From: Jonathan Nieder <jrnieder@gmail.com> To: Linus Torvalds <torvalds@linux-foundation.org> Cc: Edward Thomson <ethomson@edwardthomson.com>, "brian m. carlson" <sandals@crustytoothpaste.net>, Git Mailing List <git@vger.kernel.org>, Johannes Schindelin <Johannes.Schindelin@gmx.de>, demerphq <demerphq@gmail.com>, Adam Langley <agl@google.com>, keccak@noekeon.org Subject: Re: Hash algorithm analysis Date: Tue, 24 Jul 2018 13:49:16 -0700 Message-ID: <20180724204916.GA136514@aiede.svl.corp.google.com> (raw) In-Reply-To: <CA+55aFwSe9BF8e0hLk9pp3FVD5LaVY5GRdsV3fbNtgzekJadyA@mail.gmail.com> Hi, Linus Torvalds wrote: > On Tue, Jul 24, 2018 at 12:01 PM Edward Thomson > <ethomson@edwardthomson.com> wrote: >> Switching gears, if I look at this from the perspective of the libgit2 >> project, I would also prefer SHA-256 or SHA3 over blake2b. To support >> blake2b, we'd have to include - and support - that code ourselves. But >> to support SHA-256, we would simply use the system's crypto libraries >> that we already take a dependecy on (OpenSSL, mbedTLS, CryptoNG, or >> SecureTransport). Just to be clear, OpenSSL has built-in blake2b support. [...] > So I'm not a huge fan of sha256, partly because of my disappointment > in lack of hw acceleration in releant markets (sure, it's fairly > common in ARM, but nobody sane uses ARM for development because of > _other_ reasons). And partly because I don't like how the internal > data size is the same as the final hash. But that second issue is an > annoyance with it, not a real issue - in the absence of weaknesses > it's a non-issue, and any future weaknesses might affect any other > choice too. Thanks for saying this. With this in mind, I think we have a clear way forward: we should use SHA-256. My main complaint about it is that it is not a tree hash, but the common availability in libraries trumps that (versus SHA-256x16, say). I also was excited about K12, both because I like a world where Keccak gets wide hardware accelaration (improving PRNGs and other applications) and because of Keccak team's helpfulness throughout the process of helping us evaluate this, and it's possible that some day in the future we may want to switch to something like it. But today, as mentioned in [1] and [2], there is value in settling on one standard and SHA2-256 is the obvious standard today. Thanks, Jonathan [1] https://public-inbox.org/git/CAL9PXLyNVLCCqV1ftRa3r4kuoamDZOF29HJEhv2JXrbHj1nirA@mail.gmail.com/ [2] https://public-inbox.org/git/20180723183523.GB9285@aiede.svl.corp.google.com/
next prev parent reply other threads:[~2018-07-24 20:49 UTC|newest] Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-06-09 20:56 State of NewHash work, future directions, and discussion brian m. carlson 2018-06-09 21:26 ` Ævar Arnfjörð Bjarmason 2018-06-09 22:49 ` Hash algorithm analysis brian m. carlson 2018-06-11 19:29 ` Jonathan Nieder 2018-06-11 20:20 ` Linus Torvalds 2018-06-11 23:27 ` Ævar Arnfjörð Bjarmason 2018-06-12 0:11 ` David Lang 2018-06-12 0:45 ` Linus Torvalds 2018-06-11 22:35 ` brian m. carlson 2018-06-12 16:21 ` Gilles Van Assche 2018-06-13 23:58 ` brian m. carlson 2018-06-15 10:33 ` Gilles Van Assche 2018-07-20 21:52 ` brian m. carlson 2018-07-21 0:31 ` Jonathan Nieder 2018-07-21 19:52 ` Ævar Arnfjörð Bjarmason 2018-07-21 20:25 ` brian m. carlson 2018-07-21 22:38 ` Johannes Schindelin 2018-07-21 23:09 ` Linus Torvalds 2018-07-21 23:59 ` brian m. carlson 2018-07-22 9:34 ` Eric Deplagne 2018-07-22 14:21 ` brian m. carlson 2018-07-22 14:55 ` Eric Deplagne 2018-07-26 10:05 ` Johannes Schindelin 2018-07-22 15:23 ` Joan Daemen 2018-07-22 18:54 ` Adam Langley 2018-07-26 10:31 ` Johannes Schindelin 2018-07-23 12:40 ` demerphq 2018-07-23 12:48 ` Sitaram Chamarty 2018-07-23 12:55 ` demerphq 2018-07-23 18:23 ` Linus Torvalds 2018-07-23 17:57 ` Stefan Beller 2018-07-23 18:35 ` Jonathan Nieder 2018-07-24 19:01 ` Edward Thomson 2018-07-24 20:31 ` Linus Torvalds 2018-07-24 20:49 ` Jonathan Nieder [this message] 2018-07-24 21:13 ` Junio C Hamano 2018-07-24 22:10 ` brian m. carlson 2018-07-30 9:06 ` Johannes Schindelin 2018-07-30 20:01 ` Dan Shumow 2018-08-03 2:57 ` Jonathan Nieder 2018-09-18 15:18 ` Joan Daemen 2018-09-18 15:32 ` Jonathan Nieder 2018-09-18 16:50 ` Linus Torvalds 2018-07-25 8:30 ` [PATCH 0/2] document that NewHash is now SHA-256 Ævar Arnfjörð Bjarmason 2018-07-25 8:30 ` [PATCH 1/2] doc hash-function-transition: note the lack of a changelog Ævar Arnfjörð Bjarmason 2018-07-25 8:30 ` [PATCH 2/2] doc hash-function-transition: pick SHA-256 as NewHash Ævar Arnfjörð Bjarmason 2018-07-25 16:45 ` Junio C Hamano 2018-07-25 17:25 ` Jonathan Nieder 2018-07-25 21:32 ` Junio C Hamano 2018-07-26 13:41 ` [PATCH v2 " Ævar Arnfjörð Bjarmason 2018-08-03 7:20 ` Jonathan Nieder 2018-08-03 16:40 ` Junio C Hamano 2018-08-03 17:01 ` Linus Torvalds 2018-08-03 16:42 ` Linus Torvalds 2018-08-03 17:43 ` Ævar Arnfjörð Bjarmason 2018-08-04 8:52 ` Jonathan Nieder 2018-08-03 17:45 ` brian m. carlson 2018-07-25 22:56 ` [PATCH " brian m. carlson 2018-06-11 21:19 ` Hash algorithm analysis Ævar Arnfjörð Bjarmason 2018-06-21 8:20 ` Johannes Schindelin 2018-06-21 22:39 ` brian m. carlson 2018-06-11 18:09 ` State of NewHash work, future directions, and discussion Duy Nguyen 2018-06-12 1:28 ` brian m. carlson 2018-06-11 19:01 ` Jonathan Nieder 2018-06-12 2:28 ` brian m. carlson 2018-06-12 2:42 ` Jonathan Nieder
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