Re: [Monotone-devel] Re: RFC: Fake IDs

[Zack Weinberg]

On 7/18/06, Nathaniel Smith <address@hidden> wrote:
> If we don't trust SHA1, why are we using it at all? :-)
>
> If we hash some text, and then compare it to another equal-length
> bitstring... the collision probability is not affected by whether that
> other bitstrings was generated by pounding on the keyboard or by SHA1
> of some other text.  Am I missing something in this analysis?

Perhaps I only say this because I am not a cryptographer at all, but
it seems to me that the collision probability results might depend on
the assumption that both sides of the potential collision are in fact
SHA of some text.  In which case, maybe a bitstream generated by
pounding on the keyboard is more likely to collide.

Anyway, that's what I worry about when I see random (or, in fact, not
so random at all) bitstrings being used as fake IDs.

zw