Editing Ultra (cryptography) (section)

{{Short description|British designation for intelligence from decrypted enemy communications}}
{{Use dmy dates|date=October 2019}}
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{{multiple image | direction = vertical |width = 180 | footer = Three cipher machines that<br />were broken by the Allies to<br />yield Ultra intelligence | image1 = EnigmaMachine Warzawa.jpg | caption1 = [[Enigma machine]] out of its wooden box | image2 = Lorenz-SZ42-2.jpg | caption2 = [[Lorenz cipher|Lorenz SZ42 machine]] with covers removed | image3 = Purple code machine 2.jpg | caption3 = Part of Japanese [[Purple (cipher machine)|PURPLE machine]] }}

'''Ultra''' was the designation adopted by [[United Kingdom|British]] [[military intelligence]] in June 1941 for wartime [[signals intelligence]] obtained by breaking high-level [[encrypt]]ed enemy [[radio]] and [[teleprinter]] communications at the [[Government Code and Cypher School]] (GC&CS) at [[Bletchley Park]].{{sfn|Hinsley|Stripp|1993|p=xx}} ''Ultra'' eventually became the standard designation among the western [[Allies of World War II|Allies]] for all such intelligence. The name arose because the intelligence obtained was considered more important than that designated by the highest British [[Classified information|security classification]] then used (''Most Secret''{{--)}} and so was regarded as being ''Ultra Secret''.{{sfn|Lewin|2001|p=64}} Several other [[cryptonym]]s had been used for such intelligence.

The code name "'''Boniface'''" was used as a cover name for ''Ultra''. In order to ensure that the successful code-breaking did not become apparent to the Germans, British intelligence created a fictional [[MI6]] master spy, Boniface, who controlled a fictional series of agents throughout Germany. Information obtained through code-breaking was often attributed to the [[human intelligence (espionage)|human intelligence]] from the Boniface network.<ref>{{cite web|url=https://www.theguardian.com/science/blog/2014/nov/28/imitation-game-alan-turing-us-intelligence-ian-fleming|title=The Imitation Game: how Alan Turing played dumb to fool US intelligence - David Cox|first=David|last=Cox|date=28 November 2014|website=The Guardian}}</ref><ref>{{cite book|url=https://books.google.com/books?id=z_CtAwAAQBAJ&q=bletchley+boniface&pg=PT56|title=The Secrets of Station X: How the Bletchley Park codebreakers helped win the war|first=Michael|last=Smith|date=31 October 2011|publisher=Biteback Publishing|isbn=9781849542623|via=Google Books}}</ref> The U.S. used the codename ''[[Magic (cryptography)|Magic]]'' for its decrypts from Japanese sources, including the "[[Type B Cipher Machine#Purple|Purple]]" cipher.<ref>{{cite book|url=https://books.google.com/books?id=uccLlgJDk4gC&q=code+breaking+WW+II+code+name+magic&pg=PA6|title=Battle of Wits: The Complete Story of Codebreaking in World War II|first=Stephen|last=Budiansky|date=27 June 2018|publisher=Simon and Schuster|isbn=9780684859323|via=Google Books}}</ref>

Much of the [[Nazi Germany|German]] cipher traffic was encrypted on the [[Enigma machine]]. Used properly, the German military Enigma would have been virtually unbreakable; in practice, shortcomings in operation allowed it to be broken. The term "Ultra" has often been used almost synonymously with "[[Cryptanalysis of the Enigma|Enigma decrypts]]". However, Ultra also encompassed decrypts of the German [[Lorenz cipher|Lorenz SZ 40/42 machines]] that were used by the German High Command, and the [[C-36 (cipher machine)|Hagelin machine]].{{efn|The Hagelin C-38m (a development of the C-36) was the model used by the Italian Navy,<ref>see: {{citation|url=http://www.cryptomuseum.com/crypto/hagelin/index.htm|title=Crypto AG: Hagelin cipher machines }}</ref> and other Italian and Japanese ciphers and codes such as [[PURPLE]] and [[JN-25]].{{sfn|Hinsley|Stripp|1993|p=xx}}}}

Many observers, at the time and later, regarded Ultra as immensely valuable to the Allies. [[Winston Churchill]] was reported to have told [[King George VI]], when presenting to him [[Stewart Menzies]] (head of the [[Secret Intelligence Service]] and the person who controlled distribution of Ultra decrypts to the government): "It is thanks to the secret weapon of General Menzies, put into use on all the fronts, that we won the war!"{{efn|The original source for this quote is from Gustave Bertrand's book ''Enigma ou la plus grande énigme de la guerre 1939–1945'', p. 256, at the end of a short passage asserting the importance of Enigma-derived intelligence for Allied victory. The text there is: "Sans parler de cette entrevue historique, la guerre finie, où Sir Winston Churchill, présentant à S.M. George VI le Chef de l'I.S., prononça ces paroles; ''qui m'ont été rapportées par le général Menziès lui-même:'' « C'est grâce à l'Arme Secrète du général Menziès, mise en œuvre sur tous les Fronts, que nous avons gagné la Guerre! » "  This can be translated as: "Not to mention this historic meeting, after the war, in which Sir Winston Churchill, presenting to H.M. George VI the Chief of the I.S., stated these words, ''that were reported to me by General Menzies himself'': 'It is thanks to the secret weapon of General Menzies, put into use on all the fronts, that we won the war!'"  It is not clear when, or on what occasion, Churchill made this statement or when Menzies later related it to Bertrand, who published this in 1973.  In his 1987 book ''"C": The Secret Life of Sir Stewart Graham Menzies'', Anthony Cave Brown rendered this as "Churchill told King George VI in Menzies's presence that 'it was thanks to Ultra that we won the war.'" (p. 671) He sourced this (p. 812n) to the same page of the Bertrand book. Subsequent English-language publications have picked up and repeated Brown's formulation, but the quote related by Menzies and Bertrand was longer and Churchill did not use the term 'Ultra' to the King, who may not have been familiar with it.}} [[F. W. Winterbotham]] quoted the western Supreme Allied Commander, [[Dwight D. Eisenhower]], at war's end describing Ultra as having been "decisive" to Allied victory.{{sfn|Winterbotham|1974|pp=154, 191}} [[Harry Hinsley|Sir Harry Hinsley]], Bletchley Park veteran and official historian of British Intelligence in World War II, made a similar assessment of Ultra, saying that while the Allies would have won the war without it,{{sfn|Hinsley|1993|pp=11–13}} "the war would have been something like two years longer, perhaps three years longer, possibly four years longer than it was."{{sfn|Hinsley|1996}} However, Hinsley and others have emphasized the difficulties of [[counterfactual history]] in attempting such conclusions, and some historians, such as [[John Keegan]], have said the shortening might have been as little as the three months it took the United States to deploy the [[atomic bomb]].{{sfn|Hinsley|1993|pp=11–13}}<ref>{{Cite book|title=Intelligence in Warfare|last=Keegan|first=John |publisher=Alfred A. Knopf|year=2003|location=New York}}</ref><ref name="richelson">{{cite book | url=https://books.google.com/books?id=HohPaIyc5G0C&pg=PA196 | title=A Century of Spies: Intelligence in the Twentieth Century | first=Jeffery T. | last=Richelson | author-link=Jeffrey T. Richelson | publisher=Oxford University Press | location=New York | date=1997 | page=296| isbn=9780195113907 }}</ref>