This is the codename for the cipher machine developed from a design patented by a Dutchman, Hugo Koch, in 1919. Impressed by its security, which was based on statistical analysis, the German government acquired all rights to the machine and adapted it to the needs of its new, modern military forces. It became the standard cipher machine for Germany's military services, intelligence agents and secret police. It was also used at all echelons, from high command to front-line tactical units including individual aeroplanes, tanks, and ships.
The machine was based on a system of three rotors that substituted cipher text letters for plain text letters. The rotors would spin in conjunction with each other, thus performing varying substitutions. In order for the recipient to decode the message, they would need to know the initial settings of the rotors, then put the cipher text through the machine to find the plain text.
The Poles were reading some ENIGMA traffic by 1932, the French in 1938 and the British in 1940.
ULTRA was the code name given in 1940 to the British security classification denoting the new, highly secret intelligence produced by the decryption of intercepted German radio messages enciphered in the ENIGMA machine cipher.
An Enigma is on display in the Australian War Memorial’s Second World War Gallery.