That is incorrect, it is compatible with the current segwit implementation because it triggers a mandatory signalling period that will activate segwit on existing nodes.
On Tue, May 23, 2017 at 4:39 PM, Andrew Chow via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote: > Hi James, > > From what I understand, this proposal is incompatible with the current > segwit implementation with regards to the NODE_WITNESS service bit. I > believe it could cause network partitioning if the service bit is not > changed. > > Andrew > > > On 5/22/2017 6:40 PM, James Hilliard via bitcoin-dev wrote: >> I would like to propose an implementation that accomplishes the first >> part of the Barry Silbert proposal independently from the second: >> >> "Activate Segregated Witness at an 80% threshold, signaling at bit 4" >> in a way that >> >> The goal here is to minimize chain split risk and network disruption >> while maximizing backwards compatibility and still providing for rapid >> activation of segwit at the 80% threshold using bit 4. >> >> By activating segwit immediately and separately from any HF we can >> scale quickly without risking a rushed combined segwit+HF that would >> almost certainly cause widespread issues. >> >> Draft proposal: >> https://github.com/jameshilliard/bips/blob/bip-segsignal/bip-segsignal.mediawiki >> >> Proposal text: >> <pre> >> BIP: segsignal >> Layer: Consensus (soft fork) >> Title: Reduced signalling threshold activation of existing segwit >> deployment >> Author: James Hilliard <james.hillia...@gmail.com> >> Status: Draft >> Type: Standards Track >> Created: 2017-05-22 >> License: BSD-3-Clause >> CC0-1.0 >> </pre> >> >> ==Abstract== >> >> This document specifies a method to activate the existing BIP9 segwit >> deployment with a majority hashpower less than 95%. >> >> ==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== >> >> Segwit increases the blocksize, fixes transaction malleability, and >> makes scripting easier to upgrade as well as bringing many other >> [https://bitcoincore.org/en/2016/01/26/segwit-benefits/ benefits]. >> >> This BIP provides a way for a simple majority of miners to coordinate >> activation of the existing segwit deployment with less than 95% >> hashpower. For a number of reasons a complete redeployment of segwit >> is difficulty to do until the existing deployment expires. This is due >> to 0.13.1+ having many segwit related features active already, >> including all the P2P components, the new network service flag, the >> witness-tx and block messages, compact blocks v2 and preferential >> peering. A redeployment of segwit will need to redefine all these >> things and doing so before expiry would greatly complicate testing. >> >> ==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 a "version bits" with an 80%(this can be >> adjusted if desired) activation threshold BIP9 with the name >> "segsignal" and using bit 4. >> >> This BIP will have a start time of midnight June 1st, 2017 (epoch time >> 1496275200) and timeout on midnight November 15th 2017 (epoch time >> 1510704000). 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); >> } >> >> // SEGSIGNAL mandatory segwit signalling. >> if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(), >> Consensus::DEPLOYMENT_SEGSIGNAL, versionbitscache) == THRESHOLD_ACTIVE >> && >> !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:segsignal-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. Miners will need to upgrade their nodes to >> support segsignal otherwise they may build on top of an invalid block. >> While this bip is active users should either upgrade to segsignal 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. >> >> 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. >> >> ==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-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
