Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id CECAFD32 for ; Wed, 24 Feb 2016 05:52:34 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-lf0-f50.google.com (mail-lf0-f50.google.com [209.85.215.50]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id E442CAB for ; Wed, 24 Feb 2016 05:52:33 +0000 (UTC) Received: by mail-lf0-f50.google.com with SMTP id l143so4879603lfe.2 for ; Tue, 23 Feb 2016 21:52:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:date:message-id:subject:from:to:content-type; bh=aVMWj7w4JftQ1zzI9F6lSsq89feKDLnFKHUaCT9s+jk=; b=fjcF+UtKR23IF7wm9KeJQ3ojYy8XnH+M9Wr8ahYv7A7dpecWACo2iywNd24AeU+r/I 5Y7xkaigfkR8FmI1q2V0bLCFehxndMLqoYLsoVPIwt1FvNpXOTZdo8mXf3KX/T8OcjmB RWcfDvW9xAAWx9OZ7Cg3bkv0zD/1Axk3XoL0NcmAp7/75UGkia2uABoFRlD2rHp4VbzG sjwaqwesW5YehvUSwJBWD8D3KsuK21tCjRmMDbkSwd10MmVbKImyBw7Qd5+ukHh81rNz WmRrfoXCdx256Nfgty5LyERk0tB61Ppc8E2VEAD0tSJgTeczojiQak77bXdnUsUvOgZN E8JQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:date:message-id:subject:from:to :content-type; bh=aVMWj7w4JftQ1zzI9F6lSsq89feKDLnFKHUaCT9s+jk=; b=hxI0DJHE0/2LVlMFJj8T7FLKCjbgv2P0Yew3ha4Q5eDMFBXGteCuf8rfYBioxzdoMj u96KREc/eWrMALzXaocOinr6mEpTyMoXBeZnuIqH4PvXjam/y5vQEZP2vsgemaER9krJ JvMYU67/s8KGh42Yw3oFB0yqp8QfNrvabiQzOWLSCjLCYqnkuUp/hYmYw+3B9Vnh3McQ mS35LMpROXjSE3NyL/3Rd0riEmiDbz5DsseGOsDdXp31vpBBYYgbtQ3v1Nwos43b7jTo E10PmET0yLDTsqIDXebJMiVCxeTLgx7sB1jKklrM5G6g91Cza81gIARpasVxTGpKO8Q/ 5S9w== X-Gm-Message-State: AG10YOTuS+wqvEUp+O5Skd0uGyuSB11egP1zcK7t9nbhpssBUAnfmWajwemo/px0UDQw712Mf0AFAdAFJyjWhw== MIME-Version: 1.0 X-Received: by 10.25.28.195 with SMTP id c186mr11195110lfc.22.1456293152264; Tue, 23 Feb 2016 21:52:32 -0800 (PST) Received: by 10.112.215.3 with HTTP; Tue, 23 Feb 2016 21:52:32 -0800 (PST) Date: Tue, 23 Feb 2016 23:52:32 -0600 Message-ID: From: James Hilliard To: bitcoin-dev@lists.linuxfoundation.org Content-Type: text/plain; charset=UTF-8 X-Spam-Status: No, score=-2.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_ENVFROM_END_DIGIT,FREEMAIL_FROM, RCVD_IN_DNSWL_LOW autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org X-Mailman-Approved-At: Wed, 24 Feb 2016 08:01:09 +0000 Subject: [bitcoin-dev] Multi-Stage Merge-Mine Headers Hard-Fork BIP X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Development Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 24 Feb 2016 05:52:34 -0000 https://github.com/bitcoin/bips/pull/340 BIP: ? Title: 2016 Multi-Stage Merge-Mine Headers Hard-Fork Author: James Hilliard Status: Draft Type: Standards Track Created: 2016-02-23 ==Abstract== Use a staged hard fork to implement a headers format change that is merge mine incompatible along with a timewarp to kill the previous chain. ==Specification== We use a block version flag to activate this fork when 3900 out of the previous 4032 blocks have this the version flag set. This flag locks in both of the below stages at the same time. Merge Mine Stage: The initial hard fork is implemented using a merge mine which requires that the original pre-fork chain be mined with a generation transaction that creates no new coins in addition to not containing any transactions. Additionally we have a consensus rule that requires that ntime be manipulated on the original chain to artificially increase difficulty and hold back the original chain so that all non-upgraded clients can never catch up with current time. The artificial ntime is implemented as a consensus rule for blocks in the new chain. Headers Change Stage: This is the final stage of the hard fork where the header format is made incompatible with merge mining, this is activated ~50,000 blocks after the Merge Mine Stage and only at the start of the 2016 block difficulty boundary. ==Motivation== There are serious issues with pooled mining such as block withhold attacks that can only be fixed by making major changes to the headers format. There are a number of other desirable header format changes that can only be made in a non-merge mine compatible way. There is a high risk of there being two viable chains if we don't have a way to permanently disable the original chain. ==Rationale== Our solution is to use a two stage hard fork with a single lock in period. The first stage is designed to kill off the previous chain by holding back ntime to artificially increase network difficulty on the original chain to the point where it would be extremely difficult to mine the 2016 blocks needed to trigger a difficulty adjustment. This also makes it obvious to unupgraded clients that they are not syncing properly and need to upgrade. By locking in both stages at the same time we ensure that any clients merge mining are also locked in for the headers change stage so that the original chain is dead by the time the headers change takes place. We timewarp over a year of merge mining to massively increase the difficulty on the original chain to the point that it would be incredibly expensive to reduce the difficulty enough that the chain would be able to get caught up to current time. ==Backward Compatibility== This hardfork will permanently disable all nodes, both full and light, which do not explicitly add support for it. However, their security will not be compromised due to the implementation. To migrate, all nodes must choose to upgrade, and miners must express supermajority support. ==Reference Implementation== TODO