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Milestones:First Breaking of Enigma Code by the Team of Polish Cipher Bureau, 1932-1939

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Polish Cipher Bureau mathematicians Marian Rejewski, Jerzy Różycki and Henryk Zygalski broke the German Enigma cipher machine codes. Working with engineers from the AVA Radio Manufacturing Company, they built the ‘bomba’ – the first cryptanalytic machine to break Enigma codes. Their work was a foundation of British code breaking efforts which, with later American assistance, helped end World War II.

Street address(es) and GPS coordinates of the Milestone Plaque Sites

ul. Śniadeckich 8, 00-956 Warszawa (Warsaw), Poland GPS (latitude, longitude) 52.2213787 ; 21.0146535

Details of the physical location of the plaque

The plaque is at the front entrance of the Institute's building facing the Sniadeckich Street

How the intended plaque site is protected/secured

The plaque site is publicly accessible at one of the busy streets of Warsaw downtown area, with high concentration of academics and tourists. Click here for an article with photographs of the plaque monument

Historical significance of the work

IEEE Milestone Description During the 1930s, a trio of Polish mathematicians Marian Rejewski (1905 – 1980), Henryk Zygalski (1907 – 1978), and Jerzy Różycki (1909 – 1942) solved the German Enigma cipher machine and broke Enigma messages. Working with engineers from AVA Radio Manufacturing Company they built the bomba – the first cryptanalytic machine designed to attack Enigma and one of many cryptanalytic machines to be built by Allied codebreakers. Enigma is an electrically wired rotor machine; a sequence of ciphers is generated by the motion of rotors in the machine. It is one of several cipher machines that were developed for military or for commercial use during or just after World War I.

German Arthur Scherbius invented Enigma; he patented a rotor machine in 1918. An American, Edward Hebern, had designed a rotor cipher machine in 1917, and the Dutch inventor Hugo Koch and the Swedish inventor Arvid Damm designed machines that were patented in 1919. It is likely that both Scherbius’ and Koch’s designs resulted from a rotor machine developed in 1915 by two Dutch military officers. The weaknesses of their World War I codes and ciphers prompted the German military to adopt a cipher machine. The Reichsmarine began using Enigma in 1926, and the Reichswehr began using it in 1928.


The Polish Cipher Bureau had many successes during the Polish-Soviet War (1919 – 1921), and in the 1920s the Cipher Bureau monitored radio signals resulting from German military exercises. In 1928 the Poles were confronted by messages that – because of the randomness of letters in the messages – were thought to be generated by a machine cipher. That same year the Cipher Bureau began a cryptology course for mathematics students at Poznań University. Rejewski, Zygalski, and Różycki participated in that course. They began working for the Cipher Bureau in Poznań but moved to Warsaw, and Rejewski began his attack on Enigma in September 1932.


Although the Cipher Bureau was aware of the operation of a commercial Enigma, the rotors of the German military Enigma had different wiring than the commercial version, and the German military had complicated the machine by adding a plugboard, which further greatly scrambled the letters. By the end of 1932, Rejewski had determined the wiring of the rotors of the military version of Enigma. In 1932, Rejewski had received from the French two German manuals that described the operation of military Enigma. He had managed to write a system of equations that modeled the permutations of the six indicators (which were used by the sending operator to transmit the message setting to the receiving operator) at the beginning of Enigma messages. In December 1932, Rejewski received from the French the setting sheets for September and October. This information allowed Rejewski to substitute for some of the unknowns in his system of equations and solve for the wiring of the rotors. The Cipher Bureau arranged with AVA Radio Manufacturing Company to produce Enigma “doubles.” Doubles were produced in 1934.

AVA Company had been established by Edward Fokczyński and Antoni Palluth to design and produce telecommunications equipment for the Polish army. They were soon joined by the brothers Ludomir and Leonard Danilewicz, who had graduated from Warsaw University of Technology. In order to break Enigma messages, it was necessary to determine the machine settings. The Polish codebreakers developed several techniques to determine settings. For example, Różycki developed the “clock method,” and Zygalski developed a set of perforated sheets. Two other methods resulted in the production of codebreaking machines – one machine to produce a catalog of settings and their “characteristics” and another to determine the rotor settings.


