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Subject: Re: [bitcoin-dev] User Activated Soft Fork Split Protection
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What is the probability that a 65% threshold is too low and can allow a =
"surprise miner attack", whereby miners are kept offline before the =
deadline, and brought online immediately after, creating potential =
havoc?

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

-Greg Slepak

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

> On Jun 6, 2017, at 5:56 PM, James Hilliard via bitcoin-dev =
<bitcoin-dev@lists.linuxfoundation.org =
<mailto:bitcoin-dev@lists.linuxfoundation.org>> wrote:
>=20
> Due to the proposed calendar(https://segwit2x.github.io/ =
<https://segwit2x.github.io/>) for the
> SegWit2x agreement being too slow to activate SegWit mandatory
> signalling ahead of BIP148 using BIP91 I would like to propose another
> option that miners can use to prevent a chain split ahead of the Aug
> 1st BIP148 activation date.
>=20
> 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.
>=20
> 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.
>=20
> <pre>
>  BIP: splitprotection
>  Layer: Consensus (soft fork)
>  Title: User Activated Soft Fork Split Protection
>  Author: James Hilliard <james.hilliard1@gmail.com =
<mailto:james.hilliard1@gmail.com>>
>  Comments-Summary: No comments yet.
>  Comments-URI:
>  Status: Draft
>  Type: Standards Track
>  Created: 2017-05-22
>  License: BSD-3-Clause
>           CC0-1.0
> </pre>
>=20
> =3D=3DAbstract=3D=3D
>=20
> This document specifies a coordination mechanism for a simple majority
> of miners to prevent a chain split ahead of BIP148 activation.
>=20
> =3D=3DDefinitions=3D=3D
>=20
> "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.
>=20
> =3D=3DMotivation=3D=3D
>=20
> 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.
>=20
> 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.
>=20
> =3D=3DSpecification=3D=3D
>=20
> 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.
>=20
> =3D=3DDeployment=3D=3D
>=20
> 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.
>=20
> 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.
>=20
> =3D=3D=3D Reference implementation =3D=3D=3D
>=20
> <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) =3D=3D
> THRESHOLD_LOCKED_IN);
> }
>=20
> // 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");
>    }
> }
>=20
> // 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");
>    }
> }
> </pre>
>=20
> =
https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprote=
ction-v0.14.1 =
<https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprot=
ection-v0.14.1>
>=20
> =3D=3DBackwards Compatibility=3D=3D
>=20
> 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.
>=20
> =3D=3DRationale=3D=3D
>=20
> 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.
>=20
> 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.
>=20
> =3D=3DReferences=3D=3D
>=20
> =
*[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/01371=
4.html =
<https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714=
.html>
> Mailing list discussion]
> =
*[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283 =
<https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283>
> P2SH flag day activation]
> *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]
> *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]
> *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]
> *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]
> *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for
> Version 0 Witness Program]]
> *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element =
malleability]]
> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit =
deployment]]
> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]
> *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit =
benefits =
<https://bitcoincore.org/en/2016/01/26/segwit-benefits/%20Segwit%20benefit=
s>]
>=20
> =3D=3DCopyright=3D=3D
>=20
> This document is dual licensed as BSD 3-clause, and Creative Commons
> CC0 1.0 Universal.
