The Polish Codebreakers Who Cracked Enigma

Overview

In December 1932 – seven years before World War II began – a 27-year-old Polish mathematician named Marian Rejewski cracked the German military Enigma cipher. Working at the Polish General Staff’s Biuro Szyfrow (Cipher Bureau), Rejewski applied permutation group theory to cryptanalysis for the first time in history. Together with colleagues Jerzy Rozycki and Henryk Zygalski, he developed techniques and devices that read German Enigma traffic throughout the 1930s. Five weeks before Germany invaded Poland, the three mathematicians handed their secrets to British and French intelligence – enabling the Bletchley Park effort that followed. Their contribution was then suppressed for decades.

1. The Three Mathematicians

Marian Adam Rejewski (1905–1980)

Born: 16 August 1905, Bromberg, Prussia (now Bydgoszcz, Poland) Died: 13 February 1980, Warsaw, Poland (heart attack, returning from shopping; aged 74) Buried: Powazki Military Cemetery, Warsaw, with military honours

Family background: Parents Jozef and Matylda (nee Thoms). His father was a tobacco merchant in Bydgoszcz. Rejewski probably inherited his talent for mathematics from him. His excellent command of German, from schooling in the formerly Prussian city, proved an additional advantage.

Education:

Studied mathematics at Poznan University’s Mathematics Institute, housed in Poznan Castle
January 1929: attended a secret cryptology course organised by the Cipher Bureau at a nearby military installation, alongside future colleagues Zygalski and Rozycki
1 March 1929: graduated with a Master of Philosophy in mathematics
Briefly studied actuarial statistics at the University of Gottingen, Germany (the world centre of mathematics at the time)
Summer 1930: returned to Poznan to accept a teaching assistantship and began part-time work at the Cipher Bureau’s underground “Black Chamber”
1 September 1932: joined the Cipher Bureau in Warsaw full-time as a civilian employee

Marriage and family: On 20 June 1934, married Irena Maria Lewandowska, daughter of a prosperous dentist. Two children: son Andrzej (born 1936) and daughter Janina (born 1939), who became a mathematician. Andrzej died of polio in summer 1947, aged 11, after only five days’ illness – a devastating blow shortly after the family’s wartime reunion.

Personality: Rejewski was quiet, focused, and modest. Despite being the oldest of the three mathematicians, he never felt the urge to act as their leader. He used the form “colleague” (kolega) to address Henryk and Jerzy. He was well-suited for the secretive, intellectually demanding cryptographic work entrusted to him.

The man who cracked Enigma: In late October or early November 1932, Captain Maksymilian Ciezki assigned Rejewski to work alone on the new German military Enigma I cipher machine for a couple of hours each day. Within weeks, Rejewski had deduced the machine’s secret internal wiring using permutation group theory – a method no one had ever applied to cryptanalysis before. By year’s end 1932, all three rotor and reflector wirings were recovered.

Rejewski recalled the moment of breakthrough: after correctly assuming that the military Enigma used alphabetical wiring for the entry drum (rather than the keyboard order of the commercial version), “from my pencil, as by magic, began to issue numbers designating the connections in rotor N.”

Post-war life: See Section 5 below.

Jerzy Witold Rozycki (1909–1942)

Born: 24 July 1909, Olszana, Russian Empire (now Vilshana, Ukraine) Died: 9 January 1942, Mediterranean Sea (aged 32)

Family background: His father was a pharmacist. The family relocated to Poland in 1918. Rozycki completed secondary school in Wyszkow in 1926.

Education:

Master’s degree in mathematics from Poznan University (February 1932)
Second master’s degree in geography from the same institution (December 1937)
Attended the secret cryptology course at Poznan beginning in 1929

Career: From September 1932, civilian cryptologist at the Cipher Bureau in Warsaw.

Key contribution – the “clock” method: Rozycki invented the “clock” (zegar) method, which sometimes made it possible to determine which of the Enigma machine’s three rotors was at the far right position – the position where the rotor always turned at every key depression. This was a critical step in reducing the combinatorial space for daily key recovery.

Death – the sinking of the SS Lamoriciere: On 9 January 1942, Rozycki perished when the French passenger ship SS Lamoriciere sank in the Mediterranean Sea near the Balearic Islands, approximately 10 km northeast of Menorca.

