📅 Original date posted:2017-06-06
📝 Original message:One thing about BIP148 activation that may be affected by this is the
fact that segwit signalling non-BIP148 miners + BIP148 miners may hold
majority hash power and prevent a chain split. With this SF, that will
no longer be the case, right? Or am I completely confused on the
subject?
On Wed, Jun 7, 2017 at 9:56 AM, James Hilliard via bitcoin-dev
<bitcoin-dev at 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 at 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 at lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
Karl Johan Alm [ARCHIVE] /
npub1e7…fg307
2023-06-07 18:02:30
in reply to nevent1q…76zg
Author Public Key
npub1e7vdq905zr4xjr5nxuz58l9jcvffxq728ysl6m2xxgr024mjy5vq4fg307Published at
2023-06-07 18:02:30Event JSON
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"content": "📅 Original date posted:2017-06-06\n📝 Original message:One thing about BIP148 activation that may be affected by this is the\nfact that segwit signalling non-BIP148 miners + BIP148 miners may hold\nmajority hash power and prevent a chain split. With this SF, that will\nno longer be the case, right? Or am I completely confused on the\nsubject?\n\nOn Wed, Jun 7, 2017 at 9:56 AM, James Hilliard via bitcoin-dev\n\u003cbitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\u003e Due to the proposed calendar(https://segwit2x.github.io/) for the\n\u003e SegWit2x agreement being too slow to activate SegWit mandatory\n\u003e signalling ahead of BIP148 using BIP91 I would like to propose another\n\u003e option that miners can use to prevent a chain split ahead of the Aug\n\u003e 1st BIP148 activation date.\n\u003e\n\u003e The splitprotection soft fork is essentially BIP91 but using BIP8\n\u003e instead of BIP9 with a lower activation threshold and immediate\n\u003e mandatory signalling lock-in. This allows for a majority of miners to\n\u003e activate mandatory SegWit signalling and prevent a potential chain\n\u003e split ahead of BIP148 activation.\n\u003e\n\u003e This BIP allows for miners to respond to market forces quickly ahead\n\u003e of BIP148 activation by signalling for splitprotection. Any miners\n\u003e already running BIP148 should be encouraged to use splitprotection.\n\u003e\n\u003e \u003cpre\u003e\n\u003e BIP: splitprotection\n\u003e Layer: Consensus (soft fork)\n\u003e Title: User Activated Soft Fork Split Protection\n\u003e Author: James Hilliard \u003cjames.hilliard1 at gmail.com\u003e\n\u003e Comments-Summary: No comments yet.\n\u003e Comments-URI:\n\u003e Status: Draft\n\u003e Type: Standards Track\n\u003e Created: 2017-05-22\n\u003e License: BSD-3-Clause\n\u003e CC0-1.0\n\u003e \u003c/pre\u003e\n\u003e\n\u003e ==Abstract==\n\u003e\n\u003e This document specifies a coordination mechanism for a simple majority\n\u003e of miners to prevent a chain split ahead of BIP148 activation.\n\u003e\n\u003e ==Definitions==\n\u003e\n\u003e \"existing segwit deployment\" refer to the BIP9 \"segwit\" deployment\n\u003e using bit 1, between November 15th 2016 and November 15th 2017 to\n\u003e activate BIP141, BIP143 and BIP147.\n\u003e\n\u003e ==Motivation==\n\u003e\n\u003e The biggest risk of BIP148 is an extended chain split, this BIP\n\u003e provides a way for a simple majority of miners to eliminate that risk.\n\u003e\n\u003e This BIP provides a way for a simple majority of miners to coordinate\n\u003e activation of the existing segwit deployment with less than 95%\n\u003e hashpower before BIP148 activation. Due to time constraints unless\n\u003e immediately deployed BIP91 will likely not be able to enforce\n\u003e mandatory signalling of segwit before the Aug 1st activation of\n\u003e BIP148. This BIP provides a method for rapid miner activation of\n\u003e SegWit mandatory signalling ahead of the BIP148 activation date. Since\n\u003e the primary goal of this BIP is to reduce the chance of an extended\n\u003e chain split as much as possible we activate using a simple miner\n\u003e majority of 65% over a 504 block interval rather than a higher\n\u003e percentage. This BIP also allows miners to signal their intention to\n\u003e run BIP148 in order to prevent a chain split.\n\u003e\n\u003e ==Specification==\n\u003e\n\u003e While this BIP is active, all blocks must set the nVersion header top\n\u003e 3 bits to 001 together with bit field (1\u003c\u003c1) (according to the\n\u003e existing segwit deployment). Blocks that do not signal as required\n\u003e will be rejected.\n\u003e\n\u003e ==Deployment==\n\u003e\n\u003e This BIP will be deployed by \"version bits\" with a 65%(this can be\n\u003e adjusted if desired) activation threshold BIP9 with the name\n\u003e \"splitprotecion\" and using bit 2.\n\u003e\n\u003e This BIP starts immediately and is a BIP8 style soft fork since\n\u003e mandatory signalling will start on midnight August 1st 2017 (epoch\n\u003e time 1501545600) regardless of whether or not this BIP has reached its\n\u003e own signalling threshold. This BIP will cease to be active when segwit\n\u003e is locked-in.\n\u003e\n\u003e === Reference implementation ===\n\u003e\n\u003e \u003cpre\u003e\n\u003e // Check if Segregated Witness is Locked In\n\u003e bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const\n\u003e Consensus::Params\u0026 params)\n\u003e {\n\u003e LOCK(cs_main);\n\u003e return (VersionBitsState(pindexPrev, params,\n\u003e Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==\n\u003e THRESHOLD_LOCKED_IN);\n\u003e }\n\u003e\n\u003e // SPLITPROTECTION mandatory segwit signalling.