Polybius Square Cipher
Key
Polybius Square Cipher is essentially identical to the simple substitution cipher, except that each plaintext character is enciphered as 2 ciphertext characters. It can ususally be detected if there are only 5 or 6 different characters in the ciphertext. [Wikipedia]
This algorithm offers very little communication security, and can be easily broken even by hand, especially as the messages become longer (more than several hundred ciphertext characters).
Related Tools
Base16 Encode & Decode
Base16 Encoder & Decoder that alow you to convert data between Base16 and text. Base16 uses sixteen distinct symbols, most often the symbols "0"–"9" to represent values 0 to 9, and "A"–"F" (or alternatively "a"–"f") to represent values from 10 to 15.
