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Pin-and-lug cipher machine - wanted item

The C-35 is the first fully mechanical pin-and-lug cipher machine developed by Boris Hagelin of AB Cryptoteknik in Stockholm (Sweden). It is much smaller than most of his later machines of the same class. It has five coding wheels and a revolving cage with sideways movable bars with lugs.


The C-35 was initially developed at the request of the French Army, who wanted the machine to fit the pocket of their trousers, providing Boris Hagelin with a piece of wood of the desired size, that would fit the pocket of an army uniform.

The C-35 became the basic design on which all Hagelin's later machines would be based. At the front right are five pin-wheels that are fitted on a common axle. Behind it is a cylindrical cage with horizontal bars that can be displaced to the left side. Each bar has a vertical lug at a fixed positon. At the left is a counter and a printer.

  

Each cipher wheel has a different number of steps: 25, 23, 21, 19 and 17 (all co-primes of 26) to ensure the maximim cycle length, or period, of 3,900,225. A plaintext message is encrypted on a letter-by letter basis, by setting the alphabet knob at the left to the input letter and rotating the knob, or advance lever, at the right. The output letter is then printed on a narrow paper strip at the left. The device was an immediate hit. Hagelin sold 5000 units to the French Army in 1935.

The image above shows one of the few surviving examples of a C-35 from the internal collection of Crypto AG. It was demonstrated by former development chief Oskar Sturzinger during a book presentation in Basel in 2008. The C-35 was succeeded a year later by the improved by the C-36.


  1. US Patent 2089603
    BCW Hagelin, filed 23 August 1935.

  2. Wikipedia, C-36 (cipher machine)
    Retrieved August 2009.