[darcs-devel] [Haskell-cafe] Re: announcing darcs 2.0.0pre3
zooko at zooko.com
Wed Jan 23 17:47:20 EST 2008
> principle it is good to provide a cryptographically secure hash, as
> allows users to sign their repositories by signing a single file,
> seems like it's potentially quite a useful feature.
Can you be more specific about this -- who can "sign" a repository?
How is such a signature checked? What guarantee can you rely on if
the check passes?
As far as I know, it is impossible to use a hash value in darcs to
securely denote a specific patch, because darcs patches do not have a
canonical form. In fact, last time I checked the patch *contents*
didn't even go into the input to SHA-1, just the patch metadata
(timestamp, author, patch description).
I don't think SHA-1 is necessarily a bad choice if you need a secure
hash function (although I would like a better argument than "Linus
chose it."), but I don't understand why we need a secure hash function.
(If you need a secure hash function, Tiger is probably stronger than,
and is 150% as fast as, SHA-1.)
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