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=-2.6 required=3.0 tests=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 104BC201A9 for ; Fri, 24 Feb 2017 20:06:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751357AbdBXUGT (ORCPT ); Fri, 24 Feb 2017 15:06:19 -0500 Received: from mail-qt0-f173.google.com ([209.85.216.173]:33857 "EHLO mail-qt0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751287AbdBXUGR (ORCPT ); Fri, 24 Feb 2017 15:06:17 -0500 Received: by mail-qt0-f173.google.com with SMTP id n21so25621784qta.1 for ; Fri, 24 Feb 2017 12:06:16 -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=afZXDOpVbUrEcxmNNCBEVa+Rv9F5psPCSBEWpbS9AuU=; b=SEO+g74t/hibCQT8XtgQHogS9yhzSPcgEJhgWpK5xhvWrOhia4dD8EsZ2PHN/o4ve0 uheqp0yX1UDhVHvFqFtwa8u7cbNbqWGrKfmFj2JfE4IXNcQrUZYjNfKt3dQDvRybFHpH QTVZZlx40wWRm/Y+kSaXTvoLOr5phS+lCOrMw+pddLdmk5Wq4GU9LmhWiypm6srKl8kV 3op/Bpl8qMxOWP214jU3bKUJeWmpgXTtrcXCXiofz+y+OC4aQUliYYJVYpMaBs6R6K1o 8bEfehgCaBaBkLXRda+yqtn+K0azU8/ZECYuT7XI6Sr9yLv2y6vAdYm1xVEzGqZJ5BaE O6CA== 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=afZXDOpVbUrEcxmNNCBEVa+Rv9F5psPCSBEWpbS9AuU=; b=plNk0ls6kDQtaQlPXlI9BhtPKpFh4Crypsgcm28pmDnu2zAm/YuLBSomUbDOAD5nZ2 kix0chdGSlMxwsD31iwRcCibRZhonWOM9QCX1Hgu2qjZR8fxTZ8qzf6WyZD7PazGo8nu 133w3aDCUsyt+yjUbvYN+FdcfTtoBLWEcFyWxeEGCWMutMWFOdbLJNxnJVSvwqawE+Cn wyBxxDQjW3jcjfifnZlAOwbjVno0cdUz1NSU4LSOnlh07fWHHEiY0wzqEB8mSCJpj8AX fjrEoANqi/39BpIGnzNJrVVZRTSiz/ItZBuMHmbCkgjgpny5o4ndi4ZY4vMRnRDQ7uGz AR0g== X-Gm-Message-State: AMke39lrKx1BOT9lXd3idX5180ib6o8NOnEU+l1z+qgfHPSPAhn6jVXmMVzz6dkhNf/5VliFRa9Sph9cqSwYig== X-Received: by 10.237.57.164 with SMTP id m33mr3486773qte.293.1487966770962; Fri, 24 Feb 2017 12:06:10 -0800 (PST) MIME-Version: 1.0 Received: by 10.12.134.218 with HTTP; Fri, 24 Feb 2017 12:05:40 -0800 (PST) In-Reply-To: References: <20170223164306.spg2avxzukkggrpb@kitenet.net> <22704.19873.860148.22472@chiark.greenend.org.uk> From: ankostis Date: Fri, 24 Feb 2017 21:05:40 +0100 Message-ID: Subject: Re: SHA1 collisions found To: Junio C Hamano Cc: Stefan Beller , David Lang , Ian Jackson , Joey Hess , "git@vger.kernel.org" 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 24 February 2017 at 20:20, Junio C Hamano wrote: > Stefan Beller writes: > >> On Fri, Feb 24, 2017 at 10:14 AM, Junio C Hamano wrote: >> >>> you are inviting people to start using >>> >>> md5,54ddf8d47340e048166c45f439ce65fd >>> >>> as object names. >> >> which might even be okay for specific subsets of operations. >> (e.g. all local work including staging things, making local "fixup" commits) >> >> The addressing scheme should not be too hardcoded, we should rather >> treat it similar to the cipher schemes in pgp. The additional complexity that >> we have is the longevity of existence of things, though. > > The not-so-well-hidden agenda was exactly that we _SHOULD_ not > mimick PGP. They do not have a requirement to encourage everybody > to use the same thing because each message is encrypted/signed > independently, i.e. they do not have to chain things like we do. But there is a scenario where supporting more hashes, in parallel, is beneficial: Let's assume that git is retroffited to always support the "default" SHA-3, but support additionally more hash-funcs. If in the future SHA-3 also gets defeated, it would be highly unlikely that the same math would also break e.g. Blake. So certain high-profile repos might choose for extra security 2 or more hashes. Apologies if I'm misusing the list, Kostis