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=-4.5 required=3.0 tests=BAYES_00, 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 5B0881F744 for ; Tue, 19 Jul 2016 07:47:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752894AbcGSHrH (ORCPT ); Tue, 19 Jul 2016 03:47:07 -0400 Received: from lang.hm ([66.167.227.134]:35925 "EHLO bifrost.lang.hm" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752373AbcGSHrG (ORCPT ); Tue, 19 Jul 2016 03:47:06 -0400 Received: from asgard.lang.hm (asgard.lang.hm [10.0.0.100]) by bifrost.lang.hm (8.13.4/8.13.4/Debian-3) with ESMTP id u6J7koHq000955; Tue, 19 Jul 2016 00:46:50 -0700 Date: Tue, 19 Jul 2016 00:46:50 -0700 (PDT) From: David Lang X-X-Sender: dlang@asgard.lang.hm To: Johannes Schindelin cc: Duy Nguyen , "brian m. carlson" , Herczeg Zsolt , 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> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Tue, 19 Jul 2016, Johannes Schindelin wrote: > Hi Duy, > > On Mon, 18 Jul 2016, Duy Nguyen wrote: > >> On Sun, Jul 17, 2016 at 4:21 PM, brian m. carlson >> wrote: >>> I'm going to end up having to do something similar because of the issue >>> of submodules. Submodules may still be SHA-1, while the main repo may >>> be a newer hash. >> >> Or even the other way around, main repo is one with sha1 while >> submodule is on sha256. I wonder if we should address this separately >> (and even in parallel with sha256 support), making submodules work >> with an any external VCS system (that supports some basic operations >> we define). > > It is safe to assume that any project using a submodule with a more secure > hash would require Git tooling capable of said hash. It would hence make > no sense to use SHA-1 for the super project. > > So I do not believe that we have to support the use case of a SHA-1-based > project using SHA-256-based submodules. they have different upstreams, what if the upstream of the submodule has upgraded and is using signed commits of the sha-256 but the upstream of the parent hasn't and is using signed commits of sha1? David Lang