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The Cipher Bureau ( Polish: ''Biuro Szyfrów'', ) was the interwar
Polish General Staff Polish General Staff, formally known as the General Staff of the Polish Armed Forces ( Polish: ''Sztab Generalny Wojska Polskiego'') is the highest professional body within the Polish Armed Forces. Organizationally, it is an integral part of the M ...
's Second Department's unit charged with SIGINT and both
cryptography Cryptography, or cryptology (from "hidden, secret"; and ''graphein'', "to write", or ''-logy, -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of Adversary (cryptography), ...
(the ''use'' of
cipher In cryptography, a cipher (or cypher) is an algorithm for performing encryption or decryption—a series of well-defined steps that can be followed as a procedure. An alternative, less common term is ''encipherment''. To encipher or encode i ...
s and
code In communications and information processing, code is a system of rules to convert information—such as a letter, word, sound, image, or gesture—into another form, sometimes shortened or secret, for communication through a communicati ...
s) and
cryptanalysis Cryptanalysis (from the Greek ''kryptós'', "hidden", and ''analýein'', "to analyze") refers to the process of analyzing information systems in order to understand hidden aspects of the systems. Cryptanalysis is used to breach cryptographic se ...
(the ''study'' of ciphers and codes, for the purpose of "breaking" them). The precursor of the agency that would become the Cipher Bureau was created in May 1919, during the Polish-Soviet War (1919–1921), and played a vital role in securing Poland's survival and victory in that war. In mid-1931, the Cipher Bureau was formed by the merger of pre-existing agencies. In December 1932, the Bureau began breaking
Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
's Enigma
cipher In cryptography, a cipher (or cypher) is an algorithm for performing encryption or decryption—a series of well-defined steps that can be followed as a procedure. An alternative, less common term is ''encipherment''. To encipher or encode i ...
s. Over the next seven years, Polish cryptologists overcame the growing structural and operating complexities of the plugboard-equipped Enigma. The Bureau also broke
Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
cryptography. Five weeks before the outbreak of
World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
, on 25 July 1939, in
Warsaw Warsaw, officially the Capital City of Warsaw, is the capital and List of cities and towns in Poland, largest city of Poland. The metropolis stands on the Vistula, River Vistula in east-central Poland. Its population is officially estimated at ...
, the Polish Cipher Bureau revealed its Enigma-decryption techniques and equipment to representatives of French and British
military intelligence Military intelligence is a military discipline that uses information collection and analysis List of intelligence gathering disciplines, approaches to provide guidance and direction to assist Commanding officer, commanders in decision making pr ...
, which had been unable to make any headway against Enigma. This Polish intelligence-and-technology transfer would give the Allies an unprecedented advantage ( Ultra) in their ultimately victorious prosecution of
World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
.


