From: "Eric S. Raymond" <firstname.lastname@example.org>
To: Jonathan Nieder <email@example.com>
Subject: Re: RFC: Separate commit identification from Merkle hashing
Date: Mon, 20 May 2019 22:38:32 -0400 [thread overview]
Message-ID: <20190521023832.GA130381@thyrsus.com> (raw)
Jonathan Nieder <firstname.lastname@example.org>:
> Eric S. Raymond wrote:
> > One reason I am sure of this is the SHA-1 to whatever transition.
> > We can't count on the successor hash to survive attack forever.
> > Accordingly, git's design needs to be stable against the possibility
> > of having to accommodate multiple future hash algorithms in the
> > future.
> Have you read through Documentation/technical/hash-function-transition? It
> takes the case where the new hash function is found to be weak into account.
> Hope that helps,
At first sight I think it looks pretty compatible with what I am proposing.
The goals anyway, some of the implementation tactics would change a bit.
I think it's a weakness, though, that most of it is written as though it
assumes only one hash transition will be necessary. (This is me thinking
on long timescales again.)
Instead of having a gpgsig-sha256 field, I would change the code so all
hash cookies have an delimited optional prefix giving the hash-algorithm
type, with an absent prefix interpreted as SHA-1.
I think the idea of mapping future hashes to SHA-1s, which are then
used as fs lookup keys, is sound. The same technique (probably the
same code!) could be used to map the otherwise uninterpreted
commit-IDs I'm proposing to lookup keys.
I should have said in my previous mail that I'm prepared to put
my coding fingers into making all this happen. I am pretty sure my
gramty manager will approve.
<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>
next prev parent reply other threads:[~2019-05-21 2:38 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-21 1:32 RFC: Separate commit identification from Merkle hashing Eric S. Raymond
2019-05-21 1:57 ` Jonathan Nieder
2019-05-21 2:38 ` Eric S. Raymond [this message]
2019-05-21 2:58 ` Jonathan Nieder
2019-05-21 3:31 ` Eric S. Raymond
2019-05-23 19:09 ` Jakub Narebski
2019-05-23 20:09 ` Jonathan Nieder
2019-05-23 20:53 ` Eric S. Raymond
2019-05-23 20:50 ` Eric S. Raymond
2019-05-23 20:54 ` Jonathan Nieder
2019-05-23 21:19 ` Eric S. Raymond
2019-05-23 21:39 ` Randall S. Becker
2019-05-23 21:50 ` Ævar Arnfjörð Bjarmason
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