RSA encrption

An excellent book on Cryptography is Richard A Mollin guide to crptography. You can get software on the net that will create text that the government cannot break.
One such system is called RSA. It relies on the fact that two prime numbers when multiplied together form a third number called a co -prime. While multiplying this two numbers is easy getting them back is difficult. This is called factoring. If you have numbers that are very large this makes it more difficult for govenrments to break.It relies on two keys , one is public and the other is private. The public key is like this big number, but without knowing the private key its very difficult to get the private key.

RSA-99: defined at Paul Zimmermann's site as the number 256724393281137036243618548169692747168133997830674574560564321074494892576105743931776484232708881
its factor is 4868376167980921239824329271069101142472222111193
http://www.alpertron.com.ar/ECMREC.HTM
He uses an elliptical curve method to factor numnbers.

This is taken from the website :-
Lets take an easy example say 19 * 31 = 589 . 589 would be my public key and 19 or 31 would be my a private key. RSA also does other things, but factoring is the heart of the system. So unless people know both the public key and 1 of the private key they are stuck.
For more information see wikipedia:-
http://en.wikipedia.org/wiki/RSA