From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-5.0 required=3.0 tests=AWL,BAYES_00, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_HI,RP_MATCHES_RCVD shortcircuit=no autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id DC4AE2018B for ; Mon, 18 Jul 2016 15:58:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751689AbcGRP6F (ORCPT ); Mon, 18 Jul 2016 11:58:05 -0400 Received: from mout.gmx.net ([212.227.15.18]:49889 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751396AbcGRP6D (ORCPT ); Mon, 18 Jul 2016 11:58:03 -0400 Received: from virtualbox ([37.24.142.100]) by mail.gmx.com (mrgmx001) with ESMTPSA (Nemesis) id 0LdYdG-1az9pQ2pj0-00inl2; Mon, 18 Jul 2016 17:57:38 +0200 Date: Mon, 18 Jul 2016 17:57:37 +0200 (CEST) From: Johannes Schindelin X-X-Sender: virtualbox@virtualbox To: Herczeg Zsolt cc: "brian m. carlson" , Theodore Ts'o , Duy Nguyen , Git Mailing List Subject: Re: Git and SHA-1 security (again) In-Reply-To: Message-ID: References: <20160716201313.GA298717@vauxhall.crustytoothpaste.net> <20160717142157.GA6644@vauxhall.crustytoothpaste.net> <20160717154234.GC6644@vauxhall.crustytoothpaste.net> <20160717162349.GB11276@thunk.org> <20160717220417.GE6644@vauxhall.crustytoothpaste.net> <1468804249.2037.0@smtp.gmail.com> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Provags-ID: V03:K0:iDB6bpl3Kl322dJ/ka06AQa+7kqn7XlkM+sivvCCeDWLzyoQbj2 Mcr1eT3NnIQB1/MVq+Zbk/nzQy1jMRVhS7H/MCZW/6u3duyIq9TUj46bN/oQ3skb1SAu4/v ogQeRgROr451SkiE7QMUDIvfCwGzfn0I04fp9D2r6MQ7ysOyrM8fzxFVrYc77SR1a/3o1wO P5+/P+VMYkOCfaEA6iO+g== X-UI-Out-Filterresults: notjunk:1;V01:K0:Shzhswt4WDg=:NbzQR/DnIrPmJiXEjvV6cl ENh/e/zByVQ7lyyNDdq89+YTOZmC4/dkJQnMhGse0lQ2htLPyavgVKW6Em6Aq5F8CNV9BQZNm /IWSaZSfeuBBf51CqzMvqHbgB6cmFea6V3hKT3yAl2Lz/EY4sCVSL5G3uxIEgjA8W2+scNlOr Sr3MsCh+DKFbst2ErEMA4bR3t//oSUsF2LDWHgwFF/o6WX+Zc+TxjOGw1wRY1OdjAmDpCPiQs 6JWib2NhKutnrIO5OhG/lQkqKDrvgr0wUaKwCaRO1Ygf4mUEwKiXgnsXA4dlPD1Lb3xdstf6Q N1XTocczVhCZgKt9Tn4p8FhNkYe+o6Ys6Ism+dhodA8a1CxrfHwSGfRRrppdEBlV/hqAoW/5Z WKeFWgl/yIIZTKczzYdQQdY/nNB/r6WdWWkiPiH+/GdYsnTwid0wJo5xNH6AePM0RSjtkhEU4 3TxttBYiIL4CJM7uL6VcbdhrPZFRrYe+JAX5x92iHyxm5esdRff1CKWY7KkCv3IaL5AJlOCZp 2Cpx3jmh4p1R9JjwB2MIhAzQqLOjetVpj7FFwGm7OC/bWOLq0GPcunimUmiBAKxq0IGKXv24C 15SnYwu4JG530rsh4zhOkWMYfHGWpPOL9qNqjicFmDiCDvDUyZbGKp9m0Pzz1u1ZEO1uLqMoh b1VPjJDRlx5kpnBAwXhdXPvryVsUtarnJx4zV7zUVeyTjZ8JkMMGt4OEhKkPPjMsCnTdCB7Yw 5FK/eZ00PXBAnV8tTFgQWzp/VvZ5WGUc8X32oS6iI9+0WFS0hQLbeBCgQpSxgKA+UgXpkR0sQ pPXfle/ Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Hi Zsolt, On Mon, 18 Jul 2016, Herczeg Zsolt wrote: > >> I think converting is a much better option. Use a single-hash > >> storage, and convert everything to that on import/clone/pull. > > > > That ignores two very important issues that I already had mentioned: > > That's not true. If you double-check the next part of my message, you I > just showed that an automatic two-way mapping could solve these > problems! (I even give briefs explanation how to handle referencing and > signature verification in those cases.) > > My point is not to throw out old hashes and break signatures. My point > is to convert the data storage, and use mapping to resolve problems > with those old hashes and signatures. If you convert the data storage, then the SHA-1s listed in the commit objects will have to be rewritten, and then the GPG signature will not match anymore. Call e.g. `git cat-file commit 44cc742a8ca17b9c279be4cc195a93a6ef7a320e` to see the anatomy of a gpg-signed commit object. Ciao, Johannes