unforgeable optical tokens?

[Perry E. Metzger]

Nelson Minar <nelson at monkey.org> writes:
> More details are here:
>   http://web.media.mit.edu/~pappu/htm/res/resPOWF.htm
>   http://web.media.mit.edu/~pappu/htm/pubs/PappuPhDThesis01.pdf
> 
> Ravi's PhD has a section on replay attacks - section 10.3, page 135.
> The claim there is you can't store all possible challenge/response
> pairs because the keyspace is too big and that the actual system is
> too complex to simulate.

But if you can't simulate the system, that implies that the challenger
has to have stored the challenge-response pairs because he can't just
generate them, right? That means that only finitely many are likely to
be stored. Or was this thought of too?


-- 
Perry E. Metzger		perry at piermont.com

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