Background

On 8 May 1919 Lt. Józef Serafin Stanslicki established a
Polish Army The Land Forces () are the Army, land forces of the Polish Armed Forces. They currently contain some 110,000 active personnel and form many components of the European Union and NATO deployments around the world. Poland's recorded military histor ...
"Cipher Section" (), precursor to the "Cipher Bureau" (). The Cipher Section reported to the
Polish General Staff Polish General Staff, formally known as the General Staff of the Polish Armed Forces ( Polish: ''Sztab Generalny Wojska Polskiego'') is the highest professional body within the Polish Armed Forces. Organizationally, it is an integral part of the M ...
and contributed substantially to Poland's defense by Józef Piłsudski's forces during the Polish-Soviet War of 1919–1921, thereby helping preserve Poland's independence, recently regained in the wake of
World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...
. The ''Cipher'' Section's purview included both
cipher In cryptography, a cipher (or cypher) is an algorithm for performing encryption or decryption—a series of well-defined steps that can be followed as a procedure. An alternative, less common term is ''encipherment''. To encipher or encode i ...
s and
code In communications and information processing, code is a system of rules to convert information—such as a letter, word, sound, image, or gesture—into another form, sometimes shortened or secret, for communication through a communicati ...
s. In Polish the term "cipher" () loosely refers to ''both'' these two principal categories of
cryptography Cryptography, or cryptology (from "hidden, secret"; and ''graphein'', "to write", or ''-logy, -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of Adversary (cryptography), ...
. (Compare the opposite practice in English, which loosely refers to ''both''
code In communications and information processing, code is a system of rules to convert information—such as a letter, word, sound, image, or gesture—into another form, sometimes shortened or secret, for communication through a communicati ...
s and
cipher In cryptography, a cipher (or cypher) is an algorithm for performing encryption or decryption—a series of well-defined steps that can be followed as a procedure. An alternative, less common term is ''encipherment''. To encipher or encode i ...
s as "codes".) During the
Polish–Soviet War The Polish–Soviet War (14 February 1919 – 18 March 1921) was fought primarily between the Second Polish Republic and the Russian Soviet Federative Socialist Republic, following World War I and the Russian Revolution. After the collapse ...
(1919–1921), approximately a hundred Russian ciphers were broken by a sizable cadre of Polish cryptologists who included army Lieutenant Jan Kowalewski and three world-famous professors of mathematics – Stefan Mazurkiewicz,
Wacław Sierpiński Wacław Franciszek Sierpiński (; 14 March 1882 – 21 October 1969) was a Polish mathematician. He was known for contributions to set theory (research on the axiom of choice and the continuum hypothesis), number theory, theory of functions ...
, and Stanisław Leśniewski. Russian army staffs were still following the same disastrously ill-disciplined signals-security procedures as had Tsarist army staffs during
World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...
, to the decisive advantage of their German enemy. As a result, during the Polish-Soviet War the Polish military were regularly kept informed by Russian signals stations about the movements of Russian armies and their intentions and operational orders. The Soviet staffs, according to Polish Colonel Mieczysław Ścieżyński, In the crucial month of August 1920 alone, Polish cryptologists decrypted 410 signals: * from Soviet General
Mikhail Tukhachevsky Mikhail Nikolayevich Tukhachevsky ( rus, Михаил Николаевич Тухачевский, Mikhail Nikolayevich Tukhachevskiy, p=tʊxɐˈtɕefskʲɪj; – 12 June 1937), nicknamed the Red Napoleon, was a Soviet general who was prominen ...
, commander of the northern front * from
Leon Trotsky Lev Davidovich Bronstein ( – 21 August 1940), better known as Leon Trotsky,; ; also transliterated ''Lyev'', ''Trotski'', ''Trockij'' and ''Trotzky'' was a Russian revolutionary, Soviet politician, and political theorist. He was a key figure ...
, Soviet commissar of war * from commanders of armies, for example: ** the commander of the , ** the commander of the 1st Cavalry Army, Semyon Budionny ** the commander of the , Gai * from the staffs of the XII, XV and XVI Armies * from the staffs of: ** the Mozyr Group (named after the
Belarus Belarus, officially the Republic of Belarus, is a landlocked country in Eastern Europe. It is bordered by Russia to the east and northeast, Ukraine to the south, Poland to the west, and Lithuania and Latvia to the northwest. Belarus spans an a ...
ian city) ** the Zolochiv Group (after the Ukrainian town) ** the Yakir Group fter General Iona Emmanuilovich Yakir">Iona_Emmanuilovich_Yakir.html" ;"title="fter General Iona Emmanuilovich Yakir">fter General Iona Emmanuilovich Yakir* from the 2, 4, 7, 10, 11, 12, 16, 17, 18, 24, 27, 41, 44, 45, 53, 54, 58 and 60 Infantry Divisions * from the 8 Cavalry Division etc. The intercepts were as a rule decrypted the same day, or at latest the next day, and were immediately sent to the Polish
General Staff A military staff or general staff (also referred to as army staff, navy staff, or air staff within the individual services) is a group of officers, Enlisted rank, enlisted, and civilian staff who serve the commanding officer, commander of a ...
's Section II (Intelligence) and operational section. The more important signals were read in their entirety by the Chief of the General Staff, and even by the Commander in Chief, Marshal Józef Piłsudski. Interception and reading of the signals provided Polish intelligence with entire Russian operational orders. The Poles were able to follow the whole operation of Budionny's Cavalry Army in the second half of August 1920 with incredible precision, just by monitoring his radiotelegraphic correspondence with
Tukhachevsky Mikhail Nikolayevich Tukhachevsky ( rus, Михаил Николаевич Тухачевский, Mikhail Nikolayevich Tukhachevskiy, p=tʊxɐˈtɕefskʲɪj; – 12 June 1937), nicknamed the Red Napoleon, was a Soviet general who was prominen ...
, including the famous and historic conflict between the two Russian commanders. The intercepts even included an order from Trotsky to the revolutionary council of war of the Western Front, confirming Tukhachevsky's operational orders, thus giving them the authority of the supreme chief of the Soviet armed forces. An entire operational order from Tukhachevsky to Budionny was intercepted on 19 August and read on 20 August, stating the tasks of all of Tukhachevsky's armies, of which only the essence had previously been known. Ścieżyński surmises that the Soviets must likewise have intercepted Polish operational signals; but he doubts that this would have availed them much, since Polish cryptography "stood abreast of modern cryptography" and since only a small number of Polish higher headquarters were equipped with
radio station Radio broadcasting is the broadcasting of audio (sound), sometimes with related metadata, by radio waves to radio receivers belonging to a public audience. In terrestrial radio broadcasting the radio waves are broadcast by a land-based rad ...
s, of which there was a great shortage; and finally, Polish headquarters were more cautious than the Russians and almost every Polish division had the use of a land line. Polish cryptologists enjoyed generous support under the command of Col. Tadeusz Schaetzel, chief of the Polish General Staff's Section II (Intelligence). They worked at
Warsaw Warsaw, officially the Capital City of Warsaw, is the capital and List of cities and towns in Poland, largest city of Poland. The metropolis stands on the Vistula, River Vistula in east-central Poland. Its population is officially estimated at ...
's radio station ''WAR'', one of two Polish long-range radio transmitters at the time. The Polish cryptologists' work led, among many other things, to the discovery of a large gap on the
Red Army The Workers' and Peasants' Red Army, often shortened to the Red Army, was the army and air force of the Russian Soviet Republic and, from 1922, the Soviet Union. The army was established in January 1918 by a decree of the Council of People ...
's left flank, which enabled Poland's Marshal Józef Piłsudski to drive a war-winning wedge into that gap during the August 1920 Battle of Warsaw. The discovery of the Cipher Bureau's archives, decades after the Polish-Soviet War, has borne out Ścieżyński's assertion


