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 BC618D84 for ; Fri, 26 Feb 2016 02:35:36 +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 6F69711F for ; Fri, 26 Feb 2016 02:35:36 +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 7997938A2C94; Fri, 26 Feb 2016 02:35:25 +0000 (UTC) X-Hashcash: 1:25:160226:bitcoin-dev@lists.linuxfoundation.org::YQZqlp3cn848DFNm:pvrL X-Hashcash: 1:25:160226:joseph@lightning.network::z03/kUSthjQPnem3:Qg0= From: Luke Dashjr To: bitcoin-dev@lists.linuxfoundation.org, Joseph Poon Date: Fri, 26 Feb 2016 02:35:23 +0000 User-Agent: KMail/1.13.7 (Linux/4.1.18-gentoo; KDE/4.14.8; x86_64; ; ) References: <20160226010746.GB10295@lightning.network> In-Reply-To: <20160226010746.GB10295@lightning.network> 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-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201602260235.24687.luke@dashjr.org> X-Spam-Status: No, score=-1.8 required=5.0 tests=BAYES_00,RCVD_IN_SBL autolearn=no version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Subject: Re: [bitcoin-dev] SIGHASH_NOINPUT in Segregated Witness 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: Fri, 26 Feb 2016 02:35:36 -0000 On Friday, February 26, 2016 1:07:46 AM Joseph Poon via bitcoin-dev wrote: > This would be achieved using a SIGHASH flag, termed SIGHASH_NOINPUT. It > does not include as part of the signature, the outpoint being spent > (txid and index), nor the amount. It however, would include the spent > outpoint's script as part of the signature. Note that this is just a > SIGHASH flag, and the outpoints are still being included as part of the > txins (if they are mutated, the new txids can be updated by the wallet > without resigning). This allows for a signature to apply to anything > with that pubkey (therefore pubkeys with this flag should not be > reused). I'd like this regardless of Lightning, as it makes it possible to write fully malleability-proof wallet software also. > For safety, this only applies in SegWit transactions, as segwit > provides a sufficient malleability solution, there is no incentive to > improperly use this sighash flag as a roundabout way to resolve > malleability. SegWit's malleability solution is not really sufficient in comparison, but I don't think there's a need to make this available to pre-SegWit transactions anyway (and doing so would probably complicate it). Luke