Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 4A1FDD4D for ; Thu, 15 Mar 2018 14:14:27 +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 C1F982C3 for ; Thu, 15 Mar 2018 14:14:26 +0000 (UTC) Received: from ishibashi.localnet (unknown [IPv6:2001:470:5:265::71]) (Authenticated sender: luke-jr) by zinan.dashjr.org (Postfix) with ESMTPSA id 824D138A1306; Thu, 15 Mar 2018 14:14:07 +0000 (UTC) X-Hashcash: 1:25:180315:karljohan-alm@garage.co.jp::we3pHL1LUfTOYzhK:CUfd X-Hashcash: 1:25:180315:bitcoin-dev@lists.linuxfoundation.org::7rOJUhHQdHvW=Phc:bbDM1 From: Luke Dashjr To: Karl Johan Alm Date: Thu, 15 Mar 2018 14:14:04 +0000 User-Agent: KMail/1.13.7 (Linux/4.15.1-gentoo; KDE/4.14.37; x86_64; ; ) References: <201803141236.48869.luke@dashjr.org> 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="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <201803151414.06301.luke@dashjr.org> X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_MED, T_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 Protocol Discussion Subject: Re: [bitcoin-dev] {sign|verify}message replacement X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 15 Mar 2018 14:14:27 -0000 On Thursday 15 March 2018 7:36:48 AM Karl Johan Alm wrote: > On Wed, Mar 14, 2018 at 12:36 PM, Luke Dashjr wrote: > > Ideally, it should support not only just "proof I receive at this > > address", but also "proof of funds" (as a separate feature) since this > > is a popular misuse of the current message signing (which doesn't > > actually prove funds at all). To do this, it needs to be capable of > > signing for multiple inputs. > > Re-reading this, I think what you mean is it should be possible to > create a proof for (a) specific UTXO(s), hence "inputs". That sounds > pretty useful, yeah! Not necessarily specific UTXOs (that would contradict fungibility, as well as be impossible for hot/cold wallet separation), but just to prove funds are available. The current sign message cannot be used to prove present possession of funds, only that you receive funds.