Zygalski sheet
Demonstration of two sheets at Bletchley Park Museum

The method of perforated sheets was a cryptologic technique used by the Polish Cipher Bureau before World War II, and during the war by British cryptologists at Bletchley Park, to decrypt messages enciphered on German Enigma machines. Cryptography (or cryptology; from Greek grc κρυπτός kryptos, "hidden secret" and grc γράφω gráphō, "I write" Poland (Polska officially the Republic of Poland The Biuro Szyfrów ( Polish for " Cipher Bureau " was the Polish Interwar agency charged with both Cryptography (the World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including Bletchley Park, also known as Station X, is an estate located in the town of Bletchley, in Buckinghamshire, and (since 1967 part of Milton Keynes In Cryptography, a cipher (or cypher) is an Algorithm for performing Encryption and Decryption &mdash a series of well-defined steps The Enigma machine is any one of a family of related electro-mechanical Rotor machines used to generate Ciphers for the Encryption and decryption of The "perforated sheets" were invented about October 1938 by Polish Cipher Bureau cryptologist Henryk Zygalski, and accordingly are sometimes known as Zygalski sheets. Henryk Zygalski ( 1906 - 1978 was a Polish Mathematician and Cryptologist who worked at breaking German Enigma ciphers before and during

## Method

The method involved superposing a series of sheets — each containing a grid of holes in various positions — and aligning them in the proper manner with respect to each other, while shining a lamp underneath. Using this procedure, a large number of possibilities for the Enigma daily keys could be eliminated. If the settings were correct and sufficient data were available, a single aperture would remain, which indicated the solution.

Like Marian Rejewski's "card-catalog" method, developed using his "cyclometer," the "perforated-sheet" procedure was independent of the number of commutator plug connections. Marian Adam Rejewski ( 16 August 1905 &ndash 13 February 1980 was a Polish Mathematician and cryptologist who in 1932 solved the Enigma machine The cyclometer was a cryptologic device designed in the end of 1936 by Marian Rejewski, of the Polish Cipher Bureau 's German section (BS-4 to facilitate In Mathematics, the commutator gives an indication of the extent to which a certain Binary operation fails to be Commutative.

 v • d • eThe Enigma cipher machine
Biuro Szyfrów
Cipher Bureau edit
Cryptologic methods and technology:
Enigma "doubles"GrillClockCyclometerCard catalogCryptologic bombZygalski sheetsLacida
Location:
Saxon PalaceKabaty Woods
Personnel:
Maksymilian CiężkiJan GralińskiJan KowalewskiGwido LangerStanisław LeśniewskiStefan MazurkiewiczWiktor MichałowskiAntoni PalluthFranciszek PokornyMarian RejewskiJerzy RóżyckiWacław SierpińskiPiotr SmoleńskiHenryk Zygalski

## Use and manufacture

In late July 1939, a month before the outbreak of World War II, the Polish General Staff's Cipher Bureau disclosed to their French and British allies, at Warsaw, their cryptologic achievements in breaking Enigma ciphers. A military staff is a group of officers and enlisted personnel that provides a bi-directional flow of information between a commander and subordinate units This article is about the country For a topic outline on this subject see List of basic France topics. See also Kingdom of Great Britain Great Britain (Breatainn Mhòr Prydain Fawr Breten Veur Graet Breetain is the larger of the two main islands Warsaw (Warszawa; also known by other names) is the Capital and Largest city of Poland. Part of the disclosures involved Zygalski's "perforated-sheet" method.

With the assistance of machinery, the production of two complete sets of perforated sheets was undertaken at Bletchley Park in England by a section headed by John R. F. Jeffreys[1][2]. England is a Country which is part of the United Kingdom. Its inhabitants account for more than 83% of the total UK population whilst its mainland John R F Jeffreys (died early 1941 was a British Mathematician and World War II Codebreaker. The sheets were known at Bletchley as Netz (from Netzverfahren, "net method"), although they were later remembered by Gordon Welchman as "Jeffreys sheets"; this term, however, referred to another catalogue produced by Jeffreys's section[1]. (William Gordon Welchman ( June 15, 1906 – October 8, 1985) was a British mathematician and World War II Codebreaker

The first set was completed in late December 1939, and on 28 December 1939, part of the second set was delivered to the Polish cryptologists[2], who had by then escaped from German-overrun Poland to PC Bruno outside Paris, France. Events 1065 - Westminster Abbey is Consecrated. 1308 - The reign of Emperor Hanazono, Emperor of PC Bruno was a Polish - French intelligence station that operated outside Paris during World War II. The remaining sheets were completed on 7 January 1940, and were couriered by Alan Turing to France shortly thereafter[2]. Events 1325 - Alfonso IV becomes King of Portugal. 1558 - France takes Calais, the last continental Alan Mathison Turing, OBE, FRS (ˈt(jʊ(ərɪŋ (23 June 1912 &ndash 7 June 1954 was an English Mathematician "With their help," writes Polish cryptologist Marian Rejewski, "we continued solving Enigma daily keys. See also CategoryCryptographers for an exhaustive list Pre twentieth century Charles Babbage, UK, 19th century Mathematician "[3] The sheets were used by the Poles to make the first wartime decryption of an Enigma message on 17 January 1940[2]. Events 38 BC - Octavian marries Livia Drusilla. 1287 - King Alfonso III of Aragon invades Minorca

In May 1940, the Germans once again completely changed the procedure for enciphering message keys (with the exception of a Norwegian network). As a result, Zygalski's sheets were rendered completely useless.