From: "H. Peter Anvin" <hpa@zytor.com>
To: "git@vger.kernel.org" <git@vger.kernel.org>
Subject: Migrating away from SHA-1?
Date: Tue, 12 Apr 2016 15:38:04 -0700 [thread overview]
Message-ID: <570D78CC.9030807@zytor.com> (raw)
OK, I'm going to open this can of worms...
At what point do we migrate from SHA-1? At this point the
cryptoanalysis of SHA-1 is most likely a matter of time.
For existing repositories we will need to have a migration mechanism.
Since we can't modify objects without completely invalidating the
cryptographic properties, what I would suggest is that we leave the
existing objects as is, with a persistent lookup table from SHA-1 to
<new hash>, and have that lookup table signed (e.g. GPG) by the person
responsible for converting the repository. This freezes the
cryptographic status of the existing SHA-1 objects at the time the
conversion happens. This is a very good reason to do this before SHA-1
is actually broken In contrast. SHA-2 has been surprisingly resistant
to cryptoanalysis, to the point that SHA-3 was motivated by performance
and the desire to have a well-tested function based on entirely
different principles should a generic attack against the common
structure of MD5/SHA-1/SHA-2 would ever be found.
-hpa
next reply other threads:[~2016-04-12 22:38 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-12 22:38 H. Peter Anvin [this message]
2016-04-12 23:00 ` Migrating away from SHA-1? Stefan Beller
2016-04-12 23:06 ` H. Peter Anvin
2016-04-12 23:15 ` Jeff King
2016-04-12 23:15 ` David Turner
2016-04-12 23:44 ` Jeff King
2016-04-14 1:53 ` Theodore Ts'o
2016-04-14 16:47 ` Joey Hess
2016-04-14 17:23 ` David Turner
2016-04-14 17:28 ` H. Peter Anvin
2016-04-14 22:40 ` Theodore Ts'o
2016-04-15 2:13 ` Jeff King
2016-04-15 2:18 ` Junio C Hamano
2016-04-15 2:22 ` Jeff King
2016-04-12 23:42 ` Jeff King
2016-04-13 1:03 ` Junio C Hamano
2016-04-13 1:36 ` Jeff King
2016-04-13 1:38 ` H. Peter Anvin
2016-04-13 1:51 ` Duy Nguyen
2016-04-13 1:58 ` H. Peter Anvin
2016-04-15 1:50 ` brian m. carlson
-- strict thread matches above, loose matches on Subject: below --
2016-06-18 2:10 Leo Gaspard
2016-06-18 3:30 ` Eric Wong
2016-06-24 18:17 ` brian m. carlson
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