("ConnectBlock(): relayed block must
>>> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>>     }
>>> }
>>>
>>> // BIP148 mandatory segwit signalling.
>>> int64_t nMedianTimePast = pindex->GetMedianTimePast();
>>> if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00 UTC
>>>      (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
>>>      (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>>>  // Segwit is not locked in
>>>       !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
>>>  // and is not active.
>>> {
>>>     bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>>> VERSIONBITS_TOP_BITS;
>>>     bool fSegbit = (pindex->nVersion &
>>> VersionBitsMask(chainparams.GetConsensus(),
>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>>     if (!(fVersionBits && fSegbit)) {
>>>         return state.DoS(0, error("ConnectBlock(): relayed block must
>>> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>>     }
>>> }
>>> </pre>
>>>
>>> https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1
>>>
>>> ==Backwards Compatibility==
>>>
>>> This deployment is compatible with the existing "segwit" bit 1
>>> deployment scheduled between midnight November 15th, 2016 and midnight
>>> November 15th, 2017. This deployment is also compatible with the
>>> existing BIP148 deployment. This BIP is compatible with BIP91 only if
>>> BIP91 activates before it and before BIP148. Miners will need to
>>> upgrade their nodes to support splitprotection otherwise they may
>>> build on top of an invalid block. While this bip is active users
>>> should either upgrade to splitprotection or wait for additional
>>> confirmations when accepting payments.
>>>
>>> ==Rationale==
>>>
>>> Historically we have used IsSuperMajority() to activate soft forks
>>> such as BIP66 which has a mandatory signalling requirement for miners
>>> once activated, this ensures that miners are aware of new rules being
>>> enforced. This technique can be leveraged to lower the signalling
>>> threshold of a soft fork while it is in the process of being deployed
>>> in a backwards compatible way. We also use a BIP8 style timeout to
>>> ensure that this BIP is compatible with BIP148 and that BIP148
>>> compatible mandatory signalling activates regardless of miner
>>> signalling levels.
>>>
>>> By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
>>> deployment, this BIP can cause the existing "segwit" deployment to
>>> activate without needing to release a new deployment. As we approach
>>> BIP148 activation it may be desirable for a majority of miners to have
>>> a method that will ensure that there is no chain split.
>>>
>>> ==References==
>>>
>>> *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html
>>> Mailing list discussion]
>>> *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283
>>> P2SH flag day activation]
>>> *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
>>> *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
>>> *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
>>> *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
>>> *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
>>> Version 0 Witness Program]]
>>> *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element malleability]]
>>> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment]]
>>> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
>>> *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit benefits]
>>>
>>> ==Copyright==
>>>
>>> This document is dual licensed as BSD 3-clause, and Creative Commons
>>> CC0 1.0 Universal.
>>> _______________________________________________
>>> bitcoin-dev mailing list
>>> bitcoin-dev@lists.linuxfoundation.org
>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev

Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[James Hilliard]

On Wed, Jun 7, 2017 at 4:50 PM, Jared Lee Richardson <jaredr26@gmail.com> wrote:
> Could this risk mitigation measure be an optional flag?  And if so,
> could it+BIP91 signal on a different bit than bit4?
It's fairly trivial for miners to signal for BIP91 on bit4 or a
different bit at the same time as the code is trivial enough to
combine
>
> The reason being, if for some reason the segwit2x activation cannot
> take place in time, it would be preferable for miners to have a more
> standard approach to activation that requires stronger consensus and
> may be more forgiving than BIP148.  If the segwit2x activation is on
> time to cooperate with BIP148, it could be signaled through the
> non-bit4 approach and everything could go smoothly.  Thoughts on that
> idea?  It may add more complexity and more developer time, but may
> also address your concerns among others.
This does give miners another approach to activate segwit ahead of
BIP148, if segwit2x activation is rolled out and activated immediately
then this would not be needed however based on the timeline here
https://segwit2x.github.io/ it would not be possible for BIP91 to
enforce mandatory signalling ahead of BIP148. Maybe that can be
changed though, I've suggested an immediate rollout with a placeholder
client timeout instead of the HF code initially in order to accelerate
that.
>
>> Since this BIP
>> only activates with a clear miner majority it should not increase the
>> risk of an extended chain split.
>
> The concern I'm raising is more about the psychology of giving BIP148
> a sense of safety that may not be valid.  Without several more steps,
> BIP148 is definitely on track to be a risky chainsplit, and without
> segwit2x it will almost certainly be a small minority chain. (Unless
> the segwit2x compromise falls apart before then, and even in that case
> it is likely to be a minority chain)
There are 2 primary factors involved here, economic support and
hashpower either of which is enough to make a permanent chain split
unlikely, miners will mine whichever chain is most profitable(see
ETH/ETC hashpower profitability equilibrium for an example of how this
works in practice) however there may be lag time immediately after the
split if there is an economic majority but not a hashpower majority
initially. This is risk mitigation that only requires miners support
however. The main issue is just one of activation timelines, BIP91 as
is takes too long to activate unless started ahead of the existing
segwit2x schedule and it's unlikely that BIP148 will get pushed back
any further.
>
> Jared
>
>
> On Wed, Jun 7, 2017 at 2:42 PM, James Hilliard
> <james.hilliard1@gmail.com> wrote:
>> I don't really see how this would increase the likelihood of an
>> extended chain split assuming BIP148 is going to have
>> non-insignificant economic backing. This BIP is designed to provide a
>> risk mitigation measure that miners can safely deploy. Since this BIP
>> only activates with a clear miner majority it should not increase the
>> risk of an extended chain split. At this point it is not completely
>> clear how much economic support there is for BIP148 but support
>> certainly seems to be growing and we have nearly 2 months until BIP148
>> activation. I intentionally used a shorter activation period here so
>> that decisions by miners can be made close to the BIP148 activation
>> date.
>>
>> On Wed, Jun 7, 2017 at 4:29 PM, Jared Lee Richardson <jaredr26@gmail.com> wrote:
>>> I think this BIP represents a gamble, and the gamble may not be a good
>>> one.  The gamble here is that if the segwit2x changes are rolled out
>>> on time, and if the signatories accept the bit4 + bit1 signaling
>>> proposals within BIP91, the launch will go smoother, as intended.  But
>>> conversely, if either the segwit2x signatories balk about the Bit1
>>> signaling OR if the timelines for segwit2mb are missed even by a bit,
>>> it may cause the BIP148 chainsplit to be worse than it would be
>>> without.  Given the frequent concerns raised in multiple places about
>>> the aggressiveness of the segwit2x timelines, including the
>>> non-hardfork timelines, this does not seem like a great gamble to be
>>> making.
>>>
>>> The reason I say it may make the chainsplit be worse than it would
>>> otherwise be is that it may provide a false sense of safety for BIP148
>>> that currently does not currently exist(and should not, as it is a
>>> chainsplit).  That sense of safety would only be legitimate if the
>>> segwit2x signatories were on board, and the segwit2x code effectively
>>> enforced BIP148 simultaneously, neither of which are guaranteed.  If
>>> users and more miners had a false sense that BIP148 was *not* going to
>>> chainsplit from default / segwit2x, they might not follow the news if
>>> suddenly the segwit2x plan were delayed for a few days.  While any
>>> additional support would definitely be cheered on by BIP148
>>> supporters, the practical reality might be that this proposal would
>>> take BIP148 from the "unlikely to have any viable chain after flag day
>>> without segwit2x" category into the "small but viable minority chain"
>>> category, and even worse, it might strengthen the chainsplit just days
>>> before segwit is activated on BOTH chains, putting the BIP148
>>> supporters on the wrong pro-segwit, but still-viable chain.
>>>
>>> If Core had taken a strong stance to include BIP148 into the client,
>>> and if BIP148 support were much much broader, I would feel differently
>>> as the gamble would be more likely to discourage a chainsplit (By
>>> forcing the acceleration of segwit2x) rather than encourage it (by
>>> strengthening an extreme minority chainsplit that may wind up on the
>>> wrong side of two segwit-activated chains).  As it stands now, this
>>> seems like a very dangerous attempt to compromise with a small but
>>> vocal group that are the ones creating the threat to begin with.
>>>
>>> Jared
>>>
>>> On Tue, Jun 6, 2017 at 5:56 PM, James Hilliard via bitcoin-dev
>>> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>>>> Due to the proposed calendar(https://segwit2x.github.io/) for the
>>>> SegWit2x agreement being too slow to activate SegWit mandatory
>>>> signalling ahead of BIP148 using BIP91 I would like to propose another
>>>> option that miners can use to prevent a chain split ahead of the Aug
>>>> 1st BIP148 activation date.
>>>>
>>>> The splitprotection soft fork is essentially BIP91 but using BIP8
>>>> instead of BIP9 with a lower activation threshold and immediate
>>>> mandatory signalling lock-in. This allows for a majority of miners to
>>>> activate mandatory SegWit signalling and prevent a potential chain
>>>> split ahead of BIP148 activation.
>>>>
>>>> This BIP allows for miners to respond to market forces quickly ahead
>>>> of BIP148 activation by signalling for splitprotection. Any miners
>>>> already running BIP148 should be encouraged to use splitprotection.
>>>>
>>>> <pre>
>>>>   BIP: splitprotection
>>>>   Layer: Consensus (soft fork)
>>>>   Title: User Activated Soft Fork Split Protection
>>>>   Author: James Hilliard <james.hilliard1@gmail.com>
>>>>   Comments-Summary: No comments yet.
>>>>   Comments-URI:
>>>>   Status: Draft
>>>>   Type: Standards Track
>>>>   Created: 2017-05-22
>>>>   License: BSD-3-Clause
>>>>            CC0-1.0
>>>> </pre>
>>>>
>>>> ==Abstract==
>>>>
>>>> This document specifies a coordination mechanism for a simple majority
>>>> of miners to prevent a chain split ahead of BIP148 activation.
>>>>
>>>> ==Definitions==
>>>>
>>>> "existing segwit deployment" refer to the BIP9 "segwit" deployment
>>>> using bit 1, between November 15th 2016 and November 15th 2017 to
>>>> activate BIP141, BIP143 and BIP147.
>>>>
>>>> ==Motivation==
>>>>
>>>> The biggest risk of BIP148 is an extended chain split, this BIP
>>>> provides a way for a simple majority of miners to eliminate that risk.
>>>>
>>>> This BIP provides a way for a simple majority of miners to coordinate
>>>> activation of the existing segwit deployment with less than 95%
>>>> hashpower before BIP148 activation. Due to time constraints unless
>>>> immediately deployed BIP91 will likely not be able to enforce
>>>> mandatory signalling of segwit before the Aug 1st activation of
>>>> BIP148. This BIP provides a method for rapid miner activation of
>>>> SegWit mandatory signalling ahead of the BIP148 activation date. Since
>>>> the primary goal of this BIP is to reduce the chance of an extended
>>>> chain split as much as possible we activate using a simple miner
>>>> majority of 65% over a 504 block interval rather than a higher
>>>> percentage. This BIP also allows miners to signal their intention to
>>>> run BIP148 in order to prevent a chain split.
>>>>
>>>> ==Specification==
>>>>
>>>> While this BIP is active, all blocks must set the nVersion header top
>>>> 3 bits to 001 together with bit field (1<<1) (according to the
>>>> existing segwit deployment). Blocks that do not signal as required
>>>> will be rejected.
>>>>
>>>> ==Deployment==
>>>>
>>>> This BIP will be deployed by "version bits" with a 65%(this can be
>>>> adjusted if desired) activation threshold BIP9 with the name
>>>> "splitprotecion" and using bit 2.
>>>>
>>>> This BIP starts immediately and is a BIP8 style soft fork since
>>>> mandatory signalling will start on midnight August 1st 2017 (epoch
>>>> time 1501545600) regardless of whether or not this BIP has reached its
>>>> own signalling threshold. This BIP will cease to be active when segwit
>>>> is locked-in.
>>>>
>>>> === Reference implementation ===
>>>>
>>>> <pre>
>>>> // Check if Segregated Witness is Locked In
>>>> bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
>>>> Consensus::Params& params)
>>>> {
>>>>     LOCK(cs_main);
>>>>     return (VersionBitsState(pindexPrev, params,
>>>> Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
>>>> THRESHOLD_LOCKED_IN);
>>>> }
>>>>
>>>> // SPLITPROTECTION mandatory segwit signalling.
>>>> if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
>>>> Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
>>>> THRESHOLD_LOCKED_IN &&
>>>>      !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>>>> // Segwit is not locked in
>>>>      !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
>>>> and is not active.
>>>> {
>>>>     bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>>>> VERSIONBITS_TOP_BITS;
>>>>     bool fSegbit = (pindex->nVersion &
>>>> VersionBitsMask(chainparams.GetConsensus(),
>>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>>>     if (!(fVersionBits && fSegbit)) {
>>>>         return state.DoS(0, error("ConnectBlock(): relayed block must
>>>> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>>>     }
>>>> }
>>>>
>>>> // BIP148 mandatory segwit signalling.
>>>> int64_t nMedianTimePast = pindex->GetMedianTimePast();
>>>> if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00 UTC
>>>>      (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00 UTC
>>>>      (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>>>>  // Segwit is not locked in
>>>>       !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
>>>>  // and is not active.
>>>> {
>>>>     bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>>>> VERSIONBITS_TOP_BITS;
>>>>     bool fSegbit = (pindex->nVersion &
>>>> VersionBitsMask(chainparams.GetConsensus(),
>>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>>>>     if (!(fVersionBits && fSegbit)) {
>>>>         return state.DoS(0, error("ConnectBlock(): relayed block must
>>>> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
>>>>     }
>>>> }
>>>> </pre>
>>>>
>>>> https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1
>>>>
>>>> ==Backwards Compatibility==
>>>>
>>>> This deployment is compatible with the existing "segwit" bit 1
>>>> deployment scheduled between midnight November 15th, 2016 and midnight
>>>> November 15th, 2017. This deployment is also compatible with the
>>>> existing BIP148 deployment. This BIP is compatible with BIP91 only if
>>>> BIP91 activates before it and before BIP148. Miners will need to
>>>> upgrade their nodes to support splitprotection otherwise they may
>>>> build on top of an invalid block. While this bip is active users
>>>> should either upgrade to splitprotection or wait for additional
>>>> confirmations when accepting payments.
>>>>
>>>> ==Rationale==
>>>>
>>>> Historically we have used IsSuperMajority() to activate soft forks
>>>> such as BIP66 which has a mandatory signalling requirement for miners
>>>> once activated, this ensures that miners are aware of new rules being
>>>> enforced. This technique can be leveraged to lower the signalling
>>>> threshold of a soft fork while it is in the process of being deployed
>>>> in a backwards compatible way. We also use a BIP8 style timeout to
>>>> ensure that this BIP is compatible with BIP148 and that BIP148
>>>> compatible mandatory signalling activates regardless of miner
>>>> signalling levels.
>>>>
>>>> By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
>>>> deployment, this BIP can cause the existing "segwit" deployment to
>>>> activate without needing to release a new deployment. As we approach
>>>> BIP148 activation it may be desirable for a majority of miners to have
>>>> a method that will ensure that there is no chain split.
>>>>
>>>> ==References==
>>>>
>>>> *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html
>>>> Mailing list discussion]
>>>> *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283
>>>> P2SH flag day activation]
>>>> *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
>>>> *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
>>>> *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
>>>> *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
>>>> *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
>>>> Version 0 Witness Program]]
>>>> *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element malleability]]
>>>> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment]]
>>>> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
>>>> *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit benefits]
>>>>
>>>> ==Copyright==
>>>>
>>>> This document is dual licensed as BSD 3-clause, and Creative Commons
>>>> CC0 1.0 Universal.
>>>> _______________________________________________
>>>> bitcoin-dev mailing list
>>>> bitcoin-dev@lists.linuxfoundation.org
>>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev

Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[Jared Lee Richardson]

[-- Attachment #1: Type: text/plain, Size: 18391 bytes --]

> There are 2 primary factors involved here, economic support and
hashpower either of which is enough to make a permanent chain split
unlikely, miners will mine whichever chain is most profitable(see
ETH/ETC hashpower profitability equilibrium for an example of how this
works in practice)

That's not a comparable example.  ETC did not face potentially years of
slow blocktimes before it normalized, whereas BIP148 is on track to do
exactly that.  Moreover, ETC represented a fundamental break from the
majority consensus that could not be rectified, whereas BIP148 represents
only a minority attempt to accelerate something that an overwhelming
majority of miners have already agreed to activate under segwit2x.  Lastly
ETC was required to add replay protection, just like any minority fork
proposed by any crypto-currency has been, something that BIP148 both lacks
and refuses to add or even acknowledge the necessity of.  Without replay
protection, ETC could not have become profitable enough to be a viable
minority chain.  If BIP148's chain is not the majority chain and it does
not have replay protection, it will face the same problems, but that
required replay protection will turn it into a hardfork.  This will be a
very bad position for UASF supporters to find themselves in - Either
hardfork and hope the price is higher and the majority converts, or die as
the minority chain with no reliable methods of economic conversion.

I believe, but don't have data to back this, that most of the BIP148
insistence comes not from a legitimate attempt to gain consensus (or else
they would either outright oppose segwit2mb for its hardfork, or they would
outright support it), but rather from an attempt for BIP148 supporters to
save face for BIP148 being a failure.  If I'm correct, that's a terrible
and highly non-technical reason for segwit2mb to bend over backwards
attempting to support BIP148's attempt to save face.

> The main issue is just one of activation timelines, BIP91 as
is takes too long to activate unless started ahead of the existing
segwit2x schedule and it's unlikely that BIP148 will get pushed back
any further.

Even if I'm not correct on the above, I and others find it hard to accept
that this timeline conflict is segwit2x's fault.  Segwit2x has both some
flexibility and broad support that crosses contentious pro-segwit and
pro-blocksize-increase divisions that have existed for two years.  BIP148
is attempting to hold segwit2x's timelines and code hostage by claiming
inflexibility and claiming broad support, and not only are neither of those
assertions are backed by real data, BIP148 (by being so inflexible) is
pushing a position that deepens the divides between those groups.  For
there to be technical reasons for compatibility (so long as there are
tradeoffs, which there are), there needs to be hard data showing that
BIP148 is a viable minority fork that won't simply die off on its own.

Jared


On Wed, Jun 7, 2017 at 3:23 PM, James Hilliard <james.hilliard1@gmail.com>
wrote:

> On Wed, Jun 7, 2017 at 4:50 PM, Jared Lee Richardson <jaredr26@gmail.com>
> wrote:
> > Could this risk mitigation measure be an optional flag?  And if so,
> > could it+BIP91 signal on a different bit than bit4?
> It's fairly trivial for miners to signal for BIP91 on bit4 or a
> different bit at the same time as the code is trivial enough to
> combine
> >
> > The reason being, if for some reason the segwit2x activation cannot
> > take place in time, it would be preferable for miners to have a more
> > standard approach to activation that requires stronger consensus and
> > may be more forgiving than BIP148.  If the segwit2x activation is on
> > time to cooperate with BIP148, it could be signaled through the
> > non-bit4 approach and everything could go smoothly.  Thoughts on that
> > idea?  It may add more complexity and more developer time, but may
> > also address your concerns among others.
> This does give miners another approach to activate segwit ahead of
> BIP148, if segwit2x activation is rolled out and activated immediately
> then this would not be needed however based on the timeline here
> https://segwit2x.github.io/ it would not be possible for BIP91 to
> enforce mandatory signalling ahead of BIP148. Maybe that can be
> changed though, I've suggested an immediate rollout with a placeholder
> client timeout instead of the HF code initially in order to accelerate
> that.
> >
> >> Since this BIP
> >> only activates with a clear miner majority it should not increase the
> >> risk of an extended chain split.
> >
> > The concern I'm raising is more about the psychology of giving BIP148
> > a sense of safety that may not be valid.  Without several more steps,
> > BIP148 is definitely on track to be a risky chainsplit, and without
> > segwit2x it will almost certainly be a small minority chain. (Unless
> > the segwit2x compromise falls apart before then, and even in that case
> > it is likely to be a minority chain)
> There are 2 primary factors involved here, economic support and
> hashpower either of which is enough to make a permanent chain split
> unlikely, miners will mine whichever chain is most profitable(see
> ETH/ETC hashpower profitability equilibrium for an example of how this
> works in practice) however there may be lag time immediately after the
> split if there is an economic majority but not a hashpower majority
> initially. This is risk mitigation that only requires miners support
> however. The main issue is just one of activation timelines, BIP91 as
> is takes too long to activate unless started ahead of the existing
> segwit2x schedule and it's unlikely that BIP148 will get pushed back
> any further.
> >
> > Jared
> >
> >
> > On Wed, Jun 7, 2017 at 2:42 PM, James Hilliard
> > <james.hilliard1@gmail.com> wrote:
> >> I don't really see how this would increase the likelihood of an
> >> extended chain split assuming BIP148 is going to have
> >> non-insignificant economic backing. This BIP is designed to provide a
> >> risk mitigation measure that miners can safely deploy. Since this BIP
> >> only activates with a clear miner majority it should not increase the
> >> risk of an extended chain split. At this point it is not completely
> >> clear how much economic support there is for BIP148 but support
> >> certainly seems to be growing and we have nearly 2 months until BIP148
> >> activation. I intentionally used a shorter activation period here so
> >> that decisions by miners can be made close to the BIP148 activation
> >> date.
> >>
> >> On Wed, Jun 7, 2017 at 4:29 PM, Jared Lee Richardson <
> jaredr26@gmail.com> wrote:
> >>> I think this BIP represents a gamble, and the gamble may not be a good
> >>> one.  The gamble here is that if the segwit2x changes are rolled out
> >>> on time, and if the signatories accept the bit4 + bit1 signaling
> >>> proposals within BIP91, the launch will go smoother, as intended.  But
> >>> conversely, if either the segwit2x signatories balk about the Bit1
> >>> signaling OR if the timelines for segwit2mb are missed even by a bit,
> >>> it may cause the BIP148 chainsplit to be worse than it would be
> >>> without.  Given the frequent concerns raised in multiple places about
> >>> the aggressiveness of the segwit2x timelines, including the
> >>> non-hardfork timelines, this does not seem like a great gamble to be
> >>> making.
> >>>
> >>> The reason I say it may make the chainsplit be worse than it would
> >>> otherwise be is that it may provide a false sense of safety for BIP148
> >>> that currently does not currently exist(and should not, as it is a
> >>> chainsplit).  That sense of safety would only be legitimate if the
> >>> segwit2x signatories were on board, and the segwit2x code effectively
> >>> enforced BIP148 simultaneously, neither of which are guaranteed.  If
> >>> users and more miners had a false sense that BIP148 was *not* going to
> >>> chainsplit from default / segwit2x, they might not follow the news if
> >>> suddenly the segwit2x plan were delayed for a few days.  While any
> >>> additional support would definitely be cheered on by BIP148
> >>> supporters, the practical reality might be that this proposal would
> >>> take BIP148 from the "unlikely to have any viable chain after flag day
> >>> without segwit2x" category into the "small but viable minority chain"
> >>> category, and even worse, it might strengthen the chainsplit just days
> >>> before segwit is activated on BOTH chains, putting the BIP148
> >>> supporters on the wrong pro-segwit, but still-viable chain.
> >>>
> >>> If Core had taken a strong stance to include BIP148 into the client,
> >>> and if BIP148 support were much much broader, I would feel differently
> >>> as the gamble would be more likely to discourage a chainsplit (By
> >>> forcing the acceleration of segwit2x) rather than encourage it (by
> >>> strengthening an extreme minority chainsplit that may wind up on the
> >>> wrong side of two segwit-activated chains).  As it stands now, this
> >>> seems like a very dangerous attempt to compromise with a small but
> >>> vocal group that are the ones creating the threat to begin with.
> >>>
> >>> Jared
> >>>
> >>> On Tue, Jun 6, 2017 at 5:56 PM, James Hilliard via bitcoin-dev
> >>> <bitcoin-dev@lists.linuxfoundation.org> wrote:
> >>>> Due to the proposed calendar(https://segwit2x.github.io/) for the
> >>>> SegWit2x agreement being too slow to activate SegWit mandatory
> >>>> signalling ahead of BIP148 using BIP91 I would like to propose another
> >>>> option that miners can use to prevent a chain split ahead of the Aug
> >>>> 1st BIP148 activation date.
> >>>>
> >>>> The splitprotection soft fork is essentially BIP91 but using BIP8
> >>>> instead of BIP9 with a lower activation threshold and immediate
> >>>> mandatory signalling lock-in. This allows for a majority of miners to
> >>>> activate mandatory SegWit signalling and prevent a potential chain
> >>>> split ahead of BIP148 activation.
> >>>>
> >>>> This BIP allows for miners to respond to market forces quickly ahead
> >>>> of BIP148 activation by signalling for splitprotection. Any miners
> >>>> already running BIP148 should be encouraged to use splitprotection.
> >>>>
> >>>> <pre>
> >>>>   BIP: splitprotection
> >>>>   Layer: Consensus (soft fork)
> >>>>   Title: User Activated Soft Fork Split Protection
> >>>>   Author: James Hilliard <james.hilliard1@gmail.com>
> >>>>   Comments-Summary: No comments yet.
> >>>>   Comments-URI:
> >>>>   Status: Draft
> >>>>   Type: Standards Track
> >>>>   Created: 2017-05-22
> >>>>   License: BSD-3-Clause
> >>>>            CC0-1.0
> >>>> </pre>
> >>>>
> >>>> ==Abstract==
> >>>>
> >>>> This document specifies a coordination mechanism for a simple majority
> >>>> of miners to prevent a chain split ahead of BIP148 activation.
> >>>>
> >>>> ==Definitions==
> >>>>
> >>>> "existing segwit deployment" refer to the BIP9 "segwit" deployment
> >>>> using bit 1, between November 15th 2016 and November 15th 2017 to
> >>>> activate BIP141, BIP143 and BIP147.
> >>>>
> >>>> ==Motivation==
> >>>>
> >>>> The biggest risk of BIP148 is an extended chain split, this BIP
> >>>> provides a way for a simple majority of miners to eliminate that risk.
> >>>>
> >>>> This BIP provides a way for a simple majority of miners to coordinate
> >>>> activation of the existing segwit deployment with less than 95%
> >>>> hashpower before BIP148 activation. Due to time constraints unless
> >>>> immediately deployed BIP91 will likely not be able to enforce
> >>>> mandatory signalling of segwit before the Aug 1st activation of
> >>>> BIP148. This BIP provides a method for rapid miner activation of
> >>>> SegWit mandatory signalling ahead of the BIP148 activation date. Since
> >>>> the primary goal of this BIP is to reduce the chance of an extended
> >>>> chain split as much as possible we activate using a simple miner
> >>>> majority of 65% over a 504 block interval rather than a higher
> >>>> percentage. This BIP also allows miners to signal their intention to
> >>>> run BIP148 in order to prevent a chain split.
> >>>>
> >>>> ==Specification==
> >>>>
> >>>> While this BIP is active, all blocks must set the nVersion header top
> >>>> 3 bits to 001 together with bit field (1<<1) (according to the
> >>>> existing segwit deployment). Blocks that do not signal as required
> >>>> will be rejected.
> >>>>
> >>>> ==Deployment==
> >>>>
> >>>> This BIP will be deployed by "version bits" with a 65%(this can be
> >>>> adjusted if desired) activation threshold BIP9 with the name
> >>>> "splitprotecion" and using bit 2.
> >>>>
> >>>> This BIP starts immediately and is a BIP8 style soft fork since
> >>>> mandatory signalling will start on midnight August 1st 2017 (epoch
> >>>> time 1501545600) regardless of whether or not this BIP has reached its
> >>>> own signalling threshold. This BIP will cease to be active when segwit
> >>>> is locked-in.
> >>>>
> >>>> === Reference implementation ===
> >>>>
> >>>> <pre>
> >>>> // Check if Segregated Witness is Locked In
> >>>> bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
> >>>> Consensus::Params& params)
> >>>> {
> >>>>     LOCK(cs_main);
> >>>>     return (VersionBitsState(pindexPrev, params,
> >>>> Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
> >>>> THRESHOLD_LOCKED_IN);
> >>>> }
> >>>>
> >>>> // SPLITPROTECTION mandatory segwit signalling.
> >>>> if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
> >>>> Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
> >>>> THRESHOLD_LOCKED_IN &&
> >>>>      !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
> >>>> // Segwit is not locked in
> >>>>      !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) )
> //
> >>>> and is not active.
> >>>> {
> >>>>     bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
> >>>> VERSIONBITS_TOP_BITS;
> >>>>     bool fSegbit = (pindex->nVersion &
> >>>> VersionBitsMask(chainparams.GetConsensus(),
> >>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
> >>>>     if (!(fVersionBits && fSegbit)) {
> >>>>         return state.DoS(0, error("ConnectBlock(): relayed block must
> >>>> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
> >>>>     }
> >>>> }
> >>>>
> >>>> // BIP148 mandatory segwit signalling.
> >>>> int64_t nMedianTimePast = pindex->GetMedianTimePast();
> >>>> if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00
> UTC
> >>>>      (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00
> UTC
> >>>>      (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus())
> &&
> >>>>  // Segwit is not locked in
> >>>>       !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
> >>>>  // and is not active.
> >>>> {
> >>>>     bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
> >>>> VERSIONBITS_TOP_BITS;
> >>>>     bool fSegbit = (pindex->nVersion &
> >>>> VersionBitsMask(chainparams.GetConsensus(),
> >>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
> >>>>     if (!(fVersionBits && fSegbit)) {
> >>>>         return state.DoS(0, error("ConnectBlock(): relayed block must
> >>>> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");
> >>>>     }
> >>>> }
> >>>> </pre>
> >>>>
> >>>> https://github.com/bitcoin/bitcoin/compare/0.14...
> jameshilliard:splitprotection-v0.14.1
> >>>>
> >>>> ==Backwards Compatibility==
> >>>>
> >>>> This deployment is compatible with the existing "segwit" bit 1
> >>>> deployment scheduled between midnight November 15th, 2016 and midnight
> >>>> November 15th, 2017. This deployment is also compatible with the
> >>>> existing BIP148 deployment. This BIP is compatible with BIP91 only if
> >>>> BIP91 activates before it and before BIP148. Miners will need to
> >>>> upgrade their nodes to support splitprotection otherwise they may
> >>>> build on top of an invalid block. While this bip is active users
> >>>> should either upgrade to splitprotection or wait for additional
> >>>> confirmations when accepting payments.
> >>>>
> >>>> ==Rationale==
> >>>>
> >>>> Historically we have used IsSuperMajority() to activate soft forks
> >>>> such as BIP66 which has a mandatory signalling requirement for miners
> >>>> once activated, this ensures that miners are aware of new rules being
> >>>> enforced. This technique can be leveraged to lower the signalling
> >>>> threshold of a soft fork while it is in the process of being deployed
> >>>> in a backwards compatible way. We also use a BIP8 style timeout to
> >>>> ensure that this BIP is compatible with BIP148 and that BIP148
> >>>> compatible mandatory signalling activates regardless of miner
> >>>> signalling levels.
> >>>>
> >>>> By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
> >>>> deployment, this BIP can cause the existing "segwit" deployment to
> >>>> activate without needing to release a new deployment. As we approach
> >>>> BIP148 activation it may be desirable for a majority of miners to have
> >>>> a method that will ensure that there is no chain split.
> >>>>
> >>>> ==References==
> >>>>
> >>>> *[https://lists.linuxfoundation.org/pipermail/
> bitcoin-dev/2017-March/013714.html
> >>>> Mailing list discussion]
> >>>> *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.
> cpp#L1281-L1283
> >>>> P2SH flag day activation]
> >>>> *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
> >>>> *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
> >>>> *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
> >>>> *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
> >>>> *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
> >>>> Version 0 Witness Program]]
> >>>> *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element
> malleability]]
> >>>> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit
> deployment]]
> >>>> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
> >>>> *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit
> benefits]
> >>>>
> >>>> ==Copyright==
> >>>>
> >>>> This document is dual licensed as BSD 3-clause, and Creative Commons
> >>>> CC0 1.0 Universal.
> >>>> _______________________________________________
> >>>> bitcoin-dev mailing list
> >>>> bitcoin-dev@lists.linuxfoundation.org
> >>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>

