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 BEC96918 for ; Tue, 27 Jun 2017 04:13:14 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from outmail149055.authsmtp.co.uk (outmail149055.authsmtp.co.uk [62.13.149.55]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 0B98FCC for ; Tue, 27 Jun 2017 04:13:13 +0000 (UTC) Received: from mail-c245.authsmtp.com (mail-c245.authsmtp.com [62.13.128.245]) by punt21.authsmtp.com (8.14.2/8.14.2/) with ESMTP id v5R4DBnX062202; Tue, 27 Jun 2017 05:13:11 +0100 (BST) Received: from petertodd.org (ec2-52-5-185-120.compute-1.amazonaws.com [52.5.185.120]) (authenticated bits=0) by mail.authsmtp.com (8.14.2/8.14.2/) with ESMTP id v5R4D9iJ064003 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 27 Jun 2017 05:13:10 +0100 (BST) Received: from [127.0.0.1] (localhost [127.0.0.1]) by petertodd.org (Postfix) with ESMTPSA id 18E5A4019E; Tue, 27 Jun 2017 04:13:09 +0000 (UTC) Received: by localhost (Postfix, from userid 1000) id 6D66F207F9; Tue, 27 Jun 2017 00:13:08 -0400 (EDT) Date: Tue, 27 Jun 2017 00:13:08 -0400 From: Peter Todd To: "Russell O'Connor" Message-ID: <20170627041308.GA23776@savin.petertodd.org> References: <20170528082624.GA14552@fedora-23-dvm> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="a8Wt8u1KmwUX3Y2C" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) X-Server-Quench: ee7e8ab8-5aee-11e7-801f-9cb654bb2504 X-AuthReport-Spam: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-AuthRoute: OCd2Yg0TA1ZNQRgX IjsJECJaVQIpKltL GxAVKBZePFsRUQkR aAdMdAUUEkAaAgsB AmEbW1FeUV57WGM7 bghPaBtcak9QXgdq T0pMXVMcUgAKBWgI X2QeVB1ydwYIfXx0 ZQg3C3cOVBUofVt4 ExsBCGwHMGB9YGAe Bl1RJFFSdQcYLB1A alQxNiYHcQ5VPz4z GA41ejw8IwAXAWxw Tx0NKl5aT0ERVhU7 QggfATQpEgUgSj8w KxFuEFkbAF1ZNUt6 GF0nXk4RLxIeaEV0 HkdEGj4RG0MMSjFD X-Authentic-SMTP: 61633532353630.1039:706 X-AuthFastPath: 0 (Was 255) X-AuthSMTP-Origin: 52.5.185.120/25 X-AuthVirus-Status: No virus detected - but ensure you scan with your own anti-virus system. X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_LOW 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] A Method for Computing Merkle Roots of Annotated Binary Trees 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: Tue, 27 Jun 2017 04:13:14 -0000 --a8Wt8u1KmwUX3Y2C Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, May 29, 2017 at 10:55:37AM -0400, Russell O'Connor wrote: > > This doesn't hold true in the case of pruned trees, as for the pruning = to > > be > > useful, you don't know what produced the left merkleRoot, and thus you > > can't > > guarantee it is in fact a midstate of a genuine SHA256 hash. > > >=20 > Thanks for the review Peter. This does seem like a serious issue that I > hadn't considered yet. As far as I understand, we have no reason to think > that the SHA-256 compression function will be secure with chosen initial > values. Relevant: fixed points can be found for the SHA256 compression function, if= the attacker can control the IV: https://crypto.stackexchange.com/questions/48580/fixed-point-of-the-sha-256= -compression-function --=20 https://petertodd.org 'peter'[:-1]@petertodd.org --a8Wt8u1KmwUX3Y2C Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- iQEcBAEBCAAGBQJZUdtPAAoJECSBQD2l8JH7vW8H+wTog/EVQkNq5Zu5i8dNMSk1 u7XfJST+3iJn7BluFL2OqEQMOWw6IxVha96ETHE45rxSdpugfDg4Jz7tZ1kuuoId onkGVvAQeRXWgAY/AKjZ6CrMF1bEpmoNzed2Mz4cq4M4VfItLQupM7dmeTiM/VEN DgiBXmE3PhnLkM9Oj8evjiuW9BQaqGNfHBHxIWQyNmB7YfhlB+WPY2M4RFhsW65z s0vuQTMS7/jTSK0luRFmDmQmv781XQhgFfuqWLwZtIPKU9YODiBil3WQClQOV1J/ PDHcZvl2DaNjO2IhIh20EvJjwbuFtUC5Qv4iEJedjadv+1iwpTmsFp63rhkrc7Y= =rZye -----END PGP SIGNATURE----- --a8Wt8u1KmwUX3Y2C--