Final answer:
During World War II, Germans used the Enigma machine, an electromechanical rotor-based cipher system, which was eventually deciphered by the Allies led by Alan Turing.
Step-by-step explanation:
The Germans made use of an electromechanical rotor-based cipher system known as the Enigma during World War II. This complex machine was crucial for their military communications but was eventually deciphered by the Allies, significantly influencing the course of the war. Part of the Allied success in breaking the Enigma codes can be attributed to the efforts of a British mathematician and logician, Alan Turing, who, along with his team, developed the Bombe machine to automate the process of decoding Enigma messages.
The breaking of the Enigma cipher was a decisive factor in the outcome of World War II, showcasing not only the importance of cryptography but also leading to significant advances in the development of early computers. The work done to crack the Enigma codes laid the groundwork for post-war electronic computing devices, such as the ENIAC. Moreover, the intelligence gained from decoding German messages provided a critical advantage to the Allies, turning the tide in pivotal battles such as the Battle of the Atlantic.