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Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[James Hilliard]

On Wed, Jun 7, 2017 at 5:53 PM, Jared Lee Richardson <jaredr26@gmail.com> wrote:
>> There are 2 primary factors involved here, economic support and
> hashpower either of which is enough to make a permanent chain split
> unlikely, miners will mine whichever chain is most profitable(see
> ETH/ETC hashpower profitability equilibrium for an example of how this
> works in practice)
>
> That's not a comparable example.  ETC did not face potentially years of slow
> blocktimes before it normalized, whereas BIP148 is on track to do exactly
> that.  Moreover, ETC represented a fundamental break from the majority
> consensus that could not be rectified, whereas BIP148 represents only a
> minority attempt to accelerate something that an overwhelming majority of
> miners have already agreed to activate under segwit2x.  Lastly ETC was
> required to add replay protection, just like any minority fork proposed by
> any crypto-currency has been, something that BIP148 both lacks and refuses
> to add or even acknowledge the necessity of.  Without replay protection, ETC
> could not have become profitable enough to be a viable minority chain.  If
> BIP148's chain is not the majority chain and it does not have replay
> protection, it will face the same problems, but that required replay
> protection will turn it into a hardfork.  This will be a very bad position
> for UASF supporters to find themselves in - Either hardfork and hope the
> price is higher and the majority converts, or die as the minority chain with
> no reliable methods of economic conversion.
Higher transaction fees on a minority chain can compensate miners for
a lower price which would likely be enough to get the BIP148 chain to
a difficulty reduction. BIP148 however is a consensus change that can
be rectified if it gets more work, this would act as an additional
incentive for mine the BIP148 side since there would be no wipeout
risk there. ETC replay protection was done after the fork on an as
needed basis(there are multiple reliable techniques that can be used
to split UTXO's), the same can happen with BIP148 and it is easier to
do with Bitcoin than with the ETH/ETC split IMO.
>
> I believe, but don't have data to back this, that most of the BIP148
> insistence comes not from a legitimate attempt to gain consensus (or else
> they would either outright oppose segwit2mb for its hardfork, or they would
> outright support it), but rather from an attempt for BIP148 supporters to
> save face for BIP148 being a failure.  If I'm correct, that's a terrible and
> highly non-technical reason for segwit2mb to bend over backwards attempting
> to support BIP148's attempt to save face.
A big reason BIP148 still has support is because up until SegWit
actually activates there's no guarantee segwit2mb will actually have
the necessary support to activate SegWit.
>
>> The main issue is just one of activation timelines, BIP91 as
> is takes too long to activate unless started ahead of the existing
> segwit2x schedule and it's unlikely that BIP148 will get pushed back
> any further.
>
> Even if I'm not correct on the above, I and others find it hard to accept
> that this timeline conflict is segwit2x's fault.  Segwit2x has both some
> flexibility and broad support that crosses contentious pro-segwit and
> pro-blocksize-increase divisions that have existed for two years.  BIP148 is
> attempting to hold segwit2x's timelines and code hostage by claiming
> inflexibility and claiming broad support, and not only are neither of those
> assertions are backed by real data, BIP148 (by being so inflexible) is
> pushing a position that deepens the divides between those groups.  For there
> to be technical reasons for compatibility (so long as there are tradeoffs,
> which there are), there needs to be hard data showing that BIP148 is a
> viable minority fork that won't simply die off on its own.
This is largely an issue due to segwit2x's bundling, if the SW and HF
part of segwit2x were unbundled then there would be no reason to delay
BIP91 activation, this is especially a problem since it takes a good
deal of time to properly code and test a HF. Unfortunately segwit2x
has been quite inflexible in regards to the bundling aspect even
though there are clearly no technical reasons for it to be there.
>
> Jared
>
>
> On Wed, Jun 7, 2017 at 3:23 PM, James Hilliard <james.hilliard1@gmail.com>
> wrote:
>>
>> On Wed, Jun 7, 2017 at 4:50 PM, Jared Lee Richardson <jaredr26@gmail.com>
>> wrote:
>> > Could this risk mitigation measure be an optional flag?  And if so,
>> > could it+BIP91 signal on a different bit than bit4?
>> It's fairly trivial for miners to signal for BIP91 on bit4 or a
>> different bit at the same time as the code is trivial enough to
>> combine
>> >
>> > The reason being, if for some reason the segwit2x activation cannot
>> > take place in time, it would be preferable for miners to have a more
>> > standard approach to activation that requires stronger consensus and
>> > may be more forgiving than BIP148.  If the segwit2x activation is on
>> > time to cooperate with BIP148, it could be signaled through the
>> > non-bit4 approach and everything could go smoothly.  Thoughts on that
>> > idea?  It may add more complexity and more developer time, but may
>> > also address your concerns among others.
>> This does give miners another approach to activate segwit ahead of
>> BIP148, if segwit2x activation is rolled out and activated immediately
>> then this would not be needed however based on the timeline here
>> https://segwit2x.github.io/ it would not be possible for BIP91 to
>> enforce mandatory signalling ahead of BIP148. Maybe that can be
>> changed though, I've suggested an immediate rollout with a placeholder
>> client timeout instead of the HF code initially in order to accelerate
>> that.
>> >
>> >> Since this BIP
>> >> only activates with a clear miner majority it should not increase the
>> >> risk of an extended chain split.
>> >
>> > The concern I'm raising is more about the psychology of giving BIP148
>> > a sense of safety that may not be valid.  Without several more steps,
>> > BIP148 is definitely on track to be a risky chainsplit, and without
>> > segwit2x it will almost certainly be a small minority chain. (Unless
>> > the segwit2x compromise falls apart before then, and even in that case
>> > it is likely to be a minority chain)
>> There are 2 primary factors involved here, economic support and
>> hashpower either of which is enough to make a permanent chain split
>> unlikely, miners will mine whichever chain is most profitable(see
>> ETH/ETC hashpower profitability equilibrium for an example of how this
>> works in practice) however there may be lag time immediately after the
>> split if there is an economic majority but not a hashpower majority
>> initially. This is risk mitigation that only requires miners support
>> however. The main issue is just one of activation timelines, BIP91 as
>> is takes too long to activate unless started ahead of the existing
>> segwit2x schedule and it's unlikely that BIP148 will get pushed back
>> any further.
>> >
>> > Jared
>> >
>> >
>> > On Wed, Jun 7, 2017 at 2:42 PM, James Hilliard
>> > <james.hilliard1@gmail.com> wrote:
>> >> I don't really see how this would increase the likelihood of an
>> >> extended chain split assuming BIP148 is going to have
>> >> non-insignificant economic backing. This BIP is designed to provide a
>> >> risk mitigation measure that miners can safely deploy. Since this BIP
>> >> only activates with a clear miner majority it should not increase the
>> >> risk of an extended chain split. At this point it is not completely
>> >> clear how much economic support there is for BIP148 but support
>> >> certainly seems to be growing and we have nearly 2 months until BIP148
>> >> activation. I intentionally used a shorter activation period here so
>> >> that decisions by miners can be made close to the BIP148 activation
>> >> date.
>> >>
>> >> On Wed, Jun 7, 2017 at 4:29 PM, Jared Lee Richardson
>> >> <jaredr26@gmail.com> wrote:
>> >>> I think this BIP represents a gamble, and the gamble may not be a good
>> >>> one.  The gamble here is that if the segwit2x changes are rolled out
>> >>> on time, and if the signatories accept the bit4 + bit1 signaling
>> >>> proposals within BIP91, the launch will go smoother, as intended.  But
>> >>> conversely, if either the segwit2x signatories balk about the Bit1
>> >>> signaling OR if the timelines for segwit2mb are missed even by a bit,
>> >>> it may cause the BIP148 chainsplit to be worse than it would be
>> >>> without.  Given the frequent concerns raised in multiple places about
>> >>> the aggressiveness of the segwit2x timelines, including the
>> >>> non-hardfork timelines, this does not seem like a great gamble to be
>> >>> making.
>> >>>
>> >>> The reason I say it may make the chainsplit be worse than it would
>> >>> otherwise be is that it may provide a false sense of safety for BIP148
>> >>> that currently does not currently exist(and should not, as it is a
>> >>> chainsplit).  That sense of safety would only be legitimate if the
>> >>> segwit2x signatories were on board, and the segwit2x code effectively
>> >>> enforced BIP148 simultaneously, neither of which are guaranteed.  If
>> >>> users and more miners had a false sense that BIP148 was *not* going to
>> >>> chainsplit from default / segwit2x, they might not follow the news if
>> >>> suddenly the segwit2x plan were delayed for a few days.  While any
>> >>> additional support would definitely be cheered on by BIP148
>> >>> supporters, the practical reality might be that this proposal would
>> >>> take BIP148 from the "unlikely to have any viable chain after flag day
>> >>> without segwit2x" category into the "small but viable minority chain"
>> >>> category, and even worse, it might strengthen the chainsplit just days
>> >>> before segwit is activated on BOTH chains, putting the BIP148
>> >>> supporters on the wrong pro-segwit, but still-viable chain.
>> >>>
>> >>> If Core had taken a strong stance to include BIP148 into the client,
>> >>> and if BIP148 support were much much broader, I would feel differently
>> >>> as the gamble would be more likely to discourage a chainsplit (By
>> >>> forcing the acceleration of segwit2x) rather than encourage it (by
>> >>> strengthening an extreme minority chainsplit that may wind up on the
>> >>> wrong side of two segwit-activated chains).  As it stands now, this
>> >>> seems like a very dangerous attempt to compromise with a small but
>> >>> vocal group that are the ones creating the threat to begin with.
>> >>>
>> >>> Jared
>> >>>
>> >>> On Tue, Jun 6, 2017 at 5:56 PM, James Hilliard via bitcoin-dev
>> >>> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>> >>>> Due to the proposed calendar(https://segwit2x.github.io/) for the
>> >>>> SegWit2x agreement being too slow to activate SegWit mandatory
>> >>>> signalling ahead of BIP148 using BIP91 I would like to propose
>> >>>> another
>> >>>> option that miners can use to prevent a chain split ahead of the Aug
>> >>>> 1st BIP148 activation date.
>> >>>>
>> >>>> The splitprotection soft fork is essentially BIP91 but using BIP8
>> >>>> instead of BIP9 with a lower activation threshold and immediate
>> >>>> mandatory signalling lock-in. This allows for a majority of miners to
>> >>>> activate mandatory SegWit signalling and prevent a potential chain
>> >>>> split ahead of BIP148 activation.
>> >>>>
>> >>>> This BIP allows for miners to respond to market forces quickly ahead
>> >>>> of BIP148 activation by signalling for splitprotection. Any miners
>> >>>> already running BIP148 should be encouraged to use splitprotection.
>> >>>>
>> >>>> <pre>
>> >>>>   BIP: splitprotection
>> >>>>   Layer: Consensus (soft fork)
>> >>>>   Title: User Activated Soft Fork Split Protection
>> >>>>   Author: James Hilliard <james.hilliard1@gmail.com>
>> >>>>   Comments-Summary: No comments yet.
>> >>>>   Comments-URI:
>> >>>>   Status: Draft
>> >>>>   Type: Standards Track
>> >>>>   Created: 2017-05-22
>> >>>>   License: BSD-3-Clause
>> >>>>            CC0-1.0
>> >>>> </pre>
>> >>>>
>> >>>> ==Abstract==
>> >>>>
>> >>>> This document specifies a coordination mechanism for a simple
>> >>>> majority
>> >>>> of miners to prevent a chain split ahead of BIP148 activation.
>> >>>>
>> >>>> ==Definitions==
>> >>>>
>> >>>> "existing segwit deployment" refer to the BIP9 "segwit" deployment
>> >>>> using bit 1, between November 15th 2016 and November 15th 2017 to
>> >>>> activate BIP141, BIP143 and BIP147.
>> >>>>
>> >>>> ==Motivation==
>> >>>>
>> >>>> The biggest risk of BIP148 is an extended chain split, this BIP
>> >>>> provides a way for a simple majority of miners to eliminate that
>> >>>> risk.
>> >>>>
>> >>>> This BIP provides a way for a simple majority of miners to coordinate
>> >>>> activation of the existing segwit deployment with less than 95%
>> >>>> hashpower before BIP148 activation. Due to time constraints unless
>> >>>> immediately deployed BIP91 will likely not be able to enforce
>> >>>> mandatory signalling of segwit before the Aug 1st activation of
>> >>>> BIP148. This BIP provides a method for rapid miner activation of
>> >>>> SegWit mandatory signalling ahead of the BIP148 activation date.
>> >>>> Since
>> >>>> the primary goal of this BIP is to reduce the chance of an extended
>> >>>> chain split as much as possible we activate using a simple miner
>> >>>> majority of 65% over a 504 block interval rather than a higher
>> >>>> percentage. This BIP also allows miners to signal their intention to
>> >>>> run BIP148 in order to prevent a chain split.
>> >>>>
>> >>>> ==Specification==
>> >>>>
>> >>>> While this BIP is active, all blocks must set the nVersion header top
>> >>>> 3 bits to 001 together with bit field (1<<1) (according to the
>> >>>> existing segwit deployment). Blocks that do not signal as required
>> >>>> will be rejected.
>> >>>>
>> >>>> ==Deployment==
>> >>>>
>> >>>> This BIP will be deployed by "version bits" with a 65%(this can be
>> >>>> adjusted if desired) activation threshold BIP9 with the name
>> >>>> "splitprotecion" and using bit 2.
>> >>>>
>> >>>> This BIP starts immediately and is a BIP8 style soft fork since
>> >>>> mandatory signalling will start on midnight August 1st 2017 (epoch
>> >>>> time 1501545600) regardless of whether or not this BIP has reached
>> >>>> its
>> >>>> own signalling threshold. This BIP will cease to be active when
>> >>>> segwit
>> >>>> is locked-in.
>> >>>>
>> >>>> === Reference implementation ===
>> >>>>
>> >>>> <pre>
>> >>>> // Check if Segregated Witness is Locked In
>> >>>> bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
>> >>>> Consensus::Params& params)
>> >>>> {
>> >>>>     LOCK(cs_main);
>> >>>>     return (VersionBitsState(pindexPrev, params,
>> >>>> Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
>> >>>> THRESHOLD_LOCKED_IN);
>> >>>> }
>> >>>>
>> >>>> // SPLITPROTECTION mandatory segwit signalling.
>> >>>> if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
>> >>>> Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
>> >>>> THRESHOLD_LOCKED_IN &&
>> >>>>      !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>> >>>> // Segwit is not locked in
>> >>>>      !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) )
>> >>>> //
>> >>>> and is not active.
>> >>>> {
>> >>>>     bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>> >>>> VERSIONBITS_TOP_BITS;
>> >>>>     bool fSegbit = (pindex->nVersion &
>> >>>> VersionBitsMask(chainparams.GetConsensus(),
>> >>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>> >>>>     if (!(fVersionBits && fSegbit)) {
>> >>>>         return state.DoS(0, error("ConnectBlock(): relayed block must
>> >>>> signal for segwit, please upgrade"), REJECT_INVALID,
>> >>>> "bad-no-segwit");
>> >>>>     }
>> >>>> }
>> >>>>
>> >>>> // BIP148 mandatory segwit signalling.
>> >>>> int64_t nMedianTimePast = pindex->GetMedianTimePast();
>> >>>> if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017 00:00:00
>> >>>> UTC
>> >>>>      (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017 00:00:00
>> >>>> UTC
>> >>>>      (!IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus())
>> >>>> &&
>> >>>>  // Segwit is not locked in
>> >>>>       !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())) )
>> >>>>  // and is not active.
>> >>>> {
>> >>>>     bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK) ==
>> >>>> VERSIONBITS_TOP_BITS;
>> >>>>     bool fSegbit = (pindex->nVersion &
>> >>>> VersionBitsMask(chainparams.GetConsensus(),
>> >>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>> >>>>     if (!(fVersionBits && fSegbit)) {
>> >>>>         return state.DoS(0, error("ConnectBlock(): relayed block must
>> >>>> signal for segwit, please upgrade"), REJECT_INVALID,
>> >>>> "bad-no-segwit");
>> >>>>     }
>> >>>> }
>> >>>> </pre>
>> >>>>
>> >>>>
>> >>>> https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1
>> >>>>
>> >>>> ==Backwards Compatibility==
>> >>>>
>> >>>> This deployment is compatible with the existing "segwit" bit 1
>> >>>> deployment scheduled between midnight November 15th, 2016 and
>> >>>> midnight
>> >>>> November 15th, 2017. This deployment is also compatible with the
>> >>>> existing BIP148 deployment. This BIP is compatible with BIP91 only if
>> >>>> BIP91 activates before it and before BIP148. Miners will need to
>> >>>> upgrade their nodes to support splitprotection otherwise they may
>> >>>> build on top of an invalid block. While this bip is active users
>> >>>> should either upgrade to splitprotection or wait for additional
>> >>>> confirmations when accepting payments.
>> >>>>
>> >>>> ==Rationale==
>> >>>>
>> >>>> Historically we have used IsSuperMajority() to activate soft forks
>> >>>> such as BIP66 which has a mandatory signalling requirement for miners
>> >>>> once activated, this ensures that miners are aware of new rules being
>> >>>> enforced. This technique can be leveraged to lower the signalling
>> >>>> threshold of a soft fork while it is in the process of being deployed
>> >>>> in a backwards compatible way. We also use a BIP8 style timeout to
>> >>>> ensure that this BIP is compatible with BIP148 and that BIP148
>> >>>> compatible mandatory signalling activates regardless of miner
>> >>>> signalling levels.
>> >>>>
>> >>>> By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
>> >>>> deployment, this BIP can cause the existing "segwit" deployment to
>> >>>> activate without needing to release a new deployment. As we approach
>> >>>> BIP148 activation it may be desirable for a majority of miners to
>> >>>> have
>> >>>> a method that will ensure that there is no chain split.
>> >>>>
>> >>>> ==References==
>> >>>>
>> >>>>
>> >>>> *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html
>> >>>> Mailing list discussion]
>> >>>>
>> >>>> *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283
>> >>>> P2SH flag day activation]
>> >>>> *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
>> >>>> *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
>> >>>> *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
>> >>>> *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
>> >>>> *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
>> >>>> Version 0 Witness Program]]
>> >>>> *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element
>> >>>> malleability]]
>> >>>> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit
>> >>>> deployment]]
>> >>>> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
>> >>>> *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit
>> >>>> benefits]
>> >>>>
>> >>>> ==Copyright==
>> >>>>
>> >>>> This document is dual licensed as BSD 3-clause, and Creative Commons
>> >>>> CC0 1.0 Universal.
>> >>>> _______________________________________________
>> >>>> bitcoin-dev mailing list
>> >>>> bitcoin-dev@lists.linuxfoundation.org
>> >>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>
>

Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[Jared Lee Richardson]

[-- Attachment #1: Type: text/plain, Size: 24196 bytes --]

> BIP148 however is a consensus change that can
> be rectified if it gets more work, this would act as an additional
> incentive for mine the BIP148 side since there would be no wipeout
> risk there.

This statement is misleading.  Wipeout risks don't apply to any consensus
changes; It is a consensus change, it can only be abandoned.  The BIP148
chain carries just as many risks of being abandoned or even more with
segwit2x on the table.  No miner would consider "wipeout risk" an advantage
when the real threat is chain abandonment.

> Higher transaction fees on a minority chain can compensate miners for
> a lower price which would likely be enough to get the BIP148 chain to
> a difficulty reduction.

Higher transaction fees suffers the same problem as exchange support does.
Without replay protection, it is very difficult for any average user to
force transactions onto one chain or the other.  Thus, without replay
protection, the UASF chain is unlikely to develop any viable fee market;
Its few miners 99% of the time will simply choose from the highest fees
that were already available to the other chain, which is basically no
advantage at all.

>  ETC replay protection was done after the fork on an as
> needed basis(there are multiple reliable techniques that can be used
> to split UTXO's), the same can happen with BIP148 and it is easier to
> do with Bitcoin than with the ETH/ETC split IMO.

ETC replay protection was added because they were already a hardfork and
without it they would not have had a viable chain.  BIP148 is not supposed
to be a hardfork, and if it added replay protection to remain viable it
would lose the frequently touted "wipeout advantage" as well as the ability
to call itself a softfork.  And are you seriously suggesting that what
happened with ETC and ETH is a desirable and good situation for Bitcoin,
and that UASF is ETC?

> A big reason BIP148 still has support is because up until SegWit
> actually activates there's no guarantee segwit2mb will actually have
> the necessary support to activate SegWit.

For a miners blowing through six million dollars a day in mining
operational costs, that's a pretty crappy reason.  Serious miners can't
afford to prop up a non-viable chain based on philosophy or maybes.  BIP148
is based entirely upon people who aren't putting anything on the line
trying to convince others to take the huge risks for them.  With
deceptively fallacious logic, in my opinion.

Even segwit2x is based on the assumption that all miners can reach
consensus.  Break that assumption and segwit2x will have the same problems
as UASF.

> This is largely an issue due to segwit2x's bundling, if the SW and HF
> part of segwit2x were unbundled then there would be no reason to delay
> BIP91 activation

They are bundled.  Segwit alone doesn't have the desired overwhelming
consensus, unless core wishes to fork 71% to 29%, and maybe not even that
high.  That's the technical reason, and they can't be unbundled without
breaking that consensus.

Jared


On Wed, Jun 7, 2017 at 4:11 PM, James Hilliard <james.hilliard1@gmail.com>
wrote:

