In a monoalphabetic cipher, each letter of the cipher text corresponds to exactly one letter of the plain text.

We have examined three kinds of monoalphabetic ciphers:

1. Shift cipher: shift each letter arithmetically by a fixed amount
2. Affine cipher: shift each letter arithmetically according to a linear rule.
3. Substitution cipher: The general case. Any permutation of the alphabet

Let's look at a message.