The mission: In the summer of 1941, Rozycki had been sent from the Cadix centre (Chateau des Fouzes, near Uzes in Vichy France) to its branch office at Chateau Couba on the outskirts of Algiers, where he supervised the reading of intercepted German and Italian dispatches. Information about Axis troop movements was vital to the Allies. Having organised the decoding unit, he was ordered to return to France.

The voyage: The SS Lamoriciere, a passenger liner built by Swan Hunter in Newcastle (launched 20 May 1920, 4713 GRT, originally 17 knots), departed Algiers on 6 January 1942 at 17:00, bound for Marseille. She carried 272 passengers (88 military) and 122 crew, along with 330 tonnes of cargo, principally vegetables. She also carried a French intelligence officer, Captain Francois Lane, who accompanied the Polish cryptologists.

The disaster: The ship encountered a savage storm with winds at Force 7 on the Beaufort scale. The Lamoriciere had been converted to coal burning during the war, which reduced her speed dramatically to approximately 10 knots. The coal was of poor quality, and stokers were burning furniture to augment the dwindling fuel supply. The ship went to the rescue of a French freighter, the Jumieres, but by the time she arrived the freighter had already sunk with the loss of her 20 crew. The storm caused a developing list; water began entering through the portholes. At 11:00 on 9 January the captain ordered abandonment, and the Lamoriciere sank at 12:35.

Casualties: Of the 394 people aboard, only 93 survived, rescued by three vessels: the Gueydon (55 survivors), the Chanzy (25 survivors), and the Impetueuse (12 survivors). The dead numbered 301 – 212 passengers and 89 crew. Among the dead were Rozycki, fellow Polish cryptologists Piotr Smolenski and Captain Jan Gralinski of the prewar Cipher Bureau’s Russian section, and French officer Captain Lane.

Sabotage theory: Some historians have suggested sabotage rather than natural disaster. Rozycki was carrying intelligence of immense value to the Allies, and his death deprived the Franco-Polish cryptological team of one of its most important members. However, a 1950s French lawsuit established that the sinking was four-fifths due to the storm and one-fifth due to the unseaworthiness of the vessel. This apportioning of blame became known in French maritime law as the “Lamoriciere Principle.” No concrete evidence of sabotage has been produced.

The wreck: The remains of the Lamoriciere were found in 2008 at a depth of 156 metres, some 10 km northeast of Menorca, by a team of Spanish and Italian divers.

Family: Married Maria Barbara Mayka in 1938. Their son Janusz (born 1939) became a competitive fencer.

The youngest of the three: Rozycki was the youngest of the trio and the only one who did not survive the war. His death at 32 robbed Poland of a brilliant mathematical mind.

Henryk Zygalski (1908–1978)

Born: 15 July 1908, Posen, German Empire (now Poznan, Poland) Died: 30 August 1978, Liss, Hampshire, England Cremated: Ashes taken to London

Education: Studied mathematics at Poznan University. Attended the 1929 secret cryptology course.

Career: From September 1932, civilian cryptologist at the Cipher Bureau in Warsaw. After the war, remained in exile in the United Kingdom.

Key contribution – the Zygalski sheets: In late 1938, Zygalski designed the “perforated sheets” (plachty Zygalskiego), a manual method for finding Enigma daily settings. The method comprised 26 perforated sheets for each of the six possible rotor sequences. Each 26x26 matrix represented the 676 possible starting positions of the middle and right rotors, with holes punched at positions corresponding to so-called “females” (repeated letters at specific positions in indicators).

When sheets from multiple messages were superimposed over a light source and shifted according to a defined programme, the number of visible apertures gradually decreased. With sufficient data, a single aperture remained – corresponding to the correct daily key. Crucially, the method was independent of the number of plugboard connections, making it robust against German procedural changes.

When the Germans introduced rotors IV and V in December 1938, the number of sheets needed increased tenfold (from 6 sets of 26 to 60 sets of 26). At the British Government Code and Cypher School, John Jeffreys oversaw the production of full sets of Zygalski sheets, using the original Polish method, beginning in late 1939.

Life in exile: After the war, Zygalski remained in England. He worked as a lecturer in mathematical statistics at Battersea Polytechnic (later the University of Surrey) until his retirement. The Official Secrets Act prevented him from publicly discussing his cryptological work. He suffered a stroke in 1968.

