From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-1.v43.ch3.sourceforge.com ([172.29.43.191] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1Z1FtC-000505-2i for bitcoin-development@lists.sourceforge.net; Sat, 06 Jun 2015 15:20:02 +0000 Received-SPF: pass (sog-mx-1.v43.ch3.sourceforge.com: domain of dashjr.org designates 85.234.147.28 as permitted sender) client-ip=85.234.147.28; envelope-from=luke@dashjr.org; helo=zinan.dashjr.org; Received: from 85-234-147-28.static.as29550.net ([85.234.147.28] helo=zinan.dashjr.org) by sog-mx-1.v43.ch3.sourceforge.com with esmtp (Exim 4.76) id 1Z1FtA-00060X-Sw for bitcoin-development@lists.sourceforge.net; Sat, 06 Jun 2015 15:20:02 +0000 Received: from ishibashi.localnet (unknown [IPv6:2001:470:5:265:61b6:56a6:b03d:28d6]) (Authenticated sender: luke-jr) by zinan.dashjr.org (Postfix) with ESMTPSA id 625041083AA6; Sat, 6 Jun 2015 15:18:20 +0000 (UTC) X-Hashcash: 1:25:150606:bitcoin-development@lists.sourceforge.net::anvbofXybXPxuOtv:bwk/Y X-Hashcash: 1:25:150606:kalle@rosenbaum.se::FVGrsG3HdaoU0s6N:afce/ X-Hashcash: 1:25:150606:gmaxwell@gmail.com::OT1=2BaywKYqkIvo:crfYW From: Luke Dashjr To: bitcoin-development@lists.sourceforge.net Date: Sat, 6 Jun 2015 15:18:18 +0000 User-Agent: KMail/1.13.7 (Linux/3.14.41-gentoo; KDE/4.14.3; x86_64; ; ) References: In-Reply-To: X-PGP-Key-Fingerprint: E463 A93F 5F31 17EE DE6C 7316 BD02 9424 21F4 889F X-PGP-Key-ID: BD02942421F4889F X-PGP-Keyserver: hkp://pgp.mit.edu MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Message-Id: <201506061518.19431.luke@dashjr.org> X-Spam-Score: -1.5 (-) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. 0.0 TVD_RCVD_IP Message was received from an IP address -1.5 SPF_CHECK_PASS SPF reports sender host as permitted sender for sender-domain -0.0 SPF_PASS SPF: sender matches SPF record X-Headers-End: 1Z1FtA-00060X-Sw Subject: Re: [Bitcoin-development] BIP for Proof of Payment 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, 06 Jun 2015 15:20:02 -0000 On Saturday, June 06, 2015 2:35:17 PM Kalle Rosenbaum wrote: > Current methods of proving a payment: > > * Signing messages, chosen by the server, with the private keys used to > sign the transaction. This could meet 1 and 2 but probably not 3. This is > not standardized either. 4 Could be met if designed so. It's also not secure, since the signed messages only prove ownership of the address associated with the private key, and does not prove ownership of UTXOs currently redeemable with the private key, nor prove past UTXOs spent were approved by the owner of the address. > A proof of payment for a transaction T, here called PoP(T), is used to > prove that one has ownership of the credentials needed to unlock all the > inputs of T. This appears to be incompatible with CoinJoin at least. Maybe there's some clean way to avoid that by using https://github.com/Blockstream/contracthashtool ? > It has the exact same structure as a bitcoin transaction with > the same inputs and outputs as T and in the same order as in T. There is > also one OP_RETURN output inserted at index 0, here called the pop output. I also agree with Pieter, that this should *not* be so cleanly compatible with Bitcoin transactions. If you wish to share code, perhaps using an invalid opcode rather than OP_RETURN would be appropriate. Luke