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From: Eric Deplagne <Eric@Deplagne.name>
To: "brian m. carlson" <sandals@crustytoothpaste.net>,
	Johannes Schindelin <Johannes.Schindelin@gmx.de>,
	Jonathan Nieder <jrnieder@gmail.com>,
	git@vger.kernel.org, demerphq <demerphq@gmail.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Adam Langley <agl@google.com>,
	The Keccak Team <keccak@noekeon.org>
Subject: Re: Hash algorithm analysis
Date: Sun, 22 Jul 2018 11:34:42 +0200
Message-ID: <20180722093442.GK11431@mail.eric.deplagne.name> (raw)
In-Reply-To: <20180721235941.GG18502@genre.crustytoothpaste.net>

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On Sat, 21 Jul 2018 23:59:41 +0000, brian m. carlson wrote:
> On Sun, Jul 22, 2018 at 12:38:41AM +0200, Johannes Schindelin wrote:
> > Do you really want to value contributors' opinion more than
> > cryptographers'? I mean, that's exactly what got us into this hard-coded
> > SHA-1 mess in the first place.
> 
> I agree (believe me, of all people, I agree) that hard-coding SHA-1 was
> a bad choice in retrospect.  But I've solicited contributors' opinions
> because the Git Project needs to make a decision *for this project*
> about the algorithm we're going to use going forward.
> 
> > And to set the record straight: I do not have a strong preference of the
> > hash algorithm. But cryprographers I have the incredible luck to have
> > access to, by virtue of being a colleague, did mention their preference.
> 
> I don't know your colleagues, and they haven't commented here.  One
> person that has commented here is Adam Langley.  It is my impression
> (and anyone is free to correct me if I'm incorrect) that he is indeed a
> cryptographer.  To quote him[0]:
> 
>   I think this group can safely assume that SHA-256, SHA-512, BLAKE2,
>   K12, etc are all secure to the extent that I don't believe that making
>   comparisons between them on that axis is meaningful. Thus I think the
>   question is primarily concerned with performance and implementation
>   availability.
> 
>   […]
> 
>   So, overall, none of these choices should obviously be excluded. The
>   considerations at this point are not cryptographic and the tradeoff
>   between implementation ease and performance is one that the git
>   community would have to make.

  Am I completely out of the game, or the statement that
    "the considerations at this point are not cryptographic"
  is just the wrongest ?

  I mean, if that was true, would we not be sticking to SHA1 ?

> I'm aware that cryptographers tend to prefer algorithms that have been
> studied longer over ones that have been studied less.  They also prefer
> algorithms built in the open to ones developed behind closed doors.
> 
> SHA-256 has the benefit that it has been studied for a long time, but it
> was also designed in secret by the NSA.  SHA3-256 was created with
> significant study in the open, but is not as mature.  BLAKE2b has been
> incorporated into standards like Argon2, but has been weakened slightly
> for performance.
> 
> I'm not sure that there's a really obvious choice here.
> 
> I'm at the point where to continue the work that I'm doing, I need to
> make a decision.  I'm happy to follow the consensus if there is one, but
> it does not appear that there is.
> 
> I will admit that I don't love making this decision by myself, because
> right now, whatever I pick, somebody is going to be unhappy.  I want to
> state, unambiguously, that I'm trying to make a decision that is in the
> interests of the Git Project, the community, and our users.
> 
> I'm happy to wait a few more days to see if a consensus develops; if so,
> I'll follow it.  If we haven't come to one by, say, Wednesday, I'll make
> a decision and write my patches accordingly.  The community is free, as
> always, to reject my patches if taking them is not in the interest of
> the project.
> 
> [0] https://public-inbox.org/git/CAL9PXLzhPyE+geUdcLmd=pidT5P8eFEBbSgX_dS88knz2q_LSw@mail.gmail.com/
> -- 
> brian m. carlson: Houston, Texas, US
> OpenPGP: https://keybase.io/bk2204



-- 
  Eric Deplagne

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  reply index

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 [this message]
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
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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