Shortly before his death, the Polish University in Exile awarded him an honorary doctorate for his role in breaking Enigma.

A quiet exile: Zygalski spent his final decades in modest circumstances in southern England, teaching statistics. The man who had helped crack the most important cipher in history was bound by British secrecy laws from telling anyone what he had done.

2. The Biuro Szyfrow (Cipher Bureau)

Origins

The Cipher Bureau’s predecessor, a “Cipher Section,” was established on 8 May 1919, during the Polish-Soviet War. Polish cryptologists played a crucial role in the 1920 war, decrypting approximately 410 Soviet signals in August 1920 alone – intelligence that contributed to Poland’s victory at the Battle of Warsaw, sometimes called “the Miracle on the Vistula.”

The formal Cipher Bureau was created in mid-1931 by merging the Radio-Intelligence Office and the Polish-Cryptography Office within the Polish General Staff’s Second Department (military intelligence).

Leadership

Major (later Lieutenant Colonel) Gwido Langer (1894–1948):

Born 2 September 1894, Zylina, Poland
Graduate of the Theresia Military Academy in Wiener Neustadt, Austria, and the Higher Military School in Warsaw
Became chief of the Radio-Intelligence Office on 15 January 1929; subsequently headed the Cipher Bureau
Responsible for all Polish military cryptography, radio intelligence, tracking of clandestine enemy transmitters, and both Russian and German cryptogram interception and decryption
In March 1943, captured by Germans while attempting to escape from France to Spain, betrayed by a French guide
During German captivity, Langer “decided [to] mix truth with lies, and present my lies in such a way that they had the veneer of truth.” He told interrogators the Bureau had broken Enigma sporadically before the war but could no longer do so – thereby protecting the secret of Ultra
Died 30 March 1948 at the Polish Army signals camp at Kinross, Scotland
His remains were repatriated to Poland in December 2010, receiving a funeral with full military honours at the communal cemetery in Cieszyn

Captain (later Major) Maksymilian Ciezki (1898–1951):

Born 24 November 1898, Samter (now Szamotuly), Province of Posen
Deputy to Langer; chief of the German section (BS-4) from the early 1930s
Supervised radio-intercept stations across Poland
The man who recruited the three mathematicians and who directed the Enigma-breaking effort on a daily basis
Captured alongside Langer in March 1943; at an SS concentration camp, “they managed to protect the secret of Enigma decryption” during interrogations
After liberation in 1945, relocated to London, where he faced poor reception
Died 9 November 1951 in London, “after living the last three years on subsidies from the Assistance Board” – destitute, forgotten, the man who oversaw the greatest cryptanalytic achievement of the interwar period

The Revolutionary Decision: Mathematicians, Not Linguists

Before the Poles, cryptanalysis was primarily a linguistic discipline. Codebreakers were philologists who looked for patterns in language – letter frequencies, common words, grammatical structures. The Cipher Bureau made a deliberate, revolutionary decision: they would recruit mathematicians instead.

In 1929, Ciezki, together with Franciszek Pokorny and Antoni Palluth, organised a secret cryptology course at Poznan University for selected mathematics students. The curriculum derived from French General Marcel Givierge’s 1925 book Cours de cryptographie. Poznan was chosen specifically because it was in the formerly German-controlled part of Poland – the students there were fluent in German.

About twenty mathematics students attended the course. The three best – Rejewski, Rozycki, and Zygalski – were recruited.

This was a paradigm shift. Traditional cryptanalysis treated cipher text as a linguistic puzzle. The Poles treated it as a mathematical one. The machine cipher, they recognised, was not fundamentally a language problem – it was a problem in abstract algebra. This insight was years ahead of its time and proved decisive.

The Move to Pyry

Until 1937, the German section (BS-4) occupied cramped quarters in the Saxon Palace in Warsaw. Security concerns – particularly German Abwehr surveillance – prompted relocation to newly constructed facilities in the Kabaty Woods near Pyry, south of Warsaw. Working conditions there were “incomparably better.”

