By Dean Neal
Enigma allowed an operator to type in a message, then scramble it by using three to five notched wheels, or rotors, which displayed different letters of the alphabet. The receiver needed to know the exact settings of these rotors in order to reconstitute the coded text. Over the years the basic machine became more complicated as German code experts added plugs with electronic circuits.
How It's Used!
The Enigma Machine consisted of a wooden cabinet enclosing a typewriter keyboard and a set of 26 lamps (one for each letter of the alphabet). At the top of the machine was a slot into which three wheels or rotors could be fitted onto a shaft.
The rotors were furnished with electrical contacts and buried inside were wires that connected the contacts on one side to those on the other in a scrambled order. The cabinet contained a battery, and when a key was pressed, electric current would flow from the keyboard through each of the three rotors in turn, through a reflector, then back through the rotors, and finally through one of the lamps making it light up.
A number of different rotors were available (8 in this case) and the operator would choose which rotors to use and the order in which to use them. The operator could also select which reflector to use (2 were available).
The rotors had adjustable rings which could be turned with respect to the inner core. The ring for each rotor could be set by the operator in any one of 26 possible positions (A to Z).