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1915, two Dutch Naval officers invented a machine to encrypt messages. This became known as the Enigma machine.
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1918, Arthur Scherbius, a German businessman, patented the Enigma machine.
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Mid 1920s, mass production of Enigma machine with 30,000 machines being sold to the German military over the next 2 decades.
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The Poles set up a world leading crypt analysis bureau and hired leading mathematicians such as Marian Rejewski.
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Enigma machine adopted by the German army
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Late 1932 Polish Cryptanalyst Marian Rejewski recovers the entire machine wiring by mathematical analysis using a group of intercepts and machine settings for two months, September and October 1932, supplied by the French.
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On 2nd November Umkehrwalze B was introduced, replacing Umkehrwalze A and this remained in use until the end of the war in 1945
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On September 15th the fixed daily Grundstellung was dropped. Each message must now have a different Grundstellung selected by the operator. The message header would contain three trigrams, the Grundstellung followed by the double enciphered message key enciphered using the message Grundstellung
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On 15th December wheels IV and V were added. Three wheels could now be selected from a set of five - giving 60 possible arrangements. A different wheel arrangement could now be used for every day of the month. The two additional wheel wirings were quickly recovered by Rejewski
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On 1st January the number of plugboard connections was increased from six to ten
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The First Welchman-Turing Bombe enters service in March.
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On 1st May the double enciphered message key was dropped. The Message key was only enciphered once from now on. The message header would contain two trigrams, the message Grundstellung followed by the enciphered message key.