From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-3.v43.ch3.sourceforge.com ([172.29.43.193] helo=mx.sourceforge.net) by sfs-ml-3.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1UcaDh-0005YS-8V for bitcoin-development@lists.sourceforge.net; Wed, 15 May 2013 11:50:09 +0000 Received-SPF: pass (sog-mx-3.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.215.175 as permitted sender) client-ip=209.85.215.175; envelope-from=adam.back@gmail.com; helo=mail-ea0-f175.google.com; Received: from mail-ea0-f175.google.com ([209.85.215.175]) by sog-mx-3.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1UcaDg-0002zn-Fh for bitcoin-development@lists.sourceforge.net; Wed, 15 May 2013 11:50:09 +0000 Received: by mail-ea0-f175.google.com with SMTP id h10so841010eaj.20 for ; Wed, 15 May 2013 04:50:02 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=x-received:date:from:to:cc:subject:message-id:references :mime-version:content-type:content-disposition:in-reply-to :user-agent:x-hashcash:x-hashcash:x-hashcash; bh=/2IGc7kCtUV16C2DfeqV8Df+ctITbo3JUH5Yk1R7OX4=; b=RLnsbK/8A0QUMcAdzLBTQZqEygUElc34DEUuuVGhoTMn9DlufztTc1haSZUT25PZ0p 4v4pcL1G64bKMLBrp+8i3Py+yZxvwK4SbxGzUBe5iIpYtSTvKZdxt8d92NTQ31UusAFQ cUDSCbjTvPDW9q7Xkb5g2xHYiUOgy2kDeLZ3H17wyvm15AxxyHv34LXmzLSLbZoTthfI CMUiYVw/nDQyZad2F36delSYxpubarAIfiWR2quSsqdUjmWuQeTsW+4dn+NBnzYYR+cr NFgpnBrf1wB4ucKopzUtUvNEkyoQBo9ALU+vXeVGS7+BQKXfDbh+iAtQYOawTCOiWtWU w7DQ== X-Received: by 10.14.5.5 with SMTP id 5mr102993359eek.21.1368618602086; Wed, 15 May 2013 04:50:02 -0700 (PDT) Received: from netbook (c83-90.i07-21.onvol.net. [92.251.83.90]) by mx.google.com with ESMTPSA id n7sm3487759eeo.0.2013.05.15.04.50.00 for (version=TLSv1.1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 15 May 2013 04:50:01 -0700 (PDT) Received: by netbook (Postfix, from userid 1000) id A0B912E04CB; Wed, 15 May 2013 13:49:58 +0200 (CEST) Received: by flare (hashcash-sendmail, from uid 1000); Wed, 15 May 2013 13:49:57 +0200 Date: Wed, 15 May 2013 13:49:56 +0200 From: Adam Back To: Peter Todd Message-ID: <20130515114956.GA5863@netbook.cypherspace.org> References: <20130514115151.GA21600@netbook.cypherspace.org> <20130514140902.GA22447@netbook.cypherspace.org> <20130515102509.GA3401@netbook.cypherspace.org> <20130515111906.GA26020@savin> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20130515111906.GA26020@savin> User-Agent: Mutt/1.5.21 (2010-09-15) X-Hashcash: 1:20:130515:pete@petertodd.org::NVCPtglmb9muqfBZ:0000000000000000000 0000000000000000000000001EBZ X-Hashcash: 1:20:130515:bitcoin-development@lists.sourceforge.net::n718vnr63uBLI S7k:00000000000000000000722X X-Hashcash: 1:20:130515:adam@cypherspace.org::ahpLk4zPhzHvnjqP:00000000000000000 0000000000000000000000000gOQ X-Spam-Score: -1.5 (-) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -1.5 SPF_CHECK_PASS SPF reports sender host as permitted sender for sender-domain 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (adam.back[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record X-Headers-End: 1UcaDg-0002zn-Fh Cc: Bitcoin-Dev Subject: Re: [Bitcoin-development] blind symmetric commitment for stronger byzantine voting resilience (Re: bitcoin taint & unilateral revocability) X-BeenThere: bitcoin-development@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 15 May 2013 11:50:09 -0000 On Wed, May 15, 2013 at 07:19:06AM -0400, Peter Todd wrote: >Protocols aren't set in stone - any attacker that controls enough >hashing power to pose a 51% attack can simply demand that you use a >Bitcoin client modified [to facilitate evaluation of his policy] Protocol voting is a vote per user policy preference, not a CPU vote, which is the point. Current bitcoin protocol is vulnerable to hard to prove arbitrary policies being imposable by a quorum of > 50% miners. The blind commitment proposal fixes that, so even an 99% quorum cant easily impose policies, which leaves the weaker protocol vote attack as the remaining avenue of attack. That is a significant qualitative improvement. The feasibility of protocol voting attacks is an open question, but you might want to consider the seeming unstoppability of p2p protocols for a hint. Adam