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=-3.6 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,RCVD_IN_SORBS_SPAM, RP_MATCHES_RCVD shortcircuit=no autolearn=no 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 C74B120279 for ; Sat, 25 Feb 2017 02:27:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751473AbdBYC1D (ORCPT ); Fri, 24 Feb 2017 21:27:03 -0500 Received: from mail-lf0-f54.google.com ([209.85.215.54]:35800 "EHLO mail-lf0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751451AbdBYC1C (ORCPT ); Fri, 24 Feb 2017 21:27:02 -0500 Received: by mail-lf0-f54.google.com with SMTP id z127so15594986lfa.2 for ; Fri, 24 Feb 2017 18:27:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=aG/OPsyQM0C3YjAp8yUcBplq/FRbVQ45pSVwYeRXwCA=; b=GVfkInBaVrhI6T+VUyOYyhej8wciXvWGWRQ00vlsd8PVBWHID0Pdkmwlv1x5knrZLa 9lsXnVxeC9/tFSPfM/9wVTLOCv8ND9G3Q8v8vqegNfFH2OvA+OwDpp7lBvVKxNxbZLJ+ wgXUqhaCTIn4NOs7wK7x1MIAhIWQVd7IMVdZehoO6s039m+a9TEerR2AomMlXKZ6hpY5 QWzcKL2Izr9tAe5gFZqDmC7c9M03X+VfD7L/OCzYYNXDBSs/E8oFTJNJ3HovVhVA5DLg lGr4212i0v9SNYZQnIiSxn5FGVpy6NsIqu/ryo1TA65V3VZjwJ9kLOLQs0wgRCMSIVgm RNAw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=aG/OPsyQM0C3YjAp8yUcBplq/FRbVQ45pSVwYeRXwCA=; b=M9ArG+F53J45Qx4gkryKQJOz3Azbx+KobI+RFN9lbgyIhgxKbU5Rca1tXxFmyyiVWd f/QMxVWsCHn7h23en/Mzg2SpQ0F7Wqy9CSsUw0kU3cxUhU3eKBStMquxyiybtsy8KTmq XkM1zj1iOPbKCT57X9u4iBUZ0t58WV0UYXR//y2Py5womYiSjdPRkprQf4aBKhhxbBRz YI9GAt46lg/ScdkaIQsH1Eb1Y/rr9tgYQ7sdnBafOe/tVD277HsxCGmz5Dw7/CpjOSKh SHPAYsmMuZeYsPdqI3TOubd1ZG+FyEmfY4uaW/wzz9aNxCJXPDqA51SrpuSTum0mhjkf YkSg== X-Gm-Message-State: AMke39mlw2L7VNUKhuJHrhgMSVk7lrZCoJqzKsizxfdcx23vGmarfF1oPDwYGkr8I4I5A5JRc2lSGStZsbB0OA== X-Received: by 10.25.21.214 with SMTP id 83mr1674063lfv.66.1487989620856; Fri, 24 Feb 2017 18:27:00 -0800 (PST) MIME-Version: 1.0 Received: by 10.25.145.30 with HTTP; Fri, 24 Feb 2017 18:26:40 -0800 (PST) In-Reply-To: <20170225012100.ivfdlwspsqd7bkhf@sigill.intra.peff.net> References: <20170223164306.spg2avxzukkggrpb@kitenet.net> <22704.19873.860148.22472@chiark.greenend.org.uk> <20170224233929.p2yckbc6ksyox5nu@sigill.intra.peff.net> <20170225012100.ivfdlwspsqd7bkhf@sigill.intra.peff.net> From: Jacob Keller Date: Fri, 24 Feb 2017 18:26:40 -0800 Message-ID: Subject: Re: SHA1 collisions found To: Jeff King Cc: David Lang , Junio C Hamano , Ian Jackson , Joey Hess , 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 Fri, Feb 24, 2017 at 5:21 PM, Jeff King wrote: > On Fri, Feb 24, 2017 at 05:00:55PM -0800, David Lang wrote: > >> On Fri, 24 Feb 2017, Jeff King wrote: >> >> > >> > So I'd much rather see strong rules like: >> > >> > 1. Once a repo has flag-day switched over to the new hash format[1], >> > new references are _always_ done with the new hash. Even ones that >> > point to pre-flag-day objects! >> >> how do you define when a repo has "switched over" to the new format in a >> distributed environment? > > You don't. It's a decision for each local repo, but the rules push > everybody towards upgrading (because you forbid them pulling from or > pushing to people who have upgraded). > > So in practice, some centralized distribution point switches, and then > it floods out from there. This seems like the most reasonable strategy so far. I think that trying to allow long term co-existence is a huge pain that discourages switching, when we actually want to encourage everyone to switch someone has switched. I don't think it's sane to try and allow simultaneous use of both hashes, since that creates a lot of headaches and discourages transition somewhat. Thanks, Jake