Secret Codes

I’ve added a new puzzle, one that generates Secret Codes. See:
http://www.armoredpenguin.com/cipher/

The idea is that you type in a series of words or phrases, and the letters are substituted for other letters based upon a key. You can have a very simple (almost trivial) code known as a Caesar Cipher, or you can make it harder by randomly shuffling the alphabet. It can be even harder by having a longer key length.