PHP Puzzles: Sending and Receiving Polybius Ciphers

Ciphers come in many different forms and have been used since ancient times to encode and decode vital messages. Today, we use complicated mathematics to encrypt and decrypt messages. Typically, we depend on shared and secret keys to ensure the message is only readable by the intended recipients. What if you don’t have the computing power of a modern device at your disposal? This month, let’s look at using Polybius Squares to share secret messages.