Thanks Ed, I had read similar stuff about breaches of Enigma protocols on
www.u-boat.net/forum
Since the article comments why it was that German Army and Luftwaffe Enigma was not recorded, it is worth noting it was hardly a secret in WW2 that the RAF type X encryption machine was a licence manufactured version of the three wheel Enigma.
Indeed at the fall of Dunkirk several RAF airfield command posts were overrun and the Germans actually captured 24 RAF type X (Enigma) machines.
I would imagine that it was less secret that the three rotor machine was being decyphered, but highly sensitive that the four rotor machine was being read.
Also quite late in the war u-boats put to sea with the Krokodil 43 system. This was the combination of a four rotor machine with a three rotor Enigma. The message was first encyphered according to the appropriate key settings on a four rotor Enigma.
Settings changed twice per day according to prearranged settings (of rotor wheels to the steckkerboard [letters]) by dates. Also each service operated nets on their own frequencies. Late in the war for example the u-boat net was called Triton. Other u-boat nets included Narwhal, Shark and Bonito. The SS had several nets too as did Luftwaffe and Heerswaffen.
The message was then encyphered a second time on the three rotor machine. In addition an officer's eyes only message would sometimes be double encyphered on the four rotor machine.
The U-534 raised from the sea near Denmark in 1999 had over two tons of documents aboard her which are now in refrigerated storage by the u-boat's new owner.
U-534 also had two Enigma machines aboard when sunk and was using the Krokodil 43 system.
Some of the Kreigsmarine's archived signals were flown from Flensberg to Barcelona on 6 April 1945 by a Luftwaffe Junkers 290 (possibly operated by Deutsch Luft Hansa airlines). The load was so heavy that the aircraft's tail wheel broke off on landing and the aircraft was abandoned at the airport.