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

--001a1140e91491472e05515f4dbf
Content-Type: text/html; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr"><div>This 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 to defend themselves, with very little risk, since t=
he defense is only activated if the majority of miners do so. I would move =
for a very rapid deployment.=C2=A0=C2=A0 Only miners would need to upgrade.=
=C2=A0=C2=A0 Regular users would not have to concern themselves with this r=
elease.<br></div></div><div class=3D"gmail_extra"><br><div class=3D"gmail_q=
uote">On Wed, Jun 7, 2017 at 6:13 AM, James Hilliard via bitcoin-dev <span =
dir=3D"ltr">&lt;<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" ta=
rget=3D"_blank">bitcoin-dev@lists.linuxfoundation.org</a>&gt;</span> wrote:=
<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-lef=
t:1px #ccc solid;padding-left:1ex">I think even 55% would probably work out=
 fine simply due to incentive<br>
structures, once signalling is over 51% it&#39;s then clear to miners that<=
br>
non-signalling blocks will be orphaned and the rest will rapidly<br>
update to splitprotection/BIP148. The purpose of this BIP is to reduce<br>
chain split risk for BIP148 since it&#39;s looking like BIP148 is going to<=
br>
be run by a non-insignificant percentage of the economy at a minimum.<br>
<div class=3D"HOEnZb"><div class=3D"h5"><br>
On Wed, Jun 7, 2017 at 12:20 AM, Tao Effect &lt;<a href=3D"mailto:contact@t=
aoeffect.com">contact@taoeffect.com</a>&gt; wrote:<br>
&gt; See thread on replay attacks for why activating regardless of threshol=
d is a<br>
&gt; bad idea [1].<br>
&gt;<br>
&gt; BIP91 OTOH seems perfectly reasonable. 80% instead of 95% makes it mor=
e<br>
&gt; difficult for miners to hold together in opposition to Core. It gives =
Core<br>
&gt; more leverage in negotiations.<br>
&gt;<br>
&gt; If they don&#39;t activate with 80%, Core can release another BIP to r=
educe it<br>
&gt; to 75%.<br>
&gt;<br>
&gt; Each threshold reduction makes it both more likely to succeed, but als=
o<br>
&gt; increases the likelihood of harm to the ecosystem.<br>
&gt;<br>
&gt; Cheers,<br>
&gt; Greg<br>
&gt;<br>
&gt; [1]<br>
&gt; <a href=3D"https://lists.linuxfoundation.org/pipermail/bitcoin-dev/201=
7-June/014497.html" rel=3D"noreferrer" target=3D"_blank">https://lists.linu=
xfoundation.<wbr>org/pipermail/bitcoin-dev/<wbr>2017-June/014497.html</a><b=
r>
&gt;<br>
&gt; --<br>
&gt; Please do not email me anything that you are not comfortable also shar=
ing<br>
&gt; with the NSA.<br>
&gt;<br>
&gt; On Jun 6, 2017, at 6:54 PM, James Hilliard &lt;<a href=3D"mailto:james=
.hilliard1@gmail.com">james.hilliard1@gmail.com</a>&gt;<br>
&gt; wrote:<br>
&gt;<br>
&gt; This is a BIP8 style soft fork so mandatory signalling will be active<=
br>
&gt; after Aug 1st regardless.<br>
&gt;<br>
&gt; On Tue, Jun 6, 2017 at 8:51 PM, Tao Effect &lt;<a href=3D"mailto:conta=
ct@taoeffect.com">contact@taoeffect.com</a>&gt; wrote:<br>
&gt;<br>
&gt; What is the probability that a 65% threshold is too low and can allow =
a<br>
&gt; &quot;surprise miner attack&quot;, whereby miners are kept offline bef=
ore the<br>
&gt; deadline, and brought online immediately after, creating potential hav=
oc?<br>
&gt;<br>
&gt; (Nit: &quot;simple majority&quot; usually refers to &gt;50%, I think, =
might cause<br>
&gt; confusion.)<br>
&gt;<br>
&gt; -Greg Slepak<br>
&gt;<br>
&gt; --<br>
&gt; Please do not email me anything that you are not comfortable also shar=
ing<br>
&gt; with the NSA.<br>
&gt;<br>
&gt; On Jun 6, 2017, at 5:56 PM, James Hilliard via bitcoin-dev<br>
&gt; &lt;<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org">bitcoin-d=
ev@lists.<wbr>linuxfoundation.org</a>&gt; wrote:<br>
&gt;<br>
&gt; Due to the proposed calendar(<a href=3D"https://segwit2x.github.io/" r=