> On Wed, Jun 7, 2017 at 5:53 PM, Jared Lee Richardson <jaredr26@gmail.com>
> wrote:
> >> There are 2 primary factors involved here, economic support and
> > hashpower either of which is enough to make a permanent chain split
> > unlikely, miners will mine whichever chain is most profitable(see
> > ETH/ETC hashpower profitability equilibrium for an example of how this
> > works in practice)
> >
> > That's not a comparable example.  ETC did not face potentially years of
> slow
> > blocktimes before it normalized, whereas BIP148 is on track to do exactly
> > that.  Moreover, ETC represented a fundamental break from the majority
> > consensus that could not be rectified, whereas BIP148 represents only a
> > minority attempt to accelerate something that an overwhelming majority of
> > miners have already agreed to activate under segwit2x.  Lastly ETC was
> > required to add replay protection, just like any minority fork proposed
> by
> > any crypto-currency has been, something that BIP148 both lacks and
> refuses
> > to add or even acknowledge the necessity of.  Without replay protection,
> ETC
> > could not have become profitable enough to be a viable minority chain.
> If
> > BIP148's chain is not the majority chain and it does not have replay
> > protection, it will face the same problems, but that required replay
> > protection will turn it into a hardfork.  This will be a very bad
> position
> > for UASF supporters to find themselves in - Either hardfork and hope the
> > price is higher and the majority converts, or die as the minority chain
> with
> > no reliable methods of economic conversion.
> Higher transaction fees on a minority chain can compensate miners for
> a lower price which would likely be enough to get the BIP148 chain to
> a difficulty reduction. BIP148 however is a consensus change that can
> be rectified if it gets more work, this would act as an additional
> incentive for mine the BIP148 side since there would be no wipeout
> risk there. ETC replay protection was done after the fork on an as
> needed basis(there are multiple reliable techniques that can be used
> to split UTXO's), the same can happen with BIP148 and it is easier to
> do with Bitcoin than with the ETH/ETC split IMO.
> >
> > I believe, but don't have data to back this, that most of the BIP148
> > insistence comes not from a legitimate attempt to gain consensus (or else
> > they would either outright oppose segwit2mb for its hardfork, or they
> would
> > outright support it), but rather from an attempt for BIP148 supporters to
> > save face for BIP148 being a failure.  If I'm correct, that's a terrible
> and
> > highly non-technical reason for segwit2mb to bend over backwards
> attempting
> > to support BIP148's attempt to save face.
> A big reason BIP148 still has support is because up until SegWit
> actually activates there's no guarantee segwit2mb will actually have
> the necessary support to activate SegWit.
> >
> >> The main issue is just one of activation timelines, BIP91 as
> > is takes too long to activate unless started ahead of the existing
> > segwit2x schedule and it's unlikely that BIP148 will get pushed back
> > any further.
> >
> > Even if I'm not correct on the above, I and others find it hard to accept
> > that this timeline conflict is segwit2x's fault.  Segwit2x has both some
> > flexibility and broad support that crosses contentious pro-segwit and
> > pro-blocksize-increase divisions that have existed for two years.
> BIP148 is
> > attempting to hold segwit2x's timelines and code hostage by claiming
> > inflexibility and claiming broad support, and not only are neither of
> those
> > assertions are backed by real data, BIP148 (by being so inflexible) is
> > pushing a position that deepens the divides between those groups.  For
> there
> > to be technical reasons for compatibility (so long as there are
> tradeoffs,
> > which there are), there needs to be hard data showing that BIP148 is a
> > viable minority fork that won't simply die off on its own.
> This is largely an issue due to segwit2x's bundling, if the SW and HF
> part of segwit2x were unbundled then there would be no reason to delay
> BIP91 activation, this is especially a problem since it takes a good
> deal of time to properly code and test a HF. Unfortunately segwit2x
> has been quite inflexible in regards to the bundling aspect even
> though there are clearly no technical reasons for it to be there.
> >
> > Jared
> >
> >
> > On Wed, Jun 7, 2017 at 3:23 PM, James Hilliard <
> james.hilliard1@gmail.com>
> > wrote:
> >>
> >> On Wed, Jun 7, 2017 at 4:50 PM, Jared Lee Richardson <
> jaredr26@gmail.com>
> >> wrote:
> >> > Could this risk mitigation measure be an optional flag?  And if so,
> >> > could it+BIP91 signal on a different bit than bit4?
> >> It's fairly trivial for miners to signal for BIP91 on bit4 or a
> >> different bit at the same time as the code is trivial enough to
> >> combine
> >> >
> >> > The reason being, if for some reason the segwit2x activation cannot
> >> > take place in time, it would be preferable for miners to have a more
> >> > standard approach to activation that requires stronger consensus and
> >> > may be more forgiving than BIP148.  If the segwit2x activation is on
> >> > time to cooperate with BIP148, it could be signaled through the
> >> > non-bit4 approach and everything could go smoothly.  Thoughts on that
> >> > idea?  It may add more complexity and more developer time, but may
> >> > also address your concerns among others.
> >> This does give miners another approach to activate segwit ahead of
> >> BIP148, if segwit2x activation is rolled out and activated immediately
> >> then this would not be needed however based on the timeline here
> >> https://segwit2x.github.io/ it would not be possible for BIP91 to
> >> enforce mandatory signalling ahead of BIP148. Maybe that can be
> >> changed though, I've suggested an immediate rollout with a placeholder
> >> client timeout instead of the HF code initially in order to accelerate
> >> that.
> >> >
> >> >> Since this BIP
> >> >> only activates with a clear miner majority it should not increase the
> >> >> risk of an extended chain split.
> >> >
> >> > The concern I'm raising is more about the psychology of giving BIP148
> >> > a sense of safety that may not be valid.  Without several more steps,
> >> > BIP148 is definitely on track to be a risky chainsplit, and without
> >> > segwit2x it will almost certainly be a small minority chain. (Unless
> >> > the segwit2x compromise falls apart before then, and even in that case
> >> > it is likely to be a minority chain)
> >> There are 2 primary factors involved here, economic support and
> >> hashpower either of which is enough to make a permanent chain split
> >> unlikely, miners will mine whichever chain is most profitable(see
> >> ETH/ETC hashpower profitability equilibrium for an example of how this
> >> works in practice) however there may be lag time immediately after the
> >> split if there is an economic majority but not a hashpower majority
> >> initially. This is risk mitigation that only requires miners support
> >> however. The main issue is just one of activation timelines, BIP91 as
> >> is takes too long to activate unless started ahead of the existing
> >> segwit2x schedule and it's unlikely that BIP148 will get pushed back
> >> any further.
> >> >
> >> > Jared
> >> >
> >> >
> >> > On Wed, Jun 7, 2017 at 2:42 PM, James Hilliard
> >> > <james.hilliard1@gmail.com> wrote:
> >> >> I don't really see how this would increase the likelihood of an
> >> >> extended chain split assuming BIP148 is going to have
> >> >> non-insignificant economic backing. This BIP is designed to provide a
> >> >> risk mitigation measure that miners can safely deploy. Since this BIP
> >> >> only activates with a clear miner majority it should not increase the
> >> >> risk of an extended chain split. At this point it is not completely
> >> >> clear how much economic support there is for BIP148 but support
> >> >> certainly seems to be growing and we have nearly 2 months until
> BIP148
> >> >> activation. I intentionally used a shorter activation period here so
> >> >> that decisions by miners can be made close to the BIP148 activation
> >> >> date.
> >> >>
> >> >> On Wed, Jun 7, 2017 at 4:29 PM, Jared Lee Richardson
> >> >> <jaredr26@gmail.com> wrote:
> >> >>> I think this BIP represents a gamble, and the gamble may not be a
> good
> >> >>> one.  The gamble here is that if the segwit2x changes are rolled out
> >> >>> on time, and if the signatories accept the bit4 + bit1 signaling
> >> >>> proposals within BIP91, the launch will go smoother, as intended.
> But
> >> >>> conversely, if either the segwit2x signatories balk about the Bit1
> >> >>> signaling OR if the timelines for segwit2mb are missed even by a
> bit,
> >> >>> it may cause the BIP148 chainsplit to be worse than it would be
> >> >>> without.  Given the frequent concerns raised in multiple places
> about
> >> >>> the aggressiveness of the segwit2x timelines, including the
> >> >>> non-hardfork timelines, this does not seem like a great gamble to be
> >> >>> making.
> >> >>>
> >> >>> The reason I say it may make the chainsplit be worse than it would
> >> >>> otherwise be is that it may provide a false sense of safety for
> BIP148
> >> >>> that currently does not currently exist(and should not, as it is a
> >> >>> chainsplit).  That sense of safety would only be legitimate if the
> >> >>> segwit2x signatories were on board, and the segwit2x code
> effectively
> >> >>> enforced BIP148 simultaneously, neither of which are guaranteed.  If
> >> >>> users and more miners had a false sense that BIP148 was *not* going
> to
> >> >>> chainsplit from default / segwit2x, they might not follow the news
> if
> >> >>> suddenly the segwit2x plan were delayed for a few days.  While any
> >> >>> additional support would definitely be cheered on by BIP148
> >> >>> supporters, the practical reality might be that this proposal would
> >> >>> take BIP148 from the "unlikely to have any viable chain after flag
> day
> >> >>> without segwit2x" category into the "small but viable minority
> chain"
> >> >>> category, and even worse, it might strengthen the chainsplit just
> days
> >> >>> before segwit is activated on BOTH chains, putting the BIP148
> >> >>> supporters on the wrong pro-segwit, but still-viable chain.
> >> >>>
> >> >>> If Core had taken a strong stance to include BIP148 into the client,
> >> >>> and if BIP148 support were much much broader, I would feel
> differently
> >> >>> as the gamble would be more likely to discourage a chainsplit (By
> >> >>> forcing the acceleration of segwit2x) rather than encourage it (by
> >> >>> strengthening an extreme minority chainsplit that may wind up on the
> >> >>> wrong side of two segwit-activated chains).  As it stands now, this
> >> >>> seems like a very dangerous attempt to compromise with a small but
> >> >>> vocal group that are the ones creating the threat to begin with.
> >> >>>
> >> >>> Jared
> >> >>>
> >> >>> On Tue, Jun 6, 2017 at 5:56 PM, James Hilliard via bitcoin-dev
> >> >>> <bitcoin-dev@lists.linuxfoundation.org> wrote:
> >> >>>> Due to the proposed calendar(https://segwit2x.github.io/) for the
> >> >>>> SegWit2x agreement being too slow to activate SegWit mandatory
> >> >>>> signalling ahead of BIP148 using BIP91 I would like to propose
> >> >>>> another
> >> >>>> option that miners can use to prevent a chain split ahead of the
> Aug
> >> >>>> 1st BIP148 activation date.
> >> >>>>
> >> >>>> The splitprotection soft fork is essentially BIP91 but using BIP8
> >> >>>> instead of BIP9 with a lower activation threshold and immediate
> >> >>>> mandatory signalling lock-in. This allows for a majority of miners
> to
> >> >>>> activate mandatory SegWit signalling and prevent a potential chain
> >> >>>> split ahead of BIP148 activation.
> >> >>>>
> >> >>>> This BIP allows for miners to respond to market forces quickly
> ahead
> >> >>>> of BIP148 activation by signalling for splitprotection. Any miners
> >> >>>> already running BIP148 should be encouraged to use splitprotection.
> >> >>>>
> >> >>>> <pre>
> >> >>>>   BIP: splitprotection
> >> >>>>   Layer: Consensus (soft fork)
> >> >>>>   Title: User Activated Soft Fork Split Protection
> >> >>>>   Author: James Hilliard <james.hilliard1@gmail.com>
> >> >>>>   Comments-Summary: No comments yet.
> >> >>>>   Comments-URI:
> >> >>>>   Status: Draft
> >> >>>>   Type: Standards Track
> >> >>>>   Created: 2017-05-22
> >> >>>>   License: BSD-3-Clause
> >> >>>>            CC0-1.0
> >> >>>> </pre>
> >> >>>>
> >> >>>> ==Abstract==
> >> >>>>
> >> >>>> This document specifies a coordination mechanism for a simple
> >> >>>> majority
> >> >>>> of miners to prevent a chain split ahead of BIP148 activation.
> >> >>>>
> >> >>>> ==Definitions==
> >> >>>>
> >> >>>> "existing segwit deployment" refer to the BIP9 "segwit" deployment
> >> >>>> using bit 1, between November 15th 2016 and November 15th 2017 to
> >> >>>> activate BIP141, BIP143 and BIP147.
> >> >>>>
> >> >>>> ==Motivation==
> >> >>>>
> >> >>>> The biggest risk of BIP148 is an extended chain split, this BIP
> >> >>>> provides a way for a simple majority of miners to eliminate that
> >> >>>> risk.
> >> >>>>
> >> >>>> This BIP provides a way for a simple majority of miners to
> coordinate
> >> >>>> activation of the existing segwit deployment with less than 95%
> >> >>>> hashpower before BIP148 activation. Due to time constraints unless
> >> >>>> immediately deployed BIP91 will likely not be able to enforce
> >> >>>> mandatory signalling of segwit before the Aug 1st activation of
> >> >>>> BIP148. This BIP provides a method for rapid miner activation of
> >> >>>> SegWit mandatory signalling ahead of the BIP148 activation date.
> >> >>>> Since
> >> >>>> the primary goal of this BIP is to reduce the chance of an extended
> >> >>>> chain split as much as possible we activate using a simple miner
> >> >>>> majority of 65% over a 504 block interval rather than a higher
> >> >>>> percentage. This BIP also allows miners to signal their intention
> to
> >> >>>> run BIP148 in order to prevent a chain split.
> >> >>>>
> >> >>>> ==Specification==
> >> >>>>
> >> >>>> While this BIP is active, all blocks must set the nVersion header
> top
> >> >>>> 3 bits to 001 together with bit field (1<<1) (according to the
> >> >>>> existing segwit deployment). Blocks that do not signal as required
> >> >>>> will be rejected.
> >> >>>>
> >> >>>> ==Deployment==
> >> >>>>
> >> >>>> This BIP will be deployed by "version bits" with a 65%(this can be
> >> >>>> adjusted if desired) activation threshold BIP9 with the name
> >> >>>> "splitprotecion" and using bit 2.
> >> >>>>
> >> >>>> This BIP starts immediately and is a BIP8 style soft fork since
> >> >>>> mandatory signalling will start on midnight August 1st 2017 (epoch
> >> >>>> time 1501545600) regardless of whether or not this BIP has reached
> >> >>>> its
> >> >>>> own signalling threshold. This BIP will cease to be active when
> >> >>>> segwit
> >> >>>> is locked-in.
> >> >>>>
> >> >>>> === Reference implementation ===
> >> >>>>
> >> >>>> <pre>
> >> >>>> // Check if Segregated Witness is Locked In
> >> >>>> bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
> >> >>>> Consensus::Params& params)
> >> >>>> {
> >> >>>>     LOCK(cs_main);
> >> >>>>     return (VersionBitsState(pindexPrev, params,
> >> >>>> Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
> >> >>>> THRESHOLD_LOCKED_IN);
> >> >>>> }
> >> >>>>
> >> >>>> // SPLITPROTECTION mandatory segwit signalling.
> >> >>>> if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
> >> >>>> Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
> >> >>>> THRESHOLD_LOCKED_IN &&
> >> >>>>      !IsWitnessLockedIn(pindex->pprev,
> chainparams.GetConsensus()) &&
> >> >>>> // Segwit is not locked in
> >> >>>>      !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())
> )
> >> >>>> //
> >> >>>> and is not active.
> >> >>>> {
> >> >>>>     bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK)
> ==
> >> >>>> VERSIONBITS_TOP_BITS;
> >> >>>>     bool fSegbit = (pindex->nVersion &
> >> >>>> VersionBitsMask(chainparams.GetConsensus(),
> >> >>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
> >> >>>>     if (!(fVersionBits && fSegbit)) {
> >> >>>>         return state.DoS(0, error("ConnectBlock(): relayed block
> must
> >> >>>> signal for segwit, please upgrade"), REJECT_INVALID,
> >> >>>> "bad-no-segwit");
> >> >>>>     }
> >> >>>> }
> >> >>>>
> >> >>>> // BIP148 mandatory segwit signalling.
> >> >>>> int64_t nMedianTimePast = pindex->GetMedianTimePast();
> >> >>>> if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017
> 00:00:00
> >> >>>> UTC
> >> >>>>      (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017
> 00:00:00
> >> >>>> UTC
> >> >>>>      (!IsWitnessLockedIn(pindex->pprev,
> chainparams.GetConsensus())
> >> >>>> &&
> >> >>>>  // Segwit is not locked in
> >> >>>>       !IsWitnessEnabled(pindex->pprev,
> chainparams.GetConsensus())) )
> >> >>>>  // and is not active.
> >> >>>> {
> >> >>>>     bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK)
> ==
> >> >>>> VERSIONBITS_TOP_BITS;
> >> >>>>     bool fSegbit = (pindex->nVersion &
> >> >>>> VersionBitsMask(chainparams.GetConsensus(),
> >> >>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
> >> >>>>     if (!(fVersionBits && fSegbit)) {
> >> >>>>         return state.DoS(0, error("ConnectBlock(): relayed block
> must
> >> >>>> signal for segwit, please upgrade"), REJECT_INVALID,
> >> >>>> "bad-no-segwit");
> >> >>>>     }
> >> >>>> }
> >> >>>> </pre>
> >> >>>>
> >> >>>>
> >> >>>> https://github.com/bitcoin/bitcoin/compare/0.14...
> jameshilliard:splitprotection-v0.14.1
> >> >>>>
> >> >>>> ==Backwards Compatibility==
> >> >>>>
> >> >>>> This deployment is compatible with the existing "segwit" bit 1
> >> >>>> deployment scheduled between midnight November 15th, 2016 and
> >> >>>> midnight
> >> >>>> November 15th, 2017. This deployment is also compatible with the
> >> >>>> existing BIP148 deployment. This BIP is compatible with BIP91 only
> if
> >> >>>> BIP91 activates before it and before BIP148. Miners will need to
> >> >>>> upgrade their nodes to support splitprotection otherwise they may
> >> >>>> build on top of an invalid block. While this bip is active users
> >> >>>> should either upgrade to splitprotection or wait for additional
> >> >>>> confirmations when accepting payments.
> >> >>>>
> >> >>>> ==Rationale==
> >> >>>>
> >> >>>> Historically we have used IsSuperMajority() to activate soft forks
> >> >>>> such as BIP66 which has a mandatory signalling requirement for
> miners
> >> >>>> once activated, this ensures that miners are aware of new rules
> being
> >> >>>> enforced. This technique can be leveraged to lower the signalling
> >> >>>> threshold of a soft fork while it is in the process of being
> deployed
> >> >>>> in a backwards compatible way. We also use a BIP8 style timeout to
> >> >>>> ensure that this BIP is compatible with BIP148 and that BIP148
> >> >>>> compatible mandatory signalling activates regardless of miner
> >> >>>> signalling levels.
> >> >>>>
> >> >>>> By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
> >> >>>> deployment, this BIP can cause the existing "segwit" deployment to
> >> >>>> activate without needing to release a new deployment. As we
> approach
> >> >>>> BIP148 activation it may be desirable for a majority of miners to
> >> >>>> have
> >> >>>> a method that will ensure that there is no chain split.
> >> >>>>
> >> >>>> ==References==
> >> >>>>
> >> >>>>
> >> >>>> *[https://lists.linuxfoundation.org/pipermail/
> bitcoin-dev/2017-March/013714.html
> >> >>>> Mailing list discussion]
> >> >>>>
> >> >>>> *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.
> cpp#L1281-L1283
> >> >>>> P2SH flag day activation]
> >> >>>> *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
> >> >>>> *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
> >> >>>> *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
> >> >>>> *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
> >> >>>> *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
> >> >>>> Version 0 Witness Program]]
> >> >>>> *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element
> >> >>>> malleability]]
> >> >>>> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit
> >> >>>> deployment]]
> >> >>>> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second
> deployment)]]
> >> >>>> *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit
> >> >>>> benefits]
> >> >>>>
> >> >>>> ==Copyright==
> >> >>>>
> >> >>>> This document is dual licensed as BSD 3-clause, and Creative
> Commons
> >> >>>> CC0 1.0 Universal.
> >> >>>> _______________________________________________
> >> >>>> bitcoin-dev mailing list
> >> >>>> bitcoin-dev@lists.linuxfoundation.org
> >> >>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
> >
> >
>

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Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[James Hilliard]

On Wed, Jun 7, 2017 at 6:43 PM, Jared Lee Richardson <jaredr26@gmail.com> wrote:
>> BIP148 however is a consensus change that can
>> be rectified if it gets more work, this would act as an additional
>> incentive for mine the BIP148 side since there would be no wipeout
>> risk there.
>
> This statement is misleading.  Wipeout risks don't apply to any consensus
> changes; It is a consensus change, it can only be abandoned.  The BIP148
> chain carries just as many risks of being abandoned or even more with
> segwit2x on the table.  No miner would consider "wipeout risk" an advantage
> when the real threat is chain abandonment.
Both are issues, but wipeout risk is different, the ETH/ETC split for
example didn't have any wipeout risk for either side the same is not
true for BIP148(and it is the non-BIP148 side that carries the risk of
chain wipeout).
>
>> Higher transaction fees on a minority chain can compensate miners for
>> a lower price which would likely be enough to get the BIP148 chain to
>> a difficulty reduction.
>
> Higher transaction fees suffers the same problem as exchange support does.
> Without replay protection, it is very difficult for any average user to
> force transactions onto one chain or the other.  Thus, without replay
> protection, the UASF chain is unlikely to develop any viable fee market; Its
> few miners 99% of the time will simply choose from the highest fees that
> were already available to the other chain, which is basically no advantage
> at all.
Not really, there are a few relatively simple techniques such as RBF
which can be leveraged to get confirmations on on-side before double
spending on another. Once a transaction is confirmed on the non-BIP148
chain then the high fee transactions can be made on only the BIP148
side of the split using RBF. Exchanges will likely do this splitting
automatically for uses as well.
>
>>  ETC replay protection was done after the fork on an as
>> needed basis(there are multiple reliable techniques that can be used
>> to split UTXO's), the same can happen with BIP148 and it is easier to
>> do with Bitcoin than with the ETH/ETC split IMO.
>
> ETC replay protection was added because they were already a hardfork and
> without it they would not have had a viable chain.  BIP148 is not supposed
> to be a hardfork, and if it added replay protection to remain viable it
> would lose the frequently touted "wipeout advantage" as well as the ability
> to call itself a softfork.  And are you seriously suggesting that what
> happened with ETC and ETH is a desirable and good situation for Bitcoin, and
> that UASF is ETC?
There wasn't proper replay protection at split time for ETH/ETC since
