Security of RAF Cipher Machine (Type-X)

The following is a memorandum to "C", the head of the Secret Intelligence Service, from the Government Code and Cypher School recommending that SIS and the Foreign Office do not use the RAF cipher machine instead of one time pads for encrypted communications. Presumably the RAF machine cipher referred to in this memo is the Type-X.  GC&CS are concerned that as they are reading German Enigma machine ciphers, the RAF cipher machine could also be breakable in a similar way. Indeed a few years later, a German prisoner of war claimed that the Wehrmacht had been reading Type-X messages sent during the North African campaign for a short while.

Report on the Problems with and Solutions to Special Operations Executive Signal Ciphers

The following document is taken from the Special Operations Executive official Signals history. It discusses what went wrong with SOE cipher procedures and the piecemeal steps taken to perfect greatly enhanced cipher security for field agents. It can be seen that problems with ineffectual security checks in the early SOE missions no doubt contributed to such disasters as wrought in the Netherlands, the Abwehr’s so-called Englandspiel which wiped out SOE circuits in the country.

British Army Middle East Map Reference Point Code


The British Army Map Reference Point Code was a method of sending disguised map coordinates in a plain text communication when no other cipher or code was used. From 1st December 1943, the whole of the British Army adopted a standard system based on the one being used by forces in the Middle East.

British Army Low Grade Ciphers

British Army Low Grade ciphers used in World War II

British Army low grade ciphers were intended to be used by the headquarters of all units and formations, not possessing a common higher grade cipher, for tactical messages dealing with operations, movements and administrative plans likely to be effective in the near future. These messages dealing with plans or operations scheduled to take effect after more than 48 hours were not to be sent by wireless unless a medium or high grade cipher was available.