Cipher Bureau

In mid-1931, at the Polish
General Staff A military staff or general staff (also referred to as army staff, navy staff, or air staff within the individual services) is a group of officers, Enlisted rank, enlisted, and civilian staff who serve the commanding officer, commander of a ...
, a Cipher Bureau was formed by merging the Radio-Intelligence Office () and the Polish-Cryptography Office ()., note 6 The Bureau was charged with both
cryptography Cryptography, or cryptology (from "hidden, secret"; and ''graphein'', "to write", or ''-logy, -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of Adversary (cryptography), ...
– the generation, and supervision of the use, of
cipher In cryptography, a cipher (or cypher) is an algorithm for performing encryption or decryption—a series of well-defined steps that can be followed as a procedure. An alternative, less common term is ''encipherment''. To encipher or encode i ...
s and
code In communications and information processing, code is a system of rules to convert information—such as a letter, word, sound, image, or gesture—into another form, sometimes shortened or secret, for communication through a communicati ...
s – and cryptology – the study of ciphers and codes, particularly for the purpose of breaking them. Between 1932 and 1936, the Cipher Bureau took on additional responsibilities, including radio communications between
military intelligence Military intelligence is a military discipline that uses information collection and analysis List of intelligence gathering disciplines, approaches to provide guidance and direction to assist Commanding officer, commanders in decision making pr ...
posts in Poland and abroad, as well as radio
counterintelligence Counterintelligence (counter-intelligence) or counterespionage (counter-espionage) is any activity aimed at protecting an agency's Intelligence agency, intelligence program from an opposition's intelligence service. It includes gathering informati ...
– mobile direction-finding and intercept stations for the locating and traffic analysis of spy and fifth column transmitters operating in Poland.


Stalking Enigma

In late 1927 or early 1928, there arrived at the Warsaw Customs Office from Germany a package that, according to the accompanying declaration, was supposed to contain radio equipment. The German firm's representative strenuously demanded that the package be returned to Germany even before going through customs, as it had been shipped with other equipment by mistake. His insistent demands alerted the customs officials, who notified the Polish General Staff's Cipher Bureau, which took a keen interest in new developments in radio technology. Since it happened to be a Saturday afternoon, the Bureau's experts had ample time to look into the matter. They carefully opened the box and found that it did not, in fact, contain radio equipment but a cipher machine. They examined the machine minutely, then put it back into the box. The Bureau's leading Enigma cryptanalyst Marian Rejewski commented that the cipher machine may be surmised to have been a ''commercial''-model Enigma since at that time the military model had not yet been devised. "Hence this trivial episode was of no practical importance, though it does fix the date at which the Cipher Bureau's interest in the Enigma machine began"manifested, initially, in the entirely legal acquisition of a single commercial-model Enigma. On 15 July 1928, the first German machine-enciphered messages were broadcast by German military radio stations. Polish monitoring stations began intercepting them, and cryptologists in the Polish Cipher Bureau's German section were instructed to try to read them. The effort was fruitless, however, and was eventually abandoned. There remained very slight evidence of the effort, in the form of a few densely written-over sheets of paper and the commercial-model Enigma machine. On 15 January 1929 Major Gwido Langer, after a tour of duty as chief of staff of the 1st Legion Infantry Division, became chief of the Radio-Intelligence Office, and subsequently of the Cipher Bureau. The Bureau's deputy chief, and the chief of its German section (''BS-4''), was Captain Maksymilian Ciężki. In 1929, while the Cipher Bureau's predecessor agency was still headed by Major Franciszek Pokorny (a relative of the outstanding
World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...
Austro-Hungarian Army cryptologist, Captain Herman Pokorny), Ciężki, Franciszek Pokorny, and a civilian Bureau associate, Antoni Palluth, taught a secret cryptology course at Poznań University for selected mathematics students. Over ten years later, during
World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
while in
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, one of the students, Marian Rejewski, would discover that the entire course had been taught from French General Marcel Givièrge's book, (Course of Cryptography), published in 1925. In September 1932, Maksymilian Ciężki hired three young graduates of the Poznań course to be Bureau staff members: Marian Rejewski, Jerzy Różycki and Henryk Zygalski.


