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

[Jared Lee Richardson <jaredr26@gmail.com>]

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> 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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