31. The dockyards produced more than 300, 000 cipher machines from a model bought in an undisclosed " European country ". 32. His son, Nigel de Grey was one of the codebreakers that worked on decrypting messages from the Enigma cipher machine . 33. The German Enigma machine is a family of about a dozen different cipher machine designs, each with its own problems. 34. This led to the development of electromechanical devices as cipher machines , and to the only unbreakable cipher, the one time pad. 35. Most German messages decrypted at Bletchley were produced by one or another version of the Lorenz SZ42 on-line teleprinter cipher machine . 36. In 1964, Lyubimov's cover was blown in a failed attempt to recruit a cipher machine operator to spy for the Soviets. 37. It was during those hearings that the Japanese learned, for the first time, that the Purple cipher machine had indeed been broken. 38. Over the following two months up to January 1942, Tutte and colleagues worked out the complete logical structure of the cipher machine . 39. "" The room where I operated the cipher machine also contained a teleprinter which was connected to the main signal station in Townsville. 40. In the 1920s four men in different countries invented rotor cipher machines to produce a key stream to act instead of a tape.