Successes and setbacks

In 1926, the German Navy adopted, as its top cryptographic device, a modified civilian
Enigma machine The Enigma machine is a cipher device developed and used in the early- to mid-20th century to protect commercial, diplomatic, and military communication. It was employed extensively by Nazi Germany during World War II, in all branches of the W ...
; in 1928 the German Army followed suit. The complexity of the system was much increased in 1930 by the introduction of a plugboard (), albeit with only six connecting leads in use. In December 1932, Marian Rejewski made what historian David Kahn describes as one of the greatest advances in cryptologic history, by applying pure
mathematics Mathematics is a field of study that discovers and organizes methods, Mathematical theory, theories and theorems that are developed and Mathematical proof, proved for the needs of empirical sciences and mathematics itself. There are many ar ...
the theory of permutations and groupsto breaking the German armed forces' Enigma machine ciphers. Rejewski had worked out the precise interconnections of the Enigma rotors and reflector, after the Bureau had received, from French Military Intelligence Captain Gustave Bertrand, two German documents and two pages of Enigma daily keys (for September and October of that year). These had been obtained by a French
military intelligence Military intelligence is a military discipline that uses information collection and analysis List of intelligence gathering disciplines, approaches to provide guidance and direction to assist Commanding officer, commanders in decision making pr ...
agent, a German codenamed ''Rex'', from an agent who worked at Germany's Cipher Office in Berlin, Hans-Thilo Schmidt, whom the French codenamed . After Rejewski had worked out the military Enigma's logical structure, the Polish Cipher Bureau commissioned the AVA Radio Company, co-owned by Antoni Palluth, to build replicas (" doubles") of the Enigma to Rejewski's specifications. His method of decrypting Enigma messages exploited two weaknesses of the German operating procedures. It used what Rejewski called "characteristics" that were independent of the plugboard connections. This involved compiling a card catalog of certain features of the set of indicator settings. The Germans increased the difficulty of decrypting Enigma messages by decreasing the interval between changes in the order of the rotors from quarterly, initially, to monthly in February 1936, then daily in October of that year, when they also increased the number of plugboard leads from six to a number that varied between five and eight. This made the Biuro's grill method much less easy, as it relied on 'unsteckered' letter pairs. The German navy was more security-conscious than the army and air force, and in May 1937 it introduced a new, much more secure, indicator procedure that remained unbroken for several years. The next setback occurred in November 1937, when the scrambler's reflector was changed to one with different interconnections (known as ). Rejewski worked out the wiring in the new reflector, but the catalogue of characteristics had to be compiled anew, again using Rejewski's " cyclometer", which had been built to his specifications by the AVA Radio Company. In January 1938, Colonel Stefan Mayer directed that statistics be compiled for a two-week period, comparing the numbers of Enigma messages solved, to Enigma intercepts. The ratio came to 75 percent. "Nor", Marian Rejewski has commented, "were those 75 percent ... the limit of our possibilities. With slightly augmented personnel, we might have attained about 90 percent ... read. But a certain amount of cipher material ... due to faulty transmission or ... reception, or to various other causes, always remains unread". Information obtained from Enigma decryption seems to have been directed from B.S.-4 principally to the German Office of the General Staff's Section II (Intelligence). There, from fall 1935 to mid-April 1939, it was worked up by Major Jan Leśniak, who in April 1939 would turn the German Office over to another officer and himself form a Situation Office intended for wartime service. He would head the Situation Office to and through the September 1939 Campaign. The system of pre-defining the indicator setting for the day for all Enigma operators on a given network, on which the method of characteristics depended, was changed on 15 September 1938. The one exception to this was the network used by the (SD)—the intelligence agency of the SS and the
Nazi Party The Nazi Party, officially the National Socialist German Workers' Party ( or NSDAP), was a far-right politics, far-right political party in Germany active between 1920 and 1945 that created and supported the ideology of Nazism. Its precursor ...
—who did not make the change until 1 July 1939. Operators now chose their own indicator setting. However, the insecure procedure of sending the enciphered message key twice remained in use, and it was quickly exploited. Henryk Zygalski devised a manual method that used 26 perforated sheets, and Marian Rejewski commissioned the AVA company to produce the (cryptologic bomb). Both the Zygalski-sheet method and each worked for only a single scrambler rotor order, so six sets of Zygalski sheets and six were produced. However, the Germans introduced two new rotors on 15 December 1938, giving a choice of three out of five to assemble in the machines on a given day. This increased the number of possible rotor orders from 6 to 60. The Biuro could then only read the small minority of messages that used neither of the two new rotors. They did not have the resources to produce 54 more or 54 sets of Zygalski sheets. Fortunately, however, the fact that the SD network was still using the old method of the same indicator setting for all messages, allowed Rejewski to re-use his previous method of working out the wiring within these rotors. This information was essential for the production of a full set Zygalski sheets which allowed resumption of large-scale decryption in January 1940. On 1 January 1939, the Germans made military Enigma even more difficult to break by increasing the number of plugboard connections from between five and eight, to between seven and ten. When
World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
broke out on 1 September 1939, Leśniak and his colleagues had been working intensively for two or three years to establish the German
order of battle Order of battle of an armed force participating in a military operation or campaign shows the hierarchical organization, command structure, strength, disposition of personnel, and equipment of units and formations of the armed force. Various abbr ...
and had succeeded in working out nearly 95 percent of it. The German attack on Poland came as no surprise to the
Polish General Staff Polish General Staff, formally known as the General Staff of the Polish Armed Forces ( Polish: ''Sztab Generalny Wojska Polskiego'') is the highest professional body within the Polish Armed Forces. Organizationally, it is an integral part of the M ...
. The results that had been obtained by Polish intelligence, according to Leśniak, "absolutely exceeded what would normally have been possible".


