From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id CB73CBAA for ; Wed, 7 Jun 2017 21:43:17 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-ua0-f176.google.com (mail-ua0-f176.google.com [209.85.217.176]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id B2AE515F for ; Wed, 7 Jun 2017 21:43:16 +0000 (UTC) Received: by mail-ua0-f176.google.com with SMTP id q15so12024057uaa.2 for ; Wed, 07 Jun 2017 14:43:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=RU7fmPrBdP7RNwXwsarXZw6Y/9I3lCiWFFwpWukz3Q4=; b=Q14ppQvyZf19Y25xU7/ARoZmBf7BkpFt9nJh6UouhxkWmrlp8SkxwUWfoRxJEkxT3R K2ZcYmWIaiAnQUKnY92nqhCCK57Xfl1Of+jsCAOFNrb0YQD26ha/DJx1+jztn1b9Bd7p zFVYXLg9nSU2tGbotR7gZxyjGCuDOK8ZOVFgLoM5zUDLPvmFeru8UdtNQ4+fhqmT03TC PegmGEgsnUQFTHgsh7Hl9BnOFZElhCIw0Bn38Fjv4v/hwAq2C7KWoliVOM1pE3AiBIOz BwbpzxXnSoqXUY9rfGUf2N63NKPV9VDvqfyTL512IEnKyIhcnSKVIf0+3YFz8yyrh0/Q OTbw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=RU7fmPrBdP7RNwXwsarXZw6Y/9I3lCiWFFwpWukz3Q4=; b=laQzQQ5voXIJsN4Iggjkd/UkaU1q1w87sn2CP3hISWl1v223kWRJsRO4+cdPDQYbi5 CNLt8Qz7H1URX6RmzJV7lELnaqAMutU8Muj8PAYLuNrIMkKn84WRl8eUlbjkKV2h2SDV rF11cIiL0Kn6qJiMA+ZxpE8K4z3eFQVCmzTuuw8chIFtCsPn+heRZ5ZVDKRxVcDi/y0n jmit1+AlzSLNd7LZtIUdzWxbwv2DxhRMuaElPmPXFY3rPqNX6h0DZ94DFJW2OoS+aK27 ATMYvgepRVrh983JD4UgScBf9L1KRCnpQfDR+isXTkk6nCjTeM70j6RSK4UGJ+k/lvcw cvIQ== X-Gm-Message-State: AODbwcC8Cy5L3pPG+epnaADsxUp5mRISEmGvhnK7VHH7b1xR2hvMmFQz m8aWYixhWNp42TPbbOc8b5Sa282+YQ== X-Received: by 10.176.16.8 with SMTP id f8mr11784479uab.146.1496871795609; Wed, 07 Jun 2017 14:43:15 -0700 (PDT) MIME-Version: 1.0 Received: by 10.31.157.215 with HTTP; Wed, 7 Jun 2017 14:43:14 -0700 (PDT) In-Reply-To: References: <0CDEF5A2-0BAF-46E4-8906-39D4724AF3F2@taoeffect.com> From: Jared Lee Richardson Date: Wed, 7 Jun 2017 14:43:14 -0700 Message-ID: To: James Hilliard Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-1.7 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_ENVFROM_END_DIGIT,FREEMAIL_FROM, RCVD_IN_DNSWL_NONE autolearn=no version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org X-Mailman-Approved-At: Wed, 07 Jun 2017 21:45:04 +0000 Cc: Bitcoin Dev Subject: Re: [bitcoin-dev] User Activated Soft Fork Split Protection X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 07 Jun 2017 21:43:17 -0000 > 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 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 = 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 def= end 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 conc= ern 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 >> 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 defen= d >>> 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 co= ncern >>> themselves with this release. >>> >>> On Wed, Jun 7, 2017 at 6:13 AM, James Hilliard via bitcoin-dev >>> 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 wr= ote: >>>> > See thread on replay attacks for why activating regardless of thresh= old >>>> > is a >>>> > bad idea [1]. >>>> > >>>> > BIP91 OTOH seems perfectly reasonable. 80% instead of 95% makes it m= ore >>>> > difficult for miners to hold together in opposition to Core. It give= s >>>> > Core >>>> > more leverage in negotiations. >>>> > >>>> > If they don't activate with 80%, Core can release another BIP to red= uce >>>> > it >>>> > to 75%. >>>> > >>>> > Each threshold reduction makes it both more likely to succeed, but a= lso >>>> > increases the likelihood of harm to the ecosystem. >>>> > >>>> > Cheers, >>>> > Greg >>>> > >>>> > [1] >>>> > >>>> > https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-June/01= 4497.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 >>>> > wrote: >>>> > >>>> > This is a BIP8 style soft fork so mandatory signalling will be activ= e >>>> > after Aug 1st regardless. >>>> > >>>> > On Tue, Jun 6, 2017 at 8:51 PM, Tao Effect >>>> > wrote: >>>> > >>>> > What is the probability that a 65% threshold is too low and can allo= w 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 >>>> > 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 anoth= er >>>> > 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 t= o >>>> > 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. >>>> > >>>> > 
>>>> > BIP: splitprotection
>>>> > Layer: Consensus (soft fork)
>>>> > Title: User Activated Soft Fork Split Protection
>>>> > Author: James Hilliard 
>>>> > Comments-Summary: No comments yet.
