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=-5.4 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 0ED93202F3 for ; Wed, 20 Jul 2016 14:44:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754468AbcGTOor (ORCPT ); Wed, 20 Jul 2016 10:44:47 -0400 Received: from mail-it0-f43.google.com ([209.85.214.43]:35991 "EHLO mail-it0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754398AbcGTOoi (ORCPT ); Wed, 20 Jul 2016 10:44:38 -0400 Received: by mail-it0-f43.google.com with SMTP id f6so116862130ith.1 for ; Wed, 20 Jul 2016 07:44:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=CUBLtQi8DZiSlKjRETuwwJ4C0+EFpbhKudjE4pLEOMw=; b=khcgZOFT+IBbXVbdJEMYod1XIrhgJYiWNNX141StTNceMCFoqI0PUHoRCMvtMbkhFC 1ByJhQdgCvv6k0wJd+CPqPvvQPkAqHV0EPBlgcNR6wHX9qLS2nI2+u0a6Ui4CX/szVx1 74LKnHbBvbpMmO3JoDqx9iUSttvXQjESrCB59DffPQMEUbRh1I7zY0qJwNgRdEtfiC0P YYQUpsEHSDOWJ1gaQMpSziaZiwyZ+oblGOuc6z1KXZ3flklC3gfnXEOLYmV34ss0kPRY UdsuuQlaVHLvLmFoca0t0f1mHCFnSLpjoJxgaawq1f0eeJWm23kytjbQlL+xprKTFZzJ 37OA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=CUBLtQi8DZiSlKjRETuwwJ4C0+EFpbhKudjE4pLEOMw=; b=IeLsLyaY3/+EboUNx6/SA9rKGpMXEmRkMSfsFOKYAnLJD4EAnRyai6slNNrD1cFNbh shnq+/tCmHmFl8eA29BUgAtp3agJYUJIEmDu9RLEhWZuMOc5QdiDdEVThinJUDPObd4N DXlPH1Y+pXKbgYyQL2M4eFwYZ5CJ/QsWDjpRhKm9KX4WuX66Ang+3jtRXz9NBej3oPs2 YLcKjgmtbe7ZFUwaAQxttZToT/B1MEBJMZUxmA8nPItT+dBeqchPybQeRWRbVj9lOgNk mrvPtGKpMTY3K0ucrwKPSAkdQpd4EOCpiOr/HLKgTwW1PKXTJkwa5bo22DcDA+rfcFUF OEug== X-Gm-Message-State: ALyK8tLL2FUPelhOYmUPy0AEEC50rNxX9/wvezV5K8OJhS8/ECPlgFXYB6XWM+7stJ+HQ1rOPMbYr6OceKd0rg== X-Received: by 10.36.91.134 with SMTP id g128mr10281453itb.42.1469025877303; Wed, 20 Jul 2016 07:44:37 -0700 (PDT) MIME-Version: 1.0 Received: by 10.64.225.235 with HTTP; Wed, 20 Jul 2016 07:44:07 -0700 (PDT) In-Reply-To: References: <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> From: Duy Nguyen Date: Wed, 20 Jul 2016 16:44:07 +0200 Message-ID: Subject: Re: Git and SHA-1 security (again) To: Johannes Schindelin Cc: David Lang , Herczeg Zsolt , "brian m. carlson" , "Theodore Ts'o" , Git Mailing List Content-Type: text/plain; charset=UTF-8 Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Wed, Jul 20, 2016 at 2:28 PM, Johannes Schindelin wrote: > But that strategy *still* ignores the distributed nature of Git. Just > because *you* make that merge at a certain point does not necessarily mean > that I make it at that point, too. > > Any approach that tries to have one single point of conversion will most > likely fall short of a solution. OK I see the difference in our views now. To me an sha256 repo would see an sha1 repo as a _foreign_ DVCS, pretty much like git sees mercurial now. So a transition from sha1 to sha256 is not that different from cvs -> svn -> a dvcs bubble -> git. > To be honest, I am less concerned about the GPG-signed commits (after all, > after switching to a more secure hash algorithm, a maintainer could > cross-sign all signed commits, or only the branch tips or tags, as new > tags, to reinstitute trust). > > I am much more concerned about references to commits, both inside and > outside the repository. That is, if I read anywhere on the internet about > Git having added support for `git add --chmod=+x ` in 4e55ed3 (add: > add --chmod=+x / --chmod=-x options, 2016-05-31), I want to find that > commit by that reference. > > And I am of course concerned what should happen if a user wants to fetch > from, or push to, a SHA-1-hashed remote repository into, or from, a > SHA-256-hashed local one. to follow the above, in my view, interaction with sha1 repos go through some conversion bridges like what we have with hg and svn. I don't know if we are going this route. It's certainly simpler and people already have experiences (from previous migration) to prepare for it. -- Duy