Kabaty Woods

Until 1937 the Cipher Bureau's German section, ''BS-4'', had been housed in the Polish General Staff building – the stately 18th-century " Saxon Palace" – in Warsaw. That year BS-4 moved into specially constructed new facilities in the Kabaty Woods near Pyry, south of Warsaw. There, working conditions were incomparably better than in the cramped quarters at the General Staff building. The move was dictated as well by requirements of security. Germany's was always looking for potential traitors among the military and civilian workers at the General Staff building. Strolling agents, even if lacking access to the Staff building, could observe personnel entering and leaving, and photograph them with concealed miniature cameras. Annual intelligence assignments for German agents in Warsaw placed a priority on securing informants at the Polish General Staff.


Gift to allies

It was in the Kabaty Woods, at Pyry, on 25 and 26 July 1939, with war looming, that, on instructions from the Polish General Staff, the Cipher Bureau's chiefs, Lt. Col. Gwido Langer and Major Maksymilian Ciężki, the three civilian mathematician-cryptologists, and Col. Stefan Mayer, chief of
intelligence Intelligence has been defined in many ways: the capacity for abstraction, logic, understanding, self-awareness, learning, emotional knowledge, reasoning, planning, creativity, critical thinking, and problem-solving. It can be described as t ...
, revealed Poland's achievements to cryptanalytical representatives of France and Britain, explaining how they had broken Enigma. They undertook to give each country a Polish-reconstructed Enigma, along with details of their equipment, including Zygalski sheets and Rejewski's cryptologic bomb. In return, the British pledged to prepare two full sets of Zygalski sheets for all 60 possible wheel orders. The French contingent consisted of Major Gustave Bertrand, the French radio-intelligence and cryptology chief, and Capt. Henri Braquenié of the French Air Force staff. The British sent Commander Alastair Denniston, head of Britain's Government Code and Cypher School,
Dilly Knox Alfred Dillwyn "Dilly" Knox, CMG (23 July 1884 – 27 February 1943) was an English classics scholar and papyrologist at King's College, Cambridge and a codebreaker. As a member of the Room 40 codebreaking unit he helped decrypt the Zimme ...
, chief British cryptanalyst and Commander Humphrey Sandwith, head of the
Royal Navy The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King of the United Kingdom, King. Although warships were used by Kingdom ...
's intercept and direction-finding stations. When Rejewski had been working on reconstructing the German military Enigma machine in late 1932, he had ultimately solved a crucial element, the wiring of the letters of the alphabet into the entry drum, with the inspired guess that they might be wired in simple ''alphabetical'' order. Now, at the trilateral meetingRejewski was later to recount"the first question that ... Dillwyn Knox asked was: 'What are the connections in the entry drum? Knox was mortified to learn how simple the answer was. The Poles' gift, to their western Allies, of Enigma decryption, five weeks before the outbreak of World War II, came not a moment too soon. Former
Bletchley Park Bletchley Park is an English country house and Bletchley Park estate, estate in Bletchley, Milton Keynes (Buckinghamshire), that became the principal centre of Allies of World War II, Allied World War II cryptography, code-breaking during the S ...
mathematician-cryptologist
Gordon Welchman William Gordon Welchman OBE (15 June 1906 – 8 October 1985) was an English mathematician. During World War II, he worked at Britain's secret decryption centre at Bletchley Park, where he was one of the most important contributors. In 1948, a ...
later wrote: "Ultra would never have gotten off the ground if we had not learned from the Poles, in the nick of time, the details both of the German military ... Enigma machine, and of the operating procedures that were in use." Allied Supreme Commander Dwight D. Eisenhower, at war's end, described intelligence from Bletchley Park as having been "of priceless value to me. It has simplified my task as a commander enormously." Eisenhower expressed his thanks for this "decisive contribution to the Allied war effort". British prime minister Winston Churchill's greatest wartime fear, even after Hitler had suspended
Operation Sea Lion Operation Sea Lion, also written as Operation Sealion (), was Nazi Germany's code name for their planned invasion of the United Kingdom. It was to have taken place during the Battle of Britain, nine months after the start of the Second World ...
and invaded the Soviet Union, was that the German submarine wolfpacks would succeed in strangling sea-locked Britain. A major factor that averted Britain's defeat in the
Battle of the Atlantic The Battle of the Atlantic, the longest continuous military campaign in World War II, ran from 1939 to the defeat of Nazi Germany in 1945, covering a major part of the naval history of World War II. At its core was the Allies of World War II, ...
was her regained mastery of Naval Enigma decryption; and while the latter benefited crucially from British seizure of German Enigma-equipped naval vessels, the breaking of German naval signals ultimately relied on techniques that had been pioneered by the Polish Cipher Bureau. Had Britain capitulated to Hitler, the United States would have been deprived of an essential forward base for its subsequent involvement in the European and
North Africa North Africa (sometimes Northern Africa) is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region. However, it is sometimes defined as stretching from the Atlantic shores of t ...
n theaters. A week after the Pyry meeting, Dillwyn Knox, in a letter dated 1 August 1939, thanked the Poles, in Polish, "for your cooperation and patience". He enclosed little paper batons and a scarf picturing a Derby horse raceevidently emblematic of the cryptological race that Knox had hoped to win using the batons, and whose loss he was gallantly acknowledging. On 5 September 1939, as it became clear that Poland was unlikely to halt the ongoing German invasion, BS-4 received orders to destroy part of its files and evacuate essential personnel.


