From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id CEA56B5F for ; Wed, 7 Jun 2017 01:29:20 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-ot0-f171.google.com (mail-ot0-f171.google.com [74.125.82.171]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 063A9108 for ; Wed, 7 Jun 2017 01:29:19 +0000 (UTC) Received: by mail-ot0-f171.google.com with SMTP id a2so25095364oth.2 for ; Tue, 06 Jun 2017 18:29:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=f+4BBx45XsDgceIGGKcj9DJIngATbTyZAuthCyuA9tQ=; b=dKVaCqF07vF7j7wO+2O/Czr/28v1JNZN+73CXbPsNS6SbAYALY/i/dcvyuW197qi+n jOytz7xoZxqFgMm7H+eOv0LPKhhbo3nG9vNCyOsnsTx/DywMOB6BGhzwFc99YiQ+3lNn Dd3bR/wtgp1f5rZ7BmEUGQOLpNf3Tl+Ykl8pOS8IhnBsbxm8vzvzMIM1A5JTc7RZ5IxR FzBcCSeBCWT6gWD0QOesMZ9IL5Gad4uWDAMryp0leIQz6oMm/bOgtsi7yZzlKVx5v9mO 0pCOziDLM/YOvejXVHM3ekn/RvcUJixUhkOim7g4j8R3QKo0G3LDR1a6dvgf6bd59XJD +kFg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=f+4BBx45XsDgceIGGKcj9DJIngATbTyZAuthCyuA9tQ=; b=N2ZLMBvQxUpGKw1OArnQ7+99QVP9/7tZSZTQVZd0qHO5IPfm/9mCQLZuBTPFY7G/qA F46HlcNNdaAWJVBh5EmiXQkBrIime1W1qtGtl0lBZaZKsuGJWBbxRdE9h/fCbiBoUtqG AbMy4XPTAO/WzSKU3vJvGhEOA7eTmJkfeWBt8XPmEIdWgf2jDW7PthlDH8C7Gvs4uNxm pu9wky/gH9hC3WMy7EXH74bx6qfCmxfH0+SxZOaIKg4lEEM1SGDQotuNxOwhvwct2/CC n69dr4KFXeDTPtLVJhS0rKt1C2REAWl1Wq97jWP7+nj+qhn+ddNXAbimFj7Lmxg2f5uZ in8w== X-Gm-Message-State: AKS2vOyR26+34QIymuPiIWPe890cQX+/cvibhM1ph9PhgT9eq4uvHMJy n+yCQQJsV2pWb4Sf5d5ltReGftcxIVfI X-Received: by 10.157.7.115 with SMTP id 106mr8953310ote.167.1496798959212; Tue, 06 Jun 2017 18:29:19 -0700 (PDT) MIME-Version: 1.0 Received: by 10.182.224.230 with HTTP; Tue, 6 Jun 2017 18:29:18 -0700 (PDT) In-Reply-To: References: From: James Hilliard Date: Tue, 6 Jun 2017 20:29:18 -0500 Message-ID: To: Karl Johan Alm Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-1.7 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_ENVFROM_END_DIGIT,FREEMAIL_FROM, RCVD_IN_DNSWL_NONE autolearn=no version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Cc: Bitcoin Dev Subject: Re: [bitcoin-dev] User Activated Soft Fork Split Protection X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 07 Jun 2017 01:29:20 -0000 You need a majority of miners enforcing BIP148 upon BIP148 activation to prevent a split, not just a majority signalling segwit. This provides a miner coordination mechanism for BIP148 mandatory signalling enforcement. On Tue, Jun 6, 2017 at 8:11 PM, Karl Johan Alm wrote: > 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 > 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