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... > 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 >