The Enigma Machine
The Enigma machine, invented by Arthur Scherbius in 1918, is an electromechanical rotor-based cipher machine that was initially produced for the commercial market. While its predecessor was not very successful, the later lamp-based model known today was used by Germany during the Second World War to encrypt its communications.
It has become the most well known cipher machine in the world due to the recent publicity surrounding the work of Allied codebreakers during the Second World War.
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Enigma Stecker Cable
This is a plugboard cable from the German Enigma machine. Each machine used by the German military was equipped with 12 of these cables (although the plugboard could hold up to 13). The plugboard in the images is a reproduction. Each cable, 20cm long, had a black bakelite plug at each end with one thick pin on the top (measuring 4mm) and one thin pin below it (measuring 3mm). Connecting the two pins were two wires - one connecting the thick pin on one plug to the thin pin on the other, and vice versa. The German word for plug is "stecker", so the plugboard is known in German as the "Steckerbrett". The Steckerbrett has 26 sockets, one for each of the letters A-Z. Each socket has two contact. The sockets of the Steckerbrett are self-closing, meaning that if no plug is inserted, the two contacts are automatically shorted by an internal spring-loaded shorting bar (attached to the end of the socket, protruding behind the Steckerbrett). The cable is used to swap pairs of letters, making it self-reciprocal. If any number of cables (0≤N≤13) had been used, the number of combinations would have been 532,985,208,200,000. In reality, however, six, and then later 10 cables were used at a time, reducing the number of possibilities. In the latter case, the number of combinations would be only 150,738,274,900,000.