The Substitution Cipher is likely the most commonly known encryption algorithm. It consists of assigning each input character a unique output character, ideally one that differs from the original, and replacing all characters from the input with the output equivalent when encrypting $($and vice$-$versa when decrypting$).$

In our implementation, this mapping between input and output will provided via a shifter string. The shifter will represent the output characters corresponding to the input character at the same relative position within the overall range of encodable characters $($defined by Cipher.MIN$\_$CHAR and Cipher.MAX$\_$CHAR$).$ To picture this, we can vertically align this shifter string with the encryptable range and look at the corresponding columns to see the appropriate character mappings. Consider the following example: