Received: from sog-mx-3.v43.ch3.sourceforge.com ([172.29.43.193] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1TFK8N-0006VW-TK for bitcoin-development@lists.sourceforge.net; Sat, 22 Sep 2012 07:28:15 +0000 X-ACL-Warn: Received: from mail-qc0-f175.google.com ([209.85.216.175]) by sog-mx-3.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1TFK8J-0006Uz-E8 for bitcoin-development@lists.sourceforge.net; Sat, 22 Sep 2012 07:28:15 +0000 Received: by qcad10 with SMTP id d10so3318187qca.34 for ; Sat, 22 Sep 2012 00:28:05 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=mime-version:x-originating-ip:date:message-id:subject:from:to :content-type:x-gm-message-state; bh=8AJM3/sQjYWHn/WJDmCVBvn3qRuCRgL6DJ8sdK22bZI=; b=MkT6AFmRlZp67qjvT4RPMrPk4AfbLDr83mdHa8QTJ7MEqPp9YssNEQGjC/qmAIYKke E//IZyn9JNSxK9p5uBGuRAJERONX/Yrv120lDi8+ee8z7uZzucZ034mkF1aNgzZN55Xw QdmHWqS+3IlvQYEsveHATpmHcS9gZS11jSH6q7E7/reRHTyxzoCRCsd8TrCZxKanH/xs YdpWG+CVIQYsNWpbgDGYLIKBTVLzcdSkxKgUYZg4IgF6xZ5pkBi68AGhRl0kkWbgfcWn odju/aGvNVjHQpSMirPW1cbaKEvE2pKcfzFvBeCSFekNXDqnX7eWESEbPLZtJl+usbSD xVTg== MIME-Version: 1.0 Received: by 10.224.115.208 with SMTP id j16mr17829992qaq.54.1348298885616; Sat, 22 Sep 2012 00:28:05 -0700 (PDT) Received: by 10.49.97.6 with HTTP; Sat, 22 Sep 2012 00:28:05 -0700 (PDT) X-Originating-IP: [2001:4830:1603:2:21c:c0ff:fe79:c8c2] Date: Sat, 22 Sep 2012 03:28:05 -0400 Message-ID: From: Jeff Garzik To: Bitcoin Development Content-Type: text/plain; charset=ISO-8859-1 X-Gm-Message-State: ALoCoQmP3x4VdtsIkyEoPlU7TKlSXkyriB1Qu1qOiB2j4yJft4AM+dz3bJAr9u2834iYFIUpblkL X-Spam-Score: 0.0 (/) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. X-Headers-End: 1TFK8J-0006Uz-E8 Subject: [Bitcoin-development] Atomic coin swapping? 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: Sat, 22 Sep 2012 07:28:16 -0000 Forum URL: https://bitcointalk.org/index.php?topic=112007.0 gmaxwell was talking about colored coins[1] in IRC recently. They are potentially interesting in the context of distributed bonds[2], which I am currently pursuing with pybond[3]. Here is the problem I am trying to solve, does the crowd have an answer? 1. Alice transfers a 1-satoshi colored coin to Bob. 2. Bob transfers 100 BTC to Alice. May be restricted to 1 txout, if that eases implementation details. 3. Steps #1 and #2 happen as an atomic unit, all-or-none. 4. Alice and Bob must both approve this atomic transfer of coins, with appropriate signatures. Is this possible within the current bitcoin system? As far as I can see, the answer is "no" but maybe I'm missing something. My best guess to the answer is "possible, but requires a new SIGHASH_* type"? [1] https://bitcointalk.org/index.php?topic=106449.0 [2] https://bitcointalk.org/index.php?topic=92421.0 [3] https://github.com/jgarzik/pybond -- Jeff Garzik exMULTI, Inc. jgarzik@exmulti.com