The Cipher Department of the High Command of the Wehrmacht () (also Oberkommando der Wehrmacht Chiffrierabteilung or Chiffrierabteilung of the High Command of the Wehrmacht or Chiffrierabteilung of the OKW or OKW/Chi or Chi) was the Signal Intelligence Agency of the Supreme Command of the Armed Forces of the German Armed Forces before and during World War II. OKW/Chi, within the formal order of battle hierarchy OKW/WFsT/Ag WNV/Chi, dealt with the cryptanalysis and deciphering of enemy and neutral states' message traffic and security control of its own key processes and machinery, such as the rotor cipher ENIGMA machine. It was the successor to the former Chi bureau () of the Reichswehr Ministry.Friedrich L. Bauer: Decrypted Secrets. Methods and Maxims of cryptography. 3d revised and expanded edition. 2000, p. 412
Short name The name "Chi" for the Chiffrierabteilung ("cipher department") is, contrary to what one might expect, not in reference to the Greek letter Chi, nor anything to do with the chi-squared test, a common cryptographic test used as part of deciphering of enciphered message, and invented by Solomon Kullback, but simply the first three letters of the word Chiffrierabteilung.
German cryptology service structure during World War II From the early 1930s to the start of the war, Germany had a good understanding of, and indeed a lead in, both cryptoanalytic and cryptographic cryptology services. The various agencies had cracked the French–English inter-allied cipher, the Germans with some help from the Italian Communications Intelligence Organization stole American diplomatic codes, and codes taken from the British embassy in Rome, that enabled the breaking of the cipher, John Ferris: Intelligence and Strategy: Selected Essays. Routledge; New edition 25 June 2005, Page 337 Note 80 - RG 457/145 Major Gamba - An Account of the recovery of the keys of the Inter-allied Cipher; Admiral Maugeri - Italian Communications Intelligence Organization. leading to some gains early in the war. Although the Germans worked to ensure its cryptologic services were effective at the outbreak of the war, the service offerings fragmented considerably among the German armed forces. OKW/Chi had jurisdiction over all the military cryptologic bureaus, chairing the executive committee. However, for several reasons, including specialisation against opposing forces of a similar type, the inherent independence of agencies, and agencies vying for power and favour from Hitler, it was inevitable that the three military branches of German forces operated independently.
In total eight organizations operated within the forces, each operating on its own terms, even though OKW/Chi was considered the premier organization controlling both cipher creation and decipherment of enemy crypts. These eight bureaus which practiced cryptology were split between military and civilian control:.
Military OKW/Chi: The highest cryptologic bureau for the Wehrmacht supreme command. General der Nachrichtenaufklärung: The high command of the German Army (Wehrmacht) OKH/Chi cipher bureau. Luftnachrichten Abteilung 350: The OKL/Chi cipher bureau for high command of the Luftwaffe. B-Dienst: (Observation Service) The Navy High Command OKM/Chi cipher bureau. Abwehr: Military intelligence gathering and cipher bureau from 1941 to 1944.
Civilian AA/Pers Z S: (AA) Auswärtiges Amt (Foreign Office Personnel Department) (Pers Z) Sonderdienst (Special Service of Unit Z) The Foreign Office cipher bureau decrypting diplomatic signals. RSHA: The Reichssicherheitshauptamt (Reich Security Main Office), the main cipher bureau for Hitler's personal staff including the SS. Forschungsamt: (Research bureau). Part of OKL and Göring's personnel cipher bureau.
Although OKW/Chi continually pushed for the integration of all five military services, it was last blocked in Autumn 1943 by Ribbentrop, Göring, and Himmler. It was not until 9 November 1944, that OKW/Chi was formally made responsible for control of all signals intelligence activities across all forces, by the order of Hitler.
Background The OKW/Chi was one of the highest military agencies of the Wehrmacht, but with a dual focus: on cryptography, creating Germany's own secure communication systems, and the monitoring of enemy broadcasts and news analysis. As far as cryptanalysis was concerned, OKW/Chi tended to act as troubleshooter, providing the highest service to the Wehrmacht, instead of setting policy as its power to set military SIGINT was limited.
The unit began as the cipher section of the German Defense Ministry () in 1922. The Cipher Bureau () followed later in the 1930s. They were more interested in diplomatic communications than foreign military communications, which were in short supply, and viewed the diplomatic communications as a way to train staff during peacetime. With the rise of the Nazis, the unit grew from 10 people in 1937 to almost 200 people by the outbreak of World War II in 1939. By the end of the war, it had almost 800 individuals working there, and its focus had changed to strategy.
It was true that a certain amount of development and security work was always done. The original charter was obscure, but since the Army, Navy and the Air Force was each responsible for its own security development, the only defining commitment of OKW/Chi was to develop ciphers for the agents of the Abwehr. The separate branches were free to submit their own systems to OKW for security scrutiny. This was changed in October 1942, ensuring that no new ciphers could be introduced by the Armed Forces unless they were first checked by the OKW. OKW/Chi made some efforts to set up an additional section in section IV, but this work was buried within the organization with OKW/Chi remaining an organization that produced military intelligence.