3. The Cryptanalysis

How Rejewski Cracked Enigma (1932)

The Indicator Vulnerability

German Enigma operators began each message with a six-letter indicator that encoded the three-letter message setting – typed twice for redundancy. So if the chosen message key was “ABC,” the operator would type “ABCABC” at the beginning, and the Enigma would encrypt this into six seemingly random letters, for example “DMQVJN.”

This double encipherment was the critical vulnerability. Because the first and fourth letters encrypted the same plaintext letter (both “A”), the second and fifth encrypted the same letter (both “B”), and the third and sixth encrypted the same letter (both “C”), Rejewski could construct mathematical relationships between paired positions.

Permutation Group Theory

By collecting enough indicators from a single day’s traffic, Rejewski could build permutation cycles. For example, if position 1 mapped B->T, and position 4 mapped T->E, and later E->L, and L->B, he had a cycle: B->T->E->L->B (a cycle of length 4).

Rejewski then applied a theorem from group theory: two permutations are conjugate if and only if they have the same cycle structure. Mathematics professor and Cryptologia co-editor Cipher A. Deavours later described this as “the theorem that won World War II.”

The crucial insight was that although the plugboard (Steckerbrett) changed which specific letters appeared in the cycles, it did not change the number and lengths of the cycles themselves. The cycle structure was an invariant – independent of the plugboard settings. Rejewski called this invariant the “characteristic” of the indicator setting.

The Six Equations

Rejewski formulated a system of six equations modelling the permutations at six consecutive Enigma positions. Each equation took the form:

A = S H P N P^{-1} M L R L^{-1} M^{-1} P N^{-1} P^{-1} H^{-1} S^{-1}

where S represented the plugboard, H the entry drum, P and N the rotor settings, M and L the reflector, and R the rightmost rotor. The equations had a daunting number of unknowns.

The Mathematical Elegance: Conjugation and Invariance

The depth of Rejewski’s mathematical insight deserves emphasis. In group theory, if X and Y are any two permutations, the product XYX^{-1} is called the conjugate of Y by X. A fundamental theorem states that the disjoint cycle structure of a permutation and any of its conjugates has the same shape – that is, conjugation preserves the number and lengths of cycles, even though it changes which specific elements appear in which cycles.

Rejewski realised that the Enigma’s plugboard (Steckerbrett) acted as a conjugating permutation on the rotor-produced permutation. This meant that the plugboard changed which letters appeared in the cycle groups but did not change the number and lengths of the cycles. The cycle structure was therefore an invariant – a quantity independent of the unknown and daily-changing plugboard settings. Rejewski called this invariant the “characteristic” (charakterystyka) of the indicator setting.

This was the key insight. By collecting enough message indicators from a single day’s traffic, Rejewski could determine the characteristic without knowing the plugboard settings. The characteristic then constrained the possible rotor positions to a small number of candidates. From those candidates, the rotor wiring could be deduced.

The elegance is in the abstraction: Rejewski did not try to guess individual letters or brute-force individual settings. He lifted the problem into the abstract realm of permutation group theory, where the irrelevant complexity of the plugboard fell away and the essential structure of the machine was exposed. This was mathematics at its most powerful – not computation, but insight.

The French Documents and the Role of Intelligence

Rejewski initially could not solve the system with the available data. Then, around 9–10 December 1932, French military intelligence chief Captain Gustave Bertrand provided documents obtained from a German spy – materials that included Enigma settings for September and October 1932. These reduced the unknowns enough for Rejewski to determine the rotor and reflector wirings.

The spy was Hans-Thilo Schmidt (1888–1943), codenamed “Asche” (also “Source D”) by French intelligence. Schmidt was a German civil servant working at the German Armed Forces’ Cryptographic Agency (Chiffrierabteilung). His French handler was a German-born agent named Rodolphe Lemoine, codename “Rex.” Over several years, Schmidt photographed and delivered Enigma operating procedures manuals, rotor wiring diagrams, and monthly key settings. Bertrand first offered these materials to the British, but Dilly Knox and the Government Code and Cypher School were unable to make use of them. Bertrand then shared them with the Poles, who could.

Rejewski later acknowledged: “the intelligence material furnished to us should be regarded as having been decisive to solution of the machine.” He also noted that “he could have broken the code without the French materials, but it would have taken much longer and would instead have been based on chance.”

The combination was critical: French espionage provided the data; Polish mathematics provided the method. Neither alone would have sufficed in the available time.

