The Enigma machine was a device used by the Germans during the Second World War with which they encoded a message in billions of different ways, hindering other nations from cracking German codes. Alan Turing and other researchers, however, exploited a few weaknesses in the implementation of the Enigma code and invented another machine known as the bombe machine, which helped crack the codes produced by the Enigma machine. By decoding sensitive information from the Germans, the Allies were able to prevent many attacks during the war, and, even though they had the knowledge to stop the Nazis, they had to allow some attacks to be carried out in order to avoid suspicion. After the Second World War ended, Turing continued his research in this area, building on his earlier work and incorporating the knowledge he gained on coding and decoding during the war. Ultimately, he published a design for the ACE (Automatic Computing Engine), which was arguably the forerunner to the modern computer.