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org =
<mailto:bitcoin-dev@lists.linuxfoundation.org>
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev =
<https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev>


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<html><head><meta http-equiv=3D"Content-Type" content=3D"text/html =
charset=3Dus-ascii"><meta http-equiv=3D"Content-Type" content=3D"text/html=
 charset=3Dus-ascii"><meta http-equiv=3D"Content-Type" =
content=3D"text/html charset=3Dus-ascii"><meta http-equiv=3D"Content-Type"=
 content=3D"text/html charset=3Dus-ascii"></head><body style=3D"word-wrap:=
 break-word; -webkit-nbsp-mode: space; -webkit-line-break: =
after-white-space;" class=3D"">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?<div class=3D""><br =
class=3D""></div><div class=3D"">(Nit: "simple majority" usually refers =
to &gt;50%, I think, might cause confusion.)<br class=3D""><div =
class=3D""><div class=3D""><div class=3D""><br =
class=3D"webkit-block-placeholder"></div><div class=3D"">
<span style=3D"color: rgb(0, 0, 0); font-family: Helvetica; font-size: =
14px; font-style: normal; font-variant-caps: normal; font-weight: =
normal; letter-spacing: normal; text-align: start; text-indent: 0px; =
text-transform: none; white-space: normal; word-spacing: 0px; =
-webkit-text-stroke-width: 0px; font-variant-ligatures: normal; =
font-variant-position: normal; font-variant-numeric: normal; =
font-variant-alternates: normal; font-variant-east-asian: normal; =
line-height: normal; orphans: 2; widows: 2;" class=3D"">-Greg =
Slepak</span></div><div class=3D""><span style=3D"color: rgb(0, 0, 0); =
font-family: Helvetica; font-size: 14px; font-style: normal; =
font-variant-caps: normal; font-weight: normal; letter-spacing: normal; =
text-align: start; text-indent: 0px; text-transform: none; white-space: =
normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; =
font-variant-ligatures: normal; font-variant-position: normal; =
font-variant-numeric: normal; font-variant-alternates: normal; =
font-variant-east-asian: normal; line-height: normal; orphans: 2; =
widows: 2;" class=3D""><br =
class=3D"Apple-interchange-newline">--</span><br style=3D"color: rgb(0, =
0, 0); font-family: Helvetica; font-size: 14px; font-style: normal; =
font-variant-caps: normal; font-weight: normal; letter-spacing: normal; =
text-align: start; text-indent: 0px; text-transform: none; white-space: =
normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; =
font-variant-ligatures: normal; font-variant-position: normal; =
font-variant-numeric: normal; font-variant-alternates: normal; =
font-variant-east-asian: normal; line-height: normal; orphans: 2; =
widows: 2;" class=3D""><span style=3D"color: rgb(0, 0, 0); font-family: =
Helvetica; font-size: 14px; font-style: normal; font-variant-caps: =
normal; font-weight: normal; letter-spacing: normal; text-align: start; =
text-indent: 0px; text-transform: none; white-space: normal; =
word-spacing: 0px; -webkit-text-stroke-width: 0px; =
font-variant-ligatures: normal; font-variant-position: normal; =
font-variant-numeric: normal; font-variant-alternates: normal; =
font-variant-east-asian: normal; line-height: normal; orphans: 2; =
widows: 2;" class=3D"">Please do not email me anything that you are not =
comfortable also sharing</span><span style=3D"color: rgb(0, 0, 0); =
font-family: Helvetica; font-size: 14px; font-style: normal; =
font-variant-caps: normal; font-weight: normal; letter-spacing: normal; =
text-align: start; text-indent: 0px; text-transform: none; white-space: =
normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; =
font-variant-ligatures: normal; font-variant-position: normal; =
font-variant-numeric: normal; font-variant-alternates: normal; =
font-variant-east-asian: normal; line-height: normal; orphans: 2; =
widows: 2;" class=3D"">&nbsp;with the NSA.</span>
</div>

<br class=3D""><div><blockquote type=3D"cite" class=3D""><div =
class=3D"">On Jun 6, 2017, at 5:56 PM, James Hilliard via bitcoin-dev =
&lt;<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" =