In 1934, Rejewski was able to exploit patterns, which he called characteristics, produced by the six-letter indicators at the beginning of Enigma messages. Rejewski designed a machine called the cyclometer to catalog the characteristics of all 105,456 rotor settings. Again, the AVA Radio Manufacturing Company produced the machine. It took the codebreakers approximately a year to prepare the catalog. Unfortunately not long after its completion, the Germans changed Enigma’s reflecting rotor, and the catalog had to be redone. This method was rendered useless when the indicator procedure changed in September 1938. However, Rejewski found patterns in the new indicators. Working with the engineers at AVA, one of the most famous codebreaking machines – the bomba – was produced. The six bomby (plural in Polish for “bomba”) searched through all 105,456 rotor settings for those that exhibited patterns that could be determined from the indicators after a sufficient number of messages were intercepted. (Note: The reason that it is written both “bomba” and “bombę” is the declension endings. “Bomba” is for “who” or “what” and “bombę” is for “whom, what for?”) Usually only a small number of settings produced the patterns, and each of those settings was tried to determine the one that was correct. Because there were three rotors and three positions for rotors in Enigma, there were six possible rotor orders; therefore, six bomby were produced. In December 1938, the Germans introduced two new rotors. Then there were sixty possible ways to select three rotors from the set and place them in Enigma; sixty bomby would have been needed, and the Cipher Bureau could not afford to build them. After the change, the Cipher Bureau could break few Enigma messages.


In July 1939, as war with Germany loomed over Poland, the Polish codebreakers met just outside Warsaw with British and French codebreakers. At this meeting the Poles described their achievements against Enigma. As a result of the meeting, the British and the French each received one of the Enigma doubles and information on the methods used by the Poles to solve daily keys. On September 1, 1939, Germany attacked Poland, and British codebreakers at Bletchley Park continued the attack on Enigma. British mathematicians such as Alan Turing and Gordon Welchman and engineers such as Harold “Doc” Keen and Thomas “Tommy” Flowers developed cryptanalytic machines to attack Enigma and other German ciphers. One of the machines to attack Enigma was the Turing-Welchman bombe. (IEEE Milestone, Bletchley Park, 1939 – 1945) Both the British bombe and the Polish bomba searched through all possible Enigma rotor settings for settings that produced patterns that had been noticed by the codebreakers. The British bombe searched for patterns in Enigma messages, and the Polish bomba searched for patterns in Enigma indicators.


After the United States entered the war, US Navy mathematicians at Naval Communications in Washington, DC, designed cryptanalytic machines to attack Japanese ciphers and machines to assist the British with the attack on naval Enigma. These codebreaking machines were engineered by Joseph Desch and other engineers at the Naval Computing Machine Laboratory located at National Cash Register Company in Dayton, OH. One of the machines to attack naval Enigma was the US Navy cryptologic bombe. (IEEE Milestone, Naval Computing Machine Laboratory, 1942 – 1945) The US Navy bombe – like the British bombe – searched for patterns in Enigma messages. At the beginning of the German attack on Poland, Rejewski, Zygalski, and Różycki fled Warsaw, and they arrived in Paris in late September. By the end of October they were again working on German ciphers – now at Command Post (P.C.) Bruno at Gretz-Armainvillers near Paris. The Poles and the British exchanged Enigma keys. In January 1940, Alan Turing visited the Polish codebreakers in France. Turing brought the Poles the British version of the Zygalski sheets, and the Poles provided Turing with corrected information on the wiring of Enigma rotors IV and V. Palluth and Fokczyński had also fled to France. Palluth maintained the team’s radio contact with London and later with Algiers and was involved with monitoring German radio signals. Fokczynski repaired radio and cipher equipment.

Following the German attack on France in May 1940, Rejewski, Zygalski, and Różycki evacuated to North Africa. By October they had returned to Vichy France and continued attacking German ciphers. They were located near Uzès at P.C. Cadix. Until Germany took control of South France, the Polish codebreakers traveled to and from North Africa. On January 9, 1942, on a trip back to France after a three-month assignment in the cipher section in Algiers, Różycki died when the ship on which he was traveling sank. In November 1942, after Operation Torch, the Allied attack on North Africa, Germany occupied free France. Rejewski and Zygalski undertook a harrowing crossing into Spain, which included their being detained in Spanish prisons. After their release, they traveled to Portugal and then to Gibraltar from where they flew to Britain. Palluth and Fokczyński were both captured during the crossing into Spain. They both died in the Sachsenhausen camp – Palluth during an Allied bombing raid and Fokczyński due to illness. Rejewski and Zygalski arrived in Great Britain in August 1943 and served with the Communications Battalion of the Polish Armed Forces Commander-in-Chief’s General Staff. Both served in the German section. Their work until the end of the war was breaking manual SS and SD ciphers.

