Update

I added information from ‘Report on interrogation of Walter Schellenberg 27 June- 12 July 1945’ (which can be found in British national archives folder KV 2/95) in Intercepted conversations - Bell Labs A-3 Speech scrambler and German codebreakers, Reich security service and OKW/Chi reports and Allen Dulles and the compromise of OSS codes in WWII.

Also added information from the report E-Bericht Nr. 3/44 der NAASt 5 (Berichtszeit 1.4-30.6.44) in German intelligence on operation Overlord and The American M-209 cipher machine.