Editing Enigma machine (section)

==History==
The Enigma machine was invented by German engineer [[Arthur Scherbius]] at the end of [[World War I]].<ref name="Singh2011">{{cite book|first=Simon |last=Singh|title=The Code Book: The Science of Secrecy from Ancient Egypt to Quantum Cryptography|url={{google books | plainurl=y | id=fbp9V9dkaNkC}}|date=26 January 2011|publisher=Knopf Doubleday Publishing Group|isbn=978-0-307-78784-2}}</ref> The German firm Scherbius & Ritter, co-founded by Scherbius, patented ideas for a cipher machine in 1918 and began marketing the finished product under the brand name ''Enigma'' in 1923, initially targeted at commercial markets.<ref>{{cite web | url=http://www.cryptomuseum.com/crypto/enigma/hist.htm | title=History of the Enigma | publisher=Crypto Museum | access-date=1 December 2017}}</ref> Early models were used commercially from the early 1920s, and adopted by military and government services of several countries, most notably [[Nazi Germany]] before and during [[World War II]].<ref>{{cite web|last=Lord|first= Bob|title=Enigma Manual|year=1998–2010|url=http://www.ilord.com/enigma-manuals|access-date=31 May 2011}}</ref>

Several Enigma models were produced,<ref>{{Cite journal |last1=Hamer |first1=David H. |last2=Sullivan |first2=Geoff |last3=Weierud |first3=Frode |date=July 1998 |title=Enigma Variations: An Extended Family of Machines |journal=Cryptologia |volume=XXII |issue=3 |pages=211–229 |doi=10.1080/0161-119891886885 |url=http://www.math.utoledo.edu/~codenth/Cryptanalysis/crypt_machs/ESIM/enigvar2.PDF |access-date=18 February 2016 |issn=0161-1194}}</ref> but the [[Wehrmacht|German military]] models, having a [[plugboard]], were the most complex. Japanese and Italian models were also in use.<ref>{{Cite web |title=Four Rotor Enigma Machine |url=https://www.spymuseum.org/exhibition-experiences/about-the-collection/collection-highlights/four-rotor-enigma-machine/ |access-date=2023-02-21 |website=International Spy Museum |language=en}}</ref> With its adoption (in slightly modified form) by the German Navy in 1926 and the German Army and Air Force soon after, the name ''Enigma'' became widely known in military circles. Pre-war German military planning emphasized fast, mobile forces and tactics, later known as [[blitzkrieg]], which depended on radio communication for command and coordination. Since adversaries would likely intercept radio signals, messages had to be protected with secure encipherment. Compact and easily portable, the Enigma machine filled that need.

=== Breaking Enigma ===
{{Main|Cryptanalysis of the Enigma}}

[[Image:Poland Bydgoszcz Rejewski monument.jpg|thumb|upright=1.3|A memorial in [[Bydgoszcz]], Poland, to [[Marian Rejewski]], the mathematician who, in 1932, first broke Enigma and, in July 1939, helped educate the French and British about Polish methods of Enigma decryption]]

[[Hans-Thilo Schmidt]] was a [[Nazi Germany|German]] who spied for the [[French Third Republic|French]], obtaining access to German cipher materials that included the daily keys used in September and October 1932. Those keys included the plugboard settings. The French passed the material to [[Second Polish Republic|Poland]]. Around December 1932, [[Marian Rejewski]], a Polish mathematician and [[Cryptanalysis|cryptologist]] at the [[Biuro Szyfrów|Polish Cipher Bureau]], used the theory of permutations,{{sfn|Rejewski|1980}} and flaws in the German military-message encipherment procedures, to break message keys of the plugboard Enigma machine.{{sfn|Vázquez|Jiménez–Seral|2018}} Rejewski used the French supplied material and the message traffic that took place in September and October to solve for the unknown rotor wiring. Consequently, the Polish mathematicians were able to build their own Enigma machines, dubbed "[[Polish Enigma double|Enigma doubles]]". Rejewski was aided by fellow mathematician-cryptologists [[Jerzy Różycki]] and [[Henryk Zygalski]], both of whom had been recruited with Rejewski from [[Adam Mickiewicz University in Poznań|Poznań University]], which had been selected for its students' knowledge of the German language, since that area was held by [[German Empire|Germany]] prior to World War I. The Polish Cipher Bureau developed techniques to defeat the plugboard and find all components of the daily key, which enabled the Cipher Bureau to read German Enigma messages starting from January 1933.<ref>Władysław Kozaczuk, ''Enigma: How the German Machine Cipher was Broken, and how it was Read by the Allies in World War Two'', edited and translated by Christopher Kasparek, Frederick, Maryland, University Publications of America, 1984, ISBN 978-0-89093-547-7, p. 21.</ref>

