He explores polyalphabetic substitution ciphers, transposition ciphers, including one developed by the Spartans, connections between ciphers and computer encryption, stream ciphers, ciphers involving ...

Another is to employ a transposition cipher, in which the letters change position within the message. In this interactive, explore examples of a substitution cipher and two kinds of transposition ...

Cryptanalyst Jim Gillogly created them using the Playfair, Double Playfair, and Double Transposition ciphers, respectively.