After the war, Zygalski remained in England and worked at the Polish University. He died in 1978 in Liss, near Portsmouth. When the war ended, Rejewski returned to his home in Bydgoszcz where, despite harassment by the Polish security services, he worked for various companies until his retirement because of poor health in 1966. He moved to Warsaw in 1969 and died there of a heart attack in 1980.

IEEE Poland Section is indebted to Dr. Chris Christensen and Mr. Ralph Erskine for their editorial support and useful comments added to this manuscript, especially concerning the existing related IEEE Milestones (1939-45 Bletchley Park, and 1942-45 Naval Computing Machine Laboratory)

Features that set this work apart from similar achievements

On September 1, 1939, Germany attacked Poland, and British codebreakers at Bletchley Park continued the attack on Enigma. British mathematicians such as Alan Turing and Gordon Welchman and engineers such as Harold “Doc” Keen and Thomas “Tommy” Flowers developed cryptanalytic machines to attack Enigma and other German ciphers. One of the machines to attack Enigma was the Turing-Welchman bombe. (IEEE Milestone, Bletchley Park, 1939 – 1945) Both the British bombe and the Polish bomba searched through all possible Enigma rotor settings for settings that produced patterns that had been noticed by the codebreakers. The British bombe searched for patterns in Enigma messages, and the Polish bomba searched for patterns in Enigma indicators.

After the United States entered the war, US Navy mathematicians at Naval Communications in Washington, DC, designed cryptanalytic machines to attack Japanese ciphers and machines to assist the British with the attack on naval Enigma. These codebreaking machines were engineered by Joseph Desch and other engineers at the Naval Computing Machine Laboratory located at National Cash Register Company in Dayton, OH. One of the machines to attack naval Enigma was the US Navy cryptologic bombe. (IEEE Milestone, Naval Computing Machine Laboratory, 1942 – 1945) The US Navy bombe – like the British bombe – searched for patterns in Enigma messages.

Significant references

The achievements outlined above are covered in more detail in the following publications: [1] Frank Carter, “The First Breaking of Enigma: Some of the Pioneering Techniques Developed by the Polish Cipher Bureau,” Report No 2, Bletchley Park Trust, 2008. [2] Jennifer Wilcox, “Solving the Enigma: History of the Cryptanalytic Bombe,” Center for Cryptologic History, National Security Agency, 2006. http://www.nsa.gov/about/_files/cryptologic_heritage/publications/wwii/solving_enigma.pdf [3] Chris Christensen,”Polish Mathematicians Finding Patterns in Enigma Messages,” Mathematics Magazine, 80(4), October 2007, pp. 247-273. [4] F. H. Hinsley, et al., British Intelligence in the Second World War: Its Influence on Strategy and Operations (book). 3(2), Appendix 30. [5] Andrew Hodges, Alan Turing: The Enigma, Simon & Schuster, 1983 (book). This is also available in a Polish translation: Andrew Hodges, Enigma. Życie i śmierć Alana Turinga, Prószyński i S-ka, Warsaw, 2002. [6] Brian Johnson, The Secret War, Methuen Inc, 1978 (book). This is also available in a Polish translation: Brian Johnson, Sekrety Drugiej Wojny Światowej. Wojna Mózgów, Zysk i S-ka, Warsaw, 1997. [7] Władysław Kozaczuk, W kręgu Enigmy, Książka i Wiedza, Warsaw 1986 (book). [8] David Kahn, The Codebreakers: The Story of Secret Writing, Scribner; Revised Edition, 1996 (book). This is also available in a Polish translation: Łamacze kodów: Historia kryptologii, WNT Warszawa, 2004. [9] Marian Rejewski, Memories of My Work at the Cipher Bureau of the General Staff Second Department 1930-45, Adam Mickiewicz University Press, Poznań, Poland, 2011 (book.) Half of this book is written in Polish, and the other half is a translation into English. Websites: US National Security Agency’s Center for Cryptologic History website: http://www.nsa.gov/about/cryptologic_heritage/center_crypt_history/publications/wwii.shtml There are many Enigma websites, including Wikipedia’s comprehensive coverage at http://en.wikipedia.org/wiki/Cryptanalysis_of_the_Enigma

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