When many think about secret codes and code breaking, the German Enigma often comes to mind. The mathematical and engineering feat was unprecedented and allowed for the Germans to be able to secretly communicate without having to fear that the Allies could understand it. This was based on the fact that there were 17,576 possible combinations of the initial configuration. However, one major flaw (a letter can’t be matched to itself) helped Alan Turing and Gordon Welchman create The Bombe, which can crack the Enigma in under 20 minutes.
Before The Bombe, came The Bomba, a Polish code breaking machine that was able to crack a variant of the Enigma used by the German army. Created in 1932, was created by mathematically analyzing the codes produced by the Enigma. The several Polish mathematicians tasked with cracking the Enigma used the fact that the first 3 letters of the message were the same as the second 3 letters and used this to be able to reverse engineer the Enigma machine itself. By using the power and speed of electrical currents, the Polish were able to build The Bomba, a machine that tried every possible initial configuration. At the time, this was feasible due to the Enigma not having too many possible configurations at the time. However, during the war, the Germans altered their rotor system and added 2 more potential rotors, which drastically increased the time it took to go through all the combinations and rendered The Bomba mostly useless. However, the main strategies and ideas behind The Bomba were then transferred to the British and French in their efforts to crack the Enigma.
Back in Bletchley Park, UK, a team of code-breakers led by Alan Turing and Gordon Welchman were able to decisively crack Enigma codes in a way that The Bomba wasn’t able to accomplish. They figured out that a letter couldn’t be mapped to itself and this could be used to eliminate certain configurations. They knew that certain phrases had to exist in the message (for example in the daily weather reports, the German word for “weather report”-- “wetterbericht” was always in the message). Using this, they could scan through the entire message and deduce that some combinations weren’t possible since it would map the same letter to itself in the known phrase. Using this process of elimination method, Turing and Welchman built The Bombe which used electrical circuits to check potential configurations through contradiction (make a guess and if the guess doesn’t work then the letter mapping isn’t possible). Through these series of optimizations, The Bombe was able to break Enigma codes in under 20 minutes, rendering the codes almost useless.
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I found your article really interesting, I didn't know the initial Enigma code was broken by the Polish with the Bomba! Alan Turing is known as the father of computers, although he was called that not for his work on the Bombe because it could only perform one function, solve the Enigma code, and was therefore not considered a computer. Before the war, Turing theorized of one machine that could be programmed to perform many different tasks, and using his experience from the Bombe, Turing built some of the world's first computers in the UK.
ReplyDeleteThe first machine recognized as a computer was also built in Bletchley Park called the Colossus in 1943. While designed to break the German Lorenz cypher, it could also perform a multitude of different tasks, thus qualifying as a computer.
Source: http://www.cs4fn.org/history/bombe.php
I think this is a great post as it gives us insight into how the Allies were able to break the enigma system. The enigma system was very complex and it is impressive that these people were able to break it. Once broken, it was helpful to the Allies, as they could determine where German U-Boats were and direct their shipping around these danger zones. Additionally, the Allies wanted to capture the Enigma machines aboard German vessels so that they could find out more about it. As the Allies began to have less boats sank and more German U-Boats were being destroyed, the Germans began to question if the Enigma machine had been compromised.
ReplyDeleteSource:
http://www.bbc.co.uk/history/worldwars/wwtwo/enigma_01.shtml