Re: Improvements of SHA-1 attacks

> This does not affect hashcash, because contrary to some descriptions,
> hashcash is not based on hash collisions.  Technically it is based on
> partial preimages of zero.  No attacks are known to speed up searching
> for such values with SHA-1.  The brute force search that hashcash 
> depends
> on is still the best you can do.
>
> The only effect might be if people begin to perceive SHA-1 as "broken"
> then they might mistakenly mistrust hashcash.

In any case, it is reasonably easy to fix by redefining the token 
relative to SHA-256 or similar.  I don't mind re-doing the relevant 
optimisations for that case - in fact, I think SHA-256 has a structure 
that's slightly more compiler-friendly with respect to heavily 
optimised implementations, though these would still consume slightly 
more CPU time per bit than SHA-1.

The question is whether to make that move sooner or later?

--------------------------------------------------------------
from:     Jonathan "Chromatix" Morton
mail:     [email protected]
website:  http://www.chromatix.uklinux.net/
tagline:  The key to knowledge is not to rely on people to teach you it.