Sharing a secret with someone you don't trust, message
authentication, message integrity, user identification -- nowadays, these
are all made possible by a branch of cryptography called Public Key
Cryptography. The mathematics behind much of public key cryptography was once praised for its great uselessness -- and we'll talk about that. Finally, Chocolate Key Cryptography is a way to describe a certain public key cryptosystem, a way that is easy to learn, fun, and delicious.