> But passing it off as the safest defense is bad faith. Without this option, a miner has to guess whether a split will be economically impacting. With this option, his miner will automatically switch to the chain least likely to get wiped out... as soon as a simple majority of miners supports it.
On Wed, Jun 7, 2017 at 12:44 PM, Jacob Eliosoff <jacob.elios...@gmail.com> wrote: > This is not the safest defense against a split. If 70% of miners run > "splitprotection", and 0.1% run BIP148, there's no "safety"/"defense" > reason for splitprotection to activate segwit. It should only do so if > *BIP148* support (NB: not just segwit support!) >50%. > > The truly defensive logic is "If the majority supports orphaning > non-segwit blocks starting Aug 1, I'll join them." > > If the real goal of this BIP is to induce miners to run segwit, then fair > enough. But passing it off as the safest defense is bad faith. > > > On Wed, Jun 7, 2017 at 10:10 AM, Erik Aronesty via bitcoin-dev < > bitcoin-dev@lists.linuxfoundation.org> wrote: > >> 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 <cont...@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.hillia...@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 <cont...@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.hillia...@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...jameshilli >>> ard: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/20 >>> 17-March/013714.html >>> > Mailing list discussion] >>> > *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.cp >>> p#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 >>> >> >> >> _______________________________________________ >> bitcoin-dev mailing list >> bitcoin-dev@lists.linuxfoundation.org >> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >> >> >
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