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=AWL,BAYES_00, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_HI,T_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 A7B771F404 for ; Tue, 27 Mar 2018 14:41:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752348AbeC0OlC (ORCPT ); Tue, 27 Mar 2018 10:41:02 -0400 Received: from mout.gmx.net ([212.227.15.19]:47649 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751316AbeC0OlB (ORCPT ); Tue, 27 Mar 2018 10:41:01 -0400 Received: from [192.168.0.129] ([37.201.195.115]) by mail.gmx.com (mrgmx002 [212.227.17.190]) with ESMTPSA (Nemesis) id 0Lh7sF-1eFPOf1P5b-00oT2i; Tue, 27 Mar 2018 16:40:50 +0200 Date: Tue, 27 Mar 2018 16:40:47 +0200 (DST) From: Johannes Schindelin X-X-Sender: virtualbox@MININT-6BKU6QN.europe.corp.microsoft.com To: Junio C Hamano cc: Eric Sunshine , "brian m. carlson" , Git List , =?UTF-8?Q?Nguy=E1=BB=85n_Th=C3=A1i_Ng=E1=BB=8Dc_Duy?= , Lars Schneider Subject: Re: [PATCH 00/10] Hash-independent tests (part 1) In-Reply-To: Message-ID: References: <20180325192055.841459-1-sandals@crustytoothpaste.net> User-Agent: Alpine 2.21.1 (DEB 209 2017-03-23) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Provags-ID: V03:K0:IQz3keL5iuj2R41DAIAMtLltc2XKaRN/qLGpkMV8y/v6etD0N/i u8Xx1+vL2nTHBVxAxWasEW5emG39o/WJmY+LHQqdL8krEdrDldLika1u8hoEW3LDaAF7wr1 YBTeFCOj6FdIDcNefG0xz5zAWrYGnRfck25WschIytpsFxj74NcgFyZ7++ZF0vp7PWUDLis Gwcm7Fov4Y4sFqkCT5I4w== X-UI-Out-Filterresults: notjunk:1;V01:K0:V6qooZ6Zi7M=:E5cyVSZWfcEKapV76MeQrU eV5L0ic9oiHM2LoTrAqwQn6wUls3W6d1wY0ucqDYufIjgv2VIpnVoWZNg/bEh00+NDF6/KYQn ZJVUHqvwD3BQfLFI26eO2n8GzRazfkDOL7kU1nxDrkj1CP/JQBWYUC2lBDOhTjJVowpe48678 nvepgQ7I18iEjA4s/2TsyY0T0L5ePUgWAkmhceoBRCM3I2gztqTrq25T9VLj6CGl7eXFY347K 7C9LaAEKDJt2vjkaXnH7MtPdT9k0W88bgcd4XIJYIbdpRJO7TGUCjXZGHKkwm8mTjw11EuaJ0 2ZGIBRh9lV10s2PXEAr5fxpEm/fDO6X6byWAVJVN8oSKWR7tqxcVkV2rw1jyVLzJpBq/XVGT3 klHESnUEpKFYeOsBRxuxP2M5BKuYzkFVqZKN8o0IbvPXADLoD8DGSAiD58I8DoBdyHuOFi6V6 TaWD5KSFZXa4UiKU0/oEXKZy1sRZM1hEDDCTqduKazp2oD49jFfVGN/CZPDkLMG+gxT7giGuo TnUKp94kVatMa8ZHtokrq8ba7TC2jkwnf/YfJhZpI+lSq1dAAICLHgaPM8J78AjZGYXZZknnz HARQNboogewjoTutIBf0zridUP5ilsEQnnHBWzCoBAyMdXbxbewHqpfoNcBfHFCVoUHM0IgTO dSNsNHeKoZYEW74/Ia2ib2R8VSeGYNBnR1IDlwntotUO1sL+mt4z3fcq/7OmguBknDpaLG3za KMVI23tDdPwDQoOzkprIhm+xVmxm4ta9tSplD5UEf8QtDYj5vvXqYZa7UVaII9WWdTU79OWpA gDRY7Q9uUCuuBEmNHNI7KFoJRLmgs6u4W67sgWpGesk5vgKNlGRgn71YkPyBV6pVDP1UEiH Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Hi Junio, On Sun, 25 Mar 2018, Junio C Hamano wrote: > Eric Sunshine writes: > > > What's the plan for oddball cases such as 66ae9a57b8 (t3404: rebase > > -i: demonstrate short SHA-1 collision, 2013-08-23) which depend > > implicitly upon SHA-1 without actually hardcoding any hashes? The test > > added by 66ae9a57b8, for instance, won't start failing in the face of > > NewHash, but it also won't be testing anything meaningful. > > > > Should such tests be dropped altogether? Should they be marked with a > > 'SHA1' predicate or be annotated with a comment as being > > SHA-1-specific? Something else? > > Ideally, the existing one be annotated with prereq SHA1, and also > duplicated with a tweak to cause the same kind of (half-)collision > under the NewHash and be annotated with prereq NewHash. That's a good idea. I wonder whether we want to be a bit more specific, though, so that we have something grep'able for the future? Something like SHA1_SHORT_COLLISION or some such? > It's a different matter how feasible it is to attain such an ideal, > though. t1512 was fun to write, but it was quite a lot of work to > come up with bunch of blobs, trees and commits whose object names > share the common prefix 0{10}. Did you write a helper to brute-force those? If so, we might want to have such a helper in t/helper/ to generate/re-generate those (i.e. it could be asked to generate a blob whose ID starts with five NUL bytes, and it would have hard-coded values for already-generated ones). Even if you did not write such a helper, we might want to have such a helper. That would take the responsibility away from the shell script. Ciao, Dscho