From: Junio C Hamano <gitster@pobox.com>
To: Jonathan Nieder <jrnieder@gmail.com>
Cc: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
git@vger.kernel.org,
"Linus Torvalds" <torvalds@linux-foundation.org>,
"Edward Thomson" <ethomson@edwardthomson.com>,
"brian m . carlson" <sandals@crustytoothpaste.net>,
"Johannes Schindelin" <Johannes.Schindelin@gmx.de>,
demerphq <demerphq@gmail.com>, "Adam Langley" <agl@google.com>,
keccak@noekeon.org
Subject: Re: [PATCH v2 2/2] doc hash-function-transition: pick SHA-256 as NewHash
Date: Fri, 03 Aug 2018 09:40:21 -0700 [thread overview]
Message-ID: <xmqq600rz9my.fsf@gitster-ct.c.googlers.com> (raw)
In-Reply-To: <20180803072014.GA256410@aiede.svl.corp.google.com> (Jonathan Nieder's message of "Fri, 3 Aug 2018 00:20:14 -0700")
Jonathan Nieder <jrnieder@gmail.com> writes:
> Sorry for the slow review. I finally got a chance to look this over
> again.
>
> My main nits are about the commit message: I think it still focuses
> too much on the process instead of the usual "knowing what I know now,
> here's the clearest explanation for why we need this patch" approach.
> I can send a patch illustrating what I mean tomorrow morning.
I'll turn 'Will merge to next' to 'Hold' for now.
>> Object format
>> ~~~~~~~~~~~~~
>> The content as a byte sequence of a tag, commit, or tree object named
>> -by sha1 and newhash differ because an object named by newhash-name refers to
>> +by sha1 and sha256 differ because an object named by sha256-name refers to
>
> Not about this patch: this should say SHA-1 and SHA-256, I think.
> Leaving it as is in this patch as you did is the right thing.
Perhaps deserves a "NEEDSWORK" comment, though.
> [...]
>> @@ -255,10 +252,10 @@ network byte order):
>> up to and not including the table of CRC32 values.
>> - Zero or more NUL bytes.
>> - The trailer consists of the following:
>> - - A copy of the 20-byte NewHash checksum at the end of the
>> + - A copy of the 20-byte SHA-256 checksum at the end of the
>
> Not about this patch: a SHA-256 is 32 bytes. Leaving that for a
> separate patch as you did is the right thing, though.
>
> [...]
>> - - 20-byte NewHash checksum of all of the above.
>> + - 20-byte SHA-256 checksum of all of the above.
>
> Likewise.
Hmph, I've always assumed since NewHash plan was written that this
part was not about tamper resistance but was about bit-flipping
detection and it was deliberate to stick to 20-byte sum, truncating
as necessary.
It definitely is a good idea to leave it for a separate patch to
update this part.
Thanks.
next prev parent reply other threads:[~2018-08-03 16:40 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
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 [this message]
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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