Contrast this with Bletchley Park, the UK Government Code and Cypher School during World War II, the direct opponent of OKW/Chi, which had almost 12,000 personnel working at the end of the war. It had a singular focus on cryptanalysis services and an integrated strategy across all the services from the start of the war.
OKW/Chi was one of the primary targets of TICOM, the operation by the United States to seize military assets after the war.
Key personnel The most important individual at OKW/Chi was Chief Cryptologist Director Wilhelm Fenner, who was the Head of Main Group B, including Group IV Analytical cryptanalysis working with Specialist Dr. Erich Hüttenhain.Friedrich L. Bauer: Decrypted Secrets. Methods and Maxims of cryptography. 3 revised and expanded edition. 2000, p 447 A German by birth, Wilhelm Fenner went to high school in St Petersburg. His father was an editor of a German language newspaper. He moved back to Germany in 1909 to study at Berlin Royal Institute of Technology but was drafted into the Army when World War I started, eventually joining the Tenth Army, serving as an intelligence officer. After the war, Fenner met Professor Peter Novopaschenny, a former Tsarist cryptanalyst who taught Fenner the Black Arts of Cryptography, and who went on to become Chief of the Russian subsection of OKW/Chi.Friedrich L. Bauer: Decrypted Secrets. Methods and Maxims of cryptography. 3 revised and expanded edition. 2000, p 472 They both joined the Cipher Bureau in autumn 1922, initially working in temporary positions. The following year, Fenner was made chief of the Bureau. He worked there until just after the war, discharged on 19 June, eventually working as a car and cycle mechanic in Straubing.
Chief Cryptanalyst Specialist Dr. Erich Hüttenhain was a mathematician hired in 1937 to create a specialized cryptanalytic research unit to investigate enemy cryptologic systems and to test Germany's own cryptologic systems and processes. Together with Dr. Walter Fricke, Chief evaluator, also a mathematician of some distinction, and his assistant, he was also moved to England to be interrogated by TICOM after the war. Walter Fricke was then considered the official historian of OKW/Chi.
Colonel Hugo Kettler was an administrator who had commanded OKW/Chi from October 1943. His intimate knowledge of the working of OKW/Chi, enabled him to provide information to TICOM that the OKW/Chi archive papers had been moved to Schliersee.
Lieutenant Colonel Metting was a signals officer who worked up to command the Germany Armies cryptologic centre, Inspectorate 7/VI from November 1941 to June 1943. After working in the Signals Battalion on the Eastern Front for several months, he was assigned second in command of OKW/Chi in December 1943. After the war he was considered such a high-value target that he was moved to England to be interrogated by TICOM. He was Head of Main Group A.
Organization The following information was prepared by TICOM agents, by comparing the interrogation documents of Colonel Hugo Kettler, Director Wilhelm Fenner, Dr. Walter Fricke and Dr. Erich Hüttenhain. TICOM believed that the information was correct.
1939 to summer 1944 OKW/Chi passed from peace to war without change to its organization. Preparations had been made in 1938 to define staff numbers but at the outbreak of the war, personnel were increased by about 30%. In 1939, OKW/Chi was called The Cryptologic Bureau (German: Chiffrierstelle) and was a part of the Inspectorate of the Signal Troops. At the start of the war The Cryptologic Bureau was commanded by Oberstlt (Colonel) Fritz Boetzel as Director of Operations with his deputy being Major Andrae. He was replaced by Colonel Hugo Kettler during summer of 1943.
The organization of OKW/Chi was broken down into four groups which were named Group I to Group IV.
In 1938, OKW/Chi had no mechanical aids to use for the quick decryption of enemy messages once the cipher was broken. Although major attempts were made to mechanize the process, it was realized only in late 1943 that additional specialist personnel would be needed, and they were not available.
OKW/Chi was primarily an intelligence gathering organization at this point, with its only commitment to develop ciphers for Military Intelligence (Abwehr). Each branch of the armed forces were free to submit their system for testing, but were under no obligation to do so. In October 1943, OKW/Chi gained control for cipher development across all military agencies by an order of Field Marshall Keitel, Chief of Staff of the Supreme Command Armed Forces (OKW).
Summer 1944 to March 1945 The organisation and mission of OKW/Chi changed significantly in the summer of 1944, principally centered on the attempted assassination of Hitler. Whereas OKW/Chi had supposed jurisdiction over all cipher agencies within the Armed Forces, after Summer 1944, Director Wilhelm Fenner persuaded Generalleutnant Albert Praun, General of the Communications Troops of the need to centralise all results and efforts within OKW/Chi, and to issue an order to that effect. After the order, OKW/Chi no longer acted like a service agency, but instead set policy and became the primary jurisdiction for all work done on cipher development, message decryption and associated machinery design and construction. The organisation changed significantly, with new commanding officers, more focus for Chi IV function and increased staffing levels.
OKW/Chi classified the manner of how they would work with other agencies. How they were classified depended on whether a particular agency had influential Nazi party members in their leadership. The Army had close ties with OKW/Chi but other classifications, for example, the Kriegsmarine and Luftwaffe proved more difficult to control and were never subordinate to OKW. Agreement was needed to ensure common process, control and cipher machinery. The Waffen-SS was considered a third classification. OKW had no control over it and special orders had to be issued to enable liaison to start.