I read a bit once on cryptography and found it very interesting. But the problem with cryptography, if I remember correctly, is that whatever method is used to create encrypted text, the communication of the decoding key to the recipients is really the crux of the matter. That is why this guy (forgot hos name) at MIT developed the PGP algorithm with public keys and private keys. The plain text is encrypted with the private key and decripted with the public key, I think.
I think Zimmerman is his name?
The write-once method is the safest and the one most widely used in intelligence.
Forgot most of this stuff.
Yes, the Government got a little annoyed that he wanted to make his Pretty Good Protection available to the outside world. It made their job of intercepting messages very difficult.