el=3D"noreferrer" target=3D"_blank">https://segwit2x.<wbr>github.io/</a>) f=
or the<br>
&gt; SegWit2x agreement being too slow to activate SegWit mandatory<br>
&gt; signalling ahead of BIP148 using BIP91 I would like to propose another=
<br>
&gt; option that miners can use to prevent a chain split ahead of the Aug<b=
r>
&gt; 1st BIP148 activation date.<br>
&gt;<br>
&gt; The splitprotection soft fork is essentially BIP91 but using BIP8<br>
&gt; instead of BIP9 with a lower activation threshold and immediate<br>
&gt; mandatory signalling lock-in. This allows for a majority of miners to<=
br>
&gt; activate mandatory SegWit signalling and prevent a potential chain<br>
&gt; split ahead of BIP148 activation.<br>
&gt;<br>
&gt; This BIP allows for miners to respond to market forces quickly ahead<b=
r>
&gt; of BIP148 activation by signalling for splitprotection. Any miners<br>
&gt; already running BIP148 should be encouraged to use splitprotection.<br=
>
&gt;<br>
&gt; &lt;pre&gt;<br>
&gt; BIP: splitprotection<br>
&gt; Layer: Consensus (soft fork)<br>
&gt; Title: User Activated Soft Fork Split Protection<br>
&gt; Author: James Hilliard &lt;<a href=3D"mailto:james.hilliard1@gmail.com=
">james.hilliard1@gmail.com</a>&gt;<br>
&gt; Comments-Summary: No comments yet.<br>
&gt; Comments-URI:<br>
&gt; Status: Draft<br>
&gt; Type: Standards Track<br>
&gt; Created: 2017-05-22<br>
&gt; License: BSD-3-Clause<br>
&gt;=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 CC0-1.0<br>
&gt; &lt;/pre&gt;<br>
&gt;<br>
&gt; =3D=3DAbstract=3D=3D<br>
&gt;<br>
&gt; This document specifies a coordination mechanism for a simple majority=
<br>
&gt; of miners to prevent a chain split ahead of BIP148 activation.<br>
&gt;<br>
&gt; =3D=3DDefinitions=3D=3D<br>
&gt;<br>
&gt; &quot;existing segwit deployment&quot; refer to the BIP9 &quot;segwit&=
quot; deployment<br>
&gt; using bit 1, between November 15th 2016 and November 15th 2017 to<br>
&gt; activate BIP141, BIP143 and BIP147.<br>
&gt;<br>
&gt; =3D=3DMotivation=3D=3D<br>
&gt;<br>
&gt; The biggest risk of BIP148 is an extended chain split, this BIP<br>
&gt; provides a way for a simple majority of miners to eliminate that risk.=
<br>
&gt;<br>
&gt; This BIP provides a way for a simple majority of miners to coordinate<=
br>
&gt; activation of the existing segwit deployment with less than 95%<br>
&gt; hashpower before BIP148 activation. Due to time constraints unless<br>
&gt; immediately deployed BIP91 will likely not be able to enforce<br>
&gt; mandatory signalling of segwit before the Aug 1st activation of<br>
&gt; BIP148. This BIP provides a method for rapid miner activation of<br>
&gt; SegWit mandatory signalling ahead of the BIP148 activation date. Since=
<br>
&gt; the primary goal of this BIP is to reduce the chance of an extended<br=
>
&gt; chain split as much as possible we activate using a simple miner<br>
&gt; majority of 65% over a 504 block interval rather than a higher<br>
&gt; percentage. This BIP also allows miners to signal their intention to<b=
r>
&gt; run BIP148 in order to prevent a chain split.<br>
&gt;<br>
&gt; =3D=3DSpecification=3D=3D<br>
&gt;<br>
&gt; While this BIP is active, all blocks must set the nVersion header top<=
br>
&gt; 3 bits to 001 together with bit field (1&lt;&lt;1) (according to the<b=
r>
&gt; existing segwit deployment). Blocks that do not signal as required<br>
&gt; will be rejected.<br>
&gt;<br>
&gt; =3D=3DDeployment=3D=3D<br>
&gt;<br>
&gt; This BIP will be deployed by &quot;version bits&quot; with a 65%(this =
can be<br>
&gt; adjusted if desired) activation threshold BIP9 with the name<br>
&gt; &quot;splitprotecion&quot; and using bit 2.<br>
&gt;<br>
&gt; This BIP starts immediately and is a BIP8 style soft fork since<br>
&gt; mandatory signalling will start on midnight August 1st 2017 (epoch<br>
