From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id CB689407 for ; Thu, 22 Oct 2015 20:43:32 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from zinan.dashjr.org (zinan.dashjr.org [192.3.11.21]) by smtp1.linuxfoundation.org (Postfix) with ESMTP id 6BFC7142 for ; Thu, 22 Oct 2015 20:43:32 +0000 (UTC) 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 7305938A566F; Thu, 22 Oct 2015 20:43:18 +0000 (UTC) X-Hashcash: 1:25:151022:justus@openbitcoinprivacyproject.org::9P2tSBvIWK/a=zLJ:aBGiD X-Hashcash: 1:25:151022:bitcoin-dev@lists.linuxfoundation.org::tVWw1g3YJgGpsf+d:QEGi From: Luke Dashjr To: Justus Ranvier Date: Thu, 22 Oct 2015 20:43:16 +0000 User-Agent: KMail/1.13.7 (Linux/4.1.9-gentoo-r1; KDE/4.14.8; x86_64; ; ) References: <201510220554.00367.luke@dashjr.org> <5628F8D2.1010709@openbitcoinprivacyproject.org> In-Reply-To: <5628F8D2.1010709@openbitcoinprivacyproject.org> 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: <201510222043.17582.luke@dashjr.org> X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Cc: Bitcoin Dev Subject: Re: [bitcoin-dev] [Bitcoin-development] Reusable payment codes X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Development Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 22 Oct 2015 20:43:32 -0000 On Thursday, October 22, 2015 2:55:14 PM Justus Ranvier wrote: > On 22/10/15 00:53, Luke Dashjr wrote: > > Sorry for the late review. I'm concerned with the "notification address" > > requirement, which entails address reuse and blockchain spam. Since it > > entails address reuse, the recipient is forced to either leave them > > unspent forever (bloating the UTXO set), or spend it which potentially > > compromises the private key, and (combined with the payment code) > > possibly as much as the entire wallet. > > > > Instead, I suggest making it a single zero-value OP_RETURN output with > > two pushes: 1) a hash of the recipient's payment code, and 2) the > > encrypted payment code. This can be searched with standard bloom > > filters, or indexed with whatever other optimised algorithms are > > desired. At the same time, it never uses any space in the UTXO set, and > > never needs to be > > spent/mixed/dusted. > > The notification transaction portion is my least-favorite portion of the > spec, but I don't see any alternatives that provide an unambiguous > improvement, including your suggestion. > > One of the most highly-weighted goals of this proposal is to be usable > on as many mobile/light wallets as possible. > > I know for sure that all existing platforms for balance querying index > by address. Support for bloom filters or other querying methods is less > comprehensive, meaning the set of wallets that can support payment codes > would be smaller. No, they just need to improve their software, and only to support receiving with payment codes (not sending to them). BIPs should in general not be designed around current software, especially in this case where there is no benefit to doing so (since it requires software upgrades anyway). Luke