What is a Keyword Cipher?

A Keyword Cipher is a form of monoalphabetic substitution, where a keyword is used to create a mixed alphabet. This mixed alphabet is then used to encrypt the message.

How It Works

First, a keyword is chosen, and duplicate letters are removed. Then, the keyword is written down, and the remaining letters of the alphabet are written in order after it. For example, with the keyword "SCIOLY", the alphabet would be: S C I O L Y A B D E F G H J K M N P Q R T U V W X Z.

Practice Time!

Let's encrypt "CODE" with the keyword "SCIOLY".

C -> I

O -> N

D -> O

E -> L

So, "CODE" becomes "INOL".