class=3D"">bitcoin-dev@lists.linuxfoundation.org</a>&gt; wrote:</div><br =
class=3D"Apple-interchange-newline"><div class=3D""><div class=3D"">Due =
to the proposed calendar(<a href=3D"https://segwit2x.github.io/" =
class=3D"">https://segwit2x.github.io/</a>) for the<br class=3D"">SegWit2x=
 agreement being too slow to activate SegWit mandatory<br =
class=3D"">signalling ahead of BIP148 using BIP91 I would like to =
propose another<br class=3D"">option that miners can use to prevent a =
chain split ahead of the Aug<br class=3D"">1st BIP148 activation =
date.<br class=3D""><br class=3D"">The splitprotection soft fork is =
essentially BIP91 but using BIP8<br class=3D"">instead of BIP9 with a =
lower activation threshold and immediate<br class=3D"">mandatory =
signalling lock-in. This allows for a majority of miners to<br =
class=3D"">activate mandatory SegWit signalling and prevent a potential =
chain<br class=3D"">split ahead of BIP148 activation.<br class=3D""><br =
class=3D"">This BIP allows for miners to respond to market forces =
quickly ahead<br class=3D"">of BIP148 activation by signalling for =
splitprotection. Any miners<br class=3D"">already running BIP148 should =
be encouraged to use splitprotection.<br class=3D""><br =
class=3D"">&lt;pre&gt;<br class=3D""> &nbsp;BIP: splitprotection<br =
class=3D""> &nbsp;Layer: Consensus (soft fork)<br class=3D""> =
&nbsp;Title: User Activated Soft Fork Split Protection<br class=3D""> =
&nbsp;Author: James Hilliard &lt;<a =
href=3D"mailto:james.hilliard1@gmail.com" =
class=3D"">james.hilliard1@gmail.com</a>&gt;<br class=3D""> =
&nbsp;Comments-Summary: No comments yet.<br class=3D""> =
&nbsp;Comments-URI:<br class=3D""> &nbsp;Status: Draft<br class=3D""> =
&nbsp;Type: Standards Track<br class=3D""> &nbsp;Created: 2017-05-22<br =
class=3D""> &nbsp;License: BSD-3-Clause<br class=3D""> =
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;CC0-1.0<br =
class=3D"">&lt;/pre&gt;<br class=3D""><br class=3D"">=3D=3DAbstract=3D=3D<=
br class=3D""><br class=3D"">This document specifies a coordination =
mechanism for a simple majority<br class=3D"">of miners to prevent a =
chain split ahead of BIP148 activation.<br class=3D""><br =
class=3D"">=3D=3DDefinitions=3D=3D<br class=3D""><br class=3D"">"existing =
segwit deployment" refer to the BIP9 "segwit" deployment<br =
class=3D"">using bit 1, between November 15th 2016 and November 15th =
2017 to<br class=3D"">activate BIP141, BIP143 and BIP147.<br =
class=3D""><br class=3D"">=3D=3DMotivation=3D=3D<br class=3D""><br =
class=3D"">The biggest risk of BIP148 is an extended chain split, this =
BIP<br class=3D"">provides a way for a simple majority of miners to =
eliminate that risk.<br class=3D""><br class=3D"">This BIP provides a =
way for a simple majority of miners to coordinate<br class=3D"">activation=
 of the existing segwit deployment with less than 95%<br =
class=3D"">hashpower before BIP148 activation. Due to time constraints =
unless<br class=3D"">immediately deployed BIP91 will likely not be able =
to enforce<br class=3D"">mandatory signalling of segwit before the Aug =
1st activation of<br class=3D"">BIP148. This BIP provides a method for =
rapid miner activation of<br class=3D"">SegWit mandatory signalling =
ahead of the BIP148 activation date. Since<br class=3D"">the primary =
goal of this BIP is to reduce the chance of an extended<br =
class=3D"">chain split as much as possible we activate using a simple =
miner<br class=3D"">majority of 65% over a 504 block interval rather =
than a higher<br class=3D"">percentage. This BIP also allows miners to =
signal their intention to<br class=3D"">run BIP148 in order to prevent a =
chain split.<br class=3D""><br class=3D"">=3D=3DSpecification=3D=3D<br =
class=3D""><br class=3D"">While this BIP is active, all blocks must set =
the nVersion header top<br class=3D"">3 bits to 001 together with bit =
field (1&lt;&lt;1) (according to the<br class=3D"">existing segwit =
deployment). Blocks that do not signal as required<br class=3D"">will be =
rejected.<br class=3D""><br class=3D"">=3D=3DDeployment=3D=3D<br =
class=3D""><br class=3D"">This BIP will be deployed by "version bits" =
