C-36 (cipher machine)

The C-35 and C-36 were cipher machines designed by Swedish cryptographer Boris Hagelin in the 1930s. These were the first of Hagelin's cipher machines to feature the pin-and-lug mechanism. A later machine in the same series, the M-209, was widely-used by the United States military.

In 1934, the French military approached Hagelin to design a printing, pocket-size cipher machine; Hagelin carved a piece of wood to outline the dimensions of a machine that would fit into a pocket. He adapted one of his previous inventions from three years earlier: an adding device designed for use in vending machines, and combined it with the pinwheel mechanism from an earlier cipher machine (the B-21). The French ordered 5,000 in 1935. Italy and the USA declined the machine, although both would later use the M-209 / C-38. Completely mechanical, the C-35 machine measured 6 × 4.5 × 2 inches, and weighed less than 3 pounds.

A revised machine, the C-36, was similar to the C-35, but included moveable lugs and a protective case for the machine. Six C-36 machines were purchased by the Swedish Navy for testing in October 1937. Both machines had five pinwheels with 17, 19, 21, 23 and 25 pins, each individually settable, giving a maximum period of 3,900,225 for the machine.

One variant had a Thai alphabet on the pinwheels, rather than the usual Latin alphabet.

References

* Torbjörn Andersson, The Hagelin C-35/C-36, [http://hem.passagen.se/tan01/c35.html] , retrieved 15 November 2005.
* Boris CW Hagelin, The Story of the Hagelin Cryptos, "Cryptologia", 18(3), July 1994, pp 204–242.
* David Kahn, The Codebreakers, 1967, 2nd ed 1996, Chapter 13, pp426–427.
* Unknown, information card for a C-36 machine in the "Enigma and Friends" exhibit at Bletchley Park Museum, 2005.

Further reading

* C. A. Deavours, Solution of C-35 Texts with Partial Key, "Cryptologia", 14(2), April 1990 pp162–168.