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 91D80481 for ; Mon, 22 May 2017 22:40:15 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-oi0-f46.google.com (mail-oi0-f46.google.com [209.85.218.46]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id C51C41FE for ; Mon, 22 May 2017 22:40:14 +0000 (UTC) Received: by mail-oi0-f46.google.com with SMTP id w10so180448127oif.0 for ; Mon, 22 May 2017 15:40:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to; bh=vCS2sNQsBiyAT2iFJeX5KmdfobRH+BhVBnznquk1HKs=; b=rRWZsHiHTLrJv3/fWcl6tqoFBwGqQB3qeDw0w5ckf6/3HzeAz2lhdSbnikkZJtdhkn R5KNH/w4Xq+2L2V7zthfeaIobjnlnH+Bv660b/+HWOhstLfceRSxy0UCwqEzXSmcg4Ik Ae7VWjkiPlYzOFUx6wHzez8kNGjw90YsW6kPszq9d9H8dkzT5V8g6LSw6af/ey3h48Bg Vv53pZrCLBawlnQlbpneu/PS1ihVr6MjhEG0WiNN7HSrC4XigaXgS0hw185PrcjZ1a2R y2n21xpobefi6ShyCjyCRrPd12ZdTXIfYMx2hRus7dDKW6H/4hs88b9zSqZBj1LW4zPP 64ng== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=vCS2sNQsBiyAT2iFJeX5KmdfobRH+BhVBnznquk1HKs=; b=m3Bg5fgsfqS8HAHEzmntcZgdDv6L3BltNgPQ0Gm3P7KRak0l+9IRoD9R+9KFK/Ly1L uL+bre444lnj9wp+ruBs2pdOX9lWvPMEsFz3DbOlxLOPwutTLeJ6EjDuDhB6oY9+DzEo tpxVkFYe3Jug5nyHVTR0BHhLz/1alqD2xZ7pVpO4/3bhZzF4eDmITD2vzEHX3+osJQ98 JYQcSLVtzFOrIzFxEdHF2/LP6fYUWYsSNmg2tONRojstoM7lE6Gz4e/IpJcYtNmj34+L sY03UgiLVLAPl8YjR76Ian1DROBvOcCeC+9sFOsZSMJfZj0GKTinG0y6mYxQ65JfKe+n 82tg== X-Gm-Message-State: AODbwcDqxoq1naFVcXS0tJQxWUT7coHqvpxlx3ziC9rJ7SS2Z9FN+GKg GxeNA/QrEfaHRTRa4DgJKEfqBmp7mVJmMIs= X-Received: by 10.202.107.195 with SMTP id g186mr3357539oic.214.1495492813825; Mon, 22 May 2017 15:40:13 -0700 (PDT) MIME-Version: 1.0 Received: by 10.182.130.166 with HTTP; Mon, 22 May 2017 15:40:13 -0700 (PDT) From: James Hilliard Date: Mon, 22 May 2017 18:40:13 -0400 Message-ID: To: Bitcoin Dev Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-1.2 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_ENVFROM_END_DIGIT,FREEMAIL_FROM, 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: [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: Mon, 22 May 2017 22:40:15 -0000 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.