From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id F1CDC2018A for ; Fri, 24 Jun 2016 18:17:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751141AbcFXSRN (ORCPT ); Fri, 24 Jun 2016 14:17:13 -0400 Received: from castro.crustytoothpaste.net ([75.10.60.170]:41226 "EHLO castro.crustytoothpaste.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750997AbcFXSRN (ORCPT ); Fri, 24 Jun 2016 14:17:13 -0400 Received: from vauxhall.crustytoothpaste.net (unknown [107.18.82.227]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by castro.crustytoothpaste.net (Postfix) with ESMTPSA id 8A01A2809F; Fri, 24 Jun 2016 18:17:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=crustytoothpaste.net; s=default; t=1466792230; bh=aBpW3FXrEblB57dLgzKBG2VGhPWmBfOoS/WkFQr9GYQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=SltE6TQVPLmFivJsGzZvvz4Tm3jL2anp+PwsKyEIKeCl14y/GyG1qkglyoqshEkdd aXZjszE7iaBVXA9t4LOElV6+TAV3vphwCHlsQZ1umnfRGRUpvGg3kbwDOdzUAKNPem 9SK+4FgqnOZqCtBeO6yoSY+goeiSJuPDArwk9sph2KnTYXNlla60t1hFSjQrvj/3ZC ZklbsS93kYPgflrUfkpEkCBhiTDwhn9OsP4z08H8rALdzK+uCSqolG0n07F80VLQ9f 26tJEW58Ge3C3JYrP6CP1ziib+fMXRHqITLuDEzaSIy7HL5n21WBvmna8w5NDMCSbz rTdtqybsGhu8fRsxwybiRLxc2wSYKx/MUDMa7mNLdi578EH1RyDCmMDNg4imjfQ+rv 9xtQVolm3vIZqT0eb+b08TzUwMtjOeB5tloPmICjNVuInwjgdvIfFmF0g8yWEfsQ7b kCQsBqSBWMz4pzUE3dV5ePuwDhaBAuQtRWYceNqRhqlkdDbzdqG Date: Fri, 24 Jun 2016 18:17:06 +0000 From: "brian m. carlson" To: Leo Gaspard Cc: git@vger.kernel.org Subject: Re: Migrating away from SHA-1? Message-ID: <20160624181705.GA7035@vauxhall.crustytoothpaste.net> Mail-Followup-To: "brian m. carlson" , Leo Gaspard , git@vger.kernel.org References: <02b42587-3643-1c2e-c249-313ec96bcdca@gaspard.io> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="NzB8fVQJ5HfG6fxh" Content-Disposition: inline In-Reply-To: <02b42587-3643-1c2e-c249-313ec96bcdca@gaspard.io> X-Machine: Running on vauxhall using GNU/Linux on x86_64 (Linux kernel 4.6.0-1-amd64) User-Agent: Mutt/1.6.0 (2016-04-01) X-Spam-Score: -0.262 BAYES_00,RDNS_NONE,T_DKIM_INVALID Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org --NzB8fVQJ5HfG6fxh Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Jun 18, 2016 at 03:10:27AM +0100, Leo Gaspard wrote: > First, sorry for not having this message threaded: I'm not subscribed to > the list and haven't found a way to get a Message-Id from gmane. Sorry it's taken so long to get back to this. I've been at a conference. > So, my questions to the git team: > * Is there a consensus, that git should migrate away from SHA-1 before > it gets a collision attack, because it would mean chosen-prefix > collision isn't far away and people wouldn't have the time to upgrade? I plan on adding support for a new hash as soon as that's possible, but I don't have a firm timeline. This is a volunteer effort in my own limited free time. > * Is there a consensus, that Peter Anvin's amended transition plan is > the way to go? I'm not planning on changing algorithms in the middle of a repository. This will only be available on new or imported repositories. My current thinking on proposed algorithms is SHA3-256 or BLAKE2b-256. The cryptanalysis on SHA-256 indicates that it may not be a great long-term choice, and I expect people won't want to change algorithms frequently. If time becomes extremely urgent, we can always add support for a 160-bit hash first (e.g. BLAKE2b-160) and then finish the object_id transition later as it becomes convenient. I'd like to avoid that, though. > * If the two conditions above are fulfilled, has work started on it > yet? (I guess as Brian Carlson had started his work 9 weeks ago and he > was speaking about working on it on the week-end he should have finished > it now, so excluding this) It takes a long time to get a patch series through. I'm rather busy and don't always have time to rebase and address issues during the week. > * If the two first conditions are fulfilled, is there anything I could > do to help this transition? (including helping Brian if his work hasn't > actually ended yet) You're welcome to send patches if you like. I try to avoid areas I know are under heavy development, like the refs code. --=20 brian m. carlson / brian with sandals: Houston, Texas, US +1 832 623 2791 | https://www.crustytoothpaste.net/~bmc | My opinion only OpenPGP: https://keybase.io/bk2204 --NzB8fVQJ5HfG6fxh Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.1.13 (GNU/Linux) iQIcBAEBCgAGBQJXbXkhAAoJEL9TXYEfUvaLKpEP/0LWUUi0vQOHnQohUBZBysh7 jBz4UpnSl8QfCPADtDW9Ft8OCBp+kbvsq/pHgKUo0MiDQVxyF67ZF5+1YOlSaFuM /jiQiDQPP6I/21YCpoLALuFMIAXQ2IG8sWa+B6sTrTeXVx/biUTeMPeJKjVVJVJu jD2UGiV0OLvrKDxkmnwaHCq+dTWy6RHuRmUmV1wWB+iES/L/bzF3sprfKjIFFRp7 erWM0Wedv3VaAiYM+WC5zAx28lcoleNtibbuAnxAiGuibrLRzEr1tbA2/yiEcN0r J/wQeLHXctg3r3lpNuthXZVTLlyQvEukho4lIJMecFMtNwQHrSClExsAtnb9fH2p bUn8R2KRinKddDqhPRDeVAERPYbiSt5vLmwcwFVwPuqdDztXFq/YgRvSiOQehTDe luHKSVIxhAniQ6S0Kk5WvsPADMQ68Vs9uwjks0IPE01Cfsz3lKCWxCnT6N1HR8Ck 3he1/41O7m2uX6wD6j4rPw/A/mZ8A5OSaqJXjTxXIywSB5RvmufdtsgDdr/fGPp0 HGG2epUVa+MOrbrjf3enPh+LjTaJWFT2roVzlLtv2qUel4TaLu8ROd11xhq+3Mx+ ldilAuvREibJ2GunfGwerlzNSv6etDB9JBhf3a0wMFk+Gs/TrT4eHR5s5o2Hv9iA AIRIQM/DN+Ud0z4zOdoA =/Yxk -----END PGP SIGNATURE----- --NzB8fVQJ5HfG6fxh--