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 174ECB76 for ; Wed, 7 Jun 2017 01:54:40 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-oi0-f43.google.com (mail-oi0-f43.google.com [209.85.218.43]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 2A23C1DF for ; Wed, 7 Jun 2017 01:54:39 +0000 (UTC) Received: by mail-oi0-f43.google.com with SMTP id p7so5949311oif.2 for ; Tue, 06 Jun 2017 18:54:39 -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=dzqm6L1bgsIWuZ2GZ8eVmKLbC7heWqw7qU+diOCXCjA=; b=U4sgU1N/GxalKHQzRU1f6fTBY33+gyoT8d++kkvAxL1NqPkh7l9eiUxtUlbxoodv9O 27PW3MfdtMO0r8TJA29QPuoYe/EWMUQkJkR1I+SypjG5qshBqyGVpj1aykhL3JvWWRAE oIW8DlY8AB6yn++oTa/AehcaYfm+67bTQ9B/lTjUdZntdpSLIKwCK7wYkJVXIy/ySjQ6 rKFX3TkueCgV72qccvCJvRz40jP/r5u7t9/WdTxLJ8yIZSoH7PKfSpcsuUipyVUwl6RU 6F7pxKQnEO17xSMQgWFUpywKPC/Kh8TYGAcFm7Qda3ZpT5EWv4ubfSaORJ/yGVmJ1vu3 UTCQ== 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=dzqm6L1bgsIWuZ2GZ8eVmKLbC7heWqw7qU+diOCXCjA=; b=oFN0LuJ1to3PkOg2ZgiIO/FyoYbT5K3N48WHPB8rZAzxMMOe0aYXvhLMTjhZ2uSgYw JIVFgC4TBSQABvplKwoh6Eyqv7AmMp9Pnmww0ENIlsXZ3M7p5aEg2biXI46W7mcy346+ AJ6zYM/IfCsgDClmgnCi4qR0Mn2YiRBmNPckeBnz7p7l5PMnMXM61qu88NL0GZYNLCMd deFVWv9iGSYwsI2u7ztTfjk6D6e5X6Rmi45ko7NDEdJSh9KbT7TG2ODnTyR61yKNLoZ/ X9ebIaWRRzuBZs1NjBRZcyWbm9ZBYNTSb6htMGyI4fNHGCawt/Zb5jhnxB3TTYrkh2/k 19Kw== X-Gm-Message-State: AODbwcAL6ZBch8F+F7qXrPnnav9x0+61+nJrvAwreSnZWaBZvYtTs7Vr zU2XtxpzpwRt6y2b2Vzeo14BXGMZmKSX X-Received: by 10.202.87.21 with SMTP id l21mr13781219oib.214.1496800478362; Tue, 06 Jun 2017 18:54:38 -0700 (PDT) MIME-Version: 1.0 Received: by 10.182.224.230 with HTTP; Tue, 6 Jun 2017 18:54:37 -0700 (PDT) In-Reply-To: References: From: James Hilliard Date: Tue, 6 Jun 2017 20:54:37 -0500 Message-ID: To: Tao Effect 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 01:54:40 -0000 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 > >