Bureau abroad

During the German
Invasion of Poland The invasion of Poland, also known as the September Campaign, Polish Campaign, and Polish Defensive War of 1939 (1 September – 6 October 1939), was a joint attack on the Second Polish Republic, Republic of Poland by Nazi Germany, the Slovak R ...
in September 1939, key Cipher Bureau personnel were evacuated southeast and – after the Soviets invaded eastern Poland on 17 September – into Romania, on the way destroying their cryptological equipment and documentation. Eventually, crossing Yugoslavia and still-neutral Italy, they reached France. Some personnel of the Cipher Bureau's German section who had worked with Enigma, and most of the workers at the AVA Radio Company that had built Enigma doubles and cryptologic equipment for the German section, remained in Poland. Some were interrogated by the
Gestapo The (, ), Syllabic abbreviation, abbreviated Gestapo (), was the official secret police of Nazi Germany and in German-occupied Europe. The force was created by Hermann Göring in 1933 by combining the various political police agencies of F ...
, but no one gave away the secret of Polish mastery of Enigma decryption. At '' PC Bruno'', outside
Paris Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, largest city of France. With an estimated population of 2,048,472 residents in January 2025 in an area of more than , Paris is the List of ci ...
, on 20 October 1939 the Poles resumed work on German Enigma ciphers in close collaboration with Britain's Government Code and Cypher School at
Bletchley Park Bletchley Park is an English country house and Bletchley Park estate, estate in Bletchley, Milton Keynes (Buckinghamshire), that became the principal centre of Allies of World War II, Allied World War II cryptography, code-breaking during the S ...
. In the interest of security, the Allied cryptological services, before sending their messages over a
teleprinter A teleprinter (teletypewriter, teletype or TTY) is an electromechanical device that can be used to send and receive typed messages through various communications channels, in both point-to-point (telecommunications), point-to-point and point- ...
line, encrypted them using Enigma doubles. Henri Braquenié often closed messages with a . As late as December 1939, when Lt. Col. Gwido Langer, accompanied by Captain Braquenié, visited London and Bletchley Park, the British asked that the Polish cryptologists be turned over to them. Langer, however, took the position that the Polish team must remain where the
Polish Armed Forces The Armed Forces of the Republic of Poland (, ; abbreviated SZ RP), also called the Polish Armed Forces and popularly called in Poland (, roughly "the Polish Military"—abbreviated ''WP''), are the national Military, armed forces of the Poland, ...
were being formedon French soil. The mathematicians might actually have reached Britain much earlierand much more comfortablythan they eventually did; but in September 1939, when they went to the British embassy in
Bucharest Bucharest ( , ; ) is the capital and largest city of Romania. The metropolis stands on the River Dâmbovița (river), Dâmbovița in south-eastern Romania. Its population is officially estimated at 1.76 million residents within a greater Buc ...
, Romania, they were brushed off by a preoccupied British diplomat. In January 1940, the British cryptanalyst
Alan Turing Alan Mathison Turing (; 23 June 1912 – 7 June 1954) was an English mathematician, computer scientist, logician, cryptanalyst, philosopher and theoretical biologist. He was highly influential in the development of theoretical computer ...
spent several days at PC Bruno conferring with his Polish colleagues. He had brought the Poles a full set of Zygalski sheets that had been produced at Bletchley Park by John Jeffreys using Polish-supplied information. On 17 January 1940, the Poles made the first break into wartime Enigma traffic – that from 28 October 1939. During this period, until the collapse of France in June 1940, ultimately 83 percent of the Enigma keys that were found, were solved at Bletchley Park, the remaining 17 percent at PC Bruno. Rejewski commented: The inter-Allied cryptologic collaboration prevented duplication of effort and facilitated discoveries. Before fighting had started in
Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...
in April 1940, the Polish-French team solved an uncommonly hard three-letter
code In communications and information processing, code is a system of rules to convert information—such as a letter, word, sound, image, or gesture—into another form, sometimes shortened or secret, for communication through a communicati ...
used by the Germans to communicate with fighter and bomber squadrons and for exchange of meteorological data between aircraft and land. The code had first appeared in December 1939, but the Polish cryptologists had been too preoccupied with Enigma to give the code much attention. With the German assault on the west impending, however, the breaking of the code took on mounting urgency. The trail of the elusive code (whose system of letters changed every 24 hours) led back to Enigma. The first clue came from the British, who had noticed that the code's letters did not change randomly. If ''A'' changed to ''P'', then elsewhere ''P'' was replaced by ''A''. The British made no further headway, but the Poles realized that what was manifesting was Enigma's ''exclusivity principle'' that they had discovered in 1932. The Germans' carelessness meant that now the Poles, having after midnight solved Enigma's daily setting, could with no further effort also read the signals. The Germans, just before opening their 10 May 1940 offensive in the west that would trample
Belgium Belgium, officially the Kingdom of Belgium, is a country in Northwestern Europe. Situated in a coastal lowland region known as the Low Countries, it is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeas ...
,
Luxembourg Luxembourg, officially the Grand Duchy of Luxembourg, is a landlocked country in Western Europe. It is bordered by Belgium to the west and north, Germany to the east, and France on the south. Its capital and most populous city, Luxembour ...
and the