with a 65%(this can be<br class=3D"">adjusted if desired) activation =
threshold BIP9 with the name<br class=3D"">"splitprotecion" and using =
bit 2.<br class=3D""><br class=3D"">This BIP starts immediately and is a =
BIP8 style soft fork since<br class=3D"">mandatory signalling will start =
on midnight August 1st 2017 (epoch<br class=3D"">time 1501545600) =
regardless of whether or not this BIP has reached its<br class=3D"">own =
signalling threshold. This BIP will cease to be active when segwit<br =
class=3D"">is locked-in.<br class=3D""><br class=3D"">=3D=3D=3D =
Reference implementation =3D=3D=3D<br class=3D""><br =
class=3D"">&lt;pre&gt;<br class=3D"">// Check if Segregated Witness is =
Locked In<br class=3D"">bool IsWitnessLockedIn(const CBlockIndex* =
pindexPrev, const<br class=3D"">Consensus::Params&amp; params)<br =
class=3D"">{<br class=3D""> &nbsp;&nbsp;&nbsp;LOCK(cs_main);<br =
class=3D""> &nbsp;&nbsp;&nbsp;return (VersionBitsState(pindexPrev, =
params,<br class=3D"">Consensus::DEPLOYMENT_SEGWIT, versionbitscache) =
=3D=3D<br class=3D"">THRESHOLD_LOCKED_IN);<br class=3D"">}<br =
class=3D""><br class=3D"">// SPLITPROTECTION mandatory segwit =
signalling.<br class=3D"">if ( VersionBitsState(pindex-&gt;pprev, =
chainparams.GetConsensus(),<br =
class=3D"">Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) =
=3D=3D<br class=3D"">THRESHOLD_LOCKED_IN &amp;&amp;<br class=3D""> =
&nbsp;&nbsp;&nbsp;&nbsp;!IsWitnessLockedIn(pindex-&gt;pprev, =
chainparams.GetConsensus()) &amp;&amp;<br class=3D"">// Segwit is not =
locked in<br class=3D""> =
&nbsp;&nbsp;&nbsp;&nbsp;!IsWitnessEnabled(pindex-&gt;pprev, =
chainparams.GetConsensus()) ) //<br class=3D"">and is not active.<br =
class=3D"">{<br class=3D""> &nbsp;&nbsp;&nbsp;bool fVersionBits =3D =
(pindex-&gt;nVersion &amp; VERSIONBITS_TOP_MASK) =3D=3D<br =
class=3D"">VERSIONBITS_TOP_BITS;<br class=3D""> &nbsp;&nbsp;&nbsp;bool =
fSegbit =3D (pindex-&gt;nVersion &amp;<br =
class=3D"">VersionBitsMask(chainparams.GetConsensus(),<br =
class=3D"">Consensus::DEPLOYMENT_SEGWIT)) !=3D 0;<br class=3D""> =
&nbsp;&nbsp;&nbsp;if (!(fVersionBits &amp;&amp; fSegbit)) {<br class=3D"">=
 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return state.DoS(0, =
error("ConnectBlock(): relayed block must<br class=3D"">signal for =
segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");<br class=3D"">=
 &nbsp;&nbsp;&nbsp;}<br class=3D"">}<br class=3D""><br class=3D"">// =
BIP148 mandatory segwit signalling.<br class=3D"">int64_t =
nMedianTimePast =3D pindex-&gt;GetMedianTimePast();<br class=3D"">if ( =
(nMedianTimePast &gt;=3D 1501545600) &amp;&amp; &nbsp;// Tue 01 Aug 2017 =
00:00:00 UTC<br class=3D""> &nbsp;&nbsp;&nbsp;&nbsp;(nMedianTimePast =
&lt;=3D 1510704000) &amp;&amp; &nbsp;// Wed 15 Nov 2017 00:00:00 UTC<br =
class=3D""> =
&nbsp;&nbsp;&nbsp;&nbsp;(!IsWitnessLockedIn(pindex-&gt;pprev, =
chainparams.GetConsensus()) &amp;&amp;<br class=3D""> // Segwit is not =
locked in<br class=3D""> =
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;!IsWitnessEnabled(pindex-&gt;pprev, =
chainparams.GetConsensus())) )<br class=3D""> // and is not active.<br =
class=3D"">{<br class=3D""> &nbsp;&nbsp;&nbsp;bool fVersionBits =3D =
(pindex-&gt;nVersion &amp; VERSIONBITS_TOP_MASK) =3D=3D<br =
class=3D"">VERSIONBITS_TOP_BITS;<br class=3D""> &nbsp;&nbsp;&nbsp;bool =
fSegbit =3D (pindex-&gt;nVersion &amp;<br =
class=3D"">VersionBitsMask(chainparams.GetConsensus(),<br =
class=3D"">Consensus::DEPLOYMENT_SEGWIT)) !=3D 0;<br class=3D""> =
&nbsp;&nbsp;&nbsp;if (!(fVersionBits &amp;&amp; fSegbit)) {<br class=3D"">=
 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return state.DoS(0, =
error("ConnectBlock(): relayed block must<br class=3D"">signal for =
segwit, please upgrade"), REJECT_INVALID, "bad-no-segwit");<br class=3D"">=
 &nbsp;&nbsp;&nbsp;}<br class=3D"">}<br class=3D"">&lt;/pre&gt;<br =
class=3D""><br class=3D""><a =
href=3D"https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:sp=
litprotection-v0.14.1" =
class=3D"">https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard=
:splitprotection-v0.14.1</a><br class=3D""><br class=3D"">=3D=3DBackwards =