>>>> > Comments-URI:
>>>> > Status: Draft
>>>> > Type: Standards Track
>>>> > Created: 2017-05-22
>>>> > License: BSD-3-Clause
>>>> >          CC0-1.0
>>>> >
>>>> > >>>> > =3D=3DAbstract=3D=3D >>>> > >>>> > This document specifies a coordination mechanism for a simple majori= ty >>>> > of miners to prevent a chain split ahead of BIP148 activation. >>>> > >>>> > =3D=3DDefinitions=3D=3D >>>> > >>>> > "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. >>>> > >>>> > =3D=3DMotivation=3D=3D >>>> > >>>> > The biggest risk of BIP148 is an extended chain split, this BIP >>>> > provides a way for a simple majority of miners to eliminate that ris= k. >>>> > >>>> > This BIP provides a way for a simple majority of miners to coordinat= e >>>> > 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. Sin= ce >>>> > 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. >>>> > >>>> > =3D=3DSpecification=3D=3D >>>> > >>>> > While this BIP is active, all blocks must set the nVersion header to= p >>>> > 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. >>>> > >>>> > =3D=3DDeployment=3D=3D >>>> > >>>> > 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 i= ts >>>> > own signalling threshold. This BIP will cease to be active when segw= it >>>> > is locked-in. >>>> > >>>> > =3D=3D=3D Reference implementation =3D=3D=3D >>>> > >>>> > 
>>>> > // 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) =3D=3D
>>>> > THRESHOLD_LOCKED_IN);
>>>> > }
>>>> >
>>>> > // SPLITPROTECTION mandatory segwit signalling.
>>>> > if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
>>>> > Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) =3D=3D
>>>> > THRESHOLD_LOCKED_IN &&
>>>> >    !IsWitnessLockedIn(pindex->pprev, chainparams.GetConsensus()) &&
>>>> > // Segwit is not locked in
>>>> >    !IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) ) //
>>>> > and is not active.
>>>> > {
>>>> >   bool fVersionBits =3D (pindex->nVersion & VERSIONBITS_TOP_MASK) =
=3D=3D
>>>> > VERSIONBITS_TOP_BITS;
>>>> >   bool fSegbit =3D (pindex->nVersion &
>>>> > VersionBitsMask(chainparams.GetConsensus(),
>>>> > Consensus::DEPLOYMENT_SEGWIT)) !=3D 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 =3D pindex->GetMedianTimePast();
>>>> > if ( (nMedianTimePast >=3D 1501545600) &&  // Tue 01 Aug 2017 00:00:=
00 UTC
>>>> >    (nMedianTimePast <=3D 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 =3D (pindex->nVersion & VERSIONBITS_TOP_MASK) =
=3D=3D
>>>> > VERSIONBITS_TOP_BITS;
>>>> >   bool fSegbit =3D (pindex->nVersion &
>>>> > VersionBitsMask(chainparams.GetConsensus(),
>>>> > Consensus::DEPLOYMENT_SEGWIT)) !=3D 0;
>>>> >   if (!(fVersionBits && fSegbit)) {
>>>> >       return state.DoS(0, error("ConnectBlock(): relayed block must
>>>> > signal for segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit"=
);
>>>> >   }
>>>> > }
>>>> >
>>>> > >>>> > >>>> > https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:spli= tprotection-v0.14.1 >>>> > >>>> > =3D=3DBackwards Compatibility=3D=3D >>>> > >>>> > This deployment is compatible with the existing "segwit" bit 1 >>>> > deployment scheduled between midnight November 15th, 2016 and midnig= ht >>>> > November 15th, 2017. This deployment is also compatible with the >>>> > existing BIP148 deployment. This BIP is compatible with BIP91 only i= f >>>> > 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. >>>> > >>>> > =3D=3DRationale=3D=3D >>>> > >>>> > Historically we have used IsSuperMajority() to activate soft forks >>>> > such as BIP66 which has a mandatory signalling requirement for miner= s >>>> > once activated, this ensures that miners are aware of new rules bein= g >>>> > enforced. This technique can be leveraged to lower the signalling >>>> > threshold of a soft fork while it is in the process of being deploye= d >>>> > 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 ha= ve >>>> > a method that will ensure that there is no chain split. >>>> > >>>> > =3D=3DReferences=3D=3D >>>> > >>>> > >>>> > *[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 deployme= nt]] >>>> > *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]= ] >>>> > *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit >>>> > benefits] >>>> > >>>> > =3D=3DCopyright=3D=3D >>>> > >>>> > 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 >>>