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From: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
To: "brian m. carlson" <sandals@crustytoothpaste.net>
Cc: Jonathan Nieder <jrnieder@gmail.com>,
	git@vger.kernel.org,
	Johannes Schindelin <Johannes.Schindelin@gmx.de>,
	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: Sat, 21 Jul 2018 21:52:05 +0200
Message-ID: <87va98bc4a.fsf@evledraar.gmail.com> (raw)
In-Reply-To: <20180720215220.GB18502@genre.crustytoothpaste.net>


On Fri, Jul 20 2018, brian m. carlson wrote:

> On Mon, Jun 11, 2018 at 12:29:42PM -0700, Jonathan Nieder wrote:
>> My understanding of the discussion so far:
>>
>> Keccak team encourages us[1] to consider a variant like K12 instead of
>> SHA3.
>>
>> AGL explains[2] that the algorithms considered all seem like
>> reasonable choices and we should decide using factors like
>> implementation ease and performance.
>>
>> If we choose a Keccak-based function, AGL also[3] encourages using a
>> variant like K12 instead of SHA3.
>>
>> Dscho strongly prefers[4] SHA-256, because of
>> - wide implementation availability, including in future hardware
>> - has been widely analyzed
>> - is fast
>>
>> Yves Orton and Linus Torvalds prefer[5] SHA3 over SHA2 because of how
>> it is constructed.
>
> I know this discussion has sort of petered out, but I'd like to see if
> we can revive it.  I'm writing index v3 and having a decision would help
> me write tests for it.
>
> To summarize the discussion that's been had in addition to the above,
> Ævar has also stated a preference for SHA-256 and I would prefer BLAKE2b
> over SHA-256 over SHA3-256, although any of them would be fine.
>
> Are there other contributors who have a strong opinion?  Are there
> things I can do to help us coalesce around an option?

I have a vague recollection of suggesting something similar in the past,
but can't find that E-Mail (and maybe it never happened), but for
testing purposes isn't in simplest if we just have some "test SHA-1"
algorithm where we pretent that all inputs like "STRING" are really
"PREFIX-STRING" for the purposes of hashing, or fake shortening /
lengthening the hash to test arbitrary lenghts of N (just by repeating
the hash from the beginning is probably good enough...).

That would make such patches easier to review, since we wouldn't need to
carry hundreds/thousands of lines of dense hashing code, but a more
trivial wrapper around SHA-1, and we could have some test mode where we
could compile & run tests with an arbitrary hash length to make sure
everything's future proof even after we move to NewHash.

  parent 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 [this message]
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
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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