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Wednesday, October 27, 2010


A cipher machine developed by Arthur Scherbius in Germany in 1923 and made available commercially to banks and other financial institutions on the continent. It was adapted by the German military in 1928, and various versions of the electromechanical device were developed and distributed until May 1945. An estimated 40,000 Enigma machines were manufactured for use by the Germans, and it was used as the model  for the British equivalent, the TypeX machine.
Boasting an unbreakable cipher generated by passing an electrical current through three moving,  interchangeable rotors, each with 26 starting positions, and a complex plug board, the Enigma was a portable, easy-to-use machine which, when operated properly, offered an unprecedented level of security. Mere  possession of a machine, without a knowledge of the exact settings chosen for a particular text, made a solution practically impossible, Nevertheless, work undertaken by the Polish Cipher Bureau before World  War II indicated that certain intrinsic flaws (such as the inability of the machine to select an identical letter of  the alphabet as a substitute) and common operator errors could be exploited with the assistance of perforated sheets of paper acting as a rudimentary computer to calculate the original settings of the rotors. Study of the Enigma and a reconstruction of the plug-board wiring enabled British cryptographers to read some Luftwaffe  traffic in 1940, building on a coup with Abwehr signals achieved in 1939 after compromised hand ciphers had been found to have been reencyphered on the Abwehr’s Enigma circuits.
Access to the enemy’s Enigma ciphers gave the Allies a tremendous advantage, which shortened the conflict by an estimated two years. The sanitized summaries, distributed on a very limited basis and code-named ULTRA, had a significant impact on the war, especially in North Africa, the Battle of the Atlantic, the search for the Kriegsmarine’s surface raiders, and the success of D-Day.
When the Germans recovered British TypeX machines at Dunkirk in 1940, they recognized them as modified Enigma machines and, believing their ciphers to be impregnable, assigned only a handful of cryptographers to work on the British machine cipher traffic. In contrast, more than 15,000 people based at Bletchley Park  concentrated on the Enigma traffic.
At the end of the war GCHQ refurbished many of the enemy’s captured Enigma machines and distributed them to Commonwealth and other countries as a secure means of communication. When Fred Winterbotham revealed the scale of GCHQ’s cryptographic success in The ULTRA Secret (1974), some were still in use by the Nigerians and the Swiss military.