Netherlands , Terminology of the Low Countries, informally Holland, is a country in Northwestern Europe, with Caribbean Netherlands, overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Nether ...
in order to reach the borders of France, once again changed their procedure for enciphering message keys, rendering the Zygalski sheets "completely useless" and temporarily defeating the joint British–Polish cryptologic attacks on Enigma. According to Gustave Bertrand, "It took ''superhuman'' day-and-night effort to overcome this new difficulty: on May 20, decryption resumed." Following the capitulation of France in June 1940, the Poles were evacuated to
Algeria Algeria, officially the People's Democratic Republic of Algeria, is a country in the Maghreb region of North Africa. It is bordered to Algeria–Tunisia border, the northeast by Tunisia; to Algeria–Libya border, the east by Libya; to Alger ...
. On October 1, 1940, they resumed work at '' Cadix'', near Uzès in unoccupied southern
Vichy France Vichy France (; 10 July 1940 – 9 August 1944), officially the French State ('), was a French rump state headed by Marshal Philippe Pétain during World War II, established as a result of the French capitulation after the Battle of France, ...
, under the sponsorship of Gustave Bertrand. A little over two years later, on 8 November 1942, Bertrand learned from the
BBC The British Broadcasting Corporation (BBC) is a British public service broadcaster headquartered at Broadcasting House in London, England. Originally established in 1922 as the British Broadcasting Company, it evolved into its current sta ...
that the Allies had landed in French North Africa ("
Operation Torch Operation Torch (8–16 November 1942) was an Allies of World War II, Allied invasion of French North Africa during the Second World War. Torch was a compromise operation that met the British objective of securing victory in North Africa whil ...
"). Knowing that in such an eventuality the Germans planned to occupy
Vichy France Vichy France (; 10 July 1940 – 9 August 1944), officially the French State ('), was a French rump state headed by Marshal Philippe Pétain during World War II, established as a result of the French capitulation after the Battle of France, ...
, on 9 November he evacuated Cadix. Two days later, on 11 November, the Germans indeed marched into southern France. On the morning of 12 November they occupied Cadix. Over the two years since its establishment in October 1940, Cadix had decrypted thousands of
Wehrmacht The ''Wehrmacht'' (, ) were the unified armed forces of Nazi Germany from 1935 to 1945. It consisted of the German Army (1935–1945), ''Heer'' (army), the ''Kriegsmarine'' (navy) and the ''Luftwaffe'' (air force). The designation "''Wehrmac ...
, SS and
Gestapo The (, ), Syllabic abbreviation, abbreviated Gestapo (), was the official secret police of Nazi Germany and in German-occupied Europe. The force was created by Hermann Göring in 1933 by combining the various political police agencies of F ...
messages, originating not only from French territory but from across Europe, which provided invaluable intelligence to Allied commands and resistance movements. Cadix had also decrypted thousands of
Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
messages. Having departed Cadix, the Polish personnel evaded the occupying Italian security police and German
Gestapo The (, ), Syllabic abbreviation, abbreviated Gestapo (), was the official secret police of Nazi Germany and in German-occupied Europe. The force was created by Hermann Göring in 1933 by combining the various political police agencies of F ...
and sought to escape France via
Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...
. Jerzy Różycki, Jan Graliński and Piotr Smoleński had died in the January 1942 sinking, in the
Mediterranean Sea The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...
, of a French passenger ship, the '' SS Lamoricière'', in which they had been returning to southern France from a tour of duty in
Algeria Algeria, officially the People's Democratic Republic of Algeria, is a country in the Maghreb region of North Africa. It is bordered to Algeria–Tunisia border, the northeast by Tunisia; to Algeria–Libya border, the east by Libya; to Alger ...
. Marian Rejewski and Henryk Zygalski hiked over the Pyrenees with a guide (who robbed them at gunpoint) to the Spanish border, where they were arrested on 30 January 1943. They were incarcerated by the Spaniards for three months before being released, upon
Red Cross The organized International Red Cross and Red Crescent Movement is a Humanitarianism, humanitarian movement with approximately 16million volunteering, volunteers, members, and staff worldwide. It was founded to protect human life and health, to ...
intervention, on 4 May 1943. They then managed, by a circuitous land–sea–air route, to join the
Polish Armed Forces The Armed Forces of the Republic of Poland (, ; abbreviated SZ RP), also called the Polish Armed Forces and popularly called in Poland (, roughly "the Polish Military"—abbreviated ''WP''), are the national Military, armed forces of the Poland, ...
in Britain, Rejewski and Zygalski were inducted into the Polish Army as privates (they would eventually be promoted to lieutenant) and put to work breaking German '' SS'' and '' SD'' hand ciphers at a Polish signals facility in Boxmoor. Because of their having been in occupied France, the British considered it too risky to invite them to work at Bletchley Park. Finally, with the end of the two mathematicians' cryptologic work at the close of World War II, the Cipher Bureau ceased to exist. From nearly its inception in 1931 until war's end in 1945, the Bureau, sometimes incorporated into aggregates under cryptonyms (PC Bruno and Cadix), had been essentially the same agency, with most of the same core personnel, carrying out much the same tasks; now it was extinguished. Neither Rejewski nor Zygalski would work again as cryptologists. In late 1946 Rejewski returned to his family in a devastated and politically altered Poland, to live there another 33 years until his death in February 1980. Zygalski would remain in England until his death in August 1978.


