Yes, this is the same as BIP148, there is no mandatory signalling after segwit is locked in.
On Wed, Jun 7, 2017 at 4:43 PM, Jared Lee Richardson <[email protected]> wrote: >> Keep in mind that this is only temporary until segwit has locked in, > after that happens it becomes optional for miners again. > > I missed that, that does effectively address that concern. It appears > that BIP148 implements the same rule as would be required to prevent a > later chainsplit as well, no? > > This comment did bring to mind another concern about BIP148/91 though, > which I'll raise in the pull request discussion. Feel free to respond > to it there. > > Jared > > On Wed, Jun 7, 2017 at 2:21 PM, James Hilliard > <[email protected]> wrote: >> Keep in mind that this is only temporary until segwit has locked in, >> after that happens it becomes optional for miners again. >> >> On Wed, Jun 7, 2017 at 4:09 PM, Jared Lee Richardson <[email protected]> >> 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. >>> >>> FYI, even if very successful, this deployment and change may have a >>> severe negative impact on a small group of miners. Any miners/pools >>> who are not actively following the forums, news, or these discussions >>> may be difficult to reach and communicate with in time, particularly >>> with language barriers. Of those, any who are also either not >>> signaling segwit currently or are running an older software version >>> will have their blocks continuously and constantly orphaned, but may >>> not have any alarms or notifications set up for such an unexpected >>> failure. That may or may not be a worthy consideration, but it is >>> definitely brusque and a harsh price to pay. Considering the >>> opposition mentioned against transaction limits for the rare cases >>> where a very large transaction has already been signed, it seems that >>> this would be worthy of consideration. For the few miners in that >>> situation, it does turn segwit from an optional softfork into a >>> punishing hardfork. >>> >>> I don't think that's a sufficient reason alone to kill the idea, but >>> it should be a concern. >>> >>> Jared >>> >>> On Wed, Jun 7, 2017 at 7:10 AM, Erik Aronesty via bitcoin-dev >>> <[email protected]> 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 >>>> <[email protected]> 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 <[email protected]> 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 <[email protected]> >>>>> > 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 <[email protected]> >>>>> > 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 >>>>> > <[email protected]> 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 <[email protected]> >>>>> > 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 >>>>> > [email protected] >>>>> > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >>>>> > >>>>> > >>>>> > >>>>> _______________________________________________ >>>>> bitcoin-dev mailing list >>>>> [email protected] >>>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >>>> >>>> >>>> >>>> _______________________________________________ >>>> bitcoin-dev mailing list >>>> [email protected] >>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >>>> _______________________________________________ bitcoin-dev mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
