Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 59528C61 for ; Wed, 7 Jun 2017 18:05:56 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-qt0-f172.google.com (mail-qt0-f172.google.com [209.85.216.172]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 0E43E1E2 for ; Wed, 7 Jun 2017 18:05:53 +0000 (UTC) Received: by mail-qt0-f172.google.com with SMTP id u19so15246753qta.3 for ; Wed, 07 Jun 2017 11:05:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc; bh=vW7E8qR+dGfwbMIjZeLbMNS2trjtClHofnCMPJjOgfk=; b=uTRT1kKg7fVxP1J7lFWcuzH19rz1UcCJZfnTsFvCzXxoCferqIsQ73nIEBiejqMafo 0RmYzkyMs50dRAqiHCoGx3FCOHOWtxGfcfp9cJqle3RqAEDpgLEXt3QKIn2tEqfB+R0g BX7Uf5XWYcIhEXL1PGnqhi7w5XK6wKCwWMclVajH52z6fRNMkIYiSP+JpYWuXV4/45mV ROzpopfEM2a32mGAE3x8ks09MxD3ROhqOQIjeC6YRzEz9N7gbD5QojNVqNp62AflQMV3 EiUpAuZsP9Tg0b+IiNYyX7sCRf641PGEd11nrPV2qrws7jtU1HDti9+xUUCHJhp2X8PX IAKA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:sender:in-reply-to:references:from :date:message-id:subject:to:cc; bh=vW7E8qR+dGfwbMIjZeLbMNS2trjtClHofnCMPJjOgfk=; b=i+JVvhLH9FBGEQ/+qvoMVO8rFUSOUmiNIPxLNVrT7XEmcNT/BP4X4tmW267y/QooRa YiLELN+Ty+ML7AkylJdmyFr/WLG9mnZOgeUfTZjGnon2xSUWymTFhc7KxKyM9Ga0rRri FzIEKM6TBlsArknK06iNoSgBrGnKmLwb4f8wupAZpaXJT2CXYlyDI5nK65BPhTF8blpx uFxxRMuB44xhBJ/XAyS8N9NppbjZaWsypn3v6UQ6oOEkSeBWiN4xl+a7WsdbUvIZeB+U e951mjNVxwu0jheMzU71vIEKD2bWlOMzuB2AQGW+UWsg0Lk3Y1wzYSpzNIw+fgrs/6wU G1Qw== X-Gm-Message-State: AODbwcDqLKQaS0aWAKzG1BbHS3R7itI7n1z9tMmk97zFVwJXQ9Oki2/s kwHYEB+sDlmA7W9ImFhyrCd7qCexcRXe8m0= X-Received: by 10.200.34.98 with SMTP id p31mr45348295qtp.2.1496858753039; Wed, 07 Jun 2017 11:05:53 -0700 (PDT) MIME-Version: 1.0 Sender: earonesty@gmail.com Received: by 10.237.48.102 with HTTP; Wed, 7 Jun 2017 11:05:52 -0700 (PDT) In-Reply-To: References: <0CDEF5A2-0BAF-46E4-8906-39D4724AF3F2@taoeffect.com> From: Erik Aronesty Date: Wed, 7 Jun 2017 14:05:52 -0400 X-Google-Sender-Auth: 3vHPNsTv6ReKcbQxMWUx_0w0eEo Message-ID: To: Jacob Eliosoff Content-Type: multipart/alternative; boundary="001a11403b7a41021e0551629628" X-Spam-Status: No, score=-1.6 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, FREEMAIL_FROM, HTML_MESSAGE, HTML_OBFUSCATE_05_10, RCVD_IN_DNSWL_NONE autolearn=ham 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 18:11:18 +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 18:05:56 -0000 --001a11403b7a41021e0551629628 Content-Type: text/plain; charset="UTF-8" > 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 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 >>> 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 >>> > 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 >>> 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 >>> > 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. >>> > >>> > 
>>> > 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
>>> >
>>> > >>> > ==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 === >>> > >>> > 
>>> > // 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");
>>> >   }
>>> > }
>>> >
>>> > >>> > 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 >> >> > --001a11403b7a41021e0551629628 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
> But passing it off as the safest defense is bad = faith.

Without this option, a miner has to guess whether a split wil= l be economically impacting.=C2=A0=C2=A0 With this option, his miner will a= utomatically switch to the chain least likely to get wiped out... as soon a= s a simple majority of miners supports it.=C2=A0=C2=A0

<= /div>

On Wed= , Jun 7, 2017 at 12:44 PM, Jacob Eliosoff <jacob.eliosoff@gmail.com= > wrote:
<= div>This is not the safest defense against a split.=C2=A0 If 70% of miners = run "splitprotection", and 0.1% run BIP148, there's no "= safety"/"defense" reason for splitprotection to activate seg= wit.=C2=A0 It should only do so if *BIP148* support (NB: not just segwit su= pport!) >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.=C2=A0 But passing= it off as the safest defense is bad faith.


