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 A5E2B8EE for ; Tue, 23 May 2017 20:39:04 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-qk0-f170.google.com (mail-qk0-f170.google.com [209.85.220.170]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id EEE8910E for ; Tue, 23 May 2017 20:39:03 +0000 (UTC) Received: by mail-qk0-f170.google.com with SMTP id k74so140185081qke.1 for ; Tue, 23 May 2017 13:39:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=achow101-com.20150623.gappssmtp.com; s=20150623; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-transfer-encoding:content-language; bh=W531YKYI6GXvyR/Eddt+ypohqqYaNarUer28zXK8n/w=; b=HlxXddp6oM+z1NkXjCVaF9LIu4Qzw1Ri+sDIbpJVjkMD3/vHYLynEaMso/DKLj1Gzf JDCxAPfCFTtamph4yoitgDSH1yCpG4Z4oh7sI0bj7ttvyjxIvr3EexzQEn7Kou7qfgyx mYkn0TVwxgVnUwI6uVo13r+08iENgw7yY/EV4cV6XN1snAB/0l/h2MhQdZqy8mGYCv9V AJ3tXibtIEVa3eClJpiyTn+J72PVew0HoGdArif7MsulBzvJ2E1FEhskPTQPhmXSnP3O PTSJGc4yIagtJMOep9hGagB7jq+rIaSW2rfTKUtWWh8DNMouxMVevz+fHtVr+yK4b9Po A89A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=W531YKYI6GXvyR/Eddt+ypohqqYaNarUer28zXK8n/w=; b=S7wLGp+xRezx1mTqDGf5lTU4aRBZGQSlINxmahOihxGTX+XEGQm/EQFdBBlS0670lo NEXPlFuUCIWLtvpT2JyAsJ9D1KaGtQTXjDMe6ugCFfMIpeJHaaeetbe86u0+HPLOahZ3 ilH3jMPd/Jg92Xj44YamXRc0tvJ3FeRQhKfyFKi63EbWiNFdlaG4LypOfG3zTmC0294y sShiglWFRA9CDgmiwAEQuKB8h/sPJfIQU1YyMfuj57NPP8u+du6Kcm2tLsBOhlvJGFCx YxEvGqEsXZHFuGBYspad7e022vKrWfohkIv5WTOp/1TvbzxPNV+2oWC4l7Vrnaizn6CN KD6A== X-Gm-Message-State: AODbwcBWlGMxk74F+yhtfTZ0u1aRTowCuMk1KpYK+3heO+39iswfHVqJ Gh16zYCZFSo8jEABvMOmqg== X-Received: by 10.55.89.4 with SMTP id n4mr26571169qkb.194.1495571942803; Tue, 23 May 2017 13:39:02 -0700 (PDT) Received: from ?IPv6:2601:45:8200:e070:25a7:dff4:775:a5b8? ([2601:45:8200:e070:25a7:dff4:775:a5b8]) by smtp.gmail.com with ESMTPSA id t20sm1193457qtb.22.2017.05.23.13.39.02 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 23 May 2017 13:39:02 -0700 (PDT) To: bitcoin-dev@lists.linuxfoundation.org References: From: Andrew Chow Message-ID: Date: Tue, 23 May 2017 16:39:19 -0400 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Spam-Status: No, score=-1.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, RCVD_IN_DNSWL_NONE, RCVD_IN_SORBS_SPAM autolearn=no version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Subject: Re: [bitcoin-dev] Reduced signalling threshold activation of existing segwit deployment 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: Tue, 23 May 2017 20:39:04 -0000 Hi James, >From what I understand, this proposal is incompatible with the current segwit implementation with regards to the NODE_WITNESS service bit. I believe it could cause network partitioning if the service bit is not changed. Andrew On 5/22/2017 6:40 PM, James Hilliard via bitcoin-dev wrote: > I would like to propose an implementation that accomplishes the first > part of the Barry Silbert proposal independently from the second: > > "Activate Segregated Witness at an 80% threshold, signaling at bit 4" > in a way that > > The goal here is to minimize chain split risk and network disruption > while maximizing backwards compatibility and still providing for rapid > activation of segwit at the 80% threshold using bit 4. > > By activating segwit immediately and separately from any HF we can > scale quickly without risking a rushed combined segwit+HF that would > almost certainly cause widespread issues. > > Draft proposal: > https://github.com/jameshilliard/bips/blob/bip-segsignal/bip-segsignal.mediawiki > > Proposal text: > 
>   BIP: segsignal
>   Layer: Consensus (soft fork)
>   Title: Reduced signalling threshold activation of existing segwit deployment
>   Author: James Hilliard 
>   Status: Draft
>   Type: Standards Track
>   Created: 2017-05-22
>   License: BSD-3-Clause
>            CC0-1.0
>
> > ==Abstract== > > This document specifies a method to activate the existing BIP9 segwit > deployment with a majority hashpower less than 95%. > > ==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== > > Segwit increases the blocksize, fixes transaction malleability, and > makes scripting easier to upgrade as well as bringing many other > [https://bitcoincore.org/en/2016/01/26/segwit-benefits/ benefits]. > > This BIP provides a way for a simple majority of miners to coordinate > activation of the existing segwit deployment with less than 95% > hashpower. For a number of reasons a complete redeployment of segwit > is difficulty to do until the existing deployment expires. This is due > to 0.13.1+ having many segwit related features active already, > including all the P2P components, the new network service flag, the > witness-tx and block messages, compact blocks v2 and preferential > peering. A redeployment of segwit will need to redefine all these > things and doing so before expiry would greatly complicate testing. > > ==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 a "version bits" with an 80%(this can be > adjusted if desired) activation threshold BIP9 with the name > "segsignal" and using bit 4. > > This BIP will have a start time of midnight June 1st, 2017 (epoch time > 1496275200) and timeout on midnight November 15th 2017 (epoch time > 1510704000). 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);
> }
>
> // SEGSIGNAL mandatory segwit signalling.
> if ( VersionBitsState(pindex->pprev, chainparams.GetConsensus(),
> Consensus::DEPLOYMENT_SEGSIGNAL, versionbitscache) == THRESHOLD_ACTIVE
> &&
>      !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:segsignal-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. Miners will need to upgrade their nodes to > support segsignal otherwise they may build on top of an invalid block. > While this bip is active users should either upgrade to segsignal 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. > > 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. > > ==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-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