PGP, or Pretty Good Privacy, uses RSA encryption methods to
encrypt a message with a public key system. This means that
if you want to encrypt a message that only I can decrypt (for
example you want to send me some sensitive information), you
can use my public key to encrypt it, and only I can decrypt
it with my private key. Because of the nature of public
key encryption, the only known way to break it is to crunch
away to try to find a key pair that works on the message,
and that can take Crays a few months to do, at best.
There is currently no known algorithmic short cut because it
would involve factoring large numbers quickly.
So, if you want to send me some important information, please
encrypt it with PGP using the key block on the previous page.
After all, I want the NSA to make all those mathematicians