problem. Given a long message or several short ones of the same date, solution should be possible in an expeditious manner.
17. The solution of the B-machine has, as a concomitant, thrown considerable light upon the mechanism of the A-machine with the result that our present A-machine will be modified in the light of these discoveries and wi11 be made more efficient. The whole situation with respect to the cipher machines employed by the Japanese Foreign Office now appears to be integrated into a consistent scheme of development from its earliest and simplest beginnings, about 1930, to its present quite complex form. Problems concerning the A-machine and questions for which logical and "reasonable" answers could not be found are now explainable on the simple grounds of the type of cryptographic mechanism employed in the earlier machines, which seems to be the rotary switch used in automatic telephony, rather than the revolving commutator employed in our present A-machine.
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Part. II. Credits
18. The successful solution of the B-machine is the culmination of 18 months of intensive study by a group of cryptanalysts and assistants working as a harmonious, well-coordinated and cooperative team. Only by such cooperation and close collaboration of all concerned could the solution possibly have been reached, and the name of no one person can be selected as deserving of the major portion of credit for this achievement. The parts played by the individual members of the team may, however, be indicated.
19. The specific direction and coordination of all studies on this project was the joint work of Cryptanalyst Frank B.Rowlett and Assistant Cryptanalyst Robert O. Ferner. Their indefatigable labors and brilliant analytical work testify and are a credit to their cryptanalytic skill, training and experience. To their joint direction and efforts are due the extremely fruitful analysis of the cryptographic mechanics underlying the operation of the B-machine as a whole, the theory of its operation, and the development and solution of the "6's" at any early date in these studies. They were also extremely active in pushing the solution to a successful conclusion by organizing and directing the reconstruction of the developments or wirings of the switches for the "20's". Junior Cryptanalysts Genevieve M. Grotjan, Albert W. Small, and Samuel S. Snyder did most excellent work in recovering the "6's" during many months of apparently hopeless effort. In this work they were occasionally assisted by Cryptographic Specialists Cyrus C. Sturgis, Jr., Kenneth D. Miller, and Glenn S. Laudig. Of the latter two mentioned, it should also be stated that their very large output of work in the decoding of J code material, assisted part time by other members of the J-Section, lifted much of the heavy burden of this absolutely necessary current translation work from the
