compare-by-hash (was Re: sharing /etc/passwd)

[Jacques A. Vidrine]

On Tue, Sep 28, 2004 at 12:14:05PM +0300, Giorgos Keramidas wrote:
> There is one difference between ``looking for collisions'' and being
> bitten by undetected collisions though.
> 
> If the probability of a collision just happening with random user data
> is 1/(2^128) we can't be sure that it will necessarily take the
> transfer of an average number of 2^127 blocks before a collision
> happens.  You might get one at the very first pair of blocks and then
> no collisions ever after until the Sun burns out.
> 
> Using two different hashes for the same set of input data, which David
> G. Andersen proposed, seems like a nice idea though.

If you buy the "logic" of the paper, this would not make much
difference.  After all, composing two hashes just gives you another
hash with a longer bit length.

This paper needs a lot more peer review, although I'm not sure that
many take it seriously enough to bother.

Cheers,
-- 
Jacques A Vidrine / NTT/Verio
nectar at celabo.org / jvidrine at verio.net / nectar at FreeBSD.org