Знаминитая "Энигма", материал на английском. Шифровки.

Imagine one: Detail from the front of a message. ‘Red’ messages, sent by the German Air Force using their General Operational Key, were so named because Codebreaker Gordon Welchman used a red pencil to annotate them. Messages sent using other Enigma keys were marked with different coloured pencils. Later, when Bletchley Park ran out of colours, they named keys after plants, insects and birds.

Image two: Detail from the reverse of the same message. The message highlights a limitation of wartime communications, stating that a message failed to reach the intended recipient as they were travelling to Norway. Modern day electronic communications have overcome such problems.

Image two: A report on the night activity of a German Air Force unit under the command of Unteroffizier Jaekel. The markings used by the Codebreakers to make sense of the message are clearly visible. Vertical lines are used to separate words, a curving line under words indicates a name, and numbers are written out in Arabic numerals below the text.

Image one: Front of a ‘Red’ message, intercepted from the General Operational Key for the German Air Force (codenamed ‘Red’ at BP). Bletchley Park first began to regularly decipher ‘Red’ network messages from 22 May 1940 - their first break into German Enigma. Towards the bottom of the page is a Bombe machine menu, written in red pencil. This indicates how a Bombe machine could be set up to try to find the settings used on the Enigma machine that encrypted this message.

Image two: Reverse of the same message. When deciphered, this message turned out to be an ‘abstimspruch’ or test message - the word underlined in red. Although this may seem frustrating, the term ‘abstimspruch’ could be used as a ‘crib’ - a guessed piece of message text that gave the Codebreakers a starting point to break the message encryption. This in turn could unlock a whole day’s worth of messages on an Enigma network.