Nothing whatsoever. The ban is a joke. "Applied Cryptography", with
(paper!) source code, has been freely exported to other countries. If
you export a floppy disk *with exactly the same source code* on it, you
go to prison. Some guy is selling T-shirts with machine-readable RSA
code on them (those little bars that supermarket checkers scan with
laser pistols, I think). To get this T-shirt, you must present a
notarized document stating you are a U.S. citizen and you will guard the
T-shirt with your life, or something like that. These T-shirts, you
see, are CONTROLLED MUNITIONS.
I am not making this up.
--
sentience@pobox.com Eliezer S. Yudkowsky
http://tezcat.com/~eliezer/singularity.html
http://tezcat.com/~eliezer/algernon.html
Disclaimer: Unless otherwise specified, I'm not telling you
everything I think I know.