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2 History of Hagelin mechanical rotor cipher machines
In 1925, while working for the Swedish company A.B. Cryptograph, Boris Hagelin developed his first cipher machine, the electromechanical B-21, to compete with the Enigma when the Swedish General Staff where looking for new cipher machines to purchase. This was based on the B-18 invented by the company’s owner Arvid Gerhard Damm. The B-21 rotor machine had many similarities with the Enigma, a keyboard for input and light bulbs for output. To avoid patent infringement Hagelin used totally different ciphering operations. Instead of alphabet substitution, he used four coding pin-wheels to scramble a 5x5 matrix. The wheels had different cyclic length, 17, 19, 21 and 23, which made them align after 156009 enciphered letters. More on the pin-wheels in Chapter 3. One problem with the 5x5 matrix, was that it only allowed for a 25 letter long alphabet, so the letter W was substituted by VV. The B-21 was considered more secure than the Enigma, but this was not fact. In 1931 it was broken in less than 24 hours by Arne Beurling, a young mathematics student, attending a course in general cryptology and cryptanalysis held by the Swedish Cipher Bureau at the Swedish Navy Staff. Beurling become more famous in 1942 when he deciphered the German Geheimfernschreiber, also single handedly, with only a pencil and paper in under two weeks. This caused the Swedish Government to establish “Försvarets Radioanstalt”. [Beckman].
At the end of 1933 the French Army got interested in the B-21, but requested some modifications. They needed a portable ciphering machine that could print text. Hagelin added these changes and production of the B-211 started in France. Before the outbreak of WW2, there were produced approximately 500 machines. The ciphering method was the same pin-wheels and matrix as on the B-21. Soon after the beginning of the business with the French, they inquired Hagelin about the possibilities of a compact portable cipher machine that could print. Combining the design of the B-21 and a coin changing machine Hagelin had invented a while before, his first fully mechanical bars and lugs rot cipher machine were invented in 1935, the C-35. The calculating mechanism in the coin changing machine consisted of a cylindrical cage made out of horizontal bars. The bars were affected by keys, slid to the left and creating
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Figur 1: C-35
The Hagelin M-209 cipher machine
teeth in a cogwheel in a variable gear. A type wheel was then turned the same number of rounds as bars in their left position. The keys in the changing machine were switched with pin-wheels, and the type wheel now carried letters instead of numbers. Hagelin have now built the C-35 ciphering machine with 25 horizontal bars in the cage and five pin-wheels. The cage is also discussed in detail in chapter 3. The numbers of letters on the wheels were 17, 19, 21, 23 and 25, which made them align after 3900225 enciphered letters.
It was later made several changes to the C-35, making in more suitable for tactical use, adding one pin-wheel, and introduce movable lugs on the bars in the cage. The pin-wheel and cage changes were made in a direct response to cryptoanlysis work made by the Swedish cryptoanalyst Yves Gylden in 1935. The changes led to the model C-36. The numbers of letters on the wheels were 26, 25, 23, 21, 19 and 17, which made them align after 101405850 enciphered letters.
In 1937 Hagelin travelled to the US, trying to get the Government in Washington interested in his ciphering
machines, but was met with very little interest. Right after the war in Europe had broken out in 1939, he once again travelled to the US, trying to sell them his ciphering machine. This time they were much more interested. William Frederick Friedman, a US Army cryptographer, and the head of the research divison of the Army's Signal Intelligence Service, suggested certain changes. After these changes the machine was named M-209 by the US Army, C-38 by Hagelin,
but were most known only by the “Hagelin. In 1942 it was adopted by the US Army, and multiple other allied nations, including Norway. By the same year it was put into mass production by the company L. C. Smith & Corona Typewriters Inc.. In addition to their regular 600 typewriters a day, they now starting putting out as much as 500 olive-drab Hagelin machines a day. By 1944 there were produced approximately 50000 machines, and by the end of the war approximately 140000. The production was not discontinued before
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