In cryptography, a rotor machine is an electro-mechanical stream cipher device used for encrypting and decrypting secret messages. Rotor machines were the cryptographic state-of-the-art for a prominent period of history; they were in widespread use in the 1920s–1970s. The most famous example is the German Enigma machine, whose messages were deciphered by the Allies during World War II, producing intelligence code-named Ultra.
The primary component is a set of rotors, also termed wheels or drums, which are rotating disks with an array of electrical contacts on either side. The wiring between the contacts implements a fixed substitution of letters, replacing them in some complex fashion. On its own, this would offer little security; however, after encrypting each letter, the rotors advance positions, changing the substitution. By this means, a rotor machine produces a complex polyalphabetic substitution cipher, which changes with every keypress.
Read more about Rotor Machine: Background, Mechanization, List of Rotor Machines
Famous quotes containing the word machine:
“But a man must keep an eye on his servants, if he would not have them rule him. Man is a shrewd inventor, and is ever taking the hint of a new machine from his own structure, adapting some secret of his own anatomy in iron, wood, and leather, to some required function in the work of the world. But it is found that the machine unmans the user. What he gains in making cloth, he loses in general power.”
—Ralph Waldo Emerson (1803–1882)