B-Dienst

The B-Dienst (German: Beobachtungsdienst, observation service), also called xB-Dienst, X-B-Dienst and χB-Dienst,[1] was a Department of the German Naval Intelligence Service (German: Marinenachrichtendienst, MND III) of the OKM, that dealt with the interception and recording, decoding and analysis of the enemy, in particular British radio communications before and during World War II.[2] B-Dienst worked on cryptanalysis and deciphering (decrypting) of enemy and neutral states' message traffic and security control of Kriegsmarine key processes and machinery.

"The ultimate goal of all evaluation was recognizing the opponent's goal by pro-active identification of data."[3]

B-Dienst was instrumental in moulding Wehrmacht operations during the Battles of Norway and France in spring 1940, primarily due to the cryptanalysis successes it had achieved against early and less secure British Naval ciphers.

B-Dienst broke British Naval Combined Cypher No. 3 in October 1941, which was used to encrypt all communications between naval personnel, for Allied North Atlantic convoys.[4] This enabled B-Dienst to provide valuable signals intelligence for the German Navy in the Battle of the Atlantic. The intelligence flow largely ended when the Admiralty introduced Naval Cipher No. 5 on 10 June 1943. The new cipher became secure in January 1944 with the introduction of the Stencil Subtractor system which was used to recipher it.[5][6]

  1. ^ Friedrich L. Bauer (1 January 2000). Entzifferte Geheimnisse, Methoden und Maximen der Kryptographie 3rd. edition. Berlin: Springer. p. 449. ISBN 978-3-540-67931-8.
  2. ^ Heinz Bonatz (1 January 1981). Seekrieg im Äther. Die Leistungen der Marine-Funkaufklärung 1939–1945 (in German). Herford: Springer. p. 56. ISBN 978-3-8132-0120-8.
  3. ^ Heinz Bonatz, 1981 p. 56
  4. ^ "B-Dienst vs Bletchley Park – The invasion of Norway and the Battle of the Atlantic". Christos Military and Intelligence Corner. 14 May 2012. Retrieved 16 May 2015.
  5. ^ David Bercuson; Holger H. Herwig (13 April 2011). Deadly Seas: The Duel Between the St. Croix and the U305 in the Battle of the Atlantic. Random House of Canada. p. 74. ISBN 978-0-307-36848-5.
  6. ^ Malcolm H. Murfett (4 November 2008). Naval Warfare 1919–45: An Operational History of the Volatile War at Sea. Routledge. p. 321. ISBN 978-1-134-04813-7.