Date & time (UTC/GMT):
February 20, 2021 5:00 PM
In the 1920s, Japan as well as other countries explored the use of cipher machines. Based on what they learned from European manufacturers, during the 1930s, Japan produced two families of cipher machines for their diplomats and their Navy. The 1931 series of cipher machines were based on the Damm half-rotor. Three types of machines were designed and produced: RED (a machine for diplomatic use that enciphered Roman letters), ORANGE (a machine for use by large naval stations that enciphered kana characters), and M-2 (a machine for use by naval attachés that enciphered Roman letters). These machines were later replaced by the 1937 series of machines that were based on Strowger switches (telephone exchange switches). The three replacements machines were: PURPLE (which replaced RED), JADE (which replaced ORANGE), and CORAL (which replaced the M-2). This presentation will briefly discuss the cryptography and the history of these two families of Japanese cipher machines.