Marching Orders: The Untold Story of How the American Breaking of the Japanese Secret Codes Led to the Defeat of Nazi Germany and Japan

by Bruce Lee

The most important of these is a machine-operated system called Angooki Taipu A, or Cipher Machine A. The code produced for this machine is for high-level diplomatic traffic. It is unreadable. However, after a year of intense effort, Friedman and his Army SIS team breaks the Type A code in 1936, and Friedman labels the machine that makes the decipherment possible as Red. In 1938 the Japanese change their codes. Again they are unreadable. That is until September 25, 1940, when Friedman’s team creates a miracle—a machine that produces the first totally clear, ungarbled decryption of the new code, which Friedman immediately labels Purple.