Today’s Math Monday begins a multi-part series on the columnar transposition cipher.

We return to the series on columnar transposition ciphers to discuss permutations, how CTCs can be thought of as permutations, and some questions that this connection opens up.

In the United States, information about cryptanalysis of the cipher remained classified until a few years ago. Double Transposition consists of two applications of columnar transposition to a message.

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