The Enigma was a machine used by the German military before and during World War II to encrypt messages. To encrypt (or encipher) a message means to change its form in such a way that it (ideally) becomes unintelligible to anyone besides the sender and the intended receiver. It is the job of decryption analysts to decipher intercepted messages so that the secret information in those messages is revealed.

In 1919 a Dutch inventor patented a device to encrypt messages. A German engineer named Scherbius aided him in constructing the device. Scherbius eventually purchased the patent rights and began marketing the machine, which he dubbed the Enigma, for both commercial and military purposes. By the late 1920s the German military removed the Enigma from the commercial market for their own use. The Enigma, as pictured above, was roughly the size of a typewriter, and it possessed a...