Cipher Department of the High Command of the Wehrmacht
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.
[6] 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.
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.
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).
[12] 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.
[14] 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.
Group X's assignment was the scanning and forwarding of deciphered telegrams to suitable offices including the keeping of a day book recording the most important data.
Chi II achieved these results in spite of having to work since the outbreak of the war without pause in day and night shifts, and since August 1943, owing to bomb damage, in a deep cellar and in cramped quarters.
[17] Damage to working materials, e.g. burnt one-time pads, reciphering, and cipher texts, caused by air attacks were regularly made good by copies that had been safely stored elsewhere.
[15] The principal recipient of the most important VNs was General Alfred Jodl, Chief of Operations and Hitler, with a copies being sent to other agencies and archives and used for additional processing, for example, cribbing.
The deciding factor was always the grammatical sense and word structure of the VN,[21] and any attempt at free elaboration of an incomplete reliable report was strictly forbidden.
These copies were inserted in binders, ordered chronologically and delivered to the Chef der Heeresarchive, located in 8 Hans von Seeckt Strasse, Potsdam, whenever it was assumed that Chi no longer had an active interest in them.
[15] All intercepts were centrally controlled by the unit in order that it did justice to the requirements of the recipients and the technical demands of deciphering at the same time to remove unnecessary duplication.
The monthly averages for the period of January 1944 to June 1944 were as follows:[17] OKW/Chi ran two distinct interception networks, which included legacy systems from previous agencies.
Colonel Mettig would prepare a monthly report in conjunction with Chief Cryptologist Wilhelm Fenner, of the most interesting links (that a listening station had made) as he appreciated them, based on this knowledge.
[15] The bulk of interception was either ordinary Morse code or radio telephone, with little attempt to expand into other traffic types, e.g. Baudot[15][17] Applicants to the unit were generally academics who had achieved a doctorate, or individuals who had passed the First major State Examination e.g.
Generally, when a new member joined, who could speak a foreign language, they started as linguists and were gradually introduced into cryptology, working for two days per week in the six winter months.
[21] At the earliest, the candidate could apply after three years for admission to the Second major State Examination for life to become a Beamter of the Higher Foreign Language Service of the Armed Forces.
The Examination Commission consisted of Wilhelm Fenner, Dr Erich Hüttenhain, one of the candidate's teachers and a representative of the Armed Forces Administrative Office.
The Austrians had personal contact with the Hungarian cipher bureau, who learned of the matter and within weeks sent two men to Berlin, including Wilhelm Kabina, and within a few hours of arriving, an agreement was worked out to collaborate.
Fenner visited the agency in Helsinki in 1927 to explore collaboration with Chi, but found that the Finnish had barely any organisation, but three years later it was an equal partner in cipher work.
[14] Dr Erich Hüttenhain stated that fierce resistance was met from other departments at any attempt to control the security of all the ciphers and key processes.
[29] Even in mid 1944, when Generalleutnant Albert Praun issued a decree [Ref 5.2], that unified the security of own key processes of all the cipher bureaux within OKW/Chi, Pers Z S ignored the order.
Dr. Huettenhain said in TICOM interrogation:[30] A number of other possibly secure systems were developed including Fritz Menzer’s cipher device 39 (SG-39) (German: Schlüsselgerät 39).
He crucially failed to identify the primary and most important weakness of the Enigma machine: the lack of fixed points (letters encrypting to themselves), due to the reflector, was missed.
Originally no help from OKW/Chi was requested, but in late 1937, Dr. Hüttenhain, Senior Inspector Menzer of OKW/Chi and Dr. Werner Liebknecht, a cryptologic tester from C. Lorenz AG, tested the first SZ-40 and found it could be broken with 1000 letters of text without cribs.
Dr Hüttenhain states as follows: The US rapid analytic machine that was most nearly like the German device was the Tetragraph Tester[40] by the Eastman Kodak Company for OP-20-G and the Army Security Agency.
When asked by TICOM if they were able to take any action, Fenner stated that as a result of reading these messages, that sometimes they were able to change the place or time of an attack but that usually the reports were of a long-term strategic nature and there was little they could do about it.
These messages contained extremely valuable information, for example, the rapid breakdown of the Romanian Army due to poor supply of ammunition, or arms and rations.
[53] Rave stated that: A further piece of evidence was offered by author Dr Wilhelm F. Flicke, who is also described as an employee of OKW/Chi working in the intercept network at Lauf [23][54] and whose book, War Secrets in the Ether[24] (which was restricted (English translation) by the NSA, and Britain, until the early 1970s) described how many messages between Japanese military attache and later Japanese ambassador Hiroshi Ōshima to Nazi Germany, in Berlin, were intercepted at Lauf and deciphered by OKW/Chi.
