The Playfair Cipher is a substitution cipher. It is a little more complex than what we are going to attempt, but the lesson here isn't about recreating a cipher that was developed in the mid-19^thcentury. This is all about arrays (both single and 2-dimensional) and treating strings of text as arrays ofcharcharacters.

The original Playfair uses a digraph substitution method. This means that it encrypts pairs of letters rather than single letters used by simpler substitution methods. Ours will be more like a simple substitution method.