Over time, the German cryptographic procedures improved, and the Cipher Bureau developed techniques and designed mechanical devices to continue reading Enigma traffic. As part of that effort, the Poles exploited quirks of the rotors, compiled catalogues, built a [[cyclometer]] (invented by Rejewski) to help make a catalogue with 100,000 entries, invented and produced [[Zygalski sheets]], and built the electromechanical cryptologic [[Bomba (cryptography)|''bomba'']] (invented by Rejewski) to search for rotor settings. In 1938 the Poles had six ''bomby'' (plural of ''bomba''), but when that year the Germans added two more rotors, ten times as many ''bomby'' would have been needed to read the traffic.{{sfn|Kozaczuk|1984|p=63}}

On 26 and 27 July 1939,{{sfn|Erskine|2006|pp=294–305}} in [[Pyry, Warsaw|Pyry]], just south of [[Warsaw]], the Poles initiated French and British [[military intelligence]] representatives into the Polish [[Cryptanalysis of the Enigma|Enigma-decryption techniques]] and equipment, including Zygalski sheets and the cryptologic bomb, and promised each delegation a Polish-reconstructed Enigma (the devices were soon delivered).{{sfn|Kozaczuk|1984|pp=59–60, 236}}

In September 1939, British Military Mission 4, which included [[Colin Gubbins]] and [[Vera Atkins]], went to Poland, intending to evacuate cipher-breakers [[Marian Rejewski]], [[Jerzy Różycki]], and [[Henryk Zygalski]] from the country. The cryptologists, however, had been evacuated by their own superiors into Romania, at the time a Polish-allied country. On the way, for security reasons, the Polish Cipher Bureau personnel had deliberately destroyed their records and equipment. From Romania they traveled on to France, where they resumed their cryptological work, collaborating by teletype with the [[UK|British]], who began work on decrypting German Enigma messages, using the Polish equipment and techniques.{{sfn|Kozaczuk|1984|pp=69–94}}

[[Gordon Welchman]], who became head of [[Hut 6]] at Bletchley Park, wrote: "Hut 6 [[Ultra (cryptography)|Ultra]] would never have got off the ground if we had not learned from the Poles, in the nick of time, the details both of the German military version of the commercial Enigma machine, and of the operating procedures that were in use." The Polish transfer of theory and technology at Pyry formed the crucial basis for the subsequent World War II British Enigma-decryption effort at [[Bletchley Park]], where Welchman worked.{{sfn|Welchman|1982|p=289}}

During the war, British cryptologists decrypted a vast number of messages enciphered on Enigma. The intelligence gleaned from this source, codenamed "[[Ultra (cryptography)|Ultra]]" by the British, was a substantial aid to the [[Allies of World War II|Allied]] war effort.{{efn|Much of the German cipher traffic was encrypted on the Enigma machine, and the term "Ultra" has often been used almost synonymously with "[[Cryptanalysis of the Enigma|Enigma decrypts]]". Ultra also encompassed decrypts of the German [[Lorenz cipher|Lorenz SZ 40 and 42 machines]] that were used by the German High Command, and decrypts of [[C-36 (cipher machine)|Hagelin ciphers]] and other Italian ciphers and codes, as well as of Japanese ciphers and codes such as [[Type B Cipher Machine|Purple]] and [[Japanese naval codes#JN-25|JN-25]].}}

Though Enigma had some cryptographic weaknesses, in practice it was German procedural flaws, operator mistakes, failure to systematically introduce changes in encipherment procedures, and Allied capture of key tables and hardware that, during the war, enabled Allied cryptologists to succeed.{{sfn|Kahn|1991}}{{sfn|Stripp|1993}}

The [[Abwehr]] used different versions of Enigma machines. In November 1942, during [[Operation Torch]], a machine was captured which had no plugboard and the three rotors had been changed to rotate 11, 15, and 19 times rather than once every 26 letters, plus a plate on the left acted as a fourth rotor.<ref name="Flem11">{{cite book |title=Ian Fleming's Commandos: The Story of 30 Assault Unit in WWII |last=Rankin |first=Nicholas |publisher=Oxford University Press |isbn=978-0199782826 |date=2011}}</ref> 

The Abwehr code had been broken on 8 December 1941 by [[Dilly Knox]]. Agents sent messages to the Abwehr in a simple code which was then sent on using an Enigma machine. The simple codes were broken and helped break the daily Enigma cipher. This breaking of the code enabled the [[Double-Cross System]] to operate.<ref name="Flem11"/> From October 1944, the German Abwehr used the [[Schlüsselgerät 41]] in limited quantities.<ref name="NSA-German">{{cite web |url=https://www.nsa.gov/Portals/70/documents/about/cryptologic-heritage/historical-figures-publications/publications/wwii/german_cipher.pdf |title=German Cipher Machines of World War II |pages=22–25 |work=Center for Cryptologic History |publisher=[[National Security Agency]]|archive-url=https://web.archive.org/web/20230514055454/https://www.nsa.gov/portals/75/documents/about/cryptologic-heritage/historical-figures-publications/publications/wwii/german_cipher.pdf|archive-date=14 May 2023  |access-date=21 January 2024 |year=2014 }}</ref>