Decoder Ring

The Polybius Square is a cipher that is achieved by arranging a typical alphabet into a grid. Each letter is represented through a coordinate. For example, the letter "B" would be represented by the numerical pair "21".

The Substitution Cipher requires a standard alphabet and a substitution alphabet of 26 characters. Letters from the standard alphabet will be transposed to the substitution alphabet. This cipher requires that the recipient have the substitution alphabet, otherwise it will be difficult for them to decode the message.