In my piece on the compromise of OSS codes during WWII it was stated that Allen Dulles occasionally used diplomatic ciphers when his own systems where overloaded.
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In 1943 the Germans were apparently able to read his messages enciphered on the M-138-A strip cipher. The question is whether this was an OSS strip set or the special set used by the embassy in Berne for diplomatic traffic.
Report SRH-366 ‘History of Army Strip Cipher devices’ says that the Army Signal Intelligence agency provided M-138 strips for OSS use in 1944.
