Update

In the sources of The American M-209 cipher machine I added links to Cryptomuseum Hagelin M-209 page, Special conference on M-209 security (1950), M-209: German break

Update

1). I’ve added links to Allied agents codes and Referat 12 in several essays dealing with agents codes.

2). In The US AN/GSQ-1 (SIGJIP) speech scrambler I had written ‘The US authorities used up to mid 1943 the Bell Labs A-3 speech scrambler, a device that utilized speech inversion’. This was not correct, as the A-3 used band-splitting and inversion.

3). In WWII Myths - T-34 Best Tank of the war I added a new link to the report Evaluation of tanks T-34 and KV by workers of the Aberdeen testing grounds of the US, as the old one was not working.

4). In Enigma security measures I added information from the report ‘Änderungen beim Schlüsseln mit Maschinenschlüssel’ in paragraphs Random indicators and CY procedure.

Allied agents codes and Referat 12

In the course of WWII both the Allies and the Axis powers were able to gain information of great value from reading their enemies secret communications. In Britain the codebreakers of Bletchley Park solved several enemy systems with the most important ones being the German Enigma and Tunny cipher machines and the Italian C-38m. Codebreaking played a role in the Battle of the Atlantic, the North Africa Campaign and the Normandy invasion. 

In the United States the Army and Navy codebreakers solved many Japanese cryptosystems and used this advantage in battle. The great victory at Midway would probably not have been possible if the Americans had not solved the Japanese Navy’s JN25 code.

On the other side of the hill the codebreakers of Germany, Japan, Italy and Finland also solved many important enemy cryptosystems both military and diplomatic. The German codebreakers could eavesdrop on the radio-telephone conversations of Franklin Roosevelt and Winston Churchill, they could decode the messages of the British and US Navies during their convoy operations in the Atlantic and together with the Japanese and Finns they could solve State Department messages (both low and high level)  from embassies around the world.

Radio intelligence and codebreaking played an important role not only in the military and diplomatic fields but also in the shadow war between the Allied intelligence agencies, the European Resistance movements and the German security services. In the period 1939-41 German troops conquered most of continental Europe and the occupied countries were forced to contribute to the Axis effort by sending raw materials, agricultural products and forced labor to Germany. Thanks to the blockade of German occupied Europe by the Royal Navy and the harsh demands of the German authorities life in the occupied areas was bleak. Discontent over German occupation led many people to join resistance movements and oppose the authorities, either by printing and distributing anti-Axis leaflets and books, by sabotaging war production or by directly attacking the German troops and their collaborators in the government and the civil service.