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 ECB9EF3C for ; Fri, 18 Dec 2015 12:18:57 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from outmail149112.authsmtp.co.uk (outmail149112.authsmtp.co.uk [62.13.149.112]) by smtp1.linuxfoundation.org (Postfix) with ESMTP id 550A1108 for ; Fri, 18 Dec 2015 12:18:56 +0000 (UTC) Received: from mail-c232.authsmtp.com (mail-c232.authsmtp.com [62.13.128.232]) by punt22.authsmtp.com (8.14.2/8.14.2/) with ESMTP id tBICItjG009881; Fri, 18 Dec 2015 12:18:55 GMT Received: from muck ([24.114.39.141]) (authenticated bits=128) by mail.authsmtp.com (8.14.2/8.14.2/) with ESMTP id tBICIlgC051920 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Fri, 18 Dec 2015 12:18:51 GMT Date: Fri, 18 Dec 2015 04:18:45 -0800 From: Peter Todd To: Eric Lombrozo Message-ID: <20151218121845.GB22789@muck> References: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="St7VIuEGZ6dlpu13" Content-Disposition: inline In-Reply-To: X-Server-Quench: 80acb918-a581-11e5-829e-00151795d556 X-AuthReport-Spam: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-AuthRoute: OCd2Yg0TA1ZNQRgX IjsJECJaVQIpKltL GxAVKBZePFsRUQkR bgdMdwoUHFAXAgsB AmMbWlZeUVV7XGA7 aQ5PbARZfElHQQRu UVdMSlVNFUssc2Vy f0JJIRl3dgxEeDBx Z0diWj5TXBUpJ098 SlMFEGUHeGZhPWUC WEJRIh5UcAJPfxhM bwR6UXVDAzANdhEy HhM4ODE3eDlSNhEd ZQdFMVIfCV0GFSMm RgwTVTIhVVYCSTk9 KAYlMTYB X-Authentic-SMTP: 61633532353630.1037:706 X-AuthFastPath: 0 (Was 255) X-AuthSMTP-Origin: 24.114.39.141/587 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 Dev Subject: Re: [bitcoin-dev] On the security of softforks 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, 18 Dec 2015 12:18:58 -0000 --St7VIuEGZ6dlpu13 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Dec 18, 2015 at 03:02:36AM +0000, Eric Lombrozo via bitcoin-dev wro= te: > First of all, that's an expensive beer! >=20 > Second of all, any consensus rule change risks non-full-validating > or non-upgraded nodes seeing invalid confirmations...but assuming a > large supermajority (i.e. > 95%) of hashing power is behind the new > rule, it is extremely unlikely that very many invalid confirmations > will ever be seen by anyone. The number of confirmations you require To clarify, because the 95% of upgraded hashing power is creating valid blocks from the point of view of the remaining 5%, that 95% majority will continually reorg the 5% non-upgrading chain. This ensures that the invalid chain remains short, and thus the # of invalid confirmations possible remains small. For instance, the chance of getting one invalid confirmation is 0.05^1 =3D 5%, two invalid confirmations 0.05^2 =3D 0.25%, = three 0.05^3 =3D 0.01% etc. Whereas with a hard fork, the 5% of miners will continue mining on their own chain. While that chain's length will increase more slowly than normal, the # of confirmations that non-upgraded clients will see on it are unbounded. Anyway, we should write this up as a BIP - there's been a tremendous amount of misinformation, even flat out lies, floating around on this subject. --=20 'peter'[:-1]@petertodd.org 000000000000000001bd68962863e6fa34e9776df361d4926912f52fc5f4b618 --St7VIuEGZ6dlpu13 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- iQGrBAEBCACVBQJWc/miXhSAAAAAABUAQGJsb2NraGFzaEBiaXRjb2luLm9yZzAw MDAwMDAwMDAwMDAwMDAwMWJkNjg5NjI4NjNlNmZhMzRlOTc3NmRmMzYxZDQ5MjY5 MTJmNTJmYzVmNGI2MTgvFIAAAAAAFQARcGthLWFkZHJlc3NAZ251cGcub3JncGV0 ZUBwZXRlcnRvZC5vcmcACgkQwIXyHOf0udwwsAf8Cjiipq5Y3ZPxEchID9S+bI2p 92JYsN+HzifLSlBmQWfgLNMo3orwDQLcnsiUvc5y2GMRamK9ZHwTsOQmyFeWNI4x 7CnDFNsyr3tFeL5w3r+fDxsE+PJhdu+ya40zIgeIybQzSpbjyA9nNoE+OKjve82A i8d88LjXvGAji95YKdsXloedQUffdPRGeicqRfXCid7EPKaZ42xtKTdrZdcIk0Qz KGOjqdypaA3IGMG9npcPt+w2hkxJBcH8yc9k2KVd2GFU51/tyOAf8zk0T/8onUWY W16r/f66hZFzeqUVhJzyoEUGSGPhJa9f2ikPWnDYxJG02+Qw+tIT18dGLCim3g== =2Mka -----END PGP SIGNATURE----- --St7VIuEGZ6dlpu13--