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Japanese diplomatic codes included high-level ciphers of which the most important was that using a machine-operated system, Angooki Taipu A, Cipher Machine A. This was broken by the American Army Signal Intelligence Service (SIS), headed by Wolf Frederick Friedman, in 1936. The machine used to do this was dubbed "Red". In late 1938 the Japanese changed the code and Friedman had broken that by 25 September 1940 with, finally, a fully efficient mechanism he called "Purple". The word was also used to refer to the code which it decoded. The output of all decryptions of the diplomatic message traffic was designated MAGIC. SIS was a rival to the Naval Communications Service (NCS) which was working on JN-25 and the confusion that resulted from inter-service non-co-operation led to the establishment of a single intelligence body, the Central Intelligence Agency (CIA).

See also: Central Intelligence Agency; espionage; JN-25; MAGIC


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