After reviewing the terms with students, write a different one-line cipher on the board, using the above key, for the class to solve. Write substitution and transposition ciphers.

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

To decrypt a double transposition, construct a block with the right number of rows under the keyword, blocking off the short columns. Write the cipher in by columns, and read it out by rows.

The Union side, led by cryptographer Albert Myer, also developed various ciphers to secure their own communications, including simple transposition and substitution ciphers.