Secret preserved

Despite their travails, Rejewski and Zygalski had fared better than some of their colleagues. Cadix's Polish military chiefs, Langer and Ciężki, had also been capturedby the Germans, as they tried to escape from France into Spain on the night of 10–11 March 1943along with three other Poles: Antoni Palluth,
Edward Fokczyński Edward Fokczyński was one of the four directors of the AVA Radio Company, an electronics firm established in Warsaw, Poland, in 1929. AVA produced radio equipment for the Polish General Staff's Biuro Szyfrów, Cipher Bureau, which was responsib ...
and Kazimierz Gaca. The first two became prisoners of war; the other three were sent as slave labourers to Germany, where Palluth and Fokczyński perished. Despite the varyingly dire circumstances in which they were held, none of them Stefan Mayer emphasizesbetrayed the secret of Enigma's
decryption In cryptography, encryption (more specifically, encoding) is the process of transforming information in a way that, ideally, only authorized parties can decode. This process converts the original representation of the information, known as plai ...
, thus making it possible for the Allies to continue exploiting this vital intelligence resource. Before the war, Palluth, a lecturer in the 1929 secret Poznań University cryptology course, had been co-owner of AVA, which produced equipment for the Cipher Bureau, and knew many details of the decryption technology. In Warsaw, under German occupation, other Cipher Bureau workers were interrogated by German intelligence commissions, and some AVA workers were approached by German agents, but all kept silent about compromises to Enigma.


In popular culture

In 1967 the Polish military historian Władysław Kozaczuk, in his book ''Bitwa o tajemnice'' (''The Battle for Secrets''), first revealed that the German Enigma had been broken by Polish cryptologists before World War II. Kozaczuk's disclosure came seven years before F. W. Winterbotham's ''The Ultra Secret'' (1974) changed conventional views of the history of the war. The 1979 Polish film (The Enigma Secret) is a generally fair, if superficial, account of the Cipher Bureau's story. Twenty-two years later, the 2001 Hollywood film '' Enigma'' was criticized for its many historical inaccuracies, including omission of Poland's fundamental work in Enigma
decryption In cryptography, encryption (more specifically, encoding) is the process of transforming information in a way that, ideally, only authorized parties can decode. This process converts the original representation of the information, known as plai ...
.


See also

* Ultra * Marian Rejewski * Tadeusz Pełczyński * Polish School of Mathematics * History of Polish Intelligence Services * Wilfred Dunderdale


Notes


References


Bibliography

* * * * * * * * * * * Good, I.J., and Cipher A. Deavours, afterword to Marian Rejewski, "How Polish Mathematicians Deciphered the Enigma", ''Annals of the History of Computing'', July 1981. * * * * * * A revised and augmented translation of ''W kręgu enigmy'',
Warsaw Warsaw, officially the Capital City of Warsaw, is the capital and List of cities and towns in Poland, largest city of Poland. The metropolis stands on the Vistula, River Vistula in east-central Poland. Its population is officially estimated at ...
, Książka i Wiedza, 1979, supplemented with appendices by Marian Rejewski * Largely an abridgment of , minus Rejewski's appendices, which have been replaced with appendices of varying quality by other authors * * * * * * Appendix B to * Appendix C to * Appendix D to * Appendix E to * * * * *


External links

* Laurence Peter
How Poles cracked Nazi Enigma secret
BBC News, 20 July 2009
"Polish Enigma Double"





Enigma and Intelligence


* ttps://web.archive.org/web/20081231174812/http://www.uwic.ac.uk/shss/djs/STMsubtypes-pt3.htm A Brief History of Computing Technology, 1930 to 1939*
NSA/CSS National Cryptologic Museum Unveils New Polish Enigma Exhibit

IEEE History Center: "The Invention of Enigma and How the Polish Broke It Before the Start of WWII"


* Sir Dermot Turing said that his uncle's achievements in cracking German communications encrypted on the Enigma machines were based on work by a group of Polish mathematicians:
Turing cult has obscured role of Polish codebreakers
{{DEFAULTSORT:Cipher Bureau (Poland) Military history of the Second Polish Republic Signals intelligence agencies Defunct Polish intelligence agencies Cryptography organizations History of cryptography Military history of Poland during World War II Science and technology in Poland Signals intelligence agencies of World War II