Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192] helo=mx.sourceforge.net) by sfs-ml-4.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1Y2kxy-00050m-AC for bitcoin-development@lists.sourceforge.net; Sun, 21 Dec 2014 18:10:54 +0000 Received-SPF: pass (sog-mx-2.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.216.54 as permitted sender) client-ip=209.85.216.54; envelope-from=adam.back@gmail.com; helo=mail-qa0-f54.google.com; Received: from mail-qa0-f54.google.com ([209.85.216.54]) by sog-mx-2.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1Y2kxx-0006H4-D5 for bitcoin-development@lists.sourceforge.net; Sun, 21 Dec 2014 18:10:54 +0000 Received: by mail-qa0-f54.google.com with SMTP id i13so426441qae.13 for ; Sun, 21 Dec 2014 10:10:48 -0800 (PST) MIME-Version: 1.0 X-Received: by 10.224.22.196 with SMTP id o4mr30403810qab.85.1419185448014; Sun, 21 Dec 2014 10:10:48 -0800 (PST) Sender: adam.back@gmail.com Received: by 10.96.189.10 with HTTP; Sun, 21 Dec 2014 10:10:47 -0800 (PST) Date: Sun, 21 Dec 2014 18:10:47 +0000 X-Google-Sender-Auth: pI92Ld7gbbkCm2EbJy6i5Ic1ip4 Message-ID: From: Adam Back To: Peter Todd Content-Type: text/plain; charset=UTF-8 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 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-Headers-End: 1Y2kxx-0006H4-D5 Cc: Bitcoin Dev Subject: [Bitcoin-development] one-show signatures (Re: The relationship between Proof-of-Publication and Anti-Replay Oracles) 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: Sun, 21 Dec 2014 18:10:54 -0000 Yes you could for example define a new rule that two signatures (double-spend) authorises something - eg miners to take funds. (And this would work with existing ECDSA addresses & unrestricted R-value choices). I wasnt really making a point other than an aside that it maybe is sort-of possible to do with math what you said was not possible where you said "This [preventing signing more than one message] is impossible to implement with math alone". Adam On 21 December 2014 at 15:29, Peter Todd > There's no need to get into the specifics of crypto math so early; you > can just as easily and only slightly less efficiently obtain the same > result with a few extensions to the Bitcoin scripting system to verify > ECDSA signatures directly.