Encryption

Caesar Cypher

The simplest form of encrypting the message is the Caesar Cypher, where each letter in your message is shifted along the alphabet and replaced by one a bit further on. For example, if the shift is two characters, then DOG would become FQI, because F is two letters further on than D, and Q is two letters further on than O, etc.

This is a good plan, but suffers from the problem that you only have to try at most 26 different alternatives to find the hidden message. You can also use frequency analysis to help, because some letters are used much more often than others, so whatever letter appears most is quite likely an E, which will help you in your guesses.