Johannes Marquart

Johannes Anton Marquart (born 27 September 1909 in Erolzheim in Germany) Prior to that period Marquart had been chief cryptanalysis in KONA 5.

After the war, Marquart worked in the German insurance firm, Allianz Lebensversicherung in Stuttgart, as a field insurance agent for the territory around Mittelbiberach, that at the time was part of the French zone.

Cryptanalytic experience As head of special research section for hand ciphers, Marquart's work was of a varied nature. Marquart worked on the following hand ciphers:

Josip Broz Tito System This Josip Broz Tito cipher consisted of the alphabet substituted into figures in such a way that the commonest letters were allotted one figure equivalents while the rarer letters were expressed as figure digraphs. The resulting figures were then reciphered (recencrypted) by a periodic additive, the length of which varied from time to time. At first, the period was very short (5,7 or 9); later it rose to 35 or 45 and at the end, Marquart thought that it was used on a one-time basis, since no further successes could be achieved.

Draža Mihailović System The Draža Mihailović hand cipher was a Double Transposition cipher, using the same key for both cages, the keys being derived from a novel. Marquarts section achieved a fair measure of success with this system, owing to errors in encipherment, stereotyped signatures and also the fact that the cages were often filled up to rectangles with rare letters. Under such circumstances, it was often possible to recover the key from a single message. In some cases, by working out the basic text from which the keys had been derived, they were able to recognize and obtain the novel and hence to read all message traffic currently. All cryptanalytic work on the double transposition systems was carried out entirely by hand by Marquart, and no attempt was made to develop any statistical machine methods for solution.

British Army Double Transposition This code used two different keys, which were taken from a large group. Marquart was unable to guess at the size of the book that had never been captured. His work was looking for errors in encipherment which happened rarely and for messages in depth, which practically never occurred.

Russian Blocknots Marquart conducted research in the Soviet Union Blocknot traffic. Blocknots were random sequences of numbers contained in a book and organized by numbered rows and columns and were used as additives in reciphering. Marquart and his unit conducted extensive research in an attempt to discover the method by which they were produced. All the counts which they made, however, failed to reveal any non-random characteristics in the design of the tables, and while they thought the Blocknots must have been generated by machine, they were never able to draw any concrete deductions as a result of their research.

Polish Lublin System Lastly, Marquart worked on a system used by the military forces of the Lublin Government just before the end of the war.