Polybius Square Ciphers

Sammanfattning

In this thesis, we will define Polybius Square Ciphers and explain howit used to encrypt plaintext. We will talk about Playfair, ADFGX andADFGVX. We will introduce how Shannon entropy works and its principalproperties. We will use Shannon entropy and frequency comparison toshow whether Playfair and ADFG(V)X are uncertain and safe in today’stechnological environment.