Rotor machine

Rotor cipher machines (including rotor - key machine ) encryption are mechanical machines that usually contain multiple rotors. They were about 1920 to 1960 in use, especially during the time of the Second World War (1939-1945 ) and some not until the mid-1970s.

Operation

The rotors ( often referred to as rolls ) arranged rotatably with each other and their position changes during the operation key. At their outer surfaces, they have more contacts (often just 26 for the 26 capital letters of the Latin alphabet ), which are connected by insulated wires together inside. By the rotation of the rotors have a different ( polyalphabethische ) substitution obtained for each letter of text. The cryptographic security of the encryption depends essentially on the number of rotors used because the set of possible substitutions (also called key space ) increases multiplicatively with the number of rotors used.

Types

A variant of the rotor machines, the half - rotor design is by Boris Hagelin, in which a letter is also encrypted by two parallel half- rotors with fixed input and variable output. The actual encryption is caused by the uneven course of the rotors, which is mechanically controlled by four pinwheels. The Japanese RED machine uses this design.

One of the first rotor machines is the electric machine code of the American inventor Edward Hugh lifters. His machine had only a single rotor. Other well-known rotor cipher machines are the German ENIGMA (with three or four rotors ), the British TypeX (also known as Type -X, with five rotors ), the Soviet Fialka ( German " Violet" with ten rotors ), the Swiss NEMA ( "New machine" with ten rotors ) and the American Sigaba (15 rotors ).

The design was discovered almost simultaneously in different countries by different inventors or invented. The Polish LCD Lacida and a number of other machines works by this construction. The American M -209 with (usually) six pin rollers and their civilian Hagelin -varieties, however, are purely mechanical cipher machines with different operating principle, are only directly comparable in their application and the achieved safety with the rotor machines.