A rare, fully-operational Enigma cipher machine from World War II will go up for auction at Sothebys tomorrow as part of an amazing History of Science & Technology auction (also including Richard Feynman's Nobel Prize). The Enigma is expected to go for around $200,000.
From a 1999 article I wrote for Wired:
German soldiers issued an Enigma were to make no mistake about their orders if captured: Shoot it or throw it overboard. Based on electronic typewriters invented in the 1920s, the infamous Enigma encryption machines of World War II were controlled by wheels set with the code du jour. Each letter typed would illuminate the appropriate character to send in the coded message.
In 1940, building on work by Polish code breakers, Alan Turing and his colleagues at the famed UK cryptography center Bletchley Park devised the Bombe, a mechanical computer that deciphered Enigma-encoded messages. Even as the Nazis beefed up the Enigma architecture by adding more wheels, the codes could be cracked at the Naval Security Station in Washington, DC – giving the Allies the upper hand in the Battle of the Atlantic. The fact that the Allies had cracked the Enigma code was not officially confirmed until the 1970s.