Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 837E5266 for ; Thu, 7 Sep 2017 05:56:13 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from outmail148100.authsmtp.co.uk (outmail148100.authsmtp.co.uk [62.13.148.100]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id CFA72D3 for ; Thu, 7 Sep 2017 05:56:12 +0000 (UTC) Received: from mail-c245.authsmtp.com (mail-c245.authsmtp.com [62.13.128.245]) by punt23.authsmtp.com (8.14.2/8.14.2/) with ESMTP id v875u4QQ037254; Thu, 7 Sep 2017 06:56:04 +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 v875u1lZ007764 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 7 Sep 2017 06:56:02 +0100 (BST) Received: from [127.0.0.1] (localhost [127.0.0.1]) by petertodd.org (Postfix) with ESMTPSA id 444C840101; Thu, 7 Sep 2017 05:56:01 +0000 (UTC) Received: by localhost (Postfix, from userid 1000) id 7607A202B4; Thu, 7 Sep 2017 01:55:57 -0400 (EDT) Date: Thu, 7 Sep 2017 01:55:57 -0400 From: Peter Todd To: "Russell O'Connor" , Bitcoin Protocol Discussion Message-ID: <20170907055557.GA12638@fedora-23-dvm> References: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="0OAP2g/MAC+5xKAE" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) X-Server-Quench: 3b3a1b68-9391-11e7-801f-9cb654bb2504 X-AuthReport-Spam: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-AuthRoute: OCd2Yg0TA1ZNQRgX IjsJECJaVQIpKltL GxAVKBZePFsRUQkR aQdMdgUUC1AEAgsB AmEbW1JeVVt7WWA7 bghPaBtcak9QXgdq T0pMXVMcUg1vBFkA WnQeUh51cQEIf395 ZAhhDHMKXRZ8fVt0 QUdVCGwHMGB9YGAe Bl1RJFFSdQcYLB1A alQxNiYHcQ5VPz4z GA41ejw8IwAXBi1O XkkoIEgRRUtDIiQx Sgtq 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=-0.7 required=5.0 tests=RCVD_IN_DNSWL_LOW autolearn=disabled version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Subject: Re: [bitcoin-dev] Fast Merkle 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: Thu, 07 Sep 2017 05:56:13 -0000 --0OAP2g/MAC+5xKAE Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Sep 06, 2017 at 09:59:54PM -0400, Russell O'Connor via bitcoin-dev = wrote: > The fast hash for internal nodes needs to use an IV that is not the > standard SHA-256 IV. Instead needs to use some other fixed value, which > should itself be the SHA-256 hash of some fixed string (e.g. the string > "BIP ???" or "Fash SHA-256"). Note that in general, designs should *not* create new hash functions by usi= ng custom IVs, but rather use bog-standard SHA256, and make a fixed first bloc= k. That allows unoptimised implementations to just hash a block with the second initialization value, and optimized implementations to start with the fixed midstate. --=20 https://petertodd.org 'peter'[:-1]@petertodd.org --0OAP2g/MAC+5xKAE Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- iQEcBAEBCAAGBQJZsN9tAAoJECSBQD2l8JH77pAIAJ49ZmbMUrkSJumHkfj6YoG4 3WspIs25cWXI1wx6d4FrFck4eoBsEabWGlL3VgCj2EiU37ilwFp+tbtn1tUjO9YS aPjMKRXLuqdMPq/JxvLipAf9ftVgGBjHrHYf3vg2tAY7IgJel3ZC7lHIJToh1Y57 0r3IbW9NNI49xkUmyNpqZ/Ytv2ESgAtroxEKMztulIzkxYT/tf/MYejJxZtvIqN4 9i3nTDVUiSd+ZXFMjo6NXpo4kZRDUu4Hd/Cp2DuH1NVISr1abybpKZr7zsPdsH8n h4jlg70nL2bLe9ErDdfq8XIs+0TlRNzVFdO83xbGBUirghZWgUg3hEjeVmym2FA= =yaSx -----END PGP SIGNATURE----- --0OAP2g/MAC+5xKAE--