Why were Enigma Messages so difficult to decipher?
Although the design of the Enigma machine was simple, it exploited the rapidly increasing complexity which arose from only a few operations. For instance, the plug board consisted of six cables each of which swapped a pair of letters around. Due to the fact that there are about ten million ways in which six pairs of letters can be chosen from twenty-six it became imnpossible to decipher Enigma messages by brute force. How was the Plugboard Bipassed? In order to successfully decipher the messages it was necessary for Turing’s team to find messages which, while being different for each scrambler setting, would not be affected the exchange of the plugboard leads. The point that could be most easily exploited was the fact that the message key would be repeated twice at the beginning of each transmission. As a result of this it it was clear that the 1st and the 4th letters of each message, before encryption, would be the same, as would the 2nd and the 5th and the 3rd and the 6th. From this