Compatibility=3D=3D<br class=3D""><br class=3D"">This deployment is =
compatible with the existing "segwit" bit 1<br class=3D"">deployment =
scheduled between midnight November 15th, 2016 and midnight<br =
class=3D"">November 15th, 2017. This deployment is also compatible with =
the<br class=3D"">existing BIP148 deployment. This BIP is compatible =
with BIP91 only if<br class=3D"">BIP91 activates before it and before =
BIP148. Miners will need to<br class=3D"">upgrade their nodes to support =
splitprotection otherwise they may<br class=3D"">build on top of an =
invalid block. While this bip is active users<br class=3D"">should =
either upgrade to splitprotection or wait for additional<br =
class=3D"">confirmations when accepting payments.<br class=3D""><br =
class=3D"">=3D=3DRationale=3D=3D<br class=3D""><br class=3D"">Historically=
 we have used IsSuperMajority() to activate soft forks<br class=3D"">such =
as BIP66 which has a mandatory signalling requirement for miners<br =
class=3D"">once activated, this ensures that miners are aware of new =
rules being<br class=3D"">enforced. This technique can be leveraged to =
lower the signalling<br class=3D"">threshold of a soft fork while it is =
in the process of being deployed<br class=3D"">in a backwards compatible =
way. We also use a BIP8 style timeout to<br class=3D"">ensure that this =
BIP is compatible with BIP148 and that BIP148<br class=3D"">compatible =
mandatory signalling activates regardless of miner<br =
class=3D"">signalling levels.<br class=3D""><br class=3D"">By orphaning =
non-signalling blocks during the BIP9 bit 1 "segwit"<br =
class=3D"">deployment, this BIP can cause the existing "segwit" =
deployment to<br class=3D"">activate without needing to release a new =
deployment. As we approach<br class=3D"">BIP148 activation it may be =
desirable for a majority of miners to have<br class=3D"">a method that =
will ensure that there is no chain split.<br class=3D""><br =
class=3D"">=3D=3DReferences=3D=3D<br class=3D""><br class=3D"">*[<a =
href=3D"https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March=
/013714.html" =
class=3D"">https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-Ma=
rch/013714.html</a><br class=3D"">Mailing list discussion]<br =
class=3D"">*[<a =
href=3D"https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-=
L1283" =
class=3D"">https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L12=
81-L1283</a><br class=3D"">P2SH flag day activation]<br =
class=3D"">*[[bip-0009.mediawiki|BIP9 Version bits with timeout and =
delay]]<br class=3D"">*[[bip-0016.mediawiki|BIP16 Pay to Script =
Hash]]<br class=3D"">*[[bip-0091.mediawiki|BIP91 Reduced threshold =
Segwit MASF]]<br class=3D"">*[[bip-0141.mediawiki|BIP141 Segregated =
Witness (Consensus layer)]]<br class=3D"">*[[bip-0143.mediawiki|BIP143 =
Transaction Signature Verification for<br class=3D"">Version 0 Witness =
Program]]<br class=3D"">*[[bip-0147.mediawiki|BIP147 Dealing with dummy =
stack element malleability]]<br class=3D"">*[[bip-0148.mediawiki|BIP148 =
Mandatory activation of segwit deployment]]<br =
class=3D"">*[[bip-0149.mediawiki|BIP149 Segregated Witness (second =
deployment)]]<br class=3D"">*[<a =
href=3D"https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit =
benefits" =
class=3D"">https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit =
benefits</a>]<br class=3D""><br class=3D"">=3D=3DCopyright=3D=3D<br =
class=3D""><br class=3D"">This document is dual licensed as BSD =
3-clause, and Creative Commons<br class=3D"">CC0 1.0 Universal.<br =
class=3D"">_______________________________________________<br =
class=3D"">bitcoin-dev mailing list<br class=3D""><a =
href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" =
class=3D"">bitcoin-dev@lists.linuxfoundation.org</a><br class=3D""><a =
href=3D"https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev" =
class=3D"">https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev<=
/a><br class=3D""></div></div></blockquote></div><br =
class=3D""></div></div></div></body></html>=

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