Bletchley Park, central England. First effective decryption of a Nazi message. Brute-force decryption would be impossible (at the time, and perhaps even today). Various tricks were therefore used, such as the final sentence of many German communiqués ending with “Heil Hitler!”. Or the morning communiqué from a specific German ship anchored off the coast of Scotland always began with “Wettervorhersage,” or “Weather Forecast.” It was also extremely likely that in most messages, whatever their nature, the number “1” or the word “one” would appear at least once. In German, this is EIN, and since the ENIGMA keyboard does not have numbers, it must be written entirely in letters. Now, when the word EIN is entered into the three-wheel ENIGMA, it encodes it into one of over 70 million possible words. At Bletchley Park, the EINS BOOK (the book of ones) was created, which is the list of these 70 million possibilities. The Colossus computer searches for one of these in the messages in the morning, and when it finds it, it finds a key. Sometimes there are even lucky breaks, like when someone at Bletchley Park noticed that there wasn’t a single “L” on a whole page. ENIGMA was specifically designed to prevent the same letter from appearing when a certain letter was entered. However, this turns out to be a fatal flaw. Not finding a single “L” means that the ENIGMA operator, perhaps bored, is pressing the “L” key over and over again…