&gt; time 1501545600) regardless of whether or not this BIP has reached its=
<br>
&gt; own signalling threshold. This BIP will cease to be active when segwit=
<br>
&gt; is locked-in.<br>
&gt;<br>
&gt; =3D=3D=3D Reference implementation =3D=3D=3D<br>
&gt;<br>
&gt; &lt;pre&gt;<br>
&gt; // Check if Segregated Witness is Locked In<br>
&gt; bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const<br>
&gt; Consensus::Params&amp; params)<br>
&gt; {<br>
&gt;=C2=A0 =C2=A0LOCK(cs_main);<br>
&gt;=C2=A0 =C2=A0return (VersionBitsState(pindexPrev, params,<br>
&gt; Consensus::DEPLOYMENT_SEGWIT, versionbitscache) =3D=3D<br>
&gt; THRESHOLD_LOCKED_IN);<br>
&gt; }<br>
&gt;<br>
&gt; // SPLITPROTECTION mandatory segwit signalling.<br>
&gt; if ( VersionBitsState(pindex-&gt;<wbr>pprev, chainparams.GetConsensus(=
),<br>
&gt; Consensus::DEPLOYMENT_<wbr>SPLITPROTECTION, versionbitscache) =3D=3D<b=
r>
&gt; THRESHOLD_LOCKED_IN &amp;&amp;<br>
&gt;=C2=A0 =C2=A0 !IsWitnessLockedIn(pindex-&gt;<wbr>pprev, chainparams.Get=
Consensus()) &amp;&amp;<br>
&gt; // Segwit is not locked in<br>
&gt;=C2=A0 =C2=A0 !IsWitnessEnabled(pindex-&gt;<wbr>pprev, chainparams.GetC=
onsensus()) ) //<br>
&gt; and is not active.<br>
&gt; {<br>
&gt;=C2=A0 =C2=A0bool fVersionBits =3D (pindex-&gt;nVersion &amp; VERSIONBI=
TS_TOP_MASK) =3D=3D<br>
&gt; VERSIONBITS_TOP_BITS;<br>
&gt;=C2=A0 =C2=A0bool fSegbit =3D (pindex-&gt;nVersion &amp;<br>
&gt; VersionBitsMask(chainparams.<wbr>GetConsensus(),<br>
&gt; Consensus::DEPLOYMENT_SEGWIT)) !=3D 0;<br>
&gt;=C2=A0 =C2=A0if (!(fVersionBits &amp;&amp; fSegbit)) {<br>
&gt;=C2=A0 =C2=A0 =C2=A0 =C2=A0return state.DoS(0, error(&quot;ConnectBlock=
(): relayed block must<br>
&gt; signal for segwit, please upgrade&quot;), REJECT_INVALID, &quot;bad-no=
-segwit&quot;);<br>
&gt;=C2=A0 =C2=A0}<br>
&gt; }<br>
&gt;<br>
&gt; // BIP148 mandatory segwit signalling.<br>
&gt; int64_t nMedianTimePast =3D pindex-&gt;GetMedianTimePast();<br>
&gt; if ( (nMedianTimePast &gt;=3D 1501545600) &amp;&amp;=C2=A0 // Tue 01 A=
ug 2017 00:00:00 UTC<br>
&gt;=C2=A0 =C2=A0 (nMedianTimePast &lt;=3D 1510704000) &amp;&amp;=C2=A0 // =
Wed 15 Nov 2017 00:00:00 UTC<br>
&gt;=C2=A0 =C2=A0 (!IsWitnessLockedIn(pindex-&gt;<wbr>pprev, chainparams.Ge=
tConsensus()) &amp;&amp;<br>
&gt; // Segwit is not locked in<br>
&gt;=C2=A0 =C2=A0 =C2=A0!IsWitnessEnabled(pindex-&gt;<wbr>pprev, chainparam=
s.GetConsensus())) )<br>
&gt; // and is not active.<br>
&gt; {<br>
&gt;=C2=A0 =C2=A0bool fVersionBits =3D (pindex-&gt;nVersion &amp; VERSIONBI=
TS_TOP_MASK) =3D=3D<br>
&gt; VERSIONBITS_TOP_BITS;<br>
&gt;=C2=A0 =C2=A0bool fSegbit =3D (pindex-&gt;nVersion &amp;<br>
&gt; VersionBitsMask(chainparams.<wbr>GetConsensus(),<br>
&gt; Consensus::DEPLOYMENT_SEGWIT)) !=3D 0;<br>
&gt;=C2=A0 =C2=A0if (!(fVersionBits &amp;&amp; fSegbit)) {<br>
&gt;=C2=A0 =C2=A0 =C2=A0 =C2=A0return state.DoS(0, error(&quot;ConnectBlock=
(): relayed block must<br>
&gt; signal for segwit, please upgrade&quot;), REJECT_INVALID, &quot;bad-no=
-segwit&quot;);<br>
&gt;=C2=A0 =C2=A0}<br>
&gt; }<br>
&gt; &lt;/pre&gt;<br>
&gt;<br>
&gt; <a href=3D"https://github.com/bitcoin/bitcoin/compare/0.14...jameshill=
iard:splitprotection-v0.14.1" rel=3D"noreferrer" target=3D"_blank">https://=
github.com/bitcoin/<wbr>bitcoin/compare/0.14...<wbr>jameshilliard:splitprot=
ection-<wbr>v0.14.1</a><br>
&gt;<br>
&gt; =3D=3DBackwards Compatibility=3D=3D<br>
&gt;<br>
&gt; This deployment is compatible with the existing &quot;segwit&quot; bit=
 1<br>
&gt; deployment scheduled between midnight November 15th, 2016 and midnight=
<br>
&gt; November 15th, 2017. This deployment is also compatible with the<br>
&gt; existing BIP148 deployment. This BIP is compatible with BIP91 only if<=
br>
&gt; BIP91 activates before it and before BIP148. Miners will need to<br>
