From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-3.1 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, FROM_EXCESS_BASE64,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 797661F461 for ; Wed, 15 May 2019 12:22:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727028AbfEOMWe (ORCPT ); Wed, 15 May 2019 08:22:34 -0400 Received: from mail-ed1-f48.google.com ([209.85.208.48]:35424 "EHLO mail-ed1-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726684AbfEOMWe (ORCPT ); Wed, 15 May 2019 08:22:34 -0400 Received: by mail-ed1-f48.google.com with SMTP id p26so3854414edr.2 for ; Wed, 15 May 2019 05:22:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:user-agent:date:message-id:mime-version; bh=OaoCvXEqY0WpRfe2nFJa1HhZf0pav/J0vkzrPVfhD1o=; b=B8RT5lCB8zjYFVZoFCvOCxnc0oTqNbE0Ui54ci0kQtvHd//xugap8Ey+fOguXGKqwv 3gaTq20tpyJYUG5GUxwTZeH6ES6eMKQ0eKvGIsPXyvpTJSM548lTQjDpwKU3r/Pfojz8 i5B6s19J9AgzYedFvyrrfW/UNDxdnlSyao8a+4RV1s90gto1qxLItIRlWH0vnKMf+snl anReoWixyeFPCMZN5IqhpPBDzqz4OrDowuZL/zowPrjl4V9BJ1wqwPjlherASj99Dq4v V8myNSKaDYkUFAw6aCKMxwWPZ4lypQxTfuepmh+U1XrqXjLSPZMzL9FxTxusb7g0YKY8 mp9g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:user-agent:date:message-id :mime-version; bh=OaoCvXEqY0WpRfe2nFJa1HhZf0pav/J0vkzrPVfhD1o=; b=eelXQsM9wwV0SPqLuCrm0ZPytdGuTI4vp+6oLR/g9uJeB5wnWGffwhLj7beKiP3r1E ViekWfKo7/YmJch6abzHSCTZHpEcCec06Blm70URWzVKXB2oBGdOggYiYYF8Zqnf17Of DQ8FQK3/vFb6+jgS6EXJh5iUJo8EX18OgpSDkrwLAlAz/Ldrd2U31xFjli0G4Xo/VK44 fGF1mnfaMbz51xKlLZz1jHs+jF3Z/ZwCfiSKkA0hHziVT8oYsgbc+CaJqelooXl/b2NL mfqNUp3I6ksQAnSqgnIKTo5UDBpB0A3tGue2YzC9Gt9etsYmSgFkgz4bMSgZdzYt31UG Rt1Q== X-Gm-Message-State: APjAAAV5CGLUH9YzDl7psszWgC+ZGeOEAP/yhLN3vuY87qoGQt2ovRU/ 8kIhrYwFXg0SEV+xWTWQhB4nBtAX X-Google-Smtp-Source: APXvYqz44O6l4PAXvWK63WKgF+slW5FzKJ8d+iZm3p6JAc4daGg+Wp/68Tj9JHDfj7nxBudvmIru7g== X-Received: by 2002:a50:bdc6:: with SMTP id z6mr42173190edh.47.1557922952166; Wed, 15 May 2019 05:22:32 -0700 (PDT) Received: from evledraar ([5.57.21.49]) by smtp.gmail.com with ESMTPSA id p27sm441761ejf.65.2019.05.15.05.22.30 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 15 May 2019 05:22:30 -0700 (PDT) From: =?utf-8?B?w4Z2YXIgQXJuZmrDtnLDsA==?= Bjarmason To: "Git ML" Cc: Jeff King , Marc Stevens , gaetan.leurent@inria.fr, thomas.peyrin@ntu.edu.sg, Dan Shumow , "brian m . carlson" , Junio C Hamano , Jonathan Nieder , Eric Sunshine Subject: Git and the new SHA-1 prefix collision attack User-agent: Debian GNU/Linux buster/sid; Emacs 26.1; mu4e 1.1.0 Date: Wed, 15 May 2019 14:22:28 +0200 Message-ID: <875zqbx5yz.fsf@evledraar.gmail.com> MIME-Version: 1.0 Content-Type: text/plain Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org [CC-list carried forward from the last SHA-1 thread I found] Thought I'd sent a brief line about this since nobody else did. There's a newly published "From Collisions to Chosen-Prefix Collisions Application to Full SHA-1" paper making the news this week which builds on the SHAttered attack: https://eprint.iacr.org/2019/459.pdf See https://shattered.io for that original attack. I asked Marc Stevens on Twitter whether the sha1collisiondetection library would cover the sorts of collisions generated by the method described in this paper. He said yes: https://twitter.com/realhashbreaker/status/1128419029536923649 Not all the details are out on this new attack, in particular the researchers (CC'd) haven't yet published details[1] on improvements that would make such an attack cheaper to carry out than the current state-of-the art, which I understand from Marc's Twitter feed is something he's skeptical about. In any case, it looks like the sha1collisiondetection library will save the day again. Thanks Marc & Dan! 1. https://www.zdnet.com/article/sha-1-collision-attacks-are-now-actually-practical-and-a-looming-danger/