User:Mangoe/CORAL (cipher)

CORAL was the code name given to a 1939 cipher system used by Japanese naval attaches during World War II.

Solution of this system was slowed by the relatively low volume of traffic; it was finally solved in 1944 by a team headed by Francis Raven with assistance from Bletchley Park.

Design

The CORAL system was put into service in 1939. It used a stepping switch mechanism similar to that of the "Purple" machine used by the foreign service. Unlike "Purple", however, it did not encrypt the vowels and consonants separately (the "6-20 split")

Analysis

Coral was not broken until 1944, though Agnes Driscoll, who led one of the successful efforts which cracked PURPLE, worked on it for a year before being moved to work on German codes in 1940.

Much CORAL traffic was of benefit in the European theater. For example, Vice Admiral Katsuo Abe was naval attache in Rome from 1941 to 1943 and then in Berlin until 1944, where he took on a intelligence role. His extensive contacts with members of the German high command (and especially with head of the submarine service, Karl Dönitz) resulted in the transmission of much information on German deployments, which, passed through CORAL and decrypted, gave intelligence valuable to allied military planners.