Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 91FBE8F4 for ; Fri, 21 Aug 2015 22:23:12 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-yk0-f177.google.com (mail-yk0-f177.google.com [209.85.160.177]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 1ECC0115 for ; Fri, 21 Aug 2015 22:23:12 +0000 (UTC) Received: by ykbi184 with SMTP id i184so84685865ykb.2 for ; Fri, 21 Aug 2015 15:23:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:from:date:message-id:subject:to:content-type :content-transfer-encoding; bh=Rl+/GiROgdmwdKZ4HcMMCkfSOnnSXqY1mLKwhWuZ1hE=; b=LY8SQEqMVkEqfVKp7Hfq0fi5z9q/2WXZriIx4zJ50E2g2K/GJp6ecmnJnHuUCfTC02 M8c/QDIVIzZ8CFX5JQ57mFsbN3XiKWT6tI8/9O5khl0MyuJZgd6BUeu2moRCsBIp2UKQ /FGGU2G/398e7lEfn1tKzB//K7TltcNSBS5KrIXgzH+dbBUSECOtzeMCDnqnO35D2187 Q/fP4zi8gqiZK6Zn9IB9o43IFiLFh0zNqtkDZAdo3wJl48WBFfMflmFqiAWdBLdWoadt 2HdPszAYttZnkblKBToxjCWUZ6N5+/kkKwD3YANYHNY9pDrKH4n+LVhVy+auns0CmuEP FO7A== X-Received: by 10.13.247.3 with SMTP id h3mr15604840ywf.142.1440195791289; Fri, 21 Aug 2015 15:23:11 -0700 (PDT) MIME-Version: 1.0 Received: by 10.37.94.132 with HTTP; Fri, 21 Aug 2015 15:22:51 -0700 (PDT) From: Btc Drak Date: Fri, 21 Aug 2015 23:22:51 +0100 Message-ID: To: Bitcoin Dev Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=0.2 required=5.0 tests=BAYES_40,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, HK_RANDOM_ENVFROM, HK_RANDOM_FROM, RCVD_IN_DNSWL_LOW 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] Consensus based block size retargeting algorithm (draft) 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: Fri, 21 Aug 2015 22:23:12 -0000 I wanted to offer a potential way to adjust the block size limit in a democratic way without making it easy to game. This is meant only as a starting point for a general idea. Thresholds and exact figures and the details of the algorithm are up for debate, and possibly some formula based determination. The living document is currently a gist available at https://gist.github.com/btcdrak/1c3a323100a912b605b5 
  BIP: XX
  Title: Consensus based block size retargeting algorithm
  Author: BtcDrak 
  Status: Draft
  Type: Standards Track
  Created: 2015-08-21
=3D=3DAbstract=3D=3D A method of altering the maximum allowed block size of the Bitcoin protocol using a consensus based approach. =3D=3DMotivation=3D=3D There is a perception that Bitcoin cannot easily respond to raising the blocksize limit if popularity was to suddenly increase due to a mass adoption curve, because co-ordinating a hard fork takes considerable time, and being unable to respond in a timely manner would irreparably harm the credibility of bitcoin. Additionally, predetermined block size increases are problematic because they attempt to predict the future, and if too large could have unintended consequences like damaging the possibility for a fee market to develop as block subsidy decreases substantially over the next 9 years; introducing or exacerbating mining attack vectors; or somehow affect the network in unknown or unpredicted ways. Since fixed changes are hard to deploy, the damage could be extensive. Dynamic block size adjustments also suffer from the potential to be gamed by the larger hash power. =3D=3DRationale=3D=3D By introducing a cost to increase the block size ensures the mining community will collude to increase it only when there is a clear necessity, and reduce it when it is unnecessary. Rogue miners cannot force their wishes so easily because not only will they have to pay extra a difficulty target, then can be downvoted at no cost by the objecting hash power. =3D=3DSpecification=3D=3D The initial "base block size limit" shall be 1MB. Miners can vote for a block size increase by signalling the proposed percentage increase of the "base block size limit" in the coinbase field. For the vote to be considered valid the block they mine must meets a difficulty target which is proportionally larger than the standard difficulty target based on the percentage increase they voted for. If a miner does not vote, or the vote is invalid, it shall be counted as a vote for no change. Miners may vote the size down by signalling in the coinbase field without paying a difficulty penalty. Every 2016 blocks, the maximum allowed block size will be recalculated by the average of all votes in the last 2016 blocks, i.e. sum each vote from each block and divide by 2016 then multiply by the base block size limit. This will redefine the base block size limit for the next 2016 blocks. Blocks that are larger than the calculated base block size limit are invalid and MUST be rejected. The maximum change up or down each retargeting period shall be limited to 10% of the base block size limit. The maximum block size may not increase above 8MB. Votes shall be cast by adding the following human readable multiplier to the coinbase string =E2=80=9C/BXn.nnn/=E2=80=9D where valid votes would = exist between the ranges =E2=80=9C/BX0.900/=E2=80=9D (10% decrease) and =E2=80=9C= /BX1.100/=E2=80=9D (10% increase). =E2=80=9C/BX1.000/=E2=80=9D would be a vote for no change. Inval= id votes will be counted as a vote for no change: =E2=80=9C/BX1.000/=E2=80=9D. =3D=3DAcknowledgements=3D=3D This proposal is based on ideas and concepts derived from the writings of Meni Rosenfeld and Gregory Maxwell. =3D=3DCopyright=3D=3D This work is placed in the public domain.