enigma

The Enigma was an electro-mechanical rotor cypher machine used for both encryption and decryption, widely used in various forms in Europe from the early 1920s on. It is most famous for having been adopted by most German military forces from about 1930 on. Ease of use and the supposedly unbreakable cypher were the main reasons for its widespread use. The cypher was in fact broken, and the reading of information in the messages it didn't protect is generally credited with ending World War II at least a year earlier than it would have otherwise. The British encryption machine, Typex, and several American ones, eg the SIGABA or M-134-C, were similar in principle to Enigma, but far more secure. The first modern rotor cypher machine, by Edward Hebern, was considerably less secure, a fact noted by William F. Friedman when it was offered to the US Government.