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=-5.2 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 723B71F744 for ; Wed, 20 Jul 2016 19:26:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753552AbcGTT0t (ORCPT ); Wed, 20 Jul 2016 15:26:49 -0400 Received: from pb-smtp2.pobox.com ([64.147.108.71]:53803 "EHLO sasl.smtp.pobox.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752265AbcGTT0s (ORCPT ); Wed, 20 Jul 2016 15:26:48 -0400 Received: from sasl.smtp.pobox.com (unknown [127.0.0.1]) by pb-smtp2.pobox.com (Postfix) with ESMTP id 00A632BC8A; Wed, 20 Jul 2016 15:26:47 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=pobox.com; h=from:to:cc :subject:references:date:in-reply-to:message-id:mime-version :content-type; s=sasl; bh=Fa9/HQusFl2TdisweRteKiY2RIo=; b=Kyh6B7 F5xYYydh6+1vJNeD5AXdKfzc9QlhcEiCimf1uYmXRAOMZ3DHiCTmz433xw57rjss NW928UXW3HYYH7f73uyxGIjzNUAa+g1JhAvELtdzs2FmY/u+MJXo7ngbnRqFUyIc Sa+nXlRCLCVEVwR17vvr9DXGdipw4Bo1NET4U= DomainKey-Signature: a=rsa-sha1; c=nofws; d=pobox.com; h=from:to:cc :subject:references:date:in-reply-to:message-id:mime-version :content-type; q=dns; s=sasl; b=aS956Lc6DJ65rcRCL2QCFmzD5rVkhtsl AB5NSsEj4uofYmeewVxUONVp2tz1VNgHMHSEpqV8xSU+i8bgU941m6s/Z33qW6Uo KQRFUP3kAJX3wZphwpq1jkRiAhZV12RRUGfa7o/LzV4LzLVYb57oJX1+m+j+gfKE mC/sglEZN7w= Received: from pb-smtp2.nyi.icgroup.com (unknown [127.0.0.1]) by pb-smtp2.pobox.com (Postfix) with ESMTP id EB3622BC89; Wed, 20 Jul 2016 15:26:46 -0400 (EDT) Received: from pobox.com (unknown [104.132.0.95]) (using TLSv1.2 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by pb-smtp2.pobox.com (Postfix) with ESMTPSA id 65ACD2BC87; Wed, 20 Jul 2016 15:26:46 -0400 (EDT) From: Junio C Hamano To: Stefan Beller Cc: Duy Nguyen , Johannes Schindelin , David Lang , Herczeg Zsolt , "brian m. carlson" , "Theodore Ts'o" , Git Mailing List Subject: Re: Git and SHA-1 security (again) 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> Date: Wed, 20 Jul 2016 12:26:44 -0700 In-Reply-To: (Stefan Beller's message of "Wed, 20 Jul 2016 10:10:02 -0700") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Pobox-Relay-ID: E5E9D420-4EAF-11E6-821A-EE617A1B28F4-77302942!pb-smtp2.pobox.com Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Stefan Beller writes: >> 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. > > When treating the SHA1 version as a foreign dvcs and the SHA256 > as the real deal, we could introduce "pointer objects", and during the > conversion > create a 4e55ed3 pointer that points to the SHA256 commit of (add: > add --chmod=+x / --chmod=-x options, 2016-05-31). Hmmm. If you are designing this "pointer objects" to be extensible enough to cover other foreign vcs (i.e.e.g. you make it to be capable of mapping Subversion's r24323 to a matching commit in the converted result), I would think it may be a very useful thing to have, but I think it is pretty much orthogonal to the discussion in this topic. IOW, that can happen with or without change of the hash function. And looking at it that way, I am not sure if such a mapping feature should require adding a new type of "object".