GEHEIMSCHREIBER

World War II's “Fish” cipher was a British cover word for all kinds of encrypted German radio teleprinter messages. The GC&CS at Bletchley, Buckinghamshire, did not only attack successfully Enigma traffic (Morse signals on radio links) by the electromechanical deciphering machines called BOMBES. In addition, Bletchley's electronic text processor COLOSSUS broke the German “Tunny” ciphers, generated by TELEPRINTER ATTACHMENTS “SZ”, employed by the ‘Heer’ (Army) on HF radio links.