\n\u003e if ( VersionBitsState(pindex-\u003epprev, chainparams.GetConsensus(),\n\u003e Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==\n\u003e THRESHOLD_LOCKED_IN \u0026\u0026\n\u003e !IsWitnessLockedIn(pindex-\u003epprev, chainparams.GetConsensus()) \u0026\u0026\n\u003e // Segwit is not locked in\n\u003e !IsWitnessEnabled(pindex-\u003epprev, chainparams.GetConsensus()) ) //\n\u003e and is not active.\n\u003e {\n\u003e bool fVersionBits = (pindex-\u003enVersion \u0026 VERSIONBITS_TOP_MASK) ==\n\u003e VERSIONBITS_TOP_BITS;\n\u003e bool fSegbit = (pindex-\u003enVersion \u0026\n\u003e VersionBitsMask(chainparams.GetConsensus(),\n\u003e Consensus::DEPLOYMENT_SEGWIT)) != 0;\n\u003e if (!(fVersionBits \u0026\u0026 fSegbit)) {\n\u003e return state.DoS(0, error(\"ConnectBlock(): relayed block must\n\u003e signal for segwit, please upgrade\"), REJECT_INVALID, \"bad-no-segwit\");\n\u003e }\n\u003e }\n\u003e\n\u003e // BIP148 mandatory segwit signalling.\n\u003e int64_t nMedianTimePast = pindex-\u003eGetMedianTimePast();\n\u003e if ( (nMedianTimePast \u003e= 1501545600) \u0026\u0026 // Tue 01 Aug 2017 00:00:00 UTC\n\u003e (nMedianTimePast \u003c= 1510704000) \u0026\u0026 // Wed 15 Nov 2017 00:00:00 UTC\n\u003e (!IsWitnessLockedIn(pindex-\u003epprev, chainparams.GetConsensus()) \u0026\u0026\n\u003e // Segwit is not locked in\n\u003e !IsWitnessEnabled(pindex-\u003epprev, chainparams.GetConsensus())) )\n\u003e // and is not active.\n\u003e {\n\u003e bool fVersionBits = (pindex-\u003enVersion \u0026 VERSIONBITS_TOP_MASK) ==\n\u003e VERSIONBITS_TOP_BITS;\n\u003e bool fSegbit = (pindex-\u003enVersion \u0026\n\u003e VersionBitsMask(chainparams.GetConsensus(),\n\u003e Consensus::DEPLOYMENT_SEGWIT)) != 0;\n\u003e if (!(fVersionBits \u0026\u0026 fSegbit)) {\n\u003e return state.DoS(0, error(\"ConnectBlock(): relayed block must\n\u003e signal for segwit, please upgrade\"), REJECT_INVALID, \"bad-no-segwit\");\n\u003e }\n\u003e }\n\u003e \u003c/pre\u003e\n\u003e\n\u003e https://github.com/bitcoin/bitcoin/compare/0.14...jameshilliard:splitprotection-v0.14.1\n\u003e\n\u003e ==Backwards Compatibility==\n\u003e\n\u003e This deployment is compatible with the existing \"segwit\" bit 1\n\u003e deployment scheduled between midnight November 15th, 2016 and midnight\n\u003e November 15th, 2017. This deployment is also compatible with the\n\u003e existing BIP148 deployment. This BIP is compatible with BIP91 only if\n\u003e BIP91 activates before it and before BIP148. Miners will need to\n\u003e upgrade their nodes to support splitprotection otherwise they may\n\u003e build on top of an invalid block. While this bip is active users\n\u003e should either upgrade to splitprotection or wait for additional\n\u003e confirmations when accepting payments.\n\u003e\n\u003e ==Rationale==\n\u003e\n\u003e Historically we have used IsSuperMajority() to activate soft forks\n\u003e such as BIP66 which has a mandatory signalling requirement for miners\n\u003e once activated, this ensures that miners are aware of new rules being\n\u003e enforced. This technique can be leveraged to lower the signalling\n\u003e threshold of a soft fork while it is in the process of being deployed\n\u003e in a backwards compatible way. We also use a BIP8 style timeout to\n\u003e ensure that this BIP is compatible with BIP148 and that BIP148\n\u003e compatible mandatory signalling activates regardless of miner\n\u003e signalling levels.\n\u003e\n\u003e By orphaning non-signalling blocks during the BIP9 bit 1 \"segwit\"\n\u003e deployment, this BIP can cause the existing \"segwit\" deployment to\n\u003e activate without needing to release a new deployment. As we approach\n\u003e BIP148 activation it may be desirable for a majority of miners to have\n\u003e a method that will ensure that there is no chain split.\n\u003e\n\u003e ==References==\n\u003e\n\u003e *[https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-March/013714.html\n\u003e Mailing list discussion]\n\u003e *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cpp#L1281-L1283\n\u003e P2SH flag day activation]\n\u003e *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]]\n\u003e *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]]\n\u003e *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]]\n\u003e *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus layer)]]\n\u003e *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification for\n\u003e Version 0 Witness Program]]\n\u003e *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element malleability]]\n\u003e *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit deployment]]\n\u003e *[[bip-0149.mediawiki|BIP149 Segregated Witness (second deployment)]]\n\u003e *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit benefits]\n\u003e\n\u003e ==Copyright==\n\u003e\n\u003e This document is dual licensed as BSD 3-clause, and Creative Commons\n\u003e CC0 1.0 Universal.\n\u003e _______________________________________________\n\u003e bitcoin-dev mailing list\n\u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev",
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