From: Theodore Ts'o <tytso@mit.edu>
To: Sebastian Schuberth <sschuberth@gmail.com>
Cc: git@vger.kernel.org
Subject: Re: Exploiting SHA1's "XOR weakness" allows for faster hash calculation
Date: Wed, 5 Dec 2012 12:20:11 -0500 [thread overview]
Message-ID: <20121205172011.GH18885@thunk.org> (raw)
In-Reply-To: <k9n3jd$akg$1@ger.gmane.org>
On Wed, Dec 05, 2012 at 10:19:43AM +0100, Sebastian Schuberth wrote:
>
> to say it in advance: I do not want to trigger any bogus security
> discussion here. Instead, I believe the findings from [1] allow for
> an up to 20% faster SHA1 calculation, if my brief reading of the
> presentation is correct. Any opinions on integration this
> optimization into Git?
>
> [1] https://hashcat.net/p12/js-sha1exp_169.pdf
It's only useful if you are trying to do brute-force password
cracking, where the password is being hashed in a very specific way.
(If for example the password was replicated N times in the input
buffer for SHA-1, instead of keeping the padding constant in the rest
of theinput buffer, this particular optimization would't apply.)
In any case, it's not at all applicable for general purpose checksum
calculations, and hence wouldn't apply to git.
Regards,
- Ted
next prev parent reply other threads:[~2012-12-05 17:20 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-05 9:19 Exploiting SHA1's "XOR weakness" allows for faster hash calculation Sebastian Schuberth
2012-12-05 12:26 ` Marko Kreen
2012-12-05 17:20 ` Theodore Ts'o [this message]
2012-12-06 8:11 ` Sebastian Schuberth
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