One of the most famous cryptographic devices ever manufactured, the Enigma machine used by the Nazis in World War II, is to be sold next week at Christie's in London.

The three-rotor ENIGMA came to fame as the standard German electronic ciphering machine whose code was cracked during World War II. The design of the machine was originally patented by a Dutch inventor, H.A. Koch in 1919 and featured a an interchangeable series of three rotors bearing the 26-character alphabet, a 'reflector' and a plugboard with movable connecting cords that connected pairs of letters. 

While in use, the starting settings for the rotors was changed every 24 hours, according to pre-printed setting registers furnished in advance or supplied daily by courier. It has been calculated that the 3-rotor ENIGMA, with plugboard in use, made possible a total of 15 billion billion possible readings for each character.

ENIGMA was widely regarded by the Germans as too complex to be broken, but in the 1930s a team of Polish analysts (Marian Rejewski, Jerzy Rszycki and Henryk Zygalski) succeeded in deciphering much of the encrypted German radio traffic. Their findings, including plans for very useful mechanical devices known as 'bombes', which aided in the decryption operation, were secretly passed on in 1939 to French and British investigators. This aided the team of cryptanalysts, mathematicians and engineers, including Alan Turing, based at the UK's top-secret facility at Bletchley Park. to decipher encrypted communications.

Although thousands of Enigma machines were manufactured not many have survived intact.

According to Christie's this particular model was one of those used in the 2001 film Enigma and was subsequently on museum display. It is described as being in good overall condition with wear and scuffs consistent with age. The rotor wheels come from a different machine and the mechanics seem in working order, although as it lacks a battery pack Christie's cannot guarantee this.

Last year a similar machine that had a similar pre-sale estimate of £30-50,000 sold for £67,250.

Update: The lot realized £133,250

Related articles:

To be informed about new articles on I Programmer, subscribe to the RSS feed, follow us on Twitter or Facebook or sign up for our weekly newsletter.