After the First World War, Italian engineer Luigi Nicoletti invented a transposition cipher tool. Can you break a ciphertext I created with this device?
Two online games for crypto enthusiasts have been launched – one in Germany, one in Poland.
Blog reader Karsten Hansky has provided me a nice encrypted postcard from 1954. Can a reader decipher it?
George Lasry has found an interesting collection of challenge ciphers, probably used to train codebreakers during the early Cold War. Today, I’m going to present one of these challenges.