Ciphers hide a message (the plaintext) mainly through two methods 1) Substitution: Changing the characters in the plaintext for different ones (the number of characters in the plaintext is usually conserved). 2) Transposition: Rearranging the characters of the plaintext. There are, of course, many ways both of these methods can be achieved and combinations of them are often used. If you are interested on the subject, I found Wikipedia to be helpful. The cipher above is a simple one. Here is a hint: [spoiler]12-5-20 20-8-5 7-1-13-5-19 2-5-7-9-14 => 12-e-20 20-8-e 7-a-13-e-19 2-e-7-i-14[/spoiler]