On Wed, Jun 7, 2017 at 10:10 AM, Erik Aronesty via bitcoi= n-dev <bitcoin-dev@lists.linuxfoundation.org&= gt; wrote:
T= his is, by far, the safest way for miners to quickly defend against a chain= split, much better than a -bip148 option.=C2=A0=C2=A0 This allows miners t= o defend themselves, with very little risk, since the defense is only activ= ated if the majority of miners do so. I would move for a very rapid deploym= ent.=C2=A0=C2=A0 Only miners would need to upgrade.=C2=A0=C2=A0 Regular use= rs would not have to concern themselves with this release.
<= div class=3D"m_4542892957492321950HOEnZb">

On Wed, Jun= 7, 2017 at 6:13 AM, James Hilliard via bitcoin-dev <<= a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" target=3D"_blank">b= itcoin-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<= br> 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<= br> 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 threshol= d is a
> bad idea [1].
>
> BIP91 OTOH seems perfectly reasonable. 80% instead of 95% makes it mor= e
> 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 r= educe it
> to 75%.
>
> Each threshold reduction makes it both more likely to succeed, but als= o
> increases the likelihood of harm to the ecosystem.
>
> Cheers,
> Greg
>
> [1]
> https://lists.linu= xfoundation.org/pipermail/bitcoin-dev/2017-June/014497.html >
> --
> Please do not email me anything that you are not comfortable also shar= ing
> 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<= br> > 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 bef= ore the
> deadline, and brought online immediately after, creating potential hav= oc?
>
> (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 shar= ing
> 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/) f= or 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<= br> > 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
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 CC0-1.0
> </pre>
>
> =3D=3DAbstract=3D=3D
>
> This document specifies a coordination mechanism for a simple majority=
> of miners to prevent a chain split ahead of BIP148 activation.
>
> =3D=3DDefinitions=3D=3D
>
> "existing segwit deployment" refer to the BIP9 "segwit&= quot; 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 risk.=
>
> This BIP provides a way for a simple majority of miners to coordinate<= br> > 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.
>
> =3D=3DSpecification=3D=3D
>
> While this BIP is active, all blocks must set the nVersion header top<= br> > 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 its=
> own signalling threshold. This BIP will cease to be active when segwit=
> is locked-in.
>
> =3D=3D=3D Reference implementation =3D=3D=3D
>
> <pre>
> // Check if Segregated Witness is Locked In
> bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
> Consensus::Params& params)
> {
>=C2=A0 =C2=A0LOCK(cs_main);
>=C2=A0 =C2=A0return (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 &&
>=C2=A0 =C2=A0 !IsWitnessLockedIn(pindex->pprev, chainparams.Get= Consensus()) &&
> // Segwit is not locked in
>=C2=A0 =C2=A0 !IsWitnessEnabled(pindex->pprev, chainparams.GetC= onsensus()) ) //
> and is not active.
> {
>=C2=A0 =C2=A0bool fVersionBits =3D (pindex->nVersion & VERSIONBI= TS_TOP_MASK) =3D=3D
> VERSIONBITS_TOP_BITS;
>=C2=A0 =C2=A0bool fSegbit =3D (pindex->nVersion &
> VersionBitsMask(chainparams.GetConsensus(),
> Consensus::DEPLOYMENT_SEGWIT)) !=3D 0;
>=C2=A0 =C2=A0if (!(fVersionBits && fSegbit)) {
>=C2=A0 =C2=A0 =C2=A0 =C2=A0return state.DoS(0, error("ConnectBlock= (): relayed block must
> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no= -segwit");
>=C2=A0 =C2=A0}
> }
>
> // BIP148 mandatory segwit signalling.
> int64_t nMedianTimePast =3D pindex->GetMedianTimePast();
> if ( (nMedianTimePast >=3D 1501545600) &&=C2=A0 // Tue 01 A= ug 2017 00:00:00 UTC
>=C2=A0 =C2=A0 (nMedianTimePast <=3D 1510704000) &&=C2=A0 // = Wed 15 Nov 2017 00:00:00 UTC
>=C2=A0 =C2=A0 (!IsWitnessLockedIn(pindex->pprev, chainparams.Ge= tConsensus()) &&
> // Segwit is not locked in
>=C2=A0 =C2=A0 =C2=A0!IsWitnessEnabled(pindex->pprev, chainparam= s.GetConsensus())) )
> // and is not active.
> {
>=C2=A0 =C2=A0bool fVersionBits =3D (pindex->nVersion & VERSIONBI= TS_TOP_MASK) =3D=3D
> VERSIONBITS_TOP_BITS;
>=C2=A0 =C2=A0bool fSegbit =3D (pindex->nVersion &
> VersionBitsMask(chainparams.GetConsensus(),
> Consensus::DEPLOYMENT_SEGWIT)) !=3D 0;
>=C2=A0 =C2=A0if (!(fVersionBits && fSegbit)) {
>=C2=A0 =C2=A0 =C2=A0 =C2=A0return state.DoS(0, error("ConnectBlock= (): relayed block must
> signal for segwit, please upgrade"), REJECT_INVALID, "bad-no= -segwit");
>=C2=A0 =C2=A0}
> }
> </pre>
>
> https://= github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprot= ection-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 midnight=
> November 15th, 2017. This deployment is also compatible with the
> existing BIP148 deployment. This BIP is compatible with BIP91 only if<= br> > 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 miners<= br> > once activated, this ensures that miners are aware of new rules being<= br> > enforced. This technique can be leveraged to lower the signalling
> threshold of a soft fork while it is in the process of being deployed<= br> > 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&= quot;
> deployment, this BIP can cause the existing "segwit" deploym= ent 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.
>
> =3D=3DReferences=3D=3D
>
> *[https://lists.l= inuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html
> Mailing list discussion]
> *[https://github.com/bit= coin/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 malleabi= lity]]
> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment= ]]
> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]<= br> > *[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
>
>
>
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