Consisting of rotors, a lampboard, a keyboard, and a plugboard, what is the name of the electro-mechanical cipher machine deployed by the Germans during WWII?
John Herivel working alongside David Rees, another Cambridge mathematician recruited by Welchman, in nearby Elmers School, testing candidate solutions and working out plugboard settings. The process was slow, however, Herivel was determined to find a method to improve their attack, and he would spend his evenings trying to think up ways to do so. Intercepted Morse coded messages had been enciphered by the Germans’ Enigma, an electro-mechanical rotor cipher machine that implemented a polyalphabetic cipher. The main model in use in 1940 had three rotors that set an electrical pathway from the keyboard to the lampboard. Pressing a key caused one lamp
Type A Cipher Machine was broken by Frank Rowlett and Solomon Kullback; for the navy, Agnes Driscoll is generally credited. (She actually solved the Orange (or M-1) cipher used by naval attaches, but as it turned out the two systems were essentially the same.) The Americans also constructed a replica machine to expedite solutions; this machine had two half-rotors to solve the vowels and consonants separately. The SIS group originally referred to it simply as the "Japanese code machine", but decided that so descriptive a term was a security risk; as it was the first Japanese machine cipher solved, they decided to start at