Received: from sog-mx-1.v43.ch3.sourceforge.com ([172.29.43.191] helo=mx.sourceforge.net) by sfs-ml-3.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1S4Yg6-0001YX-FK for bitcoin-development@lists.sourceforge.net; Mon, 05 Mar 2012 14:14:18 +0000 Received-SPF: softfail (sog-mx-1.v43.ch3.sourceforge.com: transitioning domain of mac.com does not designate 95.166.54.49 as permitted sender) client-ip=95.166.54.49; envelope-from=gronager@mac.com; helo=mail.ceptacle.com; Received: from 2508ds5-oebr.0.fullrate.dk ([95.166.54.49] helo=mail.ceptacle.com) by sog-mx-1.v43.ch3.sourceforge.com with esmtp (Exim 4.76) id 1S4Yg2-0001JM-6r for bitcoin-development@lists.sourceforge.net; Mon, 05 Mar 2012 14:14:18 +0000 Received: from localhost (localhost [127.0.0.1]) by mail.ceptacle.com (Postfix) with ESMTP id 4F36C18701B8; Mon, 5 Mar 2012 15:14:08 +0100 (CET) X-Virus-Scanned: amavisd-new at ceptacle.com Received: from mail.ceptacle.com ([127.0.0.1]) by localhost (server.ceptacle.private [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id TvNnh2aLVJT0; Mon, 5 Mar 2012 15:14:08 +0100 (CET) Received: from [10.0.1.28] (2508ds5-oebr.0.fullrate.dk [95.166.54.49]) by mail.ceptacle.com (Postfix) with ESMTPSA id 2D37A18701B2; Mon, 5 Mar 2012 15:14:08 +0100 (CET) Mime-Version: 1.0 (Apple Message framework v1257) Content-Type: text/plain; charset=us-ascii From: =?iso-8859-1?Q?Michael_Gr=F8nager?= In-Reply-To: Date: Mon, 5 Mar 2012 15:14:07 +0100 Content-Transfer-Encoding: quoted-printable Message-Id: <6A095CA9-8A01-4578-A660-CED02B24F215@mac.com> References:

To: Watson Ladd X-Mailer: Apple Mail (2.1257) X-Spam-Score: 1.0 (+) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (gronager[at]mac.com) 1.0 SPF_SOFTFAIL SPF: sender does not match SPF record (softfail) X-Headers-End: 1S4Yg2-0001JM-6r Cc: bitcoin-development@lists.sourceforge.net Subject: Re: [Bitcoin-development] Proposal for a new opcode 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: Mon, 05 Mar 2012 14:14:18 -0000 Sounds interesting, however, even after a couple of days, I cannot see = how you maintain protection against double spend using OP_CHECKEXPSIG. = It is not until you redeem the OP_CHECKEXPSIG transaction that you = reveal which former transactions that was involved? I guess I am missing a point here? /M =20 On 02/03/2012, at 20:57, Watson Ladd wrote: > Dear all, > I am proposing a new opcode for the purposes of anonymous > transactions. This new opcode enables scripts to be given proof that > the receiver can carry out or has carried out a previous transaction. > I'm currently working on a paper that discusses using this opcode for > anonymous transactions. >=20 > Name: OP_CHECKEXPSIG > Stack before: > Stack after: T/F, where is true if sig is a ECDSA signature under pk > for the hash hash. (Hash is the hash of a message). > Uses: Preexisting digital cash techniques relied on keeping track of a > list of turned in notes to forbid double spending. Using > OP_CHECKEXPSIG we can instead pass the script that gives the nth note > value proof that the notes {1,...n-1} were turned in and are distinct. > This enables a coupling of the strong double spend protection of > Bitcoin with traditional digital cash's strong anonymity. >=20 > Sincerely, > Watson Ladd >=20 > = --------------------------------------------------------------------------= ---- > Virtualization & Cloud Management Using Capacity Planning > Cloud computing makes use of virtualization - but cloud computing=20 > also focuses on allowing computing to be delivered as a service. > http://www.accelacomm.com/jaw/sfnl/114/51521223/ > _______________________________________________ > Bitcoin-development mailing list > Bitcoin-development@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/bitcoin-development Michael Gronager, PhD Director, Ceptacle Jens Juels Gade 33 2100 Copenhagen E Mobile: +45 31 45 14 01 E-mail: gronager@ceptacle.com Web: http://www.ceptacle.com/