&gt; upgrade their nodes to support splitprotection otherwise they may<br>
&gt; build on top of an invalid block. While this bip is active users<br>
&gt; should either upgrade to splitprotection or wait for additional<br>
&gt; confirmations when accepting payments.<br>
&gt;<br>
&gt; =3D=3DRationale=3D=3D<br>
&gt;<br>
&gt; Historically we have used IsSuperMajority() to activate soft forks<br>
&gt; such as BIP66 which has a mandatory signalling requirement for miners<=
br>
&gt; once activated, this ensures that miners are aware of new rules being<=
br>
&gt; enforced. This technique can be leveraged to lower the signalling<br>
&gt; threshold of a soft fork while it is in the process of being deployed<=
br>
&gt; in a backwards compatible way. We also use a BIP8 style timeout to<br>
&gt; ensure that this BIP is compatible with BIP148 and that BIP148<br>
&gt; compatible mandatory signalling activates regardless of miner<br>
&gt; signalling levels.<br>
&gt;<br>
&gt; By orphaning non-signalling blocks during the BIP9 bit 1 &quot;segwit&=
quot;<br>
&gt; deployment, this BIP can cause the existing &quot;segwit&quot; deploym=
ent to<br>
&gt; activate without needing to release a new deployment. As we approach<b=
r>
&gt; BIP148 activation it may be desirable for a majority of miners to have=
<br>
&gt; a method that will ensure that there is no chain split.<br>
&gt;<br>
&gt; =3D=3DReferences=3D=3D<br>
&gt;<br>
&gt; *[<a href=3D"https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2=
017-March/013714.html" rel=3D"noreferrer" target=3D"_blank">https://lists.<=
wbr>linuxfoundation.org/pipermail/<wbr>bitcoin-dev/2017-March/013714.<wbr>h=
tml</a><br>
&gt; Mailing list discussion]<br>
&gt; *[<a href=3D"https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.c=
pp#L1281-L1283" rel=3D"noreferrer" target=3D"_blank">https://github.com/bit=
coin/<wbr>bitcoin/blob/v0.6.0/src/main.<wbr>cpp#L1281-L1283</a><br>
&gt; P2SH flag day activation]<br>
&gt; *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]<br>
&gt; *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]<br>
&gt; *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]<br>
&gt; *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]<br=
>
&gt; *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for<br=
>
&gt; Version 0 Witness Program]]<br>
&gt; *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element malleabi=
lity]]<br>
&gt; *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment=
]]<br>
&gt; *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]<=
br>
&gt; *[<a href=3D"https://bitcoincore.org/en/2016/01/26/segwit-benefits/" r=
el=3D"noreferrer" target=3D"_blank">https://bitcoincore.org/en/<wbr>2016/01=
/26/segwit-benefits/</a> Segwit benefits]<br>
&gt;<br>
&gt; =3D=3DCopyright=3D=3D<br>
&gt;<br>
&gt; This document is dual licensed as BSD 3-clause, and Creative Commons<b=
r>
&gt; CC0 1.0 Universal.<br>
&gt; ______________________________<wbr>_________________<br>
&gt; bitcoin-dev mailing list<br>
&gt; <a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org">bitcoin-dev@l=
ists.<wbr>linuxfoundation.org</a><br>
&gt; <a href=3D"https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-=
dev" rel=3D"noreferrer" target=3D"_blank">https://lists.linuxfoundation.<wb=
r>org/mailman/listinfo/bitcoin-<wbr>dev</a><br>
&gt;<br>
&gt;<br>
&gt;<br>
______________________________<wbr>_________________<br>
bitcoin-dev mailing list<br>
<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org">bitcoin-dev@lists.=
<wbr>linuxfoundation.org</a><br>
<a href=3D"https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev" =
rel=3D"noreferrer" target=3D"_blank">https://lists.linuxfoundation.<wbr>org=
/mailman/listinfo/bitcoin-<wbr>dev</a><br>
</div></div></blockquote></div><br></div>

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