Editing Enigma machine (section)

{{short description|German cipher machine}}
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[[File:Enigma (crittografia) - Museo scienza e tecnologia Milano.jpg|thumb|Military Model Enigma I, in use from 1930]]
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The '''Enigma machine''' is a [[cipher]] device developed and used in the early- to mid-20th century to protect [[Commerce|commercial]], diplomatic, and military communication. It was employed extensively by [[Nazi Germany]] during [[World War II]], in all branches of the [[Wehrmacht|German military]]. The Enigma machine was considered so secure that it was used to encipher the most top-secret messages.<ref>{{Cite web|title=EnigmaHistory|url=https://www.cryptomuseum.com/crypto/enigma/hist.htm|access-date=2020-12-16|website=cryptomuseum.com}}</ref>

The Enigma has an electromechanical [[Rotor machine|rotor mechanism]] that scrambles the 26 letters of the alphabet. In typical use, one person enters text on the Enigma's keyboard and another person writes down which of the 26 lights above the keyboard illuminated at each key press. If [[plaintext]] is entered, the illuminated letters are the [[ciphertext]]. Entering ciphertext transforms it back into readable plaintext. The rotor mechanism changes the electrical connections between the keys and the lights with each keypress.

The security of the system depends on machine settings that were generally changed daily, based on secret key lists distributed in advance, and on other settings that were changed for each message. The receiving station would have to know and use the exact settings employed by the transmitting station to decrypt a message.

Although Nazi Germany introduced a series of improvements to the Enigma over the years that hampered decryption efforts, [[cryptanalysis of the Enigma]] enabled [[Second Polish Republic|Poland]] to first crack the machine as early as December 1932 and to read messages prior to and into the war. Poland's sharing of their achievements enabled the [[Allies of World War II|Allies]] to exploit Enigma-enciphered messages as a major source of intelligence.{{sfn|Comer|2021}} Many commentators say the flow of [[Ultra (cryptography)|Ultra]] [[communications intelligence]] from the decrypting of Enigma, [[Lorenz cipher|Lorenz]], and other ciphers shortened the war substantially and may even have altered its outcome.<ref>{{Cite book|title=Intelligence in War|last=Keegan|first=John|publisher=Alfred A. Knopf|year=2003|location=New York}}</ref>
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