normal transactions would get executed on both sides originally,
however replay protection was added by wallets(mainly using splitting
contracts). I don't think a split is desirable however, which is why
I've proposed this BIP.
>
>> A big reason BIP148 still has support is because up until SegWit
>> actually activates there's no guarantee segwit2mb will actually have
>> the necessary support to activate SegWit.
>
> For a miners blowing through six million dollars a day in mining operational
> costs, that's a pretty crappy reason.  Serious miners can't afford to prop
> up a non-viable chain based on philosophy or maybes.  BIP148 is based
> entirely upon people who aren't putting anything on the line trying to
> convince others to take the huge risks for them.  With deceptively
> fallacious logic, in my opinion.
Yes, miners aren't likely to waste operational mining costs, that's
ultimately why miners would follow the BIP148 side of the chain
assuming it has sufficient economic support or if it's more profitable
to mine.
>
> Even segwit2x is based on the assumption that all miners can reach
> consensus.  Break that assumption and segwit2x will have the same problems
> as UASF.
segwit2x has more issues since the HF part requires users to reach consensus
>
>> This is largely an issue due to segwit2x's bundling, if the SW and HF
>> part of segwit2x were unbundled then there would be no reason to delay
>> BIP91 activation
>
> They are bundled.  Segwit alone doesn't have the desired overwhelming
> consensus, unless core wishes to fork 71% to 29%, and maybe not even that
> high.  That's the technical reason, and they can't be unbundled without
> breaking that consensus.
That's a political reason not a technical reason.
>
> Jared
>
>
> On Wed, Jun 7, 2017 at 4:11 PM, James Hilliard <james.hilliard1@gmail.com>
> wrote:
>>
>> On Wed, Jun 7, 2017 at 5:53 PM, Jared Lee Richardson <jaredr26@gmail.com>
>> wrote:
>> >> There are 2 primary factors involved here, economic support and
>> > hashpower either of which is enough to make a permanent chain split
>> > unlikely, miners will mine whichever chain is most profitable(see
>> > ETH/ETC hashpower profitability equilibrium for an example of how this
>> > works in practice)
>> >
>> > That's not a comparable example.  ETC did not face potentially years of
>> > slow
>> > blocktimes before it normalized, whereas BIP148 is on track to do
>> > exactly
>> > that.  Moreover, ETC represented a fundamental break from the majority
>> > consensus that could not be rectified, whereas BIP148 represents only a
>> > minority attempt to accelerate something that an overwhelming majority
>> > of
>> > miners have already agreed to activate under segwit2x.  Lastly ETC was
>> > required to add replay protection, just like any minority fork proposed
>> > by
>> > any crypto-currency has been, something that BIP148 both lacks and
>> > refuses
>> > to add or even acknowledge the necessity of.  Without replay protection,
>> > ETC
>> > could not have become profitable enough to be a viable minority chain.
>> > If
>> > BIP148's chain is not the majority chain and it does not have replay
>> > protection, it will face the same problems, but that required replay
>> > protection will turn it into a hardfork.  This will be a very bad
>> > position
>> > for UASF supporters to find themselves in - Either hardfork and hope the
>> > price is higher and the majority converts, or die as the minority chain
>> > with
>> > no reliable methods of economic conversion.
>> Higher transaction fees on a minority chain can compensate miners for
>> a lower price which would likely be enough to get the BIP148 chain to
>> a difficulty reduction. BIP148 however is a consensus change that can
>> be rectified if it gets more work, this would act as an additional
>> incentive for mine the BIP148 side since there would be no wipeout
>> risk there. ETC replay protection was done after the fork on an as
>> needed basis(there are multiple reliable techniques that can be used
>> to split UTXO's), the same can happen with BIP148 and it is easier to
>> do with Bitcoin than with the ETH/ETC split IMO.
>> >
>> > I believe, but don't have data to back this, that most of the BIP148
>> > insistence comes not from a legitimate attempt to gain consensus (or
>> > else
>> > they would either outright oppose segwit2mb for its hardfork, or they
>> > would
>> > outright support it), but rather from an attempt for BIP148 supporters
>> > to
>> > save face for BIP148 being a failure.  If I'm correct, that's a terrible
>> > and
>> > highly non-technical reason for segwit2mb to bend over backwards
>> > attempting
>> > to support BIP148's attempt to save face.
>> A big reason BIP148 still has support is because up until SegWit
>> actually activates there's no guarantee segwit2mb will actually have
>> the necessary support to activate SegWit.
>> >
>> >> The main issue is just one of activation timelines, BIP91 as
>> > is takes too long to activate unless started ahead of the existing
>> > segwit2x schedule and it's unlikely that BIP148 will get pushed back
>> > any further.
>> >
>> > Even if I'm not correct on the above, I and others find it hard to
>> > accept
>> > that this timeline conflict is segwit2x's fault.  Segwit2x has both some
>> > flexibility and broad support that crosses contentious pro-segwit and
>> > pro-blocksize-increase divisions that have existed for two years.
>> > BIP148 is
>> > attempting to hold segwit2x's timelines and code hostage by claiming
>> > inflexibility and claiming broad support, and not only are neither of
>> > those
>> > assertions are backed by real data, BIP148 (by being so inflexible) is
>> > pushing a position that deepens the divides between those groups.  For
>> > there
>> > to be technical reasons for compatibility (so long as there are
>> > tradeoffs,
>> > which there are), there needs to be hard data showing that BIP148 is a
>> > viable minority fork that won't simply die off on its own.
>> This is largely an issue due to segwit2x's bundling, if the SW and HF
>> part of segwit2x were unbundled then there would be no reason to delay
>> BIP91 activation, this is especially a problem since it takes a good
>> deal of time to properly code and test a HF. Unfortunately segwit2x
>> has been quite inflexible in regards to the bundling aspect even
>> though there are clearly no technical reasons for it to be there.
>> >
>> > Jared
>> >
>> >
>> > On Wed, Jun 7, 2017 at 3:23 PM, James Hilliard
>> > <james.hilliard1@gmail.com>
>> > wrote:
>> >>
>> >> On Wed, Jun 7, 2017 at 4:50 PM, Jared Lee Richardson
>> >> <jaredr26@gmail.com>
>> >> wrote:
>> >> > Could this risk mitigation measure be an optional flag?  And if so,
>> >> > could it+BIP91 signal on a different bit than bit4?
>> >> It's fairly trivial for miners to signal for BIP91 on bit4 or a
>> >> different bit at the same time as the code is trivial enough to
>> >> combine
>> >> >
>> >> > The reason being, if for some reason the segwit2x activation cannot
>> >> > take place in time, it would be preferable for miners to have a more
>> >> > standard approach to activation that requires stronger consensus and
>> >> > may be more forgiving than BIP148.  If the segwit2x activation is on
>> >> > time to cooperate with BIP148, it could be signaled through the
>> >> > non-bit4 approach and everything could go smoothly.  Thoughts on that
>> >> > idea?  It may add more complexity and more developer time, but may
>> >> > also address your concerns among others.
>> >> This does give miners another approach to activate segwit ahead of
>> >> BIP148, if segwit2x activation is rolled out and activated immediately
>> >> then this would not be needed however based on the timeline here
>> >> https://segwit2x.github.io/ it would not be possible for BIP91 to
>> >> enforce mandatory signalling ahead of BIP148. Maybe that can be
>> >> changed though, I've suggested an immediate rollout with a placeholder
>> >> client timeout instead of the HF code initially in order to accelerate
>> >> that.
>> >> >
>> >> >> Since this BIP
>> >> >> only activates with a clear miner majority it should not increase
>> >> >> the
>> >> >> risk of an extended chain split.
>> >> >
>> >> > The concern I'm raising is more about the psychology of giving BIP148
>> >> > a sense of safety that may not be valid.  Without several more steps,
>> >> > BIP148 is definitely on track to be a risky chainsplit, and without
>> >> > segwit2x it will almost certainly be a small minority chain. (Unless
>> >> > the segwit2x compromise falls apart before then, and even in that
>> >> > case
>> >> > it is likely to be a minority chain)
>> >> There are 2 primary factors involved here, economic support and
>> >> hashpower either of which is enough to make a permanent chain split
>> >> unlikely, miners will mine whichever chain is most profitable(see
>> >> ETH/ETC hashpower profitability equilibrium for an example of how this
>> >> works in practice) however there may be lag time immediately after the
>> >> split if there is an economic majority but not a hashpower majority
>> >> initially. This is risk mitigation that only requires miners support
>> >> however. The main issue is just one of activation timelines, BIP91 as
>> >> is takes too long to activate unless started ahead of the existing
>> >> segwit2x schedule and it's unlikely that BIP148 will get pushed back
>> >> any further.
>> >> >
>> >> > Jared
>> >> >
>> >> >
>> >> > On Wed, Jun 7, 2017 at 2:42 PM, James Hilliard
>> >> > <james.hilliard1@gmail.com> wrote:
>> >> >> I don't really see how this would increase the likelihood of an
>> >> >> extended chain split assuming BIP148 is going to have
>> >> >> non-insignificant economic backing. This BIP is designed to provide
>> >> >> a
>> >> >> risk mitigation measure that miners can safely deploy. Since this
>> >> >> BIP
>> >> >> only activates with a clear miner majority it should not increase
>> >> >> the
>> >> >> risk of an extended chain split. At this point it is not completely
>> >> >> clear how much economic support there is for BIP148 but support
>> >> >> certainly seems to be growing and we have nearly 2 months until
>> >> >> BIP148
>> >> >> activation. I intentionally used a shorter activation period here so
>> >> >> that decisions by miners can be made close to the BIP148 activation
>> >> >> date.
>> >> >>
>> >> >> On Wed, Jun 7, 2017 at 4:29 PM, Jared Lee Richardson
>> >> >> <jaredr26@gmail.com> wrote:
>> >> >>> I think this BIP represents a gamble, and the gamble may not be a
>> >> >>> good
>> >> >>> one.  The gamble here is that if the segwit2x changes are rolled
>> >> >>> out
>> >> >>> on time, and if the signatories accept the bit4 + bit1 signaling
>> >> >>> proposals within BIP91, the launch will go smoother, as intended.
>> >> >>> But
>> >> >>> conversely, if either the segwit2x signatories balk about the Bit1
>> >> >>> signaling OR if the timelines for segwit2mb are missed even by a
>> >> >>> bit,
>> >> >>> it may cause the BIP148 chainsplit to be worse than it would be
>> >> >>> without.  Given the frequent concerns raised in multiple places
>> >> >>> about
>> >> >>> the aggressiveness of the segwit2x timelines, including the
>> >> >>> non-hardfork timelines, this does not seem like a great gamble to
>> >> >>> be
>> >> >>> making.
>> >> >>>
>> >> >>> The reason I say it may make the chainsplit be worse than it would
>> >> >>> otherwise be is that it may provide a false sense of safety for
>> >> >>> BIP148
>> >> >>> that currently does not currently exist(and should not, as it is a
>> >> >>> chainsplit).  That sense of safety would only be legitimate if the
>> >> >>> segwit2x signatories were on board, and the segwit2x code
>> >> >>> effectively
>> >> >>> enforced BIP148 simultaneously, neither of which are guaranteed.
>> >> >>> If
>> >> >>> users and more miners had a false sense that BIP148 was *not* going
>> >> >>> to
>> >> >>> chainsplit from default / segwit2x, they might not follow the news
>> >> >>> if
>> >> >>> suddenly the segwit2x plan were delayed for a few days.  While any
>> >> >>> additional support would definitely be cheered on by BIP148
>> >> >>> supporters, the practical reality might be that this proposal would
>> >> >>> take BIP148 from the "unlikely to have any viable chain after flag
>> >> >>> day
>> >> >>> without segwit2x" category into the "small but viable minority
>> >> >>> chain"
>> >> >>> category, and even worse, it might strengthen the chainsplit just
>> >> >>> days
>> >> >>> before segwit is activated on BOTH chains, putting the BIP148
>> >> >>> supporters on the wrong pro-segwit, but still-viable chain.
>> >> >>>
>> >> >>> If Core had taken a strong stance to include BIP148 into the
>> >> >>> client,
>> >> >>> and if BIP148 support were much much broader, I would feel
>> >> >>> differently
>> >> >>> as the gamble would be more likely to discourage a chainsplit (By
>> >> >>> forcing the acceleration of segwit2x) rather than encourage it (by
>> >> >>> strengthening an extreme minority chainsplit that may wind up on
>> >> >>> the
>> >> >>> wrong side of two segwit-activated chains).  As it stands now, this
>> >> >>> seems like a very dangerous attempt to compromise with a small but
>> >> >>> vocal group that are the ones creating the threat to begin with.
>> >> >>>
>> >> >>> Jared
>> >> >>>
>> >> >>> On Tue, Jun 6, 2017 at 5:56 PM, James Hilliard via bitcoin-dev
>> >> >>> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>> >> >>>> Due to the proposed calendar(https://segwit2x.github.io/) for the
>> >> >>>> SegWit2x agreement being too slow to activate SegWit mandatory
>> >> >>>> signalling ahead of BIP148 using BIP91 I would like to propose
>> >> >>>> another
>> >> >>>> option that miners can use to prevent a chain split ahead of the
>> >> >>>> Aug
>> >> >>>> 1st BIP148 activation date.
>> >> >>>>
>> >> >>>> The splitprotection soft fork is essentially BIP91 but using BIP8
>> >> >>>> instead of BIP9 with a lower activation threshold and immediate
>> >> >>>> mandatory signalling lock-in. This allows for a majority of miners
>> >> >>>> to
>> >> >>>> activate mandatory SegWit signalling and prevent a potential chain
>> >> >>>> split ahead of BIP148 activation.
>> >> >>>>
>> >> >>>> This BIP allows for miners to respond to market forces quickly
>> >> >>>> ahead
>> >> >>>> of BIP148 activation by signalling for splitprotection. Any miners
>> >> >>>> already running BIP148 should be encouraged to use
>> >> >>>> splitprotection.
>> >> >>>>
>> >> >>>> <pre>
>> >> >>>>   BIP: splitprotection
>> >> >>>>   Layer: Consensus (soft fork)
>> >> >>>>   Title: User Activated Soft Fork Split Protection
>> >> >>>>   Author: James Hilliard <james.hilliard1@gmail.com>
>> >> >>>>   Comments-Summary: No comments yet.
>> >> >>>>   Comments-URI:
>> >> >>>>   Status: Draft
>> >> >>>>   Type: Standards Track
>> >> >>>>   Created: 2017-05-22
>> >> >>>>   License: BSD-3-Clause
>> >> >>>>            CC0-1.0
>> >> >>>> </pre>
>> >> >>>>
>> >> >>>> ==Abstract==
>> >> >>>>
>> >> >>>> This document specifies a coordination mechanism for a simple
>> >> >>>> majority
>> >> >>>> of miners to prevent a chain split ahead of BIP148 activation.
>> >> >>>>
>> >> >>>> ==Definitions==
>> >> >>>>
>> >> >>>> "existing segwit deployment" refer to the BIP9 "segwit" deployment
>> >> >>>> using bit 1, between November 15th 2016 and November 15th 2017 to
>> >> >>>> activate BIP141, BIP143 and BIP147.
>> >> >>>>
>> >> >>>> ==Motivation==
>> >> >>>>
>> >> >>>> The biggest risk of BIP148 is an extended chain split, this BIP
>> >> >>>> provides a way for a simple majority of miners to eliminate that
>> >> >>>> risk.
>> >> >>>>
>> >> >>>> This BIP provides a way for a simple majority of miners to
>> >> >>>> coordinate
>> >> >>>> activation of the existing segwit deployment with less than 95%
>> >> >>>> hashpower before BIP148 activation. Due to time constraints unless
>> >> >>>> immediately deployed BIP91 will likely not be able to enforce
>> >> >>>> mandatory signalling of segwit before the Aug 1st activation of
>> >> >>>> BIP148. This BIP provides a method for rapid miner activation of
>> >> >>>> SegWit mandatory signalling ahead of the BIP148 activation date.
>> >> >>>> Since
>> >> >>>> the primary goal of this BIP is to reduce the chance of an
>> >> >>>> extended
>> >> >>>> chain split as much as possible we activate using a simple miner
>> >> >>>> majority of 65% over a 504 block interval rather than a higher
>> >> >>>> percentage. This BIP also allows miners to signal their intention
>> >> >>>> to
>> >> >>>> run BIP148 in order to prevent a chain split.
>> >> >>>>
>> >> >>>> ==Specification==
>> >> >>>>
>> >> >>>> While this BIP is active, all blocks must set the nVersion header
>> >> >>>> top
>> >> >>>> 3 bits to 001 together with bit field (1<<1) (according to the
>> >> >>>> existing segwit deployment). Blocks that do not signal as required
>> >> >>>> will be rejected.
>> >> >>>>
>> >> >>>> ==Deployment==
>> >> >>>>
>> >> >>>> This BIP will be deployed by "version bits" with a 65%(this can be
>> >> >>>> adjusted if desired) activation threshold BIP9 with the name
>> >> >>>> "splitprotecion" and using bit 2.
>> >> >>>>
>> >> >>>> This BIP starts immediately and is a BIP8 style soft fork since
>> >> >>>> mandatory signalling will start on midnight August 1st 2017 (epoch
>> >> >>>> time 1501545600) regardless of whether or not this BIP has reached
>> >> >>>> its
>> >> >>>> own signalling threshold. This BIP will cease to be active when
>> >> >>>> segwit
>> >> >>>> is locked-in.
>> >> >>>>
>> >> >>>> === Reference implementation ===
>> >> >>>>
>> >> >>>> <pre>
>> >> >>>> // Check if Segregated Witness is Locked In
>> >> >>>> bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
>> >> >>>> Consensus::Params& params)
>> >> >>>> {
>> >> >>>>     LOCK(cs_main);
>> >> >>>>     return (VersionBitsState(pindexPrev, params,
>> >> >>>> Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
>> >> >>>> THRESHOLD_LOCKED_IN);
>> >> >>>> }
>> >> >>>>
>> >> >>>> // SPLITPROTECTION mandatory segwit signalling.
>> >> >>>> if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
>> >> >>>> Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
>> >> >>>> THRESHOLD_LOCKED_IN &&
>> >> >>>>      !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus())
>> >> >>>> &&
>> >> >>>> // Segwit is not locked in
>> >> >>>>      !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus())
>> >> >>>> )
>> >> >>>> //
>> >> >>>> and is not active.
>> >> >>>> {
>> >> >>>>     bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK)
>> >> >>>> ==
>> >> >>>> VERSIONBITS_TOP_BITS;
>> >> >>>>     bool fSegbit = (pindex->nVersion &
>> >> >>>> VersionBitsMask(chainparams.GetConsensus(),
>> >> >>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>> >> >>>>     if (!(fVersionBits && fSegbit)) {
>> >> >>>>         return state.DoS(0, error("ConnectBlock(): relayed block
>> >> >>>> must
>> >> >>>> signal for segwit, please upgrade"), REJECT_INVALID,
>> >> >>>> "bad-no-segwit");
>> >> >>>>     }
>> >> >>>> }
>> >> >>>>
>> >> >>>> // BIP148 mandatory segwit signalling.
>> >> >>>> int64_t nMedianTimePast = pindex->GetMedianTimePast();
>> >> >>>> if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017
>> >> >>>> 00:00:00
>> >> >>>> UTC
>> >> >>>>      (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017
>> >> >>>> 00:00:00
>> >> >>>> UTC
>> >> >>>>      (!IsWitnessLockedIn(pindex->pprev,
>> >> >>>> chainparams.GetConsensus())
>> >> >>>> &&
>> >> >>>>  // Segwit is not locked in
>> >> >>>>       !IsWitnessEnabled(pindex->pprev,
>> >> >>>> chainparams.GetConsensus())) )
>> >> >>>>  // and is not active.
>> >> >>>> {
>> >> >>>>     bool fVersionBits = (pindex->nVersion & VERSIONBITS_TOP_MASK)
>> >> >>>> ==
>> >> >>>> VERSIONBITS_TOP_BITS;
>> >> >>>>     bool fSegbit = (pindex->nVersion &
>> >> >>>> VersionBitsMask(chainparams.GetConsensus(),
>> >> >>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>> >> >>>>     if (!(fVersionBits && fSegbit)) {
>> >> >>>>         return state.DoS(0, error("ConnectBlock(): relayed block
>> >> >>>> must
>> >> >>>> signal for segwit, please upgrade"), REJECT_INVALID,
>> >> >>>> "bad-no-segwit");
>> >> >>>>     }
>> >> >>>> }
>> >> >>>> </pre>
>> >> >>>>
>> >> >>>>
>> >> >>>>
>> >> >>>> https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1
>> >> >>>>
>> >> >>>> ==Backwards Compatibility==
>> >> >>>>
>> >> >>>> This deployment is compatible with the existing "segwit" bit 1
>> >> >>>> deployment scheduled between midnight November 15th, 2016 and
>> >> >>>> midnight
>> >> >>>> November 15th, 2017. This deployment is also compatible with the
>> >> >>>> existing BIP148 deployment. This BIP is compatible with BIP91 only
>> >> >>>> if
>> >> >>>> BIP91 activates before it and before BIP148. Miners will need to
>> >> >>>> upgrade their nodes to support splitprotection otherwise they may
>> >> >>>> build on top of an invalid block. While this bip is active users
>> >> >>>> should either upgrade to splitprotection or wait for additional
>> >> >>>> confirmations when accepting payments.
>> >> >>>>
>> >> >>>> ==Rationale==
>> >> >>>>
>> >> >>>> Historically we have used IsSuperMajority() to activate soft forks
>> >> >>>> such as BIP66 which has a mandatory signalling requirement for
>> >> >>>> miners
>> >> >>>> once activated, this ensures that miners are aware of new rules
>> >> >>>> being
>> >> >>>> enforced. This technique can be leveraged to lower the signalling
>> >> >>>> threshold of a soft fork while it is in the process of being
>> >> >>>> deployed
>> >> >>>> in a backwards compatible way. We also use a BIP8 style timeout to
>> >> >>>> ensure that this BIP is compatible with BIP148 and that BIP148
>> >> >>>> compatible mandatory signalling activates regardless of miner
>> >> >>>> signalling levels.
>> >> >>>>
>> >> >>>> By orphaning non-signalling blocks during the BIP9 bit 1 "segwit"
>> >> >>>> deployment, this BIP can cause the existing "segwit" deployment to
>> >> >>>> activate without needing to release a new deployment. As we
>> >> >>>> approach
>> >> >>>> BIP148 activation it may be desirable for a majority of miners to
>> >> >>>> have
>> >> >>>> a method that will ensure that there is no chain split.
>> >> >>>>
>> >> >>>> ==References==
>> >> >>>>
>> >> >>>>
>> >> >>>>
>> >> >>>> *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html
>> >> >>>> Mailing list discussion]
>> >> >>>>
>> >> >>>>
>> >> >>>> *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283
>> >> >>>> P2SH flag day activation]
>> >> >>>> *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
>> >> >>>> *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
>> >> >>>> *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
>> >> >>>> *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus
>> >> >>>> layer)]]
>> >> >>>> *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification
>> >> >>>> for
>> >> >>>> Version 0 Witness Program]]
>> >> >>>> *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element
>> >> >>>> malleability]]
>> >> >>>> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit
>> >> >>>> deployment]]
>> >> >>>> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second
>> >> >>>> deployment)]]
>> >> >>>> *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit
>> >> >>>> benefits]
>> >> >>>>
>> >> >>>> ==Copyright==
>> >> >>>>
>> >> >>>> This document is dual licensed as BSD 3-clause, and Creative
>> >> >>>> Commons
>> >> >>>> CC0 1.0 Universal.
>> >> >>>> _______________________________________________
>> >> >>>> bitcoin-dev mailing list
>> >> >>>> bitcoin-dev@lists.linuxfoundation.org
>> >> >>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>> >
>> >
>
>

Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[Jared Lee Richardson]

[-- Attachment #1: Type: text/plain, Size: 30761 bytes --]

> Not really, there are a few relatively simple techniques such as RBF
> which can be leveraged to get confirmations on on-side before double
> spending on another. Once a transaction is confirmed on the non-BIP148
> chain then the high fee transactions can be made on only the BIP148
> side of the split using RBF.

Ah, so the BIP148 client handles this on behalf of its less technical users
on their behalf then, yes?

>  Exchanges will likely do this splitting
> automatically for uses as well.

Sure, Exchanges are going to dedicate hundreds of developer hours and
thousands of support hours to support something that they've repeatedly
told everyone must have replay protection to be supported.  They're going
to do this because 8% of nodes and <0.5% of miners say they'll be rewarded
richly.  Somehow I find that hard to believe.

Besides, if the BIP148 client does it for them, they wouldn't have to
dedicate those hundreds of developer hours.  Right?

I can't imagine how this logic is getting you from where the real data is
to the assumption that an economic majority will push BIP148 into being
such a more valuable chain that switching chains will be attractive to
enough miners.  There's got to be some real data that convinces you of this
somewhere?

> Both are issues, but wipeout risk is different, the ETH/ETC split for
> example didn't have any wipeout risk for either side the same is not
> true for BIP148(and it is the non-BIP148 side that carries the risk of
> chain wipeout).

Wipeout risk is a serious issue when 45% of the miners support one chain
and 55% support the other chain.  Segwit doesn't even have 35% of the
miners; There's no data or statements anywhere that indicate that UASF is
going to reach the point where wipeout risk is even comparable to
abandonment risk.

> Yes, miners aren't likely to waste operational mining costs, that's
> ultimately why miners would follow the BIP148 side of the chain
> assuming it has sufficient economic support or if it's more profitable
> to mine.

To convince miners you would have to have some data SOMEWHERE supporting
the economic majority argument.  Is there any such data?

> segwit2x has more issues since the HF part requires users to reach
consensus

It doesn't have those issues during the segwit activation, ergo there is no
reason for segwit-activation problems to take priority over the very real
hardfork activation problems.

> That's a political reason not a technical reason.

In a consensus system they are frequently the same, unfortunately.
Technical awesomeness without people agreeing = zero consensus.  So the
choice is either to "technically" break the consensus without a
super-majority and see what happens, or to go with the choice that has real
data showing the most consensus and hope the tiny minority chain actually
dies off.

Jared

On Wed, Jun 7, 2017 at 5:01 PM, James Hilliard <james.hilliard1@gmail.com>
wrote:

> On Wed, Jun 7, 2017 at 6:43 PM, Jared Lee Richardson <jaredr26@gmail.com>
> wrote:
> >> BIP148 however is a consensus change that can
> >> be rectified if it gets more work, this would act as an additional
> >> incentive for mine the BIP148 side since there would be no wipeout
> >> risk there.
> >
> > This statement is misleading.  Wipeout risks don't apply to any consensus
> > changes; It is a consensus change, it can only be abandoned.  The BIP148
> > chain carries just as many risks of being abandoned or even more with
> > segwit2x on the table.  No miner would consider "wipeout risk" an
> advantage
> > when the real threat is chain abandonment.
> Both are issues, but wipeout risk is different, the ETH/ETC split for
> example didn't have any wipeout risk for either side the same is not
> true for BIP148(and it is the non-BIP148 side that carries the risk of
> chain wipeout).
> >
> >> Higher transaction fees on a minority chain can compensate miners for
> >> a lower price which would likely be enough to get the BIP148 chain to
> >> a difficulty reduction.
> >
> > Higher transaction fees suffers the same problem as exchange support
> does.
> > Without replay protection, it is very difficult for any average user to
> > force transactions onto one chain or the other.  Thus, without replay
> > protection, the UASF chain is unlikely to develop any viable fee market;
> Its
> > few miners 99% of the time will simply choose from the highest fees that
> > were already available to the other chain, which is basically no
> advantage
> > at all.
> Not really, there are a few relatively simple techniques such as RBF
> which can be leveraged to get confirmations on on-side before double
> spending on another. Once a transaction is confirmed on the non-BIP148
> chain then the high fee transactions can be made on only the BIP148
> side of the split using RBF. Exchanges will likely do this splitting
> automatically for uses as well.
> >
> >>  ETC replay protection was done after the fork on an as
> >> needed basis(there are multiple reliable techniques that can be used
> >> to split UTXO's), the same can happen with BIP148 and it is easier to
> >> do with Bitcoin than with the ETH/ETC split IMO.
> >
> > ETC replay protection was added because they were already a hardfork and
> > without it they would not have had a viable chain.  BIP148 is not
> supposed
> > to be a hardfork, and if it added replay protection to remain viable it
> > would lose the frequently touted "wipeout advantage" as well as the
> ability
> > to call itself a softfork.  And are you seriously suggesting that what
> > happened with ETC and ETH is a desirable and good situation for Bitcoin,
> and
> > that UASF is ETC?
> There wasn't proper replay protection at split time for ETH/ETC since
> normal transactions would get executed on both sides originally,
> however replay protection was added by wallets(mainly using splitting
> contracts). I don't think a split is desirable however, which is why
> I've proposed this BIP.
> >
> >> A big reason BIP148 still has support is because up until SegWit
> >> actually activates there's no guarantee segwit2mb will actually have
> >> the necessary support to activate SegWit.
> >
> > For a miners blowing through six million dollars a day in mining
> operational
> > costs, that's a pretty crappy reason.  Serious miners can't afford to
> prop
> > up a non-viable chain based on philosophy or maybes.  BIP148 is based
> > entirely upon people who aren't putting anything on the line trying to
> > convince others to take the huge risks for them.  With deceptively
> > fallacious logic, in my opinion.
> Yes, miners aren't likely to waste operational mining costs, that's
> ultimately why miners would follow the BIP148 side of the chain
> assuming it has sufficient economic support or if it's more profitable
> to mine.
> >
> > Even segwit2x is based on the assumption that all miners can reach
> > consensus.  Break that assumption and segwit2x will have the same
> problems
> > as UASF.
> segwit2x has more issues since the HF part requires users to reach
> consensus
> >
> >> This is largely an issue due to segwit2x's bundling, if the SW and HF
> >> part of segwit2x were unbundled then there would be no reason to delay
> >> BIP91 activation
> >
> > They are bundled.  Segwit alone doesn't have the desired overwhelming
> > consensus, unless core wishes to fork 71% to 29%, and maybe not even that
> > high.  That's the technical reason, and they can't be unbundled without
> > breaking that consensus.
> That's a political reason not a technical reason.
> >
> > Jared
> >
> >
> > On Wed, Jun 7, 2017 at 4:11 PM, James Hilliard <
> james.hilliard1@gmail.com>
> > wrote:
> >>
> >> On Wed, Jun 7, 2017 at 5:53 PM, Jared Lee Richardson <
> jaredr26@gmail.com>
> >> wrote:
> >> >> There are 2 primary factors involved here, economic support and
> >> > hashpower either of which is enough to make a permanent chain split
> >> > unlikely, miners will mine whichever chain is most profitable(see
> >> > ETH/ETC hashpower profitability equilibrium for an example of how this
> >> > works in practice)
> >> >
> >> > That's not a comparable example.  ETC did not face potentially years
> of
> >> > slow
> >> > blocktimes before it normalized, whereas BIP148 is on track to do
> >> > exactly
> >> > that.  Moreover, ETC represented a fundamental break from the majority
> >> > consensus that could not be rectified, whereas BIP148 represents only
> a
> >> > minority attempt to accelerate something that an overwhelming majority
> >> > of
> >> > miners have already agreed to activate under segwit2x.  Lastly ETC was
> >> > required to add replay protection, just like any minority fork
> proposed
> >> > by
> >> > any crypto-currency has been, something that BIP148 both lacks and
> >> > refuses
> >> > to add or even acknowledge the necessity of.  Without replay
> protection,
> >> > ETC
> >> > could not have become profitable enough to be a viable minority chain.
> >> > If
> >> > BIP148's chain is not the majority chain and it does not have replay
> >> > protection, it will face the same problems, but that required replay
> >> > protection will turn it into a hardfork.  This will be a very bad
> >> > position
> >> > for UASF supporters to find themselves in - Either hardfork and hope
> the
> >> > price is higher and the majority converts, or die as the minority
> chain
> >> > with
> >> > no reliable methods of economic conversion.
> >> Higher transaction fees on a minority chain can compensate miners for
> >> a lower price which would likely be enough to get the BIP148 chain to
> >> a difficulty reduction. BIP148 however is a consensus change that can
> >> be rectified if it gets more work, this would act as an additional
> >> incentive for mine the BIP148 side since there would be no wipeout
> >> risk there. ETC replay protection was done after the fork on an as
> >> needed basis(there are multiple reliable techniques that can be used
> >> to split UTXO's), the same can happen with BIP148 and it is easier to
> >> do with Bitcoin than with the ETH/ETC split IMO.
> >> >
> >> > I believe, but don't have data to back this, that most of the BIP148
> >> > insistence comes not from a legitimate attempt to gain consensus (or
> >> > else
> >> > they would either outright oppose segwit2mb for its hardfork, or they
> >> > would
> >> > outright support it), but rather from an attempt for BIP148 supporters
> >> > to
> >> > save face for BIP148 being a failure.  If I'm correct, that's a
> terrible
> >> > and
> >> > highly non-technical reason for segwit2mb to bend over backwards
> >> > attempting
> >> > to support BIP148's attempt to save face.
> >> A big reason BIP148 still has support is because up until SegWit
> >> actually activates there's no guarantee segwit2mb will actually have
> >> the necessary support to activate SegWit.
> >> >
> >> >> The main issue is just one of activation timelines, BIP91 as
> >> > is takes too long to activate unless started ahead of the existing
> >> > segwit2x schedule and it's unlikely that BIP148 will get pushed back
> >> > any further.
> >> >
> >> > Even if I'm not correct on the above, I and others find it hard to
> >> > accept
> >> > that this timeline conflict is segwit2x's fault.  Segwit2x has both
> some
> >> > flexibility and broad support that crosses contentious pro-segwit and
> >> > pro-blocksize-increase divisions that have existed for two years.
> >> > BIP148 is
> >> > attempting to hold segwit2x's timelines and code hostage by claiming
> >> > inflexibility and claiming broad support, and not only are neither of
> >> > those
> >> > assertions are backed by real data, BIP148 (by being so inflexible) is
> >> > pushing a position that deepens the divides between those groups.  For
> >> > there
> >> > to be technical reasons for compatibility (so long as there are
> >> > tradeoffs,
> >> > which there are), there needs to be hard data showing that BIP148 is a
> >> > viable minority fork that won't simply die off on its own.
> >> This is largely an issue due to segwit2x's bundling, if the SW and HF
> >> part of segwit2x were unbundled then there would be no reason to delay
> >> BIP91 activation, this is especially a problem since it takes a good
> >> deal of time to properly code and test a HF. Unfortunately segwit2x
> >> has been quite inflexible in regards to the bundling aspect even
> >> though there are clearly no technical reasons for it to be there.
> >> >
> >> > Jared
> >> >
> >> >
> >> > On Wed, Jun 7, 2017 at 3:23 PM, James Hilliard
> >> > <james.hilliard1@gmail.com>
> >> > wrote:
> >> >>
> >> >> On Wed, Jun 7, 2017 at 4:50 PM, Jared Lee Richardson
> >> >> <jaredr26@gmail.com>
> >> >> wrote:
> >> >> > Could this risk mitigation measure be an optional flag?  And if so,
> >> >> > could it+BIP91 signal on a different bit than bit4?
> >> >> It's fairly trivial for miners to signal for BIP91 on bit4 or a
> >> >> different bit at the same time as the code is trivial enough to
> >> >> combine
> >> >> >
> >> >> > The reason being, if for some reason the segwit2x activation cannot
> >> >> > take place in time, it would be preferable for miners to have a
> more
> >> >> > standard approach to activation that requires stronger consensus
> and
> >> >> > may be more forgiving than BIP148.  If the segwit2x activation is
> on
> >> >> > time to cooperate with BIP148, it could be signaled through the
> >> >> > non-bit4 approach and everything could go smoothly.  Thoughts on
> that
> >> >> > idea?  It may add more complexity and more developer time, but may
> >> >> > also address your concerns among others.
> >> >> This does give miners another approach to activate segwit ahead of
> >> >> BIP148, if segwit2x activation is rolled out and activated
> immediately
> >> >> then this would not be needed however based on the timeline here
> >> >> https://segwit2x.github.io/ it would not be possible for BIP91 to
> >> >> enforce mandatory signalling ahead of BIP148. Maybe that can be
> >> >> changed though, I've suggested an immediate rollout with a
> placeholder
> >> >> client timeout instead of the HF code initially in order to
> accelerate
> >> >> that.
> >> >> >
> >> >> >> Since this BIP
> >> >> >> only activates with a clear miner majority it should not increase
> >> >> >> the
> >> >> >> risk of an extended chain split.
> >> >> >
> >> >> > The concern I'm raising is more about the psychology of giving
> BIP148
> >> >> > a sense of safety that may not be valid.  Without several more
> steps,
> >> >> > BIP148 is definitely on track to be a risky chainsplit, and without
> >> >> > segwit2x it will almost certainly be a small minority chain.
> (Unless
> >> >> > the segwit2x compromise falls apart before then, and even in that
> >> >> > case
> >> >> > it is likely to be a minority chain)
> >> >> There are 2 primary factors involved here, economic support and
> >> >> hashpower either of which is enough to make a permanent chain split
> >> >> unlikely, miners will mine whichever chain is most profitable(see
> >> >> ETH/ETC hashpower profitability equilibrium for an example of how
> this
> >> >> works in practice) however there may be lag time immediately after
> the
> >> >> split if there is an economic majority but not a hashpower majority
> >> >> initially. This is risk mitigation that only requires miners support
> >> >> however. The main issue is just one of activation timelines, BIP91 as
> >> >> is takes too long to activate unless started ahead of the existing
> >> >> segwit2x schedule and it's unlikely that BIP148 will get pushed back
> >> >> any further.
> >> >> >
> >> >> > Jared
> >> >> >
> >> >> >
> >> >> > On Wed, Jun 7, 2017 at 2:42 PM, James Hilliard
> >> >> > <james.hilliard1@gmail.com> wrote:
> >> >> >> I don't really see how this would increase the likelihood of an
> >> >> >> extended chain split assuming BIP148 is going to have
> >> >> >> non-insignificant economic backing. This BIP is designed to
> provide
> >> >> >> a
> >> >> >> risk mitigation measure that miners can safely deploy. Since this
> >> >> >> BIP
> >> >> >> only activates with a clear miner majority it should not increase
> >> >> >> the
> >> >> >> risk of an extended chain split. At this point it is not
> completely
> >> >> >> clear how much economic support there is for BIP148 but support
> >> >> >> certainly seems to be growing and we have nearly 2 months until
> >> >> >> BIP148
> >> >> >> activation. I intentionally used a shorter activation period here
> so
> >> >> >> that decisions by miners can be made close to the BIP148
> activation
> >> >> >> date.
> >> >> >>
> >> >> >> On Wed, Jun 7, 2017 at 4:29 PM, Jared Lee Richardson
> >> >> >> <jaredr26@gmail.com> wrote:
> >> >> >>> I think this BIP represents a gamble, and the gamble may not be a
> >> >> >>> good
> >> >> >>> one.  The gamble here is that if the segwit2x changes are rolled
> >> >> >>> out
> >> >> >>> on time, and if the signatories accept the bit4 + bit1 signaling
> >> >> >>> proposals within BIP91, the launch will go smoother, as intended.
> >> >> >>> But
> >> >> >>> conversely, if either the segwit2x signatories balk about the
> Bit1
> >> >> >>> signaling OR if the timelines for segwit2mb are missed even by a
> >> >> >>> bit,
> >> >> >>> it may cause the BIP148 chainsplit to be worse than it would be
> >> >> >>> without.  Given the frequent concerns raised in multiple places
> >> >> >>> about
> >> >> >>> the aggressiveness of the segwit2x timelines, including the
> >> >> >>> non-hardfork timelines, this does not seem like a great gamble to
> >> >> >>> be
> >> >> >>> making.
> >> >> >>>
> >> >> >>> The reason I say it may make the chainsplit be worse than it
> would
> >> >> >>> otherwise be is that it may provide a false sense of safety for
> >> >> >>> BIP148
> >> >> >>> that currently does not currently exist(and should not, as it is
> a
> >> >> >>> chainsplit).  That sense of safety would only be legitimate if
> the
> >> >> >>> segwit2x signatories were on board, and the segwit2x code
> >> >> >>> effectively
> >> >> >>> enforced BIP148 simultaneously, neither of which are guaranteed.
> >> >> >>> If
> >> >> >>> users and more miners had a false sense that BIP148 was *not*
> going
> >> >> >>> to
> >> >> >>> chainsplit from default / segwit2x, they might not follow the
> news
> >> >> >>> if
> >> >> >>> suddenly the segwit2x plan were delayed for a few days.  While
> any
> >> >> >>> additional support would definitely be cheered on by BIP148
> >> >> >>> supporters, the practical reality might be that this proposal
> would
> >> >> >>> take BIP148 from the "unlikely to have any viable chain after
> flag
> >> >> >>> day
> >> >> >>> without segwit2x" category into the "small but viable minority
> >> >> >>> chain"
> >> >> >>> category, and even worse, it might strengthen the chainsplit just
> >> >> >>> days
> >> >> >>> before segwit is activated on BOTH chains, putting the BIP148
> >> >> >>> supporters on the wrong pro-segwit, but still-viable chain.
> >> >> >>>
> >> >> >>> If Core had taken a strong stance to include BIP148 into the
> >> >> >>> client,
> >> >> >>> and if BIP148 support were much much broader, I would feel
> >> >> >>> differently
> >> >> >>> as the gamble would be more likely to discourage a chainsplit (By
> >> >> >>> forcing the acceleration of segwit2x) rather than encourage it
> (by
> >> >> >>> strengthening an extreme minority chainsplit that may wind up on
> >> >> >>> the
> >> >> >>> wrong side of two segwit-activated chains).  As it stands now,
> this
> >> >> >>> seems like a very dangerous attempt to compromise with a small
> but
> >> >> >>> vocal group that are the ones creating the threat to begin with.
> >> >> >>>
> >> >> >>> Jared
> >> >> >>>
> >> >> >>> On Tue, Jun 6, 2017 at 5:56 PM, James Hilliard via bitcoin-dev
> >> >> >>> <bitcoin-dev@lists.linuxfoundation.org> wrote:
> >> >> >>>> Due to the proposed calendar(https://segwit2x.github.io/) for
> the
> >> >> >>>> SegWit2x agreement being too slow to activate SegWit mandatory
> >> >> >>>> signalling ahead of BIP148 using BIP91 I would like to propose
> >> >> >>>> another
> >> >> >>>> option that miners can use to prevent a chain split ahead of the
> >> >> >>>> Aug
> >> >> >>>> 1st BIP148 activation date.
> >> >> >>>>
> >> >> >>>> The splitprotection soft fork is essentially BIP91 but using
> BIP8
> >> >> >>>> instead of BIP9 with a lower activation threshold and immediate
> >> >> >>>> mandatory signalling lock-in. This allows for a majority of
> miners
> >> >> >>>> to
> >> >> >>>> activate mandatory SegWit signalling and prevent a potential
> chain
> >> >> >>>> split ahead of BIP148 activation.
> >> >> >>>>
> >> >> >>>> This BIP allows for miners to respond to market forces quickly
> >> >> >>>> ahead
> >> >> >>>> of BIP148 activation by signalling for splitprotection. Any
> miners
> >> >> >>>> already running BIP148 should be encouraged to use
> >> >> >>>> splitprotection.
> >> >> >>>>
> >> >> >>>> <pre>
> >> >> >>>>   BIP: splitprotection
> >> >> >>>>   Layer: Consensus (soft fork)
> >> >> >>>>   Title: User Activated Soft Fork Split Protection
> >> >> >>>>   Author: James Hilliard <james.hilliard1@gmail.com>
> >> >> >>>>   Comments-Summary: No comments yet.
> >> >> >>>>   Comments-URI:
> >> >> >>>>   Status: Draft
> >> >> >>>>   Type: Standards Track
> >> >> >>>>   Created: 2017-05-22
> >> >> >>>>   License: BSD-3-Clause
> >> >> >>>>            CC0-1.0
> >> >> >>>> </pre>
> >> >> >>>>
> >> >> >>>> ==Abstract==
> >> >> >>>>
> >> >> >>>> This document specifies a coordination mechanism for a simple
> >> >> >>>> majority
> >> >> >>>> of miners to prevent a chain split ahead of BIP148 activation.
> >> >> >>>>
> >> >> >>>> ==Definitions==
> >> >> >>>>
> >> >> >>>> "existing segwit deployment" refer to the BIP9 "segwit"
> deployment
> >> >> >>>> using bit 1, between November 15th 2016 and November 15th 2017
> to
> >> >> >>>> activate BIP141, BIP143 and BIP147.
> >> >> >>>>
> >> >> >>>> ==Motivation==
> >> >> >>>>
> >> >> >>>> The biggest risk of BIP148 is an extended chain split, this BIP
> >> >> >>>> provides a way for a simple majority of miners to eliminate that
> >> >> >>>> risk.
> >> >> >>>>
> >> >> >>>> This BIP provides a way for a simple majority of miners to
> >> >> >>>> coordinate
> >> >> >>>> activation of the existing segwit deployment with less than 95%
> >> >> >>>> hashpower before BIP148 activation. Due to time constraints
> unless
> >> >> >>>> immediately deployed BIP91 will likely not be able to enforce
> >> >> >>>> mandatory signalling of segwit before the Aug 1st activation of
> >> >> >>>> BIP148. This BIP provides a method for rapid miner activation of
> >> >> >>>> SegWit mandatory signalling ahead of the BIP148 activation date.
> >> >> >>>> Since
> >> >> >>>> the primary goal of this BIP is to reduce the chance of an
> >> >> >>>> extended
> >> >> >>>> chain split as much as possible we activate using a simple miner
> >> >> >>>> majority of 65% over a 504 block interval rather than a higher
> >> >> >>>> percentage. This BIP also allows miners to signal their
> intention
> >> >> >>>> to
> >> >> >>>> run BIP148 in order to prevent a chain split.
> >> >> >>>>
> >> >> >>>> ==Specification==
> >> >> >>>>
> >> >> >>>> While this BIP is active, all blocks must set the nVersion
> header
> >> >> >>>> top
> >> >> >>>> 3 bits to 001 together with bit field (1<<1) (according to the
> >> >> >>>> existing segwit deployment). Blocks that do not signal as
> required
> >> >> >>>> will be rejected.
> >> >> >>>>
> >> >> >>>> ==Deployment==
> >> >> >>>>
> >> >> >>>> This BIP will be deployed by "version bits" with a 65%(this can
> be
> >> >> >>>> adjusted if desired) activation threshold BIP9 with the name
> >> >> >>>> "splitprotecion" and using bit 2.
> >> >> >>>>
> >> >> >>>> This BIP starts immediately and is a BIP8 style soft fork since
> >> >> >>>> mandatory signalling will start on midnight August 1st 2017
> (epoch
> >> >> >>>> time 1501545600) regardless of whether or not this BIP has
> reached
> >> >> >>>> its
> >> >> >>>> own signalling threshold. This BIP will cease to be active when
> >> >> >>>> segwit
> >> >> >>>> is locked-in.
> >> >> >>>>
> >> >> >>>> === Reference implementation ===
> >> >> >>>>
> >> >> >>>> <pre>
> >> >> >>>> // Check if Segregated Witness is Locked In
> >> >> >>>> bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
> >> >> >>>> Consensus::Params& params)
> >> >> >>>> {
> >> >> >>>>     LOCK(cs_main);
> >> >> >>>>     return (VersionBitsState(pindexPrev, params,
> >> >> >>>> Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
> >> >> >>>> THRESHOLD_LOCKED_IN);
> >> >> >>>> }
> >> >> >>>>
> >> >> >>>> // SPLITPROTECTION mandatory segwit signalling.
> >> >> >>>> if ( VersionBitsState(pindex->pprev,
> chainparams.GetConsensus(),
> >> >> >>>> Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
> >> >> >>>> THRESHOLD_LOCKED_IN &&
> >> >> >>>>      !IsWitnessLockedIn(pindex->pprev,
> chainparams.GetConsensus())
> >> >> >>>> &&
> >> >> >>>> // Segwit is not locked in
> >> >> >>>>      !IsWitnessEnabled(pindex->pprev,
> chainparams.GetConsensus())
> >> >> >>>> )
> >> >> >>>> //
> >> >> >>>> and is not active.
> >> >> >>>> {
> >> >> >>>>     bool fVersionBits = (pindex->nVersion &
> VERSIONBITS_TOP_MASK)
> >> >> >>>> ==
> >> >> >>>> VERSIONBITS_TOP_BITS;
> >> >> >>>>     bool fSegbit = (pindex->nVersion &
> >> >> >>>> VersionBitsMask(chainparams.GetConsensus(),
> >> >> >>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
> >> >> >>>>     if (!(fVersionBits && fSegbit)) {
> >> >> >>>>         return state.DoS(0, error("ConnectBlock(): relayed block
> >> >> >>>> must
> >> >> >>>> signal for segwit, please upgrade"), REJECT_INVALID,
> >> >> >>>> "bad-no-segwit");
> >> >> >>>>     }
> >> >> >>>> }
> >> >> >>>>
> >> >> >>>> // BIP148 mandatory segwit signalling.
> >> >> >>>> int64_t nMedianTimePast = pindex->GetMedianTimePast();
> >> >> >>>> if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017
> >> >> >>>> 00:00:00
> >> >> >>>> UTC
> >> >> >>>>      (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017
> >> >> >>>> 00:00:00
> >> >> >>>> UTC
> >> >> >>>>      (!IsWitnessLockedIn(pindex->pprev,
> >> >> >>>> chainparams.GetConsensus())
> >> >> >>>> &&
> >> >> >>>>  // Segwit is not locked in
> >> >> >>>>       !IsWitnessEnabled(pindex->pprev,
> >> >> >>>> chainparams.GetConsensus())) )
> >> >> >>>>  // and is not active.
> >> >> >>>> {
> >> >> >>>>     bool fVersionBits = (pindex->nVersion &
> VERSIONBITS_TOP_MASK)
> >> >> >>>> ==
> >> >> >>>> VERSIONBITS_TOP_BITS;
> >> >> >>>>     bool fSegbit = (pindex->nVersion &
> >> >> >>>> VersionBitsMask(chainparams.GetConsensus(),
> >> >> >>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
> >> >> >>>>     if (!(fVersionBits && fSegbit)) {
> >> >> >>>>         return state.DoS(0, error("ConnectBlock(): relayed block
> >> >> >>>> must
> >> >> >>>> signal for segwit, please upgrade"), REJECT_INVALID,
> >> >> >>>> "bad-no-segwit");
> >> >> >>>>     }
> >> >> >>>> }
> >> >> >>>> </pre>
> >> >> >>>>
> >> >> >>>>
> >> >> >>>>
> >> >> >>>> https://github.com/bitcoin/bitcoin/compare/0.14...
> jameshilliard:splitprotection-v0.14.1
> >> >> >>>>
> >> >> >>>> ==Backwards Compatibility==
> >> >> >>>>
> >> >> >>>> This deployment is compatible with the existing "segwit" bit 1
> >> >> >>>> deployment scheduled between midnight November 15th, 2016 and
> >> >> >>>> midnight
> >> >> >>>> November 15th, 2017. This deployment is also compatible with the
> >> >> >>>> existing BIP148 deployment. This BIP is compatible with BIP91
> only
> >> >> >>>> if
> >> >> >>>> BIP91 activates before it and before BIP148. Miners will need to
> >> >> >>>> upgrade their nodes to support splitprotection otherwise they
> may
> >> >> >>>> build on top of an invalid block. While this bip is active users
> >> >> >>>> should either upgrade to splitprotection or wait for additional
> >> >> >>>> confirmations when accepting payments.
> >> >> >>>>
> >> >> >>>> ==Rationale==
> >> >> >>>>
> >> >> >>>> Historically we have used IsSuperMajority() to activate soft
> forks
> >> >> >>>> such as BIP66 which has a mandatory signalling requirement for
> >> >> >>>> miners
> >> >> >>>> once activated, this ensures that miners are aware of new rules
> >> >> >>>> being
> >> >> >>>> enforced. This technique can be leveraged to lower the
> signalling
> >> >> >>>> threshold of a soft fork while it is in the process of being
> >> >> >>>> deployed
> >> >> >>>> in a backwards compatible way. We also use a BIP8 style timeout
> to
> >> >> >>>> ensure that this BIP is compatible with BIP148 and that BIP148
> >> >> >>>> compatible mandatory signalling activates regardless of miner
> >> >> >>>> signalling levels.
> >> >> >>>>
> >> >> >>>> By orphaning non-signalling blocks during the BIP9 bit 1
> "segwit"
> >> >> >>>> deployment, this BIP can cause the existing "segwit" deployment
> to
> >> >> >>>> activate without needing to release a new deployment. As we
> >> >> >>>> approach
> >> >> >>>> BIP148 activation it may be desirable for a majority of miners
> to
> >> >> >>>> have
> >> >> >>>> a method that will ensure that there is no chain split.
> >> >> >>>>
> >> >> >>>> ==References==
> >> >> >>>>
> >> >> >>>>
> >> >> >>>>
> >> >> >>>> *[https://lists.linuxfoundation.org/pipermail/
> bitcoin-dev/2017-March/013714.html
> >> >> >>>> Mailing list discussion]
> >> >> >>>>
> >> >> >>>>
> >> >> >>>> *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.
> cpp#L1281-L1283
> >> >> >>>> P2SH flag day activation]
> >> >> >>>> *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
> >> >> >>>> *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
> >> >> >>>> *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
> >> >> >>>> *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus
> >> >> >>>> layer)]]
> >> >> >>>> *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification
> >> >> >>>> for
> >> >> >>>> Version 0 Witness Program]]
> >> >> >>>> *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element
> >> >> >>>> malleability]]
> >> >> >>>> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit
> >> >> >>>> deployment]]
> >> >> >>>> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second
> >> >> >>>> deployment)]]
> >> >> >>>> *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit
> >> >> >>>> benefits]
> >> >> >>>>
> >> >> >>>> ==Copyright==
> >> >> >>>>
> >> >> >>>> This document is dual licensed as BSD 3-clause, and Creative
> >> >> >>>> Commons
> >> >> >>>> CC0 1.0 Universal.
> >> >> >>>> _______________________________________________
> >> >> >>>> bitcoin-dev mailing list
> >> >> >>>> bitcoin-dev@lists.linuxfoundation.org
> >> >> >>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
> >> >
> >> >
> >
> >
>

