The Elevator Problem

[Futplex]

Dave writes:
> Disregarding the "quantum properties of light" issue, if Eve can listen
> in on every communication between Alice and Bob about their keys, then
> doesn't she have enough information to reconstruct the key herself?

By "disregarding the quantum properties", I assume you are asking about
deterministic cryptosystems. Eve does not have sufficient information if 
Alice and Bob use, say, Diffie-Hellman key exchange (DH). As I said, that's
why DH is so clever. :)  (cf. any good crypto text)  But that's patented
(for now), and we were asked about a patent-free solution.

-Futplex <futplex at pseudonym.com>
"We live in a time when...individual rights are constantly expanded" -Sen. 
Orrin Hatch (R-UT), speaking in support of an anti-flag-desecration 
Constitutional amendment