Code makers and breakers of WWII

A Japanese family of high-level encryption machines using telephone selector switches came to be known in the US by their colourful code names: Coral, Jade and Purple. Their names derived from the colours of the binders US cryptanalysts used to enclose material about the respective systems.

The Japanese Imperial Navy used the Jade machine's Shift key and 25 letter keys to encrypt the 48 characters of the katakana syllabary. Although most were aboard ship, this Jade was captured on Saipan when US forces took the island in June 1944, according to the National Security Agency.

Credit: National Security Agency