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Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[James Hilliard]

On Wed, Jun 7, 2017 at 7:20 PM, Jared Lee Richardson <jaredr26@gmail.com> wrote:
>> Not really, there are a few relatively simple techniques such as RBF
>> which can be leveraged to get confirmations on on-side before double
>> spending on another. Once a transaction is confirmed on the non-BIP148
>> chain then the high fee transactions can be made on only the BIP148
>> side of the split using RBF.
>
> Ah, so the BIP148 client handles this on behalf of its less technical users
> on their behalf then, yes?
It's not automatic but exchanges will likely handle it on behalf of
the less technical users. BIP148 is not intended to cause a permanent
chain split however which is why this was not built in.
>
>>  Exchanges will likely do this splitting
>> automatically for uses as well.
>
> Sure, Exchanges are going to dedicate hundreds of developer hours and
> thousands of support hours to support something that they've repeatedly told
> everyone must have replay protection to be supported.  They're going to do
> this because 8% of nodes and <0.5% of miners say they'll be rewarded richly.
> Somehow I find that hard to believe.
They are very likely to, most have contingency plans for this sort of
thing ready to go due to their experience with the ETH/ETC fork.
>
> Besides, if the BIP148 client does it for them, they wouldn't have to
> dedicate those hundreds of developer hours.  Right?
>
> I can't imagine how this logic is getting you from where the real data is to
> the assumption that an economic majority will push BIP148 into being such a
> more valuable chain that switching chains will be attractive to enough
> miners.  There's got to be some real data that convinces you of this
> somewhere?
If you're looking for hard numbers at this point you aren't likely to
find them because not everything is easy to measure directly.
>
>> Both are issues, but wipeout risk is different, the ETH/ETC split for
>> example didn't have any wipeout risk for either side the same is not
>> true for BIP148(and it is the non-BIP148 side that carries the risk of
>> chain wipeout).
>
> Wipeout risk is a serious issue when 45% of the miners support one chain and
> 55% support the other chain.  Segwit doesn't even have 35% of the miners;
> There's no data or statements anywhere that indicate that UASF is going to
> reach the point where wipeout risk is even comparable to abandonment risk.
It's mostly economic support that will dictate this, not hashpower
support since the hashpower follows the economy.
>
>> Yes, miners aren't likely to waste operational mining costs, that's
>> ultimately why miners would follow the BIP148 side of the chain
>> assuming it has sufficient economic support or if it's more profitable
>> to mine.
>
> To convince miners you would have to have some data SOMEWHERE supporting the
> economic majority argument.  Is there any such data?
We'll know more as we get closer to BIP148 activation by looking at the markets.
>
>> segwit2x has more issues since the HF part requires users to reach
>> consensus
>
> It doesn't have those issues during the segwit activation, ergo there is no
> reason for segwit-activation problems to take priority over the very real
> hardfork activation problems.
And yet segwit2x is insisting on activation bundling which needlessly
complicates and delays SegWit activation.
>
>> That's a political reason not a technical reason.
>
> In a consensus system they are frequently the same, unfortunately.
> Technical awesomeness without people agreeing = zero consensus.  So the
> choice is either to "technically" break the consensus without a
> super-majority and see what happens, or to go with the choice that has real
> data showing the most consensus and hope the tiny minority chain actually
> dies off.
Sure, technical changes can be made for political reasons, we should
at least be clear in regards to why particular decisions are being
made. I'm supportive of a hard fork for technical reasons but not
political ones as are many others.
>
> Jared
>
> On Wed, Jun 7, 2017 at 5:01 PM, James Hilliard <james.hilliard1@gmail.com>
> wrote:
>>
>> On Wed, Jun 7, 2017 at 6:43 PM, Jared Lee Richardson <jaredr26@gmail.com>
>> wrote:
>> >> BIP148 however is a consensus change that can
>> >> be rectified if it gets more work, this would act as an additional
>> >> incentive for mine the BIP148 side since there would be no wipeout
>> >> risk there.
>> >
>> > This statement is misleading.  Wipeout risks don't apply to any
>> > consensus
>> > changes; It is a consensus change, it can only be abandoned.  The BIP148
>> > chain carries just as many risks of being abandoned or even more with
>> > segwit2x on the table.  No miner would consider "wipeout risk" an
>> > advantage
>> > when the real threat is chain abandonment.
>> Both are issues, but wipeout risk is different, the ETH/ETC split for
>> example didn't have any wipeout risk for either side the same is not
>> true for BIP148(and it is the non-BIP148 side that carries the risk of
>> chain wipeout).
>> >
>> >> Higher transaction fees on a minority chain can compensate miners for
>> >> a lower price which would likely be enough to get the BIP148 chain to
>> >> a difficulty reduction.
>> >
>> > Higher transaction fees suffers the same problem as exchange support
>> > does.
>> > Without replay protection, it is very difficult for any average user to
>> > force transactions onto one chain or the other.  Thus, without replay
>> > protection, the UASF chain is unlikely to develop any viable fee market;
>> > Its
>> > few miners 99% of the time will simply choose from the highest fees that
>> > were already available to the other chain, which is basically no
>> > advantage
>> > at all.
>> Not really, there are a few relatively simple techniques such as RBF
>> which can be leveraged to get confirmations on on-side before double
>> spending on another. Once a transaction is confirmed on the non-BIP148
>> chain then the high fee transactions can be made on only the BIP148
>> side of the split using RBF. Exchanges will likely do this splitting
>> automatically for uses as well.
>> >
>> >>  ETC replay protection was done after the fork on an as
>> >> needed basis(there are multiple reliable techniques that can be used
>> >> to split UTXO's), the same can happen with BIP148 and it is easier to
>> >> do with Bitcoin than with the ETH/ETC split IMO.
>> >
>> > ETC replay protection was added because they were already a hardfork and
>> > without it they would not have had a viable chain.  BIP148 is not
>> > supposed
>> > to be a hardfork, and if it added replay protection to remain viable it
>> > would lose the frequently touted "wipeout advantage" as well as the
>> > ability
>> > to call itself a softfork.  And are you seriously suggesting that what
>> > happened with ETC and ETH is a desirable and good situation for Bitcoin,
>> > and
>> > that UASF is ETC?
>> There wasn't proper replay protection at split time for ETH/ETC since
>> normal transactions would get executed on both sides originally,
>> however replay protection was added by wallets(mainly using splitting
>> contracts). I don't think a split is desirable however, which is why
>> I've proposed this BIP.
>> >
>> >> A big reason BIP148 still has support is because up until SegWit
>> >> actually activates there's no guarantee segwit2mb will actually have
>> >> the necessary support to activate SegWit.
>> >
>> > For a miners blowing through six million dollars a day in mining
>> > operational
>> > costs, that's a pretty crappy reason.  Serious miners can't afford to
>> > prop
>> > up a non-viable chain based on philosophy or maybes.  BIP148 is based
>> > entirely upon people who aren't putting anything on the line trying to
>> > convince others to take the huge risks for them.  With deceptively
>> > fallacious logic, in my opinion.
>> Yes, miners aren't likely to waste operational mining costs, that's
>> ultimately why miners would follow the BIP148 side of the chain
>> assuming it has sufficient economic support or if it's more profitable
>> to mine.
>> >
>> > Even segwit2x is based on the assumption that all miners can reach
>> > consensus.  Break that assumption and segwit2x will have the same
>> > problems
>> > as UASF.
>> segwit2x has more issues since the HF part requires users to reach
>> consensus
>> >
>> >> This is largely an issue due to segwit2x's bundling, if the SW and HF
>> >> part of segwit2x were unbundled then there would be no reason to delay
>> >> BIP91 activation
>> >
>> > They are bundled.  Segwit alone doesn't have the desired overwhelming
>> > consensus, unless core wishes to fork 71% to 29%, and maybe not even
>> > that
>> > high.  That's the technical reason, and they can't be unbundled without
>> > breaking that consensus.
>> That's a political reason not a technical reason.
>> >
>> > Jared
>> >
>> >
>> > On Wed, Jun 7, 2017 at 4:11 PM, James Hilliard
>> > <james.hilliard1@gmail.com>
>> > wrote:
>> >>
>> >> On Wed, Jun 7, 2017 at 5:53 PM, Jared Lee Richardson
>> >> <jaredr26@gmail.com>
>> >> wrote:
>> >> >> There are 2 primary factors involved here, economic support and
>> >> > hashpower either of which is enough to make a permanent chain split
>> >> > unlikely, miners will mine whichever chain is most profitable(see
>> >> > ETH/ETC hashpower profitability equilibrium for an example of how
>> >> > this
>> >> > works in practice)
>> >> >
>> >> > That's not a comparable example.  ETC did not face potentially years
>> >> > of
>> >> > slow
>> >> > blocktimes before it normalized, whereas BIP148 is on track to do
>> >> > exactly
>> >> > that.  Moreover, ETC represented a fundamental break from the
>> >> > majority
>> >> > consensus that could not be rectified, whereas BIP148 represents only
>> >> > a
>> >> > minority attempt to accelerate something that an overwhelming
>> >> > majority
>> >> > of
>> >> > miners have already agreed to activate under segwit2x.  Lastly ETC
>> >> > was
>> >> > required to add replay protection, just like any minority fork
>> >> > proposed
>> >> > by
>> >> > any crypto-currency has been, something that BIP148 both lacks and
>> >> > refuses
>> >> > to add or even acknowledge the necessity of.  Without replay
>> >> > protection,
>> >> > ETC
>> >> > could not have become profitable enough to be a viable minority
>> >> > chain.
>> >> > If
>> >> > BIP148's chain is not the majority chain and it does not have replay
>> >> > protection, it will face the same problems, but that required replay
>> >> > protection will turn it into a hardfork.  This will be a very bad
>> >> > position
>> >> > for UASF supporters to find themselves in - Either hardfork and hope
>> >> > the
>> >> > price is higher and the majority converts, or die as the minority
>> >> > chain
>> >> > with
>> >> > no reliable methods of economic conversion.
>> >> Higher transaction fees on a minority chain can compensate miners for
>> >> a lower price which would likely be enough to get the BIP148 chain to
>> >> a difficulty reduction. BIP148 however is a consensus change that can
>> >> be rectified if it gets more work, this would act as an additional
>> >> incentive for mine the BIP148 side since there would be no wipeout
>> >> risk there. ETC replay protection was done after the fork on an as
>> >> needed basis(there are multiple reliable techniques that can be used
>> >> to split UTXO's), the same can happen with BIP148 and it is easier to
>> >> do with Bitcoin than with the ETH/ETC split IMO.
>> >> >
>> >> > I believe, but don't have data to back this, that most of the BIP148
>> >> > insistence comes not from a legitimate attempt to gain consensus (or
>> >> > else
>> >> > they would either outright oppose segwit2mb for its hardfork, or they
>> >> > would
>> >> > outright support it), but rather from an attempt for BIP148
>> >> > supporters
>> >> > to
>> >> > save face for BIP148 being a failure.  If I'm correct, that's a
>> >> > terrible
>> >> > and
>> >> > highly non-technical reason for segwit2mb to bend over backwards
>> >> > attempting
>> >> > to support BIP148's attempt to save face.
>> >> A big reason BIP148 still has support is because up until SegWit
>> >> actually activates there's no guarantee segwit2mb will actually have
>> >> the necessary support to activate SegWit.
>> >> >
>> >> >> The main issue is just one of activation timelines, BIP91 as
>> >> > is takes too long to activate unless started ahead of the existing
>> >> > segwit2x schedule and it's unlikely that BIP148 will get pushed back
>> >> > any further.
>> >> >
>> >> > Even if I'm not correct on the above, I and others find it hard to
>> >> > accept
>> >> > that this timeline conflict is segwit2x's fault.  Segwit2x has both
>> >> > some
>> >> > flexibility and broad support that crosses contentious pro-segwit and
>> >> > pro-blocksize-increase divisions that have existed for two years.
>> >> > BIP148 is
>> >> > attempting to hold segwit2x's timelines and code hostage by claiming
>> >> > inflexibility and claiming broad support, and not only are neither of
>> >> > those
>> >> > assertions are backed by real data, BIP148 (by being so inflexible)
>> >> > is
>> >> > pushing a position that deepens the divides between those groups.
>> >> > For
>> >> > there
>> >> > to be technical reasons for compatibility (so long as there are
>> >> > tradeoffs,
>> >> > which there are), there needs to be hard data showing that BIP148 is
>> >> > a
>> >> > viable minority fork that won't simply die off on its own.
>> >> This is largely an issue due to segwit2x's bundling, if the SW and HF
>> >> part of segwit2x were unbundled then there would be no reason to delay
>> >> BIP91 activation, this is especially a problem since it takes a good
>> >> deal of time to properly code and test a HF. Unfortunately segwit2x
>> >> has been quite inflexible in regards to the bundling aspect even
>> >> though there are clearly no technical reasons for it to be there.
>> >> >
>> >> > Jared
>> >> >
>> >> >
>> >> > On Wed, Jun 7, 2017 at 3:23 PM, James Hilliard
>> >> > <james.hilliard1@gmail.com>
>> >> > wrote:
>> >> >>
>> >> >> On Wed, Jun 7, 2017 at 4:50 PM, Jared Lee Richardson
>> >> >> <jaredr26@gmail.com>
>> >> >> wrote:
>> >> >> > Could this risk mitigation measure be an optional flag?  And if
>> >> >> > so,
>> >> >> > could it+BIP91 signal on a different bit than bit4?
>> >> >> It's fairly trivial for miners to signal for BIP91 on bit4 or a
>> >> >> different bit at the same time as the code is trivial enough to
>> >> >> combine
>> >> >> >
>> >> >> > The reason being, if for some reason the segwit2x activation
>> >> >> > cannot
>> >> >> > take place in time, it would be preferable for miners to have a
>> >> >> > more
>> >> >> > standard approach to activation that requires stronger consensus
>> >> >> > and
>> >> >> > may be more forgiving than BIP148.  If the segwit2x activation is
>> >> >> > on
>> >> >> > time to cooperate with BIP148, it could be signaled through the
>> >> >> > non-bit4 approach and everything could go smoothly.  Thoughts on
>> >> >> > that
>> >> >> > idea?  It may add more complexity and more developer time, but may
>> >> >> > also address your concerns among others.
>> >> >> This does give miners another approach to activate segwit ahead of
>> >> >> BIP148, if segwit2x activation is rolled out and activated
>> >> >> immediately
>> >> >> then this would not be needed however based on the timeline here
>> >> >> https://segwit2x.github.io/ it would not be possible for BIP91 to
>> >> >> enforce mandatory signalling ahead of BIP148. Maybe that can be
>> >> >> changed though, I've suggested an immediate rollout with a
>> >> >> placeholder
>> >> >> client timeout instead of the HF code initially in order to
>> >> >> accelerate
>> >> >> that.
>> >> >> >
>> >> >> >> Since this BIP
>> >> >> >> only activates with a clear miner majority it should not increase
>> >> >> >> the
>> >> >> >> risk of an extended chain split.
>> >> >> >
>> >> >> > The concern I'm raising is more about the psychology of giving
>> >> >> > BIP148
>> >> >> > a sense of safety that may not be valid.  Without several more
>> >> >> > steps,
>> >> >> > BIP148 is definitely on track to be a risky chainsplit, and
>> >> >> > without
>> >> >> > segwit2x it will almost certainly be a small minority chain.
>> >> >> > (Unless
>> >> >> > the segwit2x compromise falls apart before then, and even in that
>> >> >> > case
>> >> >> > it is likely to be a minority chain)
>> >> >> There are 2 primary factors involved here, economic support and
>> >> >> hashpower either of which is enough to make a permanent chain split
>> >> >> unlikely, miners will mine whichever chain is most profitable(see
>> >> >> ETH/ETC hashpower profitability equilibrium for an example of how
>> >> >> this
>> >> >> works in practice) however there may be lag time immediately after
>> >> >> the
>> >> >> split if there is an economic majority but not a hashpower majority
>> >> >> initially. This is risk mitigation that only requires miners support
>> >> >> however. The main issue is just one of activation timelines, BIP91
>> >> >> as
>> >> >> is takes too long to activate unless started ahead of the existing
>> >> >> segwit2x schedule and it's unlikely that BIP148 will get pushed back
>> >> >> any further.
>> >> >> >
>> >> >> > Jared
>> >> >> >
>> >> >> >
>> >> >> > On Wed, Jun 7, 2017 at 2:42 PM, James Hilliard
>> >> >> > <james.hilliard1@gmail.com> wrote:
>> >> >> >> I don't really see how this would increase the likelihood of an
>> >> >> >> extended chain split assuming BIP148 is going to have
>> >> >> >> non-insignificant economic backing. This BIP is designed to
>> >> >> >> provide
>> >> >> >> a
>> >> >> >> risk mitigation measure that miners can safely deploy. Since this
>> >> >> >> BIP
>> >> >> >> only activates with a clear miner majority it should not increase
>> >> >> >> the
>> >> >> >> risk of an extended chain split. At this point it is not
>> >> >> >> completely
>> >> >> >> clear how much economic support there is for BIP148 but support
>> >> >> >> certainly seems to be growing and we have nearly 2 months until
>> >> >> >> BIP148
>> >> >> >> activation. I intentionally used a shorter activation period here
>> >> >> >> so
>> >> >> >> that decisions by miners can be made close to the BIP148
>> >> >> >> activation
>> >> >> >> date.
>> >> >> >>
>> >> >> >> On Wed, Jun 7, 2017 at 4:29 PM, Jared Lee Richardson
>> >> >> >> <jaredr26@gmail.com> wrote:
>> >> >> >>> I think this BIP represents a gamble, and the gamble may not be
>> >> >> >>> a
>> >> >> >>> good
>> >> >> >>> one.  The gamble here is that if the segwit2x changes are rolled
>> >> >> >>> out
>> >> >> >>> on time, and if the signatories accept the bit4 + bit1 signaling
>> >> >> >>> proposals within BIP91, the launch will go smoother, as
>> >> >> >>> intended.
>> >> >> >>> But
>> >> >> >>> conversely, if either the segwit2x signatories balk about the
>> >> >> >>> Bit1
>> >> >> >>> signaling OR if the timelines for segwit2mb are missed even by a
>> >> >> >>> bit,
>> >> >> >>> it may cause the BIP148 chainsplit to be worse than it would be
>> >> >> >>> without.  Given the frequent concerns raised in multiple places
>> >> >> >>> about
>> >> >> >>> the aggressiveness of the segwit2x timelines, including the
>> >> >> >>> non-hardfork timelines, this does not seem like a great gamble
>> >> >> >>> to
>> >> >> >>> be
>> >> >> >>> making.
>> >> >> >>>
>> >> >> >>> The reason I say it may make the chainsplit be worse than it
>> >> >> >>> would
>> >> >> >>> otherwise be is that it may provide a false sense of safety for
>> >> >> >>> BIP148
>> >> >> >>> that currently does not currently exist(and should not, as it is
>> >> >> >>> a
>> >> >> >>> chainsplit).  That sense of safety would only be legitimate if
>> >> >> >>> the
>> >> >> >>> segwit2x signatories were on board, and the segwit2x code
>> >> >> >>> effectively
>> >> >> >>> enforced BIP148 simultaneously, neither of which are guaranteed.
>> >> >> >>> If
>> >> >> >>> users and more miners had a false sense that BIP148 was *not*
>> >> >> >>> going
>> >> >> >>> to
>> >> >> >>> chainsplit from default / segwit2x, they might not follow the
>> >> >> >>> news
>> >> >> >>> if
>> >> >> >>> suddenly the segwit2x plan were delayed for a few days.  While
>> >> >> >>> any
>> >> >> >>> additional support would definitely be cheered on by BIP148
>> >> >> >>> supporters, the practical reality might be that this proposal
>> >> >> >>> would
>> >> >> >>> take BIP148 from the "unlikely to have any viable chain after
>> >> >> >>> flag
>> >> >> >>> day
>> >> >> >>> without segwit2x" category into the "small but viable minority
>> >> >> >>> chain"
>> >> >> >>> category, and even worse, it might strengthen the chainsplit
>> >> >> >>> just
>> >> >> >>> days
>> >> >> >>> before segwit is activated on BOTH chains, putting the BIP148
>> >> >> >>> supporters on the wrong pro-segwit, but still-viable chain.
>> >> >> >>>
>> >> >> >>> If Core had taken a strong stance to include BIP148 into the
>> >> >> >>> client,
>> >> >> >>> and if BIP148 support were much much broader, I would feel
>> >> >> >>> differently
>> >> >> >>> as the gamble would be more likely to discourage a chainsplit
>> >> >> >>> (By
>> >> >> >>> forcing the acceleration of segwit2x) rather than encourage it
>> >> >> >>> (by
>> >> >> >>> strengthening an extreme minority chainsplit that may wind up on
>> >> >> >>> the
>> >> >> >>> wrong side of two segwit-activated chains).  As it stands now,
>> >> >> >>> this
>> >> >> >>> seems like a very dangerous attempt to compromise with a small
>> >> >> >>> but
>> >> >> >>> vocal group that are the ones creating the threat to begin with.
>> >> >> >>>
>> >> >> >>> Jared
>> >> >> >>>
>> >> >> >>> On Tue, Jun 6, 2017 at 5:56 PM, James Hilliard via bitcoin-dev
>> >> >> >>> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>> >> >> >>>> Due to the proposed calendar(https://segwit2x.github.io/) for
>> >> >> >>>> the
>> >> >> >>>> SegWit2x agreement being too slow to activate SegWit mandatory
>> >> >> >>>> signalling ahead of BIP148 using BIP91 I would like to propose
>> >> >> >>>> another
>> >> >> >>>> option that miners can use to prevent a chain split ahead of
>> >> >> >>>> the
>> >> >> >>>> Aug
>> >> >> >>>> 1st BIP148 activation date.
>> >> >> >>>>
>> >> >> >>>> The splitprotection soft fork is essentially BIP91 but using
>> >> >> >>>> BIP8
>> >> >> >>>> instead of BIP9 with a lower activation threshold and immediate
>> >> >> >>>> mandatory signalling lock-in. This allows for a majority of
>> >> >> >>>> miners
>> >> >> >>>> to
>> >> >> >>>> activate mandatory SegWit signalling and prevent a potential
>> >> >> >>>> chain
>> >> >> >>>> split ahead of BIP148 activation.
>> >> >> >>>>
>> >> >> >>>> This BIP allows for miners to respond to market forces quickly
>> >> >> >>>> ahead
>> >> >> >>>> of BIP148 activation by signalling for splitprotection. Any
>> >> >> >>>> miners
>> >> >> >>>> already running BIP148 should be encouraged to use
>> >> >> >>>> splitprotection.
>> >> >> >>>>
>> >> >> >>>> <pre>
>> >> >> >>>>   BIP: splitprotection
>> >> >> >>>>   Layer: Consensus (soft fork)
>> >> >> >>>>   Title: User Activated Soft Fork Split Protection
>> >> >> >>>>   Author: James Hilliard <james.hilliard1@gmail.com>
>> >> >> >>>>   Comments-Summary: No comments yet.
>> >> >> >>>>   Comments-URI:
>> >> >> >>>>   Status: Draft
>> >> >> >>>>   Type: Standards Track
>> >> >> >>>>   Created: 2017-05-22
>> >> >> >>>>   License: BSD-3-Clause
>> >> >> >>>>            CC0-1.0
>> >> >> >>>> </pre>
>> >> >> >>>>
>> >> >> >>>> ==Abstract==
>> >> >> >>>>
>> >> >> >>>> This document specifies a coordination mechanism for a simple
>> >> >> >>>> majority
>> >> >> >>>> of miners to prevent a chain split ahead of BIP148 activation.
>> >> >> >>>>
>> >> >> >>>> ==Definitions==
>> >> >> >>>>
>> >> >> >>>> "existing segwit deployment" refer to the BIP9 "segwit"
>> >> >> >>>> deployment
>> >> >> >>>> using bit 1, between November 15th 2016 and November 15th 2017
>> >> >> >>>> to
>> >> >> >>>> activate BIP141, BIP143 and BIP147.
>> >> >> >>>>
>> >> >> >>>> ==Motivation==
>> >> >> >>>>
>> >> >> >>>> The biggest risk of BIP148 is an extended chain split, this BIP
>> >> >> >>>> provides a way for a simple majority of miners to eliminate
>> >> >> >>>> that
>> >> >> >>>> risk.
>> >> >> >>>>
>> >> >> >>>> This BIP provides a way for a simple majority of miners to
>> >> >> >>>> coordinate
>> >> >> >>>> activation of the existing segwit deployment with less than 95%
>> >> >> >>>> hashpower before BIP148 activation. Due to time constraints
>> >> >> >>>> unless
>> >> >> >>>> immediately deployed BIP91 will likely not be able to enforce
>> >> >> >>>> mandatory signalling of segwit before the Aug 1st activation of
>> >> >> >>>> BIP148. This BIP provides a method for rapid miner activation
>> >> >> >>>> of
>> >> >> >>>> SegWit mandatory signalling ahead of the BIP148 activation
>> >> >> >>>> date.
>> >> >> >>>> Since
>> >> >> >>>> the primary goal of this BIP is to reduce the chance of an
>> >> >> >>>> extended
>> >> >> >>>> chain split as much as possible we activate using a simple
>> >> >> >>>> miner
>> >> >> >>>> majority of 65% over a 504 block interval rather than a higher
>> >> >> >>>> percentage. This BIP also allows miners to signal their
>> >> >> >>>> intention
>> >> >> >>>> to
>> >> >> >>>> run BIP148 in order to prevent a chain split.
>> >> >> >>>>
>> >> >> >>>> ==Specification==
>> >> >> >>>>
>> >> >> >>>> While this BIP is active, all blocks must set the nVersion
>> >> >> >>>> header
>> >> >> >>>> top
>> >> >> >>>> 3 bits to 001 together with bit field (1<<1) (according to the
>> >> >> >>>> existing segwit deployment). Blocks that do not signal as
>> >> >> >>>> required
>> >> >> >>>> will be rejected.
>> >> >> >>>>
>> >> >> >>>> ==Deployment==
>> >> >> >>>>
>> >> >> >>>> This BIP will be deployed by "version bits" with a 65%(this can
>> >> >> >>>> be
>> >> >> >>>> adjusted if desired) activation threshold BIP9 with the name
>> >> >> >>>> "splitprotecion" and using bit 2.
>> >> >> >>>>
>> >> >> >>>> This BIP starts immediately and is a BIP8 style soft fork since
>> >> >> >>>> mandatory signalling will start on midnight August 1st 2017
>> >> >> >>>> (epoch
>> >> >> >>>> time 1501545600) regardless of whether or not this BIP has
>> >> >> >>>> reached
>> >> >> >>>> its
>> >> >> >>>> own signalling threshold. This BIP will cease to be active when
>> >> >> >>>> segwit
>> >> >> >>>> is locked-in.
>> >> >> >>>>
>> >> >> >>>> === Reference implementation ===
>> >> >> >>>>
>> >> >> >>>> <pre>
>> >> >> >>>> // Check if Segregated Witness is Locked In
>> >> >> >>>> bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
>> >> >> >>>> Consensus::Params& params)
>> >> >> >>>> {
>> >> >> >>>>     LOCK(cs_main);
>> >> >> >>>>     return (VersionBitsState(pindexPrev, params,
>> >> >> >>>> Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
>> >> >> >>>> THRESHOLD_LOCKED_IN);
>> >> >> >>>> }
>> >> >> >>>>
>> >> >> >>>> // SPLITPROTECTION mandatory segwit signalling.
>> >> >> >>>> if ( VersionBitsState(pindex->pprev,
>> >> >> >>>> chainparams.GetConsensus(),
>> >> >> >>>> Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
>> >> >> >>>> THRESHOLD_LOCKED_IN &&
>> >> >> >>>>      !IsWitnessLockedIn(pindex->pprev,
>> >> >> >>>> chainparams.GetConsensus())
>> >> >> >>>> &&
>> >> >> >>>> // Segwit is not locked in
>> >> >> >>>>      !IsWitnessEnabled(pindex->pprev,
>> >> >> >>>> chainparams.GetConsensus())
>> >> >> >>>> )
>> >> >> >>>> //
>> >> >> >>>> and is not active.
>> >> >> >>>> {
>> >> >> >>>>     bool fVersionBits = (pindex->nVersion &
>> >> >> >>>> VERSIONBITS_TOP_MASK)
>> >> >> >>>> ==
>> >> >> >>>> VERSIONBITS_TOP_BITS;
>> >> >> >>>>     bool fSegbit = (pindex->nVersion &
>> >> >> >>>> VersionBitsMask(chainparams.GetConsensus(),
>> >> >> >>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>> >> >> >>>>     if (!(fVersionBits && fSegbit)) {
>> >> >> >>>>         return state.DoS(0, error("ConnectBlock(): relayed
>> >> >> >>>> block
>> >> >> >>>> must
>> >> >> >>>> signal for segwit, please upgrade"), REJECT_INVALID,
>> >> >> >>>> "bad-no-segwit");
>> >> >> >>>>     }
>> >> >> >>>> }
>> >> >> >>>>
>> >> >> >>>> // BIP148 mandatory segwit signalling.
>> >> >> >>>> int64_t nMedianTimePast = pindex->GetMedianTimePast();
>> >> >> >>>> if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017
>> >> >> >>>> 00:00:00
>> >> >> >>>> UTC
>> >> >> >>>>      (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017
>> >> >> >>>> 00:00:00
>> >> >> >>>> UTC
>> >> >> >>>>      (!IsWitnessLockedIn(pindex->pprev,
>> >> >> >>>> chainparams.GetConsensus())
>> >> >> >>>> &&
>> >> >> >>>>  // Segwit is not locked in
>> >> >> >>>>       !IsWitnessEnabled(pindex->pprev,
>> >> >> >>>> chainparams.GetConsensus())) )
>> >> >> >>>>  // and is not active.
>> >> >> >>>> {
>> >> >> >>>>     bool fVersionBits = (pindex->nVersion &
>> >> >> >>>> VERSIONBITS_TOP_MASK)
>> >> >> >>>> ==
>> >> >> >>>> VERSIONBITS_TOP_BITS;
>> >> >> >>>>     bool fSegbit = (pindex->nVersion &
>> >> >> >>>> VersionBitsMask(chainparams.GetConsensus(),
>> >> >> >>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>> >> >> >>>>     if (!(fVersionBits && fSegbit)) {
>> >> >> >>>>         return state.DoS(0, error("ConnectBlock(): relayed
>> >> >> >>>> block
>> >> >> >>>> must
>> >> >> >>>> signal for segwit, please upgrade"), REJECT_INVALID,
>> >> >> >>>> "bad-no-segwit");
>> >> >> >>>>     }
>> >> >> >>>> }
>> >> >> >>>> </pre>
>> >> >> >>>>
>> >> >> >>>>
>> >> >> >>>>
>> >> >> >>>>
>> >> >> >>>> https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1
>> >> >> >>>>
>> >> >> >>>> ==Backwards Compatibility==
>> >> >> >>>>
>> >> >> >>>> This deployment is compatible with the existing "segwit" bit 1
>> >> >> >>>> deployment scheduled between midnight November 15th, 2016 and
>> >> >> >>>> midnight
>> >> >> >>>> November 15th, 2017. This deployment is also compatible with
>> >> >> >>>> the
>> >> >> >>>> existing BIP148 deployment. This BIP is compatible with BIP91
>> >> >> >>>> only
>> >> >> >>>> if
>> >> >> >>>> BIP91 activates before it and before BIP148. Miners will need
>> >> >> >>>> to
>> >> >> >>>> upgrade their nodes to support splitprotection otherwise they
>> >> >> >>>> may
>> >> >> >>>> build on top of an invalid block. While this bip is active
>> >> >> >>>> users
>> >> >> >>>> should either upgrade to splitprotection or wait for additional
>> >> >> >>>> confirmations when accepting payments.
>> >> >> >>>>
>> >> >> >>>> ==Rationale==
>> >> >> >>>>
>> >> >> >>>> Historically we have used IsSuperMajority() to activate soft
>> >> >> >>>> forks
>> >> >> >>>> such as BIP66 which has a mandatory signalling requirement for
>> >> >> >>>> miners
>> >> >> >>>> once activated, this ensures that miners are aware of new rules
>> >> >> >>>> being
>> >> >> >>>> enforced. This technique can be leveraged to lower the
>> >> >> >>>> signalling
>> >> >> >>>> threshold of a soft fork while it is in the process of being
>> >> >> >>>> deployed
>> >> >> >>>> in a backwards compatible way. We also use a BIP8 style timeout
>> >> >> >>>> to
>> >> >> >>>> ensure that this BIP is compatible with BIP148 and that BIP148
>> >> >> >>>> compatible mandatory signalling activates regardless of miner
>> >> >> >>>> signalling levels.
>> >> >> >>>>
>> >> >> >>>> By orphaning non-signalling blocks during the BIP9 bit 1
>> >> >> >>>> "segwit"
>> >> >> >>>> deployment, this BIP can cause the existing "segwit" deployment
>> >> >> >>>> to
>> >> >> >>>> activate without needing to release a new deployment. As we
>> >> >> >>>> approach
>> >> >> >>>> BIP148 activation it may be desirable for a majority of miners
>> >> >> >>>> to
>> >> >> >>>> have
>> >> >> >>>> a method that will ensure that there is no chain split.
>> >> >> >>>>
>> >> >> >>>> ==References==
>> >> >> >>>>
>> >> >> >>>>
>> >> >> >>>>
>> >> >> >>>>
>> >> >> >>>> *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html
>> >> >> >>>> Mailing list discussion]
>> >> >> >>>>
>> >> >> >>>>
>> >> >> >>>>
>> >> >> >>>> *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283
>> >> >> >>>> P2SH flag day activation]
>> >> >> >>>> *[[bip-0009.mediawiki|BIP9 Version bits with timeout and
>> >> >> >>>> delay]]
>> >> >> >>>> *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
>> >> >> >>>> *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
>> >> >> >>>> *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus
>> >> >> >>>> layer)]]
>> >> >> >>>> *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification
>> >> >> >>>> for
>> >> >> >>>> Version 0 Witness Program]]
>> >> >> >>>> *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element
>> >> >> >>>> malleability]]
>> >> >> >>>> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit
>> >> >> >>>> deployment]]
>> >> >> >>>> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second
>> >> >> >>>> deployment)]]
>> >> >> >>>> *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit
>> >> >> >>>> benefits]
>> >> >> >>>>
>> >> >> >>>> ==Copyright==
>> >> >> >>>>
>> >> >> >>>> This document is dual licensed as BSD 3-clause, and Creative
>> >> >> >>>> Commons
>> >> >> >>>> CC0 1.0 Universal.
>> >> >> >>>> _______________________________________________
>> >> >> >>>> bitcoin-dev mailing list
>> >> >> >>>> bitcoin-dev@lists.linuxfoundation.org
>> >> >> >>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>> >> >
>> >> >
>> >
>> >
>
>

Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[Jared Lee Richardson]

[-- Attachment #1: Type: text/plain, Size: 37496 bytes --]

> If you're looking for hard numbers at this point you aren't likely to
> find them because not everything is easy to measure directly.

There's quite a few hard numbers that are available that are of varying
use.  Mining commitments are a major one because of the stalled chain
problem.  Node signaling represents some data because while it can be
sybiled, they are cheap but not free to run.  Upvotes and comments on
reddit and other forums might be of some use, but there's not a clear
supermajority driving every pro-uasf comment up and every anti-uasf comment
down, and Reddit obscures the upvote/downvotes pretty well.  It could be a
gleaned datapoint if someone pulled the comments, manually evaluated their
likely position on the matter(neutrally), and then reported on it, but that
is a lot of work and I think it is unlikely to show anything except how
deep the rifts in the community are.  Of the two main statistics available,
they do not support the idea that UASF has any chance of success.  Of the
third, it at least shows that there is deep opposition that is nearly equal
to the support amongst the forums most likely to support UASF.

So I'll take anything, any statistic that actually indicates UASF has a
chance in hell of succeeding, at least that would be worth something.
Otherwise it's all much ado about nothing.

> We'll know more as we get closer to BIP148 activation by looking at the
markets.

What markets?  Where?  How would we know?

> > It doesn't have those issues during the segwit activation, ergo there
is no
> > reason for segwit-activation problems to take priority over the very
real
> > hardfork activation problems.

> And yet segwit2x is insisting on activation bundling which needlessly
> complicates and delays SegWit activation.

Because it is not segwit that has appears to have the supermajority
consensus.

> Sure, technical changes can be made for political reasons, we should
> at least be clear in regards to why particular decisions are being
> made. I'm supportive of a hard fork for technical reasons but not
> political ones as are many others.

Well, then we have a point of agreement at least. :)


On Wed, Jun 7, 2017 at 5:44 PM, James Hilliard <james.hilliard1@gmail.com>
wrote:

> On Wed, Jun 7, 2017 at 7:20 PM, Jared Lee Richardson <jaredr26@gmail.com>
> wrote:
> >> Not really, there are a few relatively simple techniques such as RBF
> >> which can be leveraged to get confirmations on on-side before double
> >> spending on another. Once a transaction is confirmed on the non-BIP148
> >> chain then the high fee transactions can be made on only the BIP148
> >> side of the split using RBF.
> >
> > Ah, so the BIP148 client handles this on behalf of its less technical
> users
> > on their behalf then, yes?
> It's not automatic but exchanges will likely handle it on behalf of
> the less technical users. BIP148 is not intended to cause a permanent
> chain split however which is why this was not built in.
> >
> >>  Exchanges will likely do this splitting
> >> automatically for uses as well.
> >
> > Sure, Exchanges are going to dedicate hundreds of developer hours and
> > thousands of support hours to support something that they've repeatedly
> told
> > everyone must have replay protection to be supported.  They're going to
> do
> > this because 8% of nodes and <0.5% of miners say they'll be rewarded
> richly.
> > Somehow I find that hard to believe.
> They are very likely to, most have contingency plans for this sort of
> thing ready to go due to their experience with the ETH/ETC fork.
> >
> > Besides, if the BIP148 client does it for them, they wouldn't have to
> > dedicate those hundreds of developer hours.  Right?
> >
> > I can't imagine how this logic is getting you from where the real data
> is to
> > the assumption that an economic majority will push BIP148 into being
> such a
> > more valuable chain that switching chains will be attractive to enough
> > miners.  There's got to be some real data that convinces you of this
> > somewhere?
> If you're looking for hard numbers at this point you aren't likely to
> find them because not everything is easy to measure directly.
> >
> >> Both are issues, but wipeout risk is different, the ETH/ETC split for
> >> example didn't have any wipeout risk for either side the same is not
> >> true for BIP148(and it is the non-BIP148 side that carries the risk of
> >> chain wipeout).
> >
> > Wipeout risk is a serious issue when 45% of the miners support one chain
> and
> > 55% support the other chain.  Segwit doesn't even have 35% of the miners;
> > There's no data or statements anywhere that indicate that UASF is going
> to
> > reach the point where wipeout risk is even comparable to abandonment
> risk.
> It's mostly economic support that will dictate this, not hashpower
> support since the hashpower follows the economy.
> >
> >> Yes, miners aren't likely to waste operational mining costs, that's
> >> ultimately why miners would follow the BIP148 side of the chain
> >> assuming it has sufficient economic support or if it's more profitable
> >> to mine.
> >
> > To convince miners you would have to have some data SOMEWHERE supporting
> the
> > economic majority argument.  Is there any such data?
> We'll know more as we get closer to BIP148 activation by looking at the
> markets.
> >
> >> segwit2x has more issues since the HF part requires users to reach
> >> consensus
> >
> > It doesn't have those issues during the segwit activation, ergo there is
> no
> > reason for segwit-activation problems to take priority over the very real
> > hardfork activation problems.
> And yet segwit2x is insisting on activation bundling which needlessly
> complicates and delays SegWit activation.
> >
> >> That's a political reason not a technical reason.
> >
> > In a consensus system they are frequently the same, unfortunately.
> > Technical awesomeness without people agreeing = zero consensus.  So the
> > choice is either to "technically" break the consensus without a
> > super-majority and see what happens, or to go with the choice that has
> real
> > data showing the most consensus and hope the tiny minority chain actually
> > dies off.
> Sure, technical changes can be made for political reasons, we should
> at least be clear in regards to why particular decisions are being
> made. I'm supportive of a hard fork for technical reasons but not
> political ones as are many others.
> >
> > Jared
> >
> > On Wed, Jun 7, 2017 at 5:01 PM, James Hilliard <
> james.hilliard1@gmail.com>
> > wrote:
> >>
> >> On Wed, Jun 7, 2017 at 6:43 PM, Jared Lee Richardson <
> jaredr26@gmail.com>
> >> wrote:
> >> >> BIP148 however is a consensus change that can
> >> >> be rectified if it gets more work, this would act as an additional
> >> >> incentive for mine the BIP148 side since there would be no wipeout
> >> >> risk there.
> >> >
> >> > This statement is misleading.  Wipeout risks don't apply to any
> >> > consensus
> >> > changes; It is a consensus change, it can only be abandoned.  The
> BIP148
> >> > chain carries just as many risks of being abandoned or even more with
> >> > segwit2x on the table.  No miner would consider "wipeout risk" an
> >> > advantage
> >> > when the real threat is chain abandonment.
> >> Both are issues, but wipeout risk is different, the ETH/ETC split for
> >> example didn't have any wipeout risk for either side the same is not
> >> true for BIP148(and it is the non-BIP148 side that carries the risk of
> >> chain wipeout).
> >> >
> >> >> Higher transaction fees on a minority chain can compensate miners for
> >> >> a lower price which would likely be enough to get the BIP148 chain to
> >> >> a difficulty reduction.
> >> >
> >> > Higher transaction fees suffers the same problem as exchange support
> >> > does.
> >> > Without replay protection, it is very difficult for any average user
> to
> >> > force transactions onto one chain or the other.  Thus, without replay
> >> > protection, the UASF chain is unlikely to develop any viable fee
> market;
> >> > Its
> >> > few miners 99% of the time will simply choose from the highest fees
> that
> >> > were already available to the other chain, which is basically no
> >> > advantage
> >> > at all.
> >> Not really, there are a few relatively simple techniques such as RBF
> >> which can be leveraged to get confirmations on on-side before double
> >> spending on another. Once a transaction is confirmed on the non-BIP148
> >> chain then the high fee transactions can be made on only the BIP148
> >> side of the split using RBF. Exchanges will likely do this splitting
> >> automatically for uses as well.
> >> >
> >> >>  ETC replay protection was done after the fork on an as
> >> >> needed basis(there are multiple reliable techniques that can be used
> >> >> to split UTXO's), the same can happen with BIP148 and it is easier to
> >> >> do with Bitcoin than with the ETH/ETC split IMO.
> >> >
> >> > ETC replay protection was added because they were already a hardfork
> and
> >> > without it they would not have had a viable chain.  BIP148 is not
> >> > supposed
> >> > to be a hardfork, and if it added replay protection to remain viable
> it
> >> > would lose the frequently touted "wipeout advantage" as well as the
> >> > ability
> >> > to call itself a softfork.  And are you seriously suggesting that what
> >> > happened with ETC and ETH is a desirable and good situation for
> Bitcoin,
> >> > and
> >> > that UASF is ETC?
> >> There wasn't proper replay protection at split time for ETH/ETC since
> >> normal transactions would get executed on both sides originally,
> >> however replay protection was added by wallets(mainly using splitting
> >> contracts). I don't think a split is desirable however, which is why
> >> I've proposed this BIP.
> >> >
> >> >> A big reason BIP148 still has support is because up until SegWit
> >> >> actually activates there's no guarantee segwit2mb will actually have
> >> >> the necessary support to activate SegWit.
> >> >
> >> > For a miners blowing through six million dollars a day in mining
> >> > operational
> >> > costs, that's a pretty crappy reason.  Serious miners can't afford to
> >> > prop
> >> > up a non-viable chain based on philosophy or maybes.  BIP148 is based
> >> > entirely upon people who aren't putting anything on the line trying to
> >> > convince others to take the huge risks for them.  With deceptively
> >> > fallacious logic, in my opinion.
> >> Yes, miners aren't likely to waste operational mining costs, that's
> >> ultimately why miners would follow the BIP148 side of the chain
> >> assuming it has sufficient economic support or if it's more profitable
> >> to mine.
> >> >
> >> > Even segwit2x is based on the assumption that all miners can reach
> >> > consensus.  Break that assumption and segwit2x will have the same
> >> > problems
> >> > as UASF.
> >> segwit2x has more issues since the HF part requires users to reach
> >> consensus
> >> >
> >> >> This is largely an issue due to segwit2x's bundling, if the SW and HF
> >> >> part of segwit2x were unbundled then there would be no reason to
> delay
> >> >> BIP91 activation
> >> >
> >> > They are bundled.  Segwit alone doesn't have the desired overwhelming
> >> > consensus, unless core wishes to fork 71% to 29%, and maybe not even
> >> > that
> >> > high.  That's the technical reason, and they can't be unbundled
> without
> >> > breaking that consensus.
> >> That's a political reason not a technical reason.
> >> >
> >> > Jared
> >> >
> >> >
> >> > On Wed, Jun 7, 2017 at 4:11 PM, James Hilliard
> >> > <james.hilliard1@gmail.com>
> >> > wrote:
> >> >>
> >> >> On Wed, Jun 7, 2017 at 5:53 PM, Jared Lee Richardson
> >> >> <jaredr26@gmail.com>
> >> >> wrote:
> >> >> >> There are 2 primary factors involved here, economic support and
> >> >> > hashpower either of which is enough to make a permanent chain split
> >> >> > unlikely, miners will mine whichever chain is most profitable(see
> >> >> > ETH/ETC hashpower profitability equilibrium for an example of how
> >> >> > this
> >> >> > works in practice)
> >> >> >
> >> >> > That's not a comparable example.  ETC did not face potentially
> years
> >> >> > of
> >> >> > slow
> >> >> > blocktimes before it normalized, whereas BIP148 is on track to do
> >> >> > exactly
> >> >> > that.  Moreover, ETC represented a fundamental break from the
> >> >> > majority
> >> >> > consensus that could not be rectified, whereas BIP148 represents
> only
> >> >> > a
> >> >> > minority attempt to accelerate something that an overwhelming
> >> >> > majority
> >> >> > of
> >> >> > miners have already agreed to activate under segwit2x.  Lastly ETC
> >> >> > was
> >> >> > required to add replay protection, just like any minority fork
> >> >> > proposed
> >> >> > by
> >> >> > any crypto-currency has been, something that BIP148 both lacks and
> >> >> > refuses
> >> >> > to add or even acknowledge the necessity of.  Without replay
> >> >> > protection,
> >> >> > ETC
> >> >> > could not have become profitable enough to be a viable minority
> >> >> > chain.
> >> >> > If
> >> >> > BIP148's chain is not the majority chain and it does not have
> replay
> >> >> > protection, it will face the same problems, but that required
> replay
> >> >> > protection will turn it into a hardfork.  This will be a very bad
> >> >> > position
> >> >> > for UASF supporters to find themselves in - Either hardfork and
> hope
> >> >> > the
> >> >> > price is higher and the majority converts, or die as the minority
> >> >> > chain
> >> >> > with
> >> >> > no reliable methods of economic conversion.
> >> >> Higher transaction fees on a minority chain can compensate miners for
> >> >> a lower price which would likely be enough to get the BIP148 chain to
> >> >> a difficulty reduction. BIP148 however is a consensus change that can
> >> >> be rectified if it gets more work, this would act as an additional
> >> >> incentive for mine the BIP148 side since there would be no wipeout
> >> >> risk there. ETC replay protection was done after the fork on an as
> >> >> needed basis(there are multiple reliable techniques that can be used
> >> >> to split UTXO's), the same can happen with BIP148 and it is easier to
> >> >> do with Bitcoin than with the ETH/ETC split IMO.
> >> >> >
> >> >> > I believe, but don't have data to back this, that most of the
> BIP148
> >> >> > insistence comes not from a legitimate attempt to gain consensus
> (or
> >> >> > else
> >> >> > they would either outright oppose segwit2mb for its hardfork, or
> they
> >> >> > would
> >> >> > outright support it), but rather from an attempt for BIP148
> >> >> > supporters
> >> >> > to
> >> >> > save face for BIP148 being a failure.  If I'm correct, that's a
> >> >> > terrible
> >> >> > and
> >> >> > highly non-technical reason for segwit2mb to bend over backwards
> >> >> > attempting
> >> >> > to support BIP148's attempt to save face.
> >> >> A big reason BIP148 still has support is because up until SegWit
> >> >> actually activates there's no guarantee segwit2mb will actually have
> >> >> the necessary support to activate SegWit.
> >> >> >
> >> >> >> The main issue is just one of activation timelines, BIP91 as
> >> >> > is takes too long to activate unless started ahead of the existing
> >> >> > segwit2x schedule and it's unlikely that BIP148 will get pushed
> back
> >> >> > any further.
> >> >> >
> >> >> > Even if I'm not correct on the above, I and others find it hard to
> >> >> > accept
> >> >> > that this timeline conflict is segwit2x's fault.  Segwit2x has both
> >> >> > some
> >> >> > flexibility and broad support that crosses contentious pro-segwit
> and
> >> >> > pro-blocksize-increase divisions that have existed for two years.
> >> >> > BIP148 is
> >> >> > attempting to hold segwit2x's timelines and code hostage by
> claiming
> >> >> > inflexibility and claiming broad support, and not only are neither
> of
> >> >> > those
> >> >> > assertions are backed by real data, BIP148 (by being so inflexible)
> >> >> > is
> >> >> > pushing a position that deepens the divides between those groups.
> >> >> > For
> >> >> > there
> >> >> > to be technical reasons for compatibility (so long as there are
> >> >> > tradeoffs,
> >> >> > which there are), there needs to be hard data showing that BIP148
> is
> >> >> > a
> >> >> > viable minority fork that won't simply die off on its own.
> >> >> This is largely an issue due to segwit2x's bundling, if the SW and HF
> >> >> part of segwit2x were unbundled then there would be no reason to
> delay
> >> >> BIP91 activation, this is especially a problem since it takes a good
> >> >> deal of time to properly code and test a HF. Unfortunately segwit2x
> >> >> has been quite inflexible in regards to the bundling aspect even
> >> >> though there are clearly no technical reasons for it to be there.
> >> >> >
> >> >> > Jared
> >> >> >
> >> >> >
> >> >> > On Wed, Jun 7, 2017 at 3:23 PM, James Hilliard
> >> >> > <james.hilliard1@gmail.com>
> >> >> > wrote:
> >> >> >>
> >> >> >> On Wed, Jun 7, 2017 at 4:50 PM, Jared Lee Richardson
> >> >> >> <jaredr26@gmail.com>
> >> >> >> wrote:
> >> >> >> > Could this risk mitigation measure be an optional flag?  And if
> >> >> >> > so,
> >> >> >> > could it+BIP91 signal on a different bit than bit4?
> >> >> >> It's fairly trivial for miners to signal for BIP91 on bit4 or a
> >> >> >> different bit at the same time as the code is trivial enough to
> >> >> >> combine
> >> >> >> >
> >> >> >> > The reason being, if for some reason the segwit2x activation
> >> >> >> > cannot
> >> >> >> > take place in time, it would be preferable for miners to have a
> >> >> >> > more
> >> >> >> > standard approach to activation that requires stronger consensus
> >> >> >> > and
> >> >> >> > may be more forgiving than BIP148.  If the segwit2x activation
> is
> >> >> >> > on
> >> >> >> > time to cooperate with BIP148, it could be signaled through the
> >> >> >> > non-bit4 approach and everything could go smoothly.  Thoughts on
> >> >> >> > that
> >> >> >> > idea?  It may add more complexity and more developer time, but
> may
> >> >> >> > also address your concerns among others.
> >> >> >> This does give miners another approach to activate segwit ahead of
> >> >> >> BIP148, if segwit2x activation is rolled out and activated
> >> >> >> immediately
> >> >> >> then this would not be needed however based on the timeline here
> >> >> >> https://segwit2x.github.io/ it would not be possible for BIP91 to
> >> >> >> enforce mandatory signalling ahead of BIP148. Maybe that can be
> >> >> >> changed though, I've suggested an immediate rollout with a
> >> >> >> placeholder
> >> >> >> client timeout instead of the HF code initially in order to
> >> >> >> accelerate
> >> >> >> that.
> >> >> >> >
> >> >> >> >> Since this BIP
> >> >> >> >> only activates with a clear miner majority it should not
> increase
> >> >> >> >> the
> >> >> >> >> risk of an extended chain split.
> >> >> >> >
> >> >> >> > The concern I'm raising is more about the psychology of giving
> >> >> >> > BIP148
> >> >> >> > a sense of safety that may not be valid.  Without several more
> >> >> >> > steps,
> >> >> >> > BIP148 is definitely on track to be a risky chainsplit, and
> >> >> >> > without
> >> >> >> > segwit2x it will almost certainly be a small minority chain.
> >> >> >> > (Unless
> >> >> >> > the segwit2x compromise falls apart before then, and even in
> that
> >> >> >> > case
> >> >> >> > it is likely to be a minority chain)
> >> >> >> There are 2 primary factors involved here, economic support and
> >> >> >> hashpower either of which is enough to make a permanent chain
> split
> >> >> >> unlikely, miners will mine whichever chain is most profitable(see
> >> >> >> ETH/ETC hashpower profitability equilibrium for an example of how
> >> >> >> this
> >> >> >> works in practice) however there may be lag time immediately after
> >> >> >> the
> >> >> >> split if there is an economic majority but not a hashpower
> majority
> >> >> >> initially. This is risk mitigation that only requires miners
> support
> >> >> >> however. The main issue is just one of activation timelines, BIP91
> >> >> >> as
> >> >> >> is takes too long to activate unless started ahead of the existing
> >> >> >> segwit2x schedule and it's unlikely that BIP148 will get pushed
> back
> >> >> >> any further.
> >> >> >> >
> >> >> >> > Jared
> >> >> >> >
> >> >> >> >
> >> >> >> > On Wed, Jun 7, 2017 at 2:42 PM, James Hilliard
> >> >> >> > <james.hilliard1@gmail.com> wrote:
> >> >> >> >> I don't really see how this would increase the likelihood of an
> >> >> >> >> extended chain split assuming BIP148 is going to have
> >> >> >> >> non-insignificant economic backing. This BIP is designed to
> >> >> >> >> provide
> >> >> >> >> a
> >> >> >> >> risk mitigation measure that miners can safely deploy. Since
> this
> >> >> >> >> BIP
> >> >> >> >> only activates with a clear miner majority it should not
> increase
> >> >> >> >> the
> >> >> >> >> risk of an extended chain split. At this point it is not
> >> >> >> >> completely
> >> >> >> >> clear how much economic support there is for BIP148 but support
> >> >> >> >> certainly seems to be growing and we have nearly 2 months until
> >> >> >> >> BIP148
> >> >> >> >> activation. I intentionally used a shorter activation period
> here
> >> >> >> >> so
> >> >> >> >> that decisions by miners can be made close to the BIP148
> >> >> >> >> activation
> >> >> >> >> date.
> >> >> >> >>
> >> >> >> >> On Wed, Jun 7, 2017 at 4:29 PM, Jared Lee Richardson
> >> >> >> >> <jaredr26@gmail.com> wrote:
> >> >> >> >>> I think this BIP represents a gamble, and the gamble may not
> be
> >> >> >> >>> a
> >> >> >> >>> good
> >> >> >> >>> one.  The gamble here is that if the segwit2x changes are
> rolled
> >> >> >> >>> out
> >> >> >> >>> on time, and if the signatories accept the bit4 + bit1
> signaling
> >> >> >> >>> proposals within BIP91, the launch will go smoother, as
> >> >> >> >>> intended.
> >> >> >> >>> But
> >> >> >> >>> conversely, if either the segwit2x signatories balk about the
> >> >> >> >>> Bit1
> >> >> >> >>> signaling OR if the timelines for segwit2mb are missed even
> by a
> >> >> >> >>> bit,
> >> >> >> >>> it may cause the BIP148 chainsplit to be worse than it would
> be
> >> >> >> >>> without.  Given the frequent concerns raised in multiple
> places
> >> >> >> >>> about
> >> >> >> >>> the aggressiveness of the segwit2x timelines, including the
> >> >> >> >>> non-hardfork timelines, this does not seem like a great gamble
> >> >> >> >>> to
> >> >> >> >>> be
> >> >> >> >>> making.
> >> >> >> >>>
> >> >> >> >>> The reason I say it may make the chainsplit be worse than it
> >> >> >> >>> would
> >> >> >> >>> otherwise be is that it may provide a false sense of safety
> for
> >> >> >> >>> BIP148
> >> >> >> >>> that currently does not currently exist(and should not, as it
> is
> >> >> >> >>> a
> >> >> >> >>> chainsplit).  That sense of safety would only be legitimate if
> >> >> >> >>> the
> >> >> >> >>> segwit2x signatories were on board, and the segwit2x code
> >> >> >> >>> effectively
> >> >> >> >>> enforced BIP148 simultaneously, neither of which are
> guaranteed.
> >> >> >> >>> If
> >> >> >> >>> users and more miners had a false sense that BIP148 was *not*
> >> >> >> >>> going
> >> >> >> >>> to
> >> >> >> >>> chainsplit from default / segwit2x, they might not follow the
> >> >> >> >>> news
> >> >> >> >>> if
> >> >> >> >>> suddenly the segwit2x plan were delayed for a few days.  While
> >> >> >> >>> any
> >> >> >> >>> additional support would definitely be cheered on by BIP148
> >> >> >> >>> supporters, the practical reality might be that this proposal
> >> >> >> >>> would
> >> >> >> >>> take BIP148 from the "unlikely to have any viable chain after
> >> >> >> >>> flag
> >> >> >> >>> day
> >> >> >> >>> without segwit2x" category into the "small but viable minority
> >> >> >> >>> chain"
> >> >> >> >>> category, and even worse, it might strengthen the chainsplit
> >> >> >> >>> just
> >> >> >> >>> days
> >> >> >> >>> before segwit is activated on BOTH chains, putting the BIP148
> >> >> >> >>> supporters on the wrong pro-segwit, but still-viable chain.
> >> >> >> >>>
> >> >> >> >>> If Core had taken a strong stance to include BIP148 into the
> >> >> >> >>> client,
> >> >> >> >>> and if BIP148 support were much much broader, I would feel
> >> >> >> >>> differently
> >> >> >> >>> as the gamble would be more likely to discourage a chainsplit
> >> >> >> >>> (By
> >> >> >> >>> forcing the acceleration of segwit2x) rather than encourage it
> >> >> >> >>> (by
> >> >> >> >>> strengthening an extreme minority chainsplit that may wind up
> on
> >> >> >> >>> the
> >> >> >> >>> wrong side of two segwit-activated chains).  As it stands now,
> >> >> >> >>> this
> >> >> >> >>> seems like a very dangerous attempt to compromise with a small
> >> >> >> >>> but
> >> >> >> >>> vocal group that are the ones creating the threat to begin
> with.
> >> >> >> >>>
> >> >> >> >>> Jared
> >> >> >> >>>
> >> >> >> >>> On Tue, Jun 6, 2017 at 5:56 PM, James Hilliard via bitcoin-dev
> >> >> >> >>> <bitcoin-dev@lists.linuxfoundation.org> wrote:
> >> >> >> >>>> Due to the proposed calendar(https://segwit2x.github.io/)
> for
> >> >> >> >>>> the
> >> >> >> >>>> SegWit2x agreement being too slow to activate SegWit
> mandatory
> >> >> >> >>>> signalling ahead of BIP148 using BIP91 I would like to
> propose
> >> >> >> >>>> another
> >> >> >> >>>> option that miners can use to prevent a chain split ahead of
> >> >> >> >>>> the
> >> >> >> >>>> Aug
> >> >> >> >>>> 1st BIP148 activation date.
> >> >> >> >>>>
> >> >> >> >>>> The splitprotection soft fork is essentially BIP91 but using
> >> >> >> >>>> BIP8
> >> >> >> >>>> instead of BIP9 with a lower activation threshold and
> immediate
> >> >> >> >>>> mandatory signalling lock-in. This allows for a majority of
> >> >> >> >>>> miners
> >> >> >> >>>> to
> >> >> >> >>>> activate mandatory SegWit signalling and prevent a potential
> >> >> >> >>>> chain
> >> >> >> >>>> split ahead of BIP148 activation.
> >> >> >> >>>>
> >> >> >> >>>> This BIP allows for miners to respond to market forces
> quickly
> >> >> >> >>>> ahead
> >> >> >> >>>> of BIP148 activation by signalling for splitprotection. Any
> >> >> >> >>>> miners
> >> >> >> >>>> already running BIP148 should be encouraged to use
> >> >> >> >>>> splitprotection.
> >> >> >> >>>>
> >> >> >> >>>> <pre>
> >> >> >> >>>>   BIP: splitprotection
> >> >> >> >>>>   Layer: Consensus (soft fork)
> >> >> >> >>>>   Title: User Activated Soft Fork Split Protection
> >> >> >> >>>>   Author: James Hilliard <james.hilliard1@gmail.com>
> >> >> >> >>>>   Comments-Summary: No comments yet.
> >> >> >> >>>>   Comments-URI:
> >> >> >> >>>>   Status: Draft
> >> >> >> >>>>   Type: Standards Track
> >> >> >> >>>>   Created: 2017-05-22
> >> >> >> >>>>   License: BSD-3-Clause
> >> >> >> >>>>            CC0-1.0
> >> >> >> >>>> </pre>
> >> >> >> >>>>
> >> >> >> >>>> ==Abstract==
> >> >> >> >>>>
> >> >> >> >>>> This document specifies a coordination mechanism for a simple
> >> >> >> >>>> majority
> >> >> >> >>>> of miners to prevent a chain split ahead of BIP148
> activation.
> >> >> >> >>>>
> >> >> >> >>>> ==Definitions==
> >> >> >> >>>>
> >> >> >> >>>> "existing segwit deployment" refer to the BIP9 "segwit"
> >> >> >> >>>> deployment
> >> >> >> >>>> using bit 1, between November 15th 2016 and November 15th
> 2017
> >> >> >> >>>> to
> >> >> >> >>>> activate BIP141, BIP143 and BIP147.
> >> >> >> >>>>
> >> >> >> >>>> ==Motivation==
> >> >> >> >>>>
> >> >> >> >>>> The biggest risk of BIP148 is an extended chain split, this
> BIP
> >> >> >> >>>> provides a way for a simple majority of miners to eliminate
> >> >> >> >>>> that
> >> >> >> >>>> risk.
> >> >> >> >>>>
> >> >> >> >>>> This BIP provides a way for a simple majority of miners to
> >> >> >> >>>> coordinate
> >> >> >> >>>> activation of the existing segwit deployment with less than
> 95%
> >> >> >> >>>> hashpower before BIP148 activation. Due to time constraints
> >> >> >> >>>> unless
> >> >> >> >>>> immediately deployed BIP91 will likely not be able to enforce
> >> >> >> >>>> mandatory signalling of segwit before the Aug 1st activation
> of
> >> >> >> >>>> BIP148. This BIP provides a method for rapid miner activation
> >> >> >> >>>> of
> >> >> >> >>>> SegWit mandatory signalling ahead of the BIP148 activation
> >> >> >> >>>> date.
> >> >> >> >>>> Since
> >> >> >> >>>> the primary goal of this BIP is to reduce the chance of an
> >> >> >> >>>> extended
> >> >> >> >>>> chain split as much as possible we activate using a simple
> >> >> >> >>>> miner
> >> >> >> >>>> majority of 65% over a 504 block interval rather than a
> higher
> >> >> >> >>>> percentage. This BIP also allows miners to signal their
> >> >> >> >>>> intention
> >> >> >> >>>> to
> >> >> >> >>>> run BIP148 in order to prevent a chain split.
> >> >> >> >>>>
> >> >> >> >>>> ==Specification==
> >> >> >> >>>>
> >> >> >> >>>> While this BIP is active, all blocks must set the nVersion
> >> >> >> >>>> header
> >> >> >> >>>> top
> >> >> >> >>>> 3 bits to 001 together with bit field (1<<1) (according to
> the
> >> >> >> >>>> existing segwit deployment). Blocks that do not signal as
> >> >> >> >>>> required
> >> >> >> >>>> will be rejected.
> >> >> >> >>>>
> >> >> >> >>>> ==Deployment==
> >> >> >> >>>>
> >> >> >> >>>> This BIP will be deployed by "version bits" with a 65%(this
> can
> >> >> >> >>>> be
> >> >> >> >>>> adjusted if desired) activation threshold BIP9 with the name
> >> >> >> >>>> "splitprotecion" and using bit 2.
> >> >> >> >>>>
> >> >> >> >>>> This BIP starts immediately and is a BIP8 style soft fork
> since
> >> >> >> >>>> mandatory signalling will start on midnight August 1st 2017
> >> >> >> >>>> (epoch
> >> >> >> >>>> time 1501545600) regardless of whether or not this BIP has
> >> >> >> >>>> reached
> >> >> >> >>>> its
> >> >> >> >>>> own signalling threshold. This BIP will cease to be active
> when
> >> >> >> >>>> segwit
> >> >> >> >>>> is locked-in.
> >> >> >> >>>>
> >> >> >> >>>> === Reference implementation ===
> >> >> >> >>>>
> >> >> >> >>>> <pre>
> >> >> >> >>>> // Check if Segregated Witness is Locked In
> >> >> >> >>>> bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
> >> >> >> >>>> Consensus::Params& params)
> >> >> >> >>>> {
> >> >> >> >>>>     LOCK(cs_main);
> >> >> >> >>>>     return (VersionBitsState(pindexPrev, params,
> >> >> >> >>>> Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
> >> >> >> >>>> THRESHOLD_LOCKED_IN);
> >> >> >> >>>> }
> >> >> >> >>>>
> >> >> >> >>>> // SPLITPROTECTION mandatory segwit signalling.
> >> >> >> >>>> if ( VersionBitsState(pindex->pprev,
> >> >> >> >>>> chainparams.GetConsensus(),
> >> >> >> >>>> Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
> >> >> >> >>>> THRESHOLD_LOCKED_IN &&
> >> >> >> >>>>      !IsWitnessLockedIn(pindex->pprev,
> >> >> >> >>>> chainparams.GetConsensus())
> >> >> >> >>>> &&
> >> >> >> >>>> // Segwit is not locked in
> >> >> >> >>>>      !IsWitnessEnabled(pindex->pprev,
> >> >> >> >>>> chainparams.GetConsensus())
> >> >> >> >>>> )
> >> >> >> >>>> //
> >> >> >> >>>> and is not active.
> >> >> >> >>>> {
> >> >> >> >>>>     bool fVersionBits = (pindex->nVersion &
> >> >> >> >>>> VERSIONBITS_TOP_MASK)
> >> >> >> >>>> ==
> >> >> >> >>>> VERSIONBITS_TOP_BITS;
> >> >> >> >>>>     bool fSegbit = (pindex->nVersion &
> >> >> >> >>>> VersionBitsMask(chainparams.GetConsensus(),
> >> >> >> >>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
> >> >> >> >>>>     if (!(fVersionBits && fSegbit)) {
> >> >> >> >>>>         return state.DoS(0, error("ConnectBlock(): relayed
> >> >> >> >>>> block
> >> >> >> >>>> must
> >> >> >> >>>> signal for segwit, please upgrade"), REJECT_INVALID,
> >> >> >> >>>> "bad-no-segwit");
> >> >> >> >>>>     }
> >> >> >> >>>> }
> >> >> >> >>>>
> >> >> >> >>>> // BIP148 mandatory segwit signalling.
> >> >> >> >>>> int64_t nMedianTimePast = pindex->GetMedianTimePast();
> >> >> >> >>>> if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017
> >> >> >> >>>> 00:00:00
> >> >> >> >>>> UTC
> >> >> >> >>>>      (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017
> >> >> >> >>>> 00:00:00
> >> >> >> >>>> UTC
> >> >> >> >>>>      (!IsWitnessLockedIn(pindex->pprev,
> >> >> >> >>>> chainparams.GetConsensus())
> >> >> >> >>>> &&
> >> >> >> >>>>  // Segwit is not locked in
> >> >> >> >>>>       !IsWitnessEnabled(pindex->pprev,
> >> >> >> >>>> chainparams.GetConsensus())) )
> >> >> >> >>>>  // and is not active.
> >> >> >> >>>> {
> >> >> >> >>>>     bool fVersionBits = (pindex->nVersion &
> >> >> >> >>>> VERSIONBITS_TOP_MASK)
> >> >> >> >>>> ==
> >> >> >> >>>> VERSIONBITS_TOP_BITS;
> >> >> >> >>>>     bool fSegbit = (pindex->nVersion &
> >> >> >> >>>> VersionBitsMask(chainparams.GetConsensus(),
> >> >> >> >>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
> >> >> >> >>>>     if (!(fVersionBits && fSegbit)) {
> >> >> >> >>>>         return state.DoS(0, error("ConnectBlock(): relayed
> >> >> >> >>>> block
> >> >> >> >>>> must
> >> >> >> >>>> signal for segwit, please upgrade"), REJECT_INVALID,
> >> >> >> >>>> "bad-no-segwit");
> >> >> >> >>>>     }
> >> >> >> >>>> }
> >> >> >> >>>> </pre>
> >> >> >> >>>>
> >> >> >> >>>>
> >> >> >> >>>>
> >> >> >> >>>>
> >> >> >> >>>> https://github.com/bitcoin/bitcoin/compare/0.14...
> jameshilliard:splitprotection-v0.14.1
> >> >> >> >>>>
> >> >> >> >>>> ==Backwards Compatibility==
> >> >> >> >>>>
> >> >> >> >>>> This deployment is compatible with the existing "segwit" bit
> 1
> >> >> >> >>>> deployment scheduled between midnight November 15th, 2016 and
> >> >> >> >>>> midnight
> >> >> >> >>>> November 15th, 2017. This deployment is also compatible with
> >> >> >> >>>> the
> >> >> >> >>>> existing BIP148 deployment. This BIP is compatible with BIP91
> >> >> >> >>>> only
> >> >> >> >>>> if
> >> >> >> >>>> BIP91 activates before it and before BIP148. Miners will need
> >> >> >> >>>> to
> >> >> >> >>>> upgrade their nodes to support splitprotection otherwise they
> >> >> >> >>>> may
> >> >> >> >>>> build on top of an invalid block. While this bip is active
> >> >> >> >>>> users
> >> >> >> >>>> should either upgrade to splitprotection or wait for
> additional
> >> >> >> >>>> confirmations when accepting payments.
> >> >> >> >>>>
> >> >> >> >>>> ==Rationale==
> >> >> >> >>>>
> >> >> >> >>>> Historically we have used IsSuperMajority() to activate soft
> >> >> >> >>>> forks
> >> >> >> >>>> such as BIP66 which has a mandatory signalling requirement
> for
> >> >> >> >>>> miners
> >> >> >> >>>> once activated, this ensures that miners are aware of new
> rules
> >> >> >> >>>> being
> >> >> >> >>>> enforced. This technique can be leveraged to lower the
> >> >> >> >>>> signalling
> >> >> >> >>>> threshold of a soft fork while it is in the process of being
> >> >> >> >>>> deployed
> >> >> >> >>>> in a backwards compatible way. We also use a BIP8 style
> timeout
> >> >> >> >>>> to
> >> >> >> >>>> ensure that this BIP is compatible with BIP148 and that
> BIP148
> >> >> >> >>>> compatible mandatory signalling activates regardless of miner
> >> >> >> >>>> signalling levels.
> >> >> >> >>>>
> >> >> >> >>>> By orphaning non-signalling blocks during the BIP9 bit 1
> >> >> >> >>>> "segwit"
> >> >> >> >>>> deployment, this BIP can cause the existing "segwit"
> deployment
> >> >> >> >>>> to
> >> >> >> >>>> activate without needing to release a new deployment. As we
> >> >> >> >>>> approach
> >> >> >> >>>> BIP148 activation it may be desirable for a majority of
> miners
> >> >> >> >>>> to
> >> >> >> >>>> have
> >> >> >> >>>> a method that will ensure that there is no chain split.
> >> >> >> >>>>
> >> >> >> >>>> ==References==
> >> >> >> >>>>
> >> >> >> >>>>
> >> >> >> >>>>
> >> >> >> >>>>
> >> >> >> >>>> *[https://lists.linuxfoundation.org/pipermail/
> bitcoin-dev/2017-March/013714.html
> >> >> >> >>>> Mailing list discussion]
> >> >> >> >>>>
> >> >> >> >>>>
> >> >> >> >>>>
> >> >> >> >>>> *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.
> cpp#L1281-L1283
> >> >> >> >>>> P2SH flag day activation]
> >> >> >> >>>> *[[bip-0009.mediawiki|BIP9 Version bits with timeout and
> >> >> >> >>>> delay]]
> >> >> >> >>>> *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
> >> >> >> >>>> *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
> >> >> >> >>>> *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus
> >> >> >> >>>> layer)]]
> >> >> >> >>>> *[[bip-0143.mediawiki|BIP143 Transaction Signature
> Verification
> >> >> >> >>>> for
> >> >> >> >>>> Version 0 Witness Program]]
> >> >> >> >>>> *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element
> >> >> >> >>>> malleability]]
> >> >> >> >>>> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit
> >> >> >> >>>> deployment]]
> >> >> >> >>>> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second
> >> >> >> >>>> deployment)]]
> >> >> >> >>>> *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/
> Segwit
> >> >> >> >>>> benefits]
> >> >> >> >>>>
> >> >> >> >>>> ==Copyright==
> >> >> >> >>>>
> >> >> >> >>>> This document is dual licensed as BSD 3-clause, and Creative
> >> >> >> >>>> Commons
> >> >> >> >>>> CC0 1.0 Universal.
> >> >> >> >>>> _______________________________________________
> >> >> >> >>>> bitcoin-dev mailing list
> >> >> >> >>>> bitcoin-dev@lists.linuxfoundation.org
> >> >> >> >>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-
> dev
> >> >> >
> >> >> >
> >> >
> >> >
> >
> >
>

