Cryptanalysis of the Enigma
decryption of the code of the Enigma-machine
Cryptanalysis of the Enigma ciphering system enabled the western Allies in World War II to read substantial amounts of Morse-coded radio communications of the Axis powers that had been enciphered using Enigma machines. This yielded military intelligence which, along with that from other decrypted Axis radio and teleprinter transmissions, was given the codename Ultra.
The Enigma machines were a family of portable cipher machines with rotor scramblers. Good operating procedures, properly enforced, would have made the plugboard Enigma machine unbreakable to the Allies at that time.
The German plugboard-equipped Enigma became the principal crypto-system of the German Reich and later of other Axis powers. In December 1932 it was broken by mathematician Marian Rejewski at the Polish General Staff's Cipher Bureau, using mathematical permutation group theory combined with French-supplied intelligence material obtained from German spy Hans-Thilo Schmidt. By 1938 Rejewski had invented a device, the cryptologic bomb, and Henryk Zygalski had devised his sheets, to make the cipher-breaking more efficient. Five weeks before the outbreak of World War II, in late July 1939 at a conference just south of Warsaw, the Polish Cipher Bureau shared its Enigma-breaking techniques and technology with the French and British.
During the German invasion of Poland, core Polish Cipher Bureau personnel were evacuated via Romania to France, where they established the PC Bruno signals intelligence station with French facilities support. Successful cooperation among the Poles, French, and British continued until June 1940, when France surrendered to the Germans.
The public source identifies “Cryptanalysis of the Enigma” as decryption of the code of the Enigma-machine. This brief keeps that definition visible, then builds a research path around Cryptanalysis, Enigma and decryption.
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Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Sep 18, 2026. The linked authority identifier is Q2665859. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1932, 1938, 1939 and 1940.
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This entry incorporates text from “Cryptanalysis of the Enigma” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.