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Re: [bitcoin-dev] User Activated Soft Fork Split Protection

[James Hilliard]

On Wed, Jun 7, 2017 at 8:01 PM, Jared Lee Richardson <jaredr26@gmail.com> wrote:
>> If you're looking for hard numbers at this point you aren't likely to
>> find them because not everything is easy to measure directly.
>
> There's quite a few hard numbers that are available that are of varying use.
> Mining commitments are a major one because of the stalled chain problem.
> Node signaling represents some data because while it can be sybiled, they
> are cheap but not free to run.  Upvotes and comments on reddit and other
> forums might be of some use, but there's not a clear supermajority driving
> every pro-uasf comment up and every anti-uasf comment down, and Reddit
> obscures the upvote/downvotes pretty well.  It could be a gleaned datapoint
> if someone pulled the comments, manually evaluated their likely position on
> the matter(neutrally), and then reported on it, but that is a lot of work
> and I think it is unlikely to show anything except how deep the rifts in the
> community are.  Of the two main statistics available, they do not support
> the idea that UASF has any chance of success.  Of the third, it at least
> shows that there is deep opposition that is nearly equal to the support
> amongst the forums most likely to support UASF.
Right, it's not straight forward to measure because the hard numbers
that we do have tell an incomplete story. In addition the metric that
BIP148 primarily depends on(economic support) is much harder to
measure than other metrics such as hashpower support.
>
> So I'll take anything, any statistic that actually indicates UASF has a
> chance in hell of succeeding, at least that would be worth something.
> Otherwise it's all much ado about nothing.
>
>> We'll know more as we get closer to BIP148 activation by looking at the
>> markets.
>
> What markets?  Where?  How would we know?
There will likely be some exchanges offering markets for each side of
a potential split separately ahead of BIP148 activation.
>
>> > It doesn't have those issues during the segwit activation, ergo there is
>> > no
>> > reason for segwit-activation problems to take priority over the very
>> > real
>> > hardfork activation problems.
>
>> And yet segwit2x is insisting on activation bundling which needlessly
>> complicates and delays SegWit activation.
>
> Because it is not segwit that has appears to have the supermajority
> consensus.
I think you've misunderstood the situation, SegWit has widespread
support but has been turned into a political bargaining chip for other
less desirable changes that do not have widespread support.
>
>> Sure, technical changes can be made for political reasons, we should
>> at least be clear in regards to why particular decisions are being
>> made. I'm supportive of a hard fork for technical reasons but not
>> political ones as are many others.
>
> Well, then we have a point of agreement at least. :)
>
>
> On Wed, Jun 7, 2017 at 5:44 PM, James Hilliard <james.hilliard1@gmail.com>
> wrote:
>>
>> On Wed, Jun 7, 2017 at 7:20 PM, Jared Lee Richardson <jaredr26@gmail.com>
>> wrote:
>> >> Not really, there are a few relatively simple techniques such as RBF
>> >> which can be leveraged to get confirmations on on-side before double
>> >> spending on another. Once a transaction is confirmed on the non-BIP148
>> >> chain then the high fee transactions can be made on only the BIP148
>> >> side of the split using RBF.
>> >
>> > Ah, so the BIP148 client handles this on behalf of its less technical
>> > users
>> > on their behalf then, yes?
>> It's not automatic but exchanges will likely handle it on behalf of
>> the less technical users. BIP148 is not intended to cause a permanent
>> chain split however which is why this was not built in.
>> >
>> >>  Exchanges will likely do this splitting
>> >> automatically for uses as well.
>> >
>> > Sure, Exchanges are going to dedicate hundreds of developer hours and
>> > thousands of support hours to support something that they've repeatedly
>> > told
>> > everyone must have replay protection to be supported.  They're going to
>> > do
>> > this because 8% of nodes and <0.5% of miners say they'll be rewarded
>> > richly.
>> > Somehow I find that hard to believe.
>> They are very likely to, most have contingency plans for this sort of
>> thing ready to go due to their experience with the ETH/ETC fork.
>> >
>> > Besides, if the BIP148 client does it for them, they wouldn't have to
>> > dedicate those hundreds of developer hours.  Right?
>> >
>> > I can't imagine how this logic is getting you from where the real data
>> > is to
>> > the assumption that an economic majority will push BIP148 into being
>> > such a
>> > more valuable chain that switching chains will be attractive to enough
>> > miners.  There's got to be some real data that convinces you of this
>> > somewhere?
>> If you're looking for hard numbers at this point you aren't likely to
>> find them because not everything is easy to measure directly.
>> >
>> >> Both are issues, but wipeout risk is different, the ETH/ETC split for
>> >> example didn't have any wipeout risk for either side the same is not
>> >> true for BIP148(and it is the non-BIP148 side that carries the risk of
>> >> chain wipeout).
>> >
>> > Wipeout risk is a serious issue when 45% of the miners support one chain
>> > and
>> > 55% support the other chain.  Segwit doesn't even have 35% of the
>> > miners;
>> > There's no data or statements anywhere that indicate that UASF is going
>> > to
>> > reach the point where wipeout risk is even comparable to abandonment
>> > risk.
>> It's mostly economic support that will dictate this, not hashpower
>> support since the hashpower follows the economy.
>> >
>> >> Yes, miners aren't likely to waste operational mining costs, that's
>> >> ultimately why miners would follow the BIP148 side of the chain
>> >> assuming it has sufficient economic support or if it's more profitable
>> >> to mine.
>> >
>> > To convince miners you would have to have some data SOMEWHERE supporting
>> > the
>> > economic majority argument.  Is there any such data?
>> We'll know more as we get closer to BIP148 activation by looking at the
>> markets.
>> >
>> >> segwit2x has more issues since the HF part requires users to reach
>> >> consensus
>> >
>> > It doesn't have those issues during the segwit activation, ergo there is
>> > no
>> > reason for segwit-activation problems to take priority over the very
>> > real
>> > hardfork activation problems.
>> And yet segwit2x is insisting on activation bundling which needlessly
>> complicates and delays SegWit activation.
>> >
>> >> That's a political reason not a technical reason.
>> >
>> > In a consensus system they are frequently the same, unfortunately.
>> > Technical awesomeness without people agreeing = zero consensus.  So the
>> > choice is either to "technically" break the consensus without a
>> > super-majority and see what happens, or to go with the choice that has
>> > real
>> > data showing the most consensus and hope the tiny minority chain
>> > actually
>> > dies off.
>> Sure, technical changes can be made for political reasons, we should
>> at least be clear in regards to why particular decisions are being
>> made. I'm supportive of a hard fork for technical reasons but not
>> political ones as are many others.
>> >
>> > Jared
>> >
>> > On Wed, Jun 7, 2017 at 5:01 PM, James Hilliard
>> > <james.hilliard1@gmail.com>
>> > wrote:
>> >>
>> >> On Wed, Jun 7, 2017 at 6:43 PM, Jared Lee Richardson
>> >> <jaredr26@gmail.com>
>> >> wrote:
>> >> >> BIP148 however is a consensus change that can
>> >> >> be rectified if it gets more work, this would act as an additional
>> >> >> incentive for mine the BIP148 side since there would be no wipeout
>> >> >> risk there.
>> >> >
>> >> > This statement is misleading.  Wipeout risks don't apply to any
>> >> > consensus
>> >> > changes; It is a consensus change, it can only be abandoned.  The
>> >> > BIP148
>> >> > chain carries just as many risks of being abandoned or even more with
>> >> > segwit2x on the table.  No miner would consider "wipeout risk" an
>> >> > advantage
>> >> > when the real threat is chain abandonment.
>> >> Both are issues, but wipeout risk is different, the ETH/ETC split for
>> >> example didn't have any wipeout risk for either side the same is not
>> >> true for BIP148(and it is the non-BIP148 side that carries the risk of
>> >> chain wipeout).
>> >> >
>> >> >> Higher transaction fees on a minority chain can compensate miners
>> >> >> for
>> >> >> a lower price which would likely be enough to get the BIP148 chain
>> >> >> to
>> >> >> a difficulty reduction.
>> >> >
>> >> > Higher transaction fees suffers the same problem as exchange support
>> >> > does.
>> >> > Without replay protection, it is very difficult for any average user
>> >> > to
>> >> > force transactions onto one chain or the other.  Thus, without replay
>> >> > protection, the UASF chain is unlikely to develop any viable fee
>> >> > market;
>> >> > Its
>> >> > few miners 99% of the time will simply choose from the highest fees
>> >> > that
>> >> > were already available to the other chain, which is basically no
>> >> > advantage
>> >> > at all.
>> >> Not really, there are a few relatively simple techniques such as RBF
>> >> which can be leveraged to get confirmations on on-side before double
>> >> spending on another. Once a transaction is confirmed on the non-BIP148
>> >> chain then the high fee transactions can be made on only the BIP148
>> >> side of the split using RBF. Exchanges will likely do this splitting
>> >> automatically for uses as well.
>> >> >
>> >> >>  ETC replay protection was done after the fork on an as
>> >> >> needed basis(there are multiple reliable techniques that can be used
>> >> >> to split UTXO's), the same can happen with BIP148 and it is easier
>> >> >> to
>> >> >> do with Bitcoin than with the ETH/ETC split IMO.
>> >> >
>> >> > ETC replay protection was added because they were already a hardfork
>> >> > and
>> >> > without it they would not have had a viable chain.  BIP148 is not
>> >> > supposed
>> >> > to be a hardfork, and if it added replay protection to remain viable
>> >> > it
>> >> > would lose the frequently touted "wipeout advantage" as well as the
>> >> > ability
>> >> > to call itself a softfork.  And are you seriously suggesting that
>> >> > what
>> >> > happened with ETC and ETH is a desirable and good situation for
>> >> > Bitcoin,
>> >> > and
>> >> > that UASF is ETC?
>> >> There wasn't proper replay protection at split time for ETH/ETC since
>> >> normal transactions would get executed on both sides originally,
>> >> however replay protection was added by wallets(mainly using splitting
>> >> contracts). I don't think a split is desirable however, which is why
>> >> I've proposed this BIP.
>> >> >
>> >> >> A big reason BIP148 still has support is because up until SegWit
>> >> >> actually activates there's no guarantee segwit2mb will actually have
>> >> >> the necessary support to activate SegWit.
>> >> >
>> >> > For a miners blowing through six million dollars a day in mining
>> >> > operational
>> >> > costs, that's a pretty crappy reason.  Serious miners can't afford to
>> >> > prop
>> >> > up a non-viable chain based on philosophy or maybes.  BIP148 is based
>> >> > entirely upon people who aren't putting anything on the line trying
>> >> > to
>> >> > convince others to take the huge risks for them.  With deceptively
>> >> > fallacious logic, in my opinion.
>> >> Yes, miners aren't likely to waste operational mining costs, that's
>> >> ultimately why miners would follow the BIP148 side of the chain
>> >> assuming it has sufficient economic support or if it's more profitable
>> >> to mine.
>> >> >
>> >> > Even segwit2x is based on the assumption that all miners can reach
>> >> > consensus.  Break that assumption and segwit2x will have the same
>> >> > problems
>> >> > as UASF.
>> >> segwit2x has more issues since the HF part requires users to reach
>> >> consensus
>> >> >
>> >> >> This is largely an issue due to segwit2x's bundling, if the SW and
>> >> >> HF
>> >> >> part of segwit2x were unbundled then there would be no reason to
>> >> >> delay
>> >> >> BIP91 activation
>> >> >
>> >> > They are bundled.  Segwit alone doesn't have the desired overwhelming
>> >> > consensus, unless core wishes to fork 71% to 29%, and maybe not even
>> >> > that
>> >> > high.  That's the technical reason, and they can't be unbundled
>> >> > without
>> >> > breaking that consensus.
>> >> That's a political reason not a technical reason.
>> >> >
>> >> > Jared
>> >> >
>> >> >
>> >> > On Wed, Jun 7, 2017 at 4:11 PM, James Hilliard
>> >> > <james.hilliard1@gmail.com>
>> >> > wrote:
>> >> >>
>> >> >> On Wed, Jun 7, 2017 at 5:53 PM, Jared Lee Richardson
>> >> >> <jaredr26@gmail.com>
>> >> >> wrote:
>> >> >> >> There are 2 primary factors involved here, economic support and
>> >> >> > hashpower either of which is enough to make a permanent chain
>> >> >> > split
>> >> >> > unlikely, miners will mine whichever chain is most profitable(see
>> >> >> > ETH/ETC hashpower profitability equilibrium for an example of how
>> >> >> > this
>> >> >> > works in practice)
>> >> >> >
>> >> >> > That's not a comparable example.  ETC did not face potentially
>> >> >> > years
>> >> >> > of
>> >> >> > slow
>> >> >> > blocktimes before it normalized, whereas BIP148 is on track to do
>> >> >> > exactly
>> >> >> > that.  Moreover, ETC represented a fundamental break from the
>> >> >> > majority
>> >> >> > consensus that could not be rectified, whereas BIP148 represents
>> >> >> > only
>> >> >> > a
>> >> >> > minority attempt to accelerate something that an overwhelming
>> >> >> > majority
>> >> >> > of
>> >> >> > miners have already agreed to activate under segwit2x.  Lastly ETC
>> >> >> > was
>> >> >> > required to add replay protection, just like any minority fork
>> >> >> > proposed
>> >> >> > by
>> >> >> > any crypto-currency has been, something that BIP148 both lacks and
>> >> >> > refuses
>> >> >> > to add or even acknowledge the necessity of.  Without replay
>> >> >> > protection,
>> >> >> > ETC
>> >> >> > could not have become profitable enough to be a viable minority
>> >> >> > chain.
>> >> >> > If
>> >> >> > BIP148's chain is not the majority chain and it does not have
>> >> >> > replay
>> >> >> > protection, it will face the same problems, but that required
>> >> >> > replay
>> >> >> > protection will turn it into a hardfork.  This will be a very bad
>> >> >> > position
>> >> >> > for UASF supporters to find themselves in - Either hardfork and
>> >> >> > hope
>> >> >> > the
>> >> >> > price is higher and the majority converts, or die as the minority
>> >> >> > chain
>> >> >> > with
>> >> >> > no reliable methods of economic conversion.
>> >> >> Higher transaction fees on a minority chain can compensate miners
>> >> >> for
>> >> >> a lower price which would likely be enough to get the BIP148 chain
>> >> >> to
>> >> >> a difficulty reduction. BIP148 however is a consensus change that
>> >> >> can
>> >> >> be rectified if it gets more work, this would act as an additional
>> >> >> incentive for mine the BIP148 side since there would be no wipeout
>> >> >> risk there. ETC replay protection was done after the fork on an as
>> >> >> needed basis(there are multiple reliable techniques that can be used
>> >> >> to split UTXO's), the same can happen with BIP148 and it is easier
>> >> >> to
>> >> >> do with Bitcoin than with the ETH/ETC split IMO.
>> >> >> >
>> >> >> > I believe, but don't have data to back this, that most of the
>> >> >> > BIP148
>> >> >> > insistence comes not from a legitimate attempt to gain consensus
>> >> >> > (or
>> >> >> > else
>> >> >> > they would either outright oppose segwit2mb for its hardfork, or
>> >> >> > they
>> >> >> > would
>> >> >> > outright support it), but rather from an attempt for BIP148
>> >> >> > supporters
>> >> >> > to
>> >> >> > save face for BIP148 being a failure.  If I'm correct, that's a
>> >> >> > terrible
>> >> >> > and
>> >> >> > highly non-technical reason for segwit2mb to bend over backwards
>> >> >> > attempting
>> >> >> > to support BIP148's attempt to save face.
>> >> >> A big reason BIP148 still has support is because up until SegWit
>> >> >> actually activates there's no guarantee segwit2mb will actually have
>> >> >> the necessary support to activate SegWit.
>> >> >> >
>> >> >> >> The main issue is just one of activation timelines, BIP91 as
>> >> >> > is takes too long to activate unless started ahead of the existing
>> >> >> > segwit2x schedule and it's unlikely that BIP148 will get pushed
>> >> >> > back
>> >> >> > any further.
>> >> >> >
>> >> >> > Even if I'm not correct on the above, I and others find it hard to
>> >> >> > accept
>> >> >> > that this timeline conflict is segwit2x's fault.  Segwit2x has
>> >> >> > both
>> >> >> > some
>> >> >> > flexibility and broad support that crosses contentious pro-segwit
>> >> >> > and
>> >> >> > pro-blocksize-increase divisions that have existed for two years.
>> >> >> > BIP148 is
>> >> >> > attempting to hold segwit2x's timelines and code hostage by
>> >> >> > claiming
>> >> >> > inflexibility and claiming broad support, and not only are neither
>> >> >> > of
>> >> >> > those
>> >> >> > assertions are backed by real data, BIP148 (by being so
>> >> >> > inflexible)
>> >> >> > is
>> >> >> > pushing a position that deepens the divides between those groups.
>> >> >> > For
>> >> >> > there
>> >> >> > to be technical reasons for compatibility (so long as there are
>> >> >> > tradeoffs,
>> >> >> > which there are), there needs to be hard data showing that BIP148
>> >> >> > is
>> >> >> > a
>> >> >> > viable minority fork that won't simply die off on its own.
>> >> >> This is largely an issue due to segwit2x's bundling, if the SW and
>> >> >> HF
>> >> >> part of segwit2x were unbundled then there would be no reason to
>> >> >> delay
>> >> >> BIP91 activation, this is especially a problem since it takes a good
>> >> >> deal of time to properly code and test a HF. Unfortunately segwit2x
>> >> >> has been quite inflexible in regards to the bundling aspect even
>> >> >> though there are clearly no technical reasons for it to be there.
>> >> >> >
>> >> >> > Jared
>> >> >> >
>> >> >> >
>> >> >> > On Wed, Jun 7, 2017 at 3:23 PM, James Hilliard
>> >> >> > <james.hilliard1@gmail.com>
>> >> >> > wrote:
>> >> >> >>
>> >> >> >> On Wed, Jun 7, 2017 at 4:50 PM, Jared Lee Richardson
>> >> >> >> <jaredr26@gmail.com>
>> >> >> >> wrote:
>> >> >> >> > Could this risk mitigation measure be an optional flag?  And if
>> >> >> >> > so,
>> >> >> >> > could it+BIP91 signal on a different bit than bit4?
>> >> >> >> It's fairly trivial for miners to signal for BIP91 on bit4 or a
>> >> >> >> different bit at the same time as the code is trivial enough to
>> >> >> >> combine
>> >> >> >> >
>> >> >> >> > The reason being, if for some reason the segwit2x activation
>> >> >> >> > cannot
>> >> >> >> > take place in time, it would be preferable for miners to have a
>> >> >> >> > more
>> >> >> >> > standard approach to activation that requires stronger
>> >> >> >> > consensus
>> >> >> >> > and
>> >> >> >> > may be more forgiving than BIP148.  If the segwit2x activation
>> >> >> >> > is
>> >> >> >> > on
>> >> >> >> > time to cooperate with BIP148, it could be signaled through the
>> >> >> >> > non-bit4 approach and everything could go smoothly.  Thoughts
>> >> >> >> > on
>> >> >> >> > that
>> >> >> >> > idea?  It may add more complexity and more developer time, but
>> >> >> >> > may
>> >> >> >> > also address your concerns among others.
>> >> >> >> This does give miners another approach to activate segwit ahead
>> >> >> >> of
>> >> >> >> BIP148, if segwit2x activation is rolled out and activated
>> >> >> >> immediately
>> >> >> >> then this would not be needed however based on the timeline here
>> >> >> >> https://segwit2x.github.io/ it would not be possible for BIP91 to
>> >> >> >> enforce mandatory signalling ahead of BIP148. Maybe that can be
>> >> >> >> changed though, I've suggested an immediate rollout with a
>> >> >> >> placeholder
>> >> >> >> client timeout instead of the HF code initially in order to
>> >> >> >> accelerate
>> >> >> >> that.
>> >> >> >> >
>> >> >> >> >> Since this BIP
>> >> >> >> >> only activates with a clear miner majority it should not
>> >> >> >> >> increase
>> >> >> >> >> the
>> >> >> >> >> risk of an extended chain split.
>> >> >> >> >
>> >> >> >> > The concern I'm raising is more about the psychology of giving
>> >> >> >> > BIP148
>> >> >> >> > a sense of safety that may not be valid.  Without several more
>> >> >> >> > steps,
>> >> >> >> > BIP148 is definitely on track to be a risky chainsplit, and
>> >> >> >> > without
>> >> >> >> > segwit2x it will almost certainly be a small minority chain.
>> >> >> >> > (Unless
>> >> >> >> > the segwit2x compromise falls apart before then, and even in
>> >> >> >> > that
>> >> >> >> > case
>> >> >> >> > it is likely to be a minority chain)
>> >> >> >> There are 2 primary factors involved here, economic support and
>> >> >> >> hashpower either of which is enough to make a permanent chain
>> >> >> >> split
>> >> >> >> unlikely, miners will mine whichever chain is most profitable(see
>> >> >> >> ETH/ETC hashpower profitability equilibrium for an example of how
>> >> >> >> this
>> >> >> >> works in practice) however there may be lag time immediately
>> >> >> >> after
>> >> >> >> the
>> >> >> >> split if there is an economic majority but not a hashpower
>> >> >> >> majority
>> >> >> >> initially. This is risk mitigation that only requires miners
>> >> >> >> support
>> >> >> >> however. The main issue is just one of activation timelines,
>> >> >> >> BIP91
>> >> >> >> as
>> >> >> >> is takes too long to activate unless started ahead of the
>> >> >> >> existing
>> >> >> >> segwit2x schedule and it's unlikely that BIP148 will get pushed
>> >> >> >> back
>> >> >> >> any further.
>> >> >> >> >
>> >> >> >> > Jared
>> >> >> >> >
>> >> >> >> >
>> >> >> >> > On Wed, Jun 7, 2017 at 2:42 PM, James Hilliard
>> >> >> >> > <james.hilliard1@gmail.com> wrote:
>> >> >> >> >> I don't really see how this would increase the likelihood of
>> >> >> >> >> an
>> >> >> >> >> extended chain split assuming BIP148 is going to have
>> >> >> >> >> non-insignificant economic backing. This BIP is designed to
>> >> >> >> >> provide
>> >> >> >> >> a
>> >> >> >> >> risk mitigation measure that miners can safely deploy. Since
>> >> >> >> >> this
>> >> >> >> >> BIP
>> >> >> >> >> only activates with a clear miner majority it should not
>> >> >> >> >> increase
>> >> >> >> >> the
>> >> >> >> >> risk of an extended chain split. At this point it is not
>> >> >> >> >> completely
>> >> >> >> >> clear how much economic support there is for BIP148 but
>> >> >> >> >> support
>> >> >> >> >> certainly seems to be growing and we have nearly 2 months
>> >> >> >> >> until
>> >> >> >> >> BIP148
>> >> >> >> >> activation. I intentionally used a shorter activation period
>> >> >> >> >> here
>> >> >> >> >> so
>> >> >> >> >> that decisions by miners can be made close to the BIP148
>> >> >> >> >> activation
>> >> >> >> >> date.
>> >> >> >> >>
>> >> >> >> >> On Wed, Jun 7, 2017 at 4:29 PM, Jared Lee Richardson
>> >> >> >> >> <jaredr26@gmail.com> wrote:
>> >> >> >> >>> I think this BIP represents a gamble, and the gamble may not
>> >> >> >> >>> be
>> >> >> >> >>> a
>> >> >> >> >>> good
>> >> >> >> >>> one.  The gamble here is that if the segwit2x changes are
>> >> >> >> >>> rolled
>> >> >> >> >>> out
>> >> >> >> >>> on time, and if the signatories accept the bit4 + bit1
>> >> >> >> >>> signaling
>> >> >> >> >>> proposals within BIP91, the launch will go smoother, as
>> >> >> >> >>> intended.
>> >> >> >> >>> But
>> >> >> >> >>> conversely, if either the segwit2x signatories balk about the
>> >> >> >> >>> Bit1
>> >> >> >> >>> signaling OR if the timelines for segwit2mb are missed even
>> >> >> >> >>> by a
>> >> >> >> >>> bit,
>> >> >> >> >>> it may cause the BIP148 chainsplit to be worse than it would
>> >> >> >> >>> be
>> >> >> >> >>> without.  Given the frequent concerns raised in multiple
>> >> >> >> >>> places
>> >> >> >> >>> about
>> >> >> >> >>> the aggressiveness of the segwit2x timelines, including the
>> >> >> >> >>> non-hardfork timelines, this does not seem like a great
>> >> >> >> >>> gamble
>> >> >> >> >>> to
>> >> >> >> >>> be
>> >> >> >> >>> making.
>> >> >> >> >>>
>> >> >> >> >>> The reason I say it may make the chainsplit be worse than it
>> >> >> >> >>> would
>> >> >> >> >>> otherwise be is that it may provide a false sense of safety
>> >> >> >> >>> for
>> >> >> >> >>> BIP148
>> >> >> >> >>> that currently does not currently exist(and should not, as it
>> >> >> >> >>> is
>> >> >> >> >>> a
>> >> >> >> >>> chainsplit).  That sense of safety would only be legitimate
>> >> >> >> >>> if
>> >> >> >> >>> the
>> >> >> >> >>> segwit2x signatories were on board, and the segwit2x code
>> >> >> >> >>> effectively
>> >> >> >> >>> enforced BIP148 simultaneously, neither of which are
>> >> >> >> >>> guaranteed.
>> >> >> >> >>> If
>> >> >> >> >>> users and more miners had a false sense that BIP148 was *not*
>> >> >> >> >>> going
>> >> >> >> >>> to
>> >> >> >> >>> chainsplit from default / segwit2x, they might not follow the
>> >> >> >> >>> news
>> >> >> >> >>> if
>> >> >> >> >>> suddenly the segwit2x plan were delayed for a few days.
>> >> >> >> >>> While
>> >> >> >> >>> any
>> >> >> >> >>> additional support would definitely be cheered on by BIP148
>> >> >> >> >>> supporters, the practical reality might be that this proposal
>> >> >> >> >>> would
>> >> >> >> >>> take BIP148 from the "unlikely to have any viable chain after
>> >> >> >> >>> flag
>> >> >> >> >>> day
>> >> >> >> >>> without segwit2x" category into the "small but viable
>> >> >> >> >>> minority
>> >> >> >> >>> chain"
>> >> >> >> >>> category, and even worse, it might strengthen the chainsplit
>> >> >> >> >>> just
>> >> >> >> >>> days
>> >> >> >> >>> before segwit is activated on BOTH chains, putting the BIP148
>> >> >> >> >>> supporters on the wrong pro-segwit, but still-viable chain.
>> >> >> >> >>>
>> >> >> >> >>> If Core had taken a strong stance to include BIP148 into the
>> >> >> >> >>> client,
>> >> >> >> >>> and if BIP148 support were much much broader, I would feel
>> >> >> >> >>> differently
>> >> >> >> >>> as the gamble would be more likely to discourage a chainsplit
>> >> >> >> >>> (By
>> >> >> >> >>> forcing the acceleration of segwit2x) rather than encourage
>> >> >> >> >>> it
>> >> >> >> >>> (by
>> >> >> >> >>> strengthening an extreme minority chainsplit that may wind up
>> >> >> >> >>> on
>> >> >> >> >>> the
>> >> >> >> >>> wrong side of two segwit-activated chains).  As it stands
>> >> >> >> >>> now,
>> >> >> >> >>> this
>> >> >> >> >>> seems like a very dangerous attempt to compromise with a
>> >> >> >> >>> small
>> >> >> >> >>> but
>> >> >> >> >>> vocal group that are the ones creating the threat to begin
>> >> >> >> >>> with.
>> >> >> >> >>>
>> >> >> >> >>> Jared
>> >> >> >> >>>
>> >> >> >> >>> On Tue, Jun 6, 2017 at 5:56 PM, James Hilliard via
>> >> >> >> >>> bitcoin-dev
>> >> >> >> >>> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>> >> >> >> >>>> Due to the proposed calendar(https://segwit2x.github.io/)
>> >> >> >> >>>> for
>> >> >> >> >>>> the
>> >> >> >> >>>> SegWit2x agreement being too slow to activate SegWit
>> >> >> >> >>>> mandatory
>> >> >> >> >>>> signalling ahead of BIP148 using BIP91 I would like to
>> >> >> >> >>>> propose
>> >> >> >> >>>> another
>> >> >> >> >>>> option that miners can use to prevent a chain split ahead of
>> >> >> >> >>>> the
>> >> >> >> >>>> Aug
>> >> >> >> >>>> 1st BIP148 activation date.
>> >> >> >> >>>>
>> >> >> >> >>>> The splitprotection soft fork is essentially BIP91 but using
>> >> >> >> >>>> BIP8
>> >> >> >> >>>> instead of BIP9 with a lower activation threshold and
>> >> >> >> >>>> immediate
>> >> >> >> >>>> mandatory signalling lock-in. This allows for a majority of
>> >> >> >> >>>> miners
>> >> >> >> >>>> to
>> >> >> >> >>>> activate mandatory SegWit signalling and prevent a potential
>> >> >> >> >>>> chain
>> >> >> >> >>>> split ahead of BIP148 activation.
>> >> >> >> >>>>
>> >> >> >> >>>> This BIP allows for miners to respond to market forces
>> >> >> >> >>>> quickly
>> >> >> >> >>>> ahead
>> >> >> >> >>>> of BIP148 activation by signalling for splitprotection. Any
>> >> >> >> >>>> miners
>> >> >> >> >>>> already running BIP148 should be encouraged to use
>> >> >> >> >>>> splitprotection.
>> >> >> >> >>>>
>> >> >> >> >>>> <pre>
>> >> >> >> >>>>   BIP: splitprotection
>> >> >> >> >>>>   Layer: Consensus (soft fork)
>> >> >> >> >>>>   Title: User Activated Soft Fork Split Protection
>> >> >> >> >>>>   Author: James Hilliard <james.hilliard1@gmail.com>
>> >> >> >> >>>>   Comments-Summary: No comments yet.
>> >> >> >> >>>>   Comments-URI:
>> >> >> >> >>>>   Status: Draft
>> >> >> >> >>>>   Type: Standards Track
>> >> >> >> >>>>   Created: 2017-05-22
>> >> >> >> >>>>   License: BSD-3-Clause
>> >> >> >> >>>>            CC0-1.0
>> >> >> >> >>>> </pre>
>> >> >> >> >>>>
>> >> >> >> >>>> ==Abstract==
>> >> >> >> >>>>
>> >> >> >> >>>> This document specifies a coordination mechanism for a
>> >> >> >> >>>> simple
>> >> >> >> >>>> majority
>> >> >> >> >>>> of miners to prevent a chain split ahead of BIP148
>> >> >> >> >>>> activation.
>> >> >> >> >>>>
>> >> >> >> >>>> ==Definitions==
>> >> >> >> >>>>
>> >> >> >> >>>> "existing segwit deployment" refer to the BIP9 "segwit"
>> >> >> >> >>>> deployment
>> >> >> >> >>>> using bit 1, between November 15th 2016 and November 15th
>> >> >> >> >>>> 2017
>> >> >> >> >>>> to
>> >> >> >> >>>> activate BIP141, BIP143 and BIP147.
>> >> >> >> >>>>
>> >> >> >> >>>> ==Motivation==
>> >> >> >> >>>>
>> >> >> >> >>>> The biggest risk of BIP148 is an extended chain split, this
>> >> >> >> >>>> BIP
>> >> >> >> >>>> provides a way for a simple majority of miners to eliminate
>> >> >> >> >>>> that
>> >> >> >> >>>> risk.
>> >> >> >> >>>>
>> >> >> >> >>>> This BIP provides a way for a simple majority of miners to
>> >> >> >> >>>> coordinate
>> >> >> >> >>>> activation of the existing segwit deployment with less than
>> >> >> >> >>>> 95%
>> >> >> >> >>>> hashpower before BIP148 activation. Due to time constraints
>> >> >> >> >>>> unless
>> >> >> >> >>>> immediately deployed BIP91 will likely not be able to
>> >> >> >> >>>> enforce
>> >> >> >> >>>> mandatory signalling of segwit before the Aug 1st activation
>> >> >> >> >>>> of
>> >> >> >> >>>> BIP148. This BIP provides a method for rapid miner
>> >> >> >> >>>> activation
>> >> >> >> >>>> of
>> >> >> >> >>>> SegWit mandatory signalling ahead of the BIP148 activation
>> >> >> >> >>>> date.
>> >> >> >> >>>> Since
>> >> >> >> >>>> the primary goal of this BIP is to reduce the chance of an
>> >> >> >> >>>> extended
>> >> >> >> >>>> chain split as much as possible we activate using a simple
>> >> >> >> >>>> miner
>> >> >> >> >>>> majority of 65% over a 504 block interval rather than a
>> >> >> >> >>>> higher
>> >> >> >> >>>> percentage. This BIP also allows miners to signal their
>> >> >> >> >>>> intention
>> >> >> >> >>>> to
>> >> >> >> >>>> run BIP148 in order to prevent a chain split.
>> >> >> >> >>>>
>> >> >> >> >>>> ==Specification==
>> >> >> >> >>>>
>> >> >> >> >>>> While this BIP is active, all blocks must set the nVersion
>> >> >> >> >>>> header
>> >> >> >> >>>> top
>> >> >> >> >>>> 3 bits to 001 together with bit field (1<<1) (according to
>> >> >> >> >>>> the
>> >> >> >> >>>> existing segwit deployment). Blocks that do not signal as
>> >> >> >> >>>> required
>> >> >> >> >>>> will be rejected.
>> >> >> >> >>>>
>> >> >> >> >>>> ==Deployment==
>> >> >> >> >>>>
>> >> >> >> >>>> This BIP will be deployed by "version bits" with a 65%(this
>> >> >> >> >>>> can
>> >> >> >> >>>> be
>> >> >> >> >>>> adjusted if desired) activation threshold BIP9 with the name
>> >> >> >> >>>> "splitprotecion" and using bit 2.
>> >> >> >> >>>>
>> >> >> >> >>>> This BIP starts immediately and is a BIP8 style soft fork
>> >> >> >> >>>> since
>> >> >> >> >>>> mandatory signalling will start on midnight August 1st 2017
>> >> >> >> >>>> (epoch
>> >> >> >> >>>> time 1501545600) regardless of whether or not this BIP has
>> >> >> >> >>>> reached
>> >> >> >> >>>> its
>> >> >> >> >>>> own signalling threshold. This BIP will cease to be active
>> >> >> >> >>>> when
>> >> >> >> >>>> segwit
>> >> >> >> >>>> is locked-in.
>> >> >> >> >>>>
>> >> >> >> >>>> === Reference implementation ===
>> >> >> >> >>>>
>> >> >> >> >>>> <pre>
>> >> >> >> >>>> // Check if Segregated Witness is Locked In
>> >> >> >> >>>> bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
>> >> >> >> >>>> Consensus::Params& params)
>> >> >> >> >>>> {
>> >> >> >> >>>>     LOCK(cs_main);
>> >> >> >> >>>>     return (VersionBitsState(pindexPrev, params,
>> >> >> >> >>>> Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
>> >> >> >> >>>> THRESHOLD_LOCKED_IN);
>> >> >> >> >>>> }
>> >> >> >> >>>>
>> >> >> >> >>>> // SPLITPROTECTION mandatory segwit signalling.
>> >> >> >> >>>> if ( VersionBitsState(pindex->pprev,
>> >> >> >> >>>> chainparams.GetConsensus(),
>> >> >> >> >>>> Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
>> >> >> >> >>>> THRESHOLD_LOCKED_IN &&
>> >> >> >> >>>>      !IsWitnessLockedIn(pindex->pprev,
>> >> >> >> >>>> chainparams.GetConsensus())
>> >> >> >> >>>> &&
>> >> >> >> >>>> // Segwit is not locked in
>> >> >> >> >>>>      !IsWitnessEnabled(pindex->pprev,
>> >> >> >> >>>> chainparams.GetConsensus())
>> >> >> >> >>>> )
>> >> >> >> >>>> //
>> >> >> >> >>>> and is not active.
>> >> >> >> >>>> {
>> >> >> >> >>>>     bool fVersionBits = (pindex->nVersion &
>> >> >> >> >>>> VERSIONBITS_TOP_MASK)
>> >> >> >> >>>> ==
>> >> >> >> >>>> VERSIONBITS_TOP_BITS;
>> >> >> >> >>>>     bool fSegbit = (pindex->nVersion &
>> >> >> >> >>>> VersionBitsMask(chainparams.GetConsensus(),
>> >> >> >> >>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>> >> >> >> >>>>     if (!(fVersionBits && fSegbit)) {
>> >> >> >> >>>>         return state.DoS(0, error("ConnectBlock(): relayed
>> >> >> >> >>>> block
>> >> >> >> >>>> must
>> >> >> >> >>>> signal for segwit, please upgrade"), REJECT_INVALID,
>> >> >> >> >>>> "bad-no-segwit");
>> >> >> >> >>>>     }
>> >> >> >> >>>> }
>> >> >> >> >>>>
>> >> >> >> >>>> // BIP148 mandatory segwit signalling.
>> >> >> >> >>>> int64_t nMedianTimePast = pindex->GetMedianTimePast();
>> >> >> >> >>>> if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017
>> >> >> >> >>>> 00:00:00
>> >> >> >> >>>> UTC
>> >> >> >> >>>>      (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017
>> >> >> >> >>>> 00:00:00
>> >> >> >> >>>> UTC
>> >> >> >> >>>>      (!IsWitnessLockedIn(pindex->pprev,
>> >> >> >> >>>> chainparams.GetConsensus())
>> >> >> >> >>>> &&
>> >> >> >> >>>>  // Segwit is not locked in
>> >> >> >> >>>>       !IsWitnessEnabled(pindex->pprev,
>> >> >> >> >>>> chainparams.GetConsensus())) )
>> >> >> >> >>>>  // and is not active.
>> >> >> >> >>>> {
>> >> >> >> >>>>     bool fVersionBits = (pindex->nVersion &
>> >> >> >> >>>> VERSIONBITS_TOP_MASK)
>> >> >> >> >>>> ==
>> >> >> >> >>>> VERSIONBITS_TOP_BITS;
>> >> >> >> >>>>     bool fSegbit = (pindex->nVersion &
>> >> >> >> >>>> VersionBitsMask(chainparams.GetConsensus(),
>> >> >> >> >>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
>> >> >> >> >>>>     if (!(fVersionBits && fSegbit)) {
>> >> >> >> >>>>         return state.DoS(0, error("ConnectBlock(): relayed
>> >> >> >> >>>> block
>> >> >> >> >>>> must
>> >> >> >> >>>> signal for segwit, please upgrade"), REJECT_INVALID,
>> >> >> >> >>>> "bad-no-segwit");
>> >> >> >> >>>>     }
>> >> >> >> >>>> }
>> >> >> >> >>>> </pre>
>> >> >> >> >>>>
>> >> >> >> >>>>
>> >> >> >> >>>>
>> >> >> >> >>>>
>> >> >> >> >>>>
>> >> >> >> >>>> https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1
>> >> >> >> >>>>
>> >> >> >> >>>> ==Backwards Compatibility==
>> >> >> >> >>>>
>> >> >> >> >>>> This deployment is compatible with the existing "segwit" bit
>> >> >> >> >>>> 1
>> >> >> >> >>>> deployment scheduled between midnight November 15th, 2016
>> >> >> >> >>>> and
>> >> >> >> >>>> midnight
>> >> >> >> >>>> November 15th, 2017. This deployment is also compatible with
>> >> >> >> >>>> the
>> >> >> >> >>>> existing BIP148 deployment. This BIP is compatible with
>> >> >> >> >>>> BIP91
>> >> >> >> >>>> only
>> >> >> >> >>>> if
>> >> >> >> >>>> BIP91 activates before it and before BIP148. Miners will
>> >> >> >> >>>> need
>> >> >> >> >>>> to
>> >> >> >> >>>> upgrade their nodes to support splitprotection otherwise
>> >> >> >> >>>> they
>> >> >> >> >>>> may
>> >> >> >> >>>> build on top of an invalid block. While this bip is active
>> >> >> >> >>>> users
>> >> >> >> >>>> should either upgrade to splitprotection or wait for
>> >> >> >> >>>> additional
>> >> >> >> >>>> confirmations when accepting payments.
>> >> >> >> >>>>
>> >> >> >> >>>> ==Rationale==
>> >> >> >> >>>>
>> >> >> >> >>>> Historically we have used IsSuperMajority() to activate soft
>> >> >> >> >>>> forks
>> >> >> >> >>>> such as BIP66 which has a mandatory signalling requirement
>> >> >> >> >>>> for
>> >> >> >> >>>> miners
>> >> >> >> >>>> once activated, this ensures that miners are aware of new
>> >> >> >> >>>> rules
>> >> >> >> >>>> being
>> >> >> >> >>>> enforced. This technique can be leveraged to lower the
>> >> >> >> >>>> signalling
>> >> >> >> >>>> threshold of a soft fork while it is in the process of being
>> >> >> >> >>>> deployed
>> >> >> >> >>>> in a backwards compatible way. We also use a BIP8 style
>> >> >> >> >>>> timeout
>> >> >> >> >>>> to
>> >> >> >> >>>> ensure that this BIP is compatible with BIP148 and that
>> >> >> >> >>>> BIP148
>> >> >> >> >>>> compatible mandatory signalling activates regardless of
>> >> >> >> >>>> miner
>> >> >> >> >>>> signalling levels.
>> >> >> >> >>>>
>> >> >> >> >>>> By orphaning non-signalling blocks during the BIP9 bit 1
>> >> >> >> >>>> "segwit"
>> >> >> >> >>>> deployment, this BIP can cause the existing "segwit"
>> >> >> >> >>>> deployment
>> >> >> >> >>>> to
>> >> >> >> >>>> activate without needing to release a new deployment. As we
>> >> >> >> >>>> approach
>> >> >> >> >>>> BIP148 activation it may be desirable for a majority of
>> >> >> >> >>>> miners
>> >> >> >> >>>> to
>> >> >> >> >>>> have
>> >> >> >> >>>> a method that will ensure that there is no chain split.
>> >> >> >> >>>>
>> >> >> >> >>>> ==References==
>> >> >> >> >>>>
>> >> >> >> >>>>
>> >> >> >> >>>>
>> >> >> >> >>>>
>> >> >> >> >>>>
>> >> >> >> >>>> *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html
>> >> >> >> >>>> Mailing list discussion]
>> >> >> >> >>>>
>> >> >> >> >>>>
>> >> >> >> >>>>
>> >> >> >> >>>>
>> >> >> >> >>>> *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283
>> >> >> >> >>>> P2SH flag day activation]
>> >> >> >> >>>> *[[bip-0009.mediawiki|BIP9 Version bits with timeout and
>> >> >> >> >>>> delay]]
>> >> >> >> >>>> *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
>> >> >> >> >>>> *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
>> >> >> >> >>>> *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus
>> >> >> >> >>>> layer)]]
>> >> >> >> >>>> *[[bip-0143.mediawiki|BIP143 Transaction Signature
>> >> >> >> >>>> Verification
>> >> >> >> >>>> for
>> >> >> >> >>>> Version 0 Witness Program]]
>> >> >> >> >>>> *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack
>> >> >> >> >>>> element
>> >> >> >> >>>> malleability]]
>> >> >> >> >>>> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit
>> >> >> >> >>>> deployment]]
>> >> >> >> >>>> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second
>> >> >> >> >>>> deployment)]]
>> >> >> >> >>>> *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/
>> >> >> >> >>>> Segwit
>> >> >> >> >>>> benefits]
>> >> >> >> >>>>
>> >> >> >> >>>> ==Copyright==
>> >> >> >> >>>>
>> >> >> >> >>>> This document is dual licensed as BSD 3-clause, and Creative
>> >> >> >> >>>> Commons
>> >> >> >> >>>> CC0 1.0 Universal.
>> >> >> >> >>>> _______________________________________________
>> >> >> >> >>>> bitcoin-dev mailing list
>> >> >> >> >>>> bitcoin-dev@lists.linuxfoundation.org
>> >> >> >> >>>>
>> >> >> >> >>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>> >> >> >
>> >> >> >
>> >> >
>> >> >
>> >
>> >
>
>