The Alphabetical Insight

One crucial step was Rejewski’s assumption that the military Enigma wired its entry drum in straight alphabetical order (ABCDEFG…) rather than in the keyboard order (QWERTZU…) used by the commercial Enigma. As Peter Twinn at Bletchley Park later remarked: “It was such an obvious thing to do, rather a silly thing, that nobody – not Dilly Knox, not Alan Turing – ever thought it worthwhile trying.”

When Rejewski tried the alphabetical assumption, the rotor wirings fell out immediately – “from my pencil, as by magic.”

The Result

By the end of December 1932, Rejewski had recovered the internal wiring of all three rotors and the reflector – reconstructing the machine sight-unseen. The Cipher Bureau could now build replica Enigma machines and, with methods to determine the daily key settings, read German military traffic.

By 1935, the Bureau was reading 75% of Enigma intercepts. David Kahn, the foremost historian of cryptology, wrote: “The solution was Rejewski’s own stunning achievement, one that elevates him to the pantheon of the greatest cryptanalysts of all time.”

The Cyclometer (circa 1934–1935)

Rejewski devised the cyclometer, a special-purpose device comprising two sets of Enigma rotors, to systematically catalog the cycle structures (characteristics) produced by all possible rotor positions. The resulting “card catalog” contained (6 rotor orderings) x (17576 positions) = 105456 entries. Preparation “was laborious and took over a year.”

Once the catalog was complete, recovering a day’s key required only 12–20 minutes: the cryptanalyst would determine the characteristic from intercepted indicators, look it up in the catalog, and obtain the rotor settings.

When Germany replaced the reflector on 1–2 November 1937, the entire catalog had to be recalculated from scratch.

The Bomba Kryptologiczna (October 1938)

After the Germans changed their indicator procedure on 15 September 1938 (eliminating the doubled key), the card catalog method was rendered useless. Rejewski responded by designing the bomba kryptologiczna (“cryptologic bomb”) – an electrically powered aggregate of six interconnected Enigma replicas (lacking plugboards) that automatically cycled through all 17576 possible three-rotor positions.

Six bombas were built in Warsaw by the AVA Radio Manufacturing Company before September 1939. Each machine “took the place of some one hundred workers” and could reconstruct the daily key in approximately two hours.

The bomba exploited a different vulnerability in the indicator system, requiring only unchanged individual letters (not unchanged pairs), making it functional despite 5–8 plugboard connections.

The bomba was the first electromechanical cryptanalytic machine in history. It was the direct ancestor of Alan Turing’s Bombe at Bletchley Park. As RUSI (the Royal United Services Institute) noted: “it was the Polish use of electromechanical technology that moved cryptanalysis into the industrial age.”

When the Germans introduced two additional rotors (IV and V) in December 1938, the number of possible rotor orderings increased from 6 to 60, and the bomba workload increased tenfold. This was one factor – though not the primary one – behind the decision to share the Polish secrets with Britain and France.

The Zygalski Sheets (Late 1938)

See Zygalski’s entry above for technical details. The sheets provided a backup method independent of the bomba, and crucially independent of plugboard settings. They remained usable even after the introduction of rotors IV and V, though the number of sheets required grew from 156 to 1560.

Connection to Computing History

The Polish cryptanalytic methods represent a critical – and often overlooked – link in the chain from pure mathematics to electronic computing.

The Bomba as Computing Precursor

The bomba kryptologiczna was a special-purpose electromechanical computer: it took a defined problem (find which of 17576 rotor positions produces a specific permutation pattern), automated the search through all possibilities, and returned the answer. Each bomba “took the place of some one hundred workers” – the same language later used to describe general-purpose electronic computers. The bomba was not programmable in the modern sense, but it embodied the same fundamental idea: replace human computation with machine computation to solve problems that are combinatorially infeasible for manual labour.

The British Bombe, designed by Alan Turing and improved by Gordon Welchman, was directly inspired by the Polish bomba – and its name was derived from the Polish original. But Turing designed his Bombe on a more general principle: the assumption of a “crib” (known or predicted plaintext) at a defined point in the message. This moved from the Polish approach of exploiting a specific procedural vulnerability to a more general-purpose cryptanalytic technique. Over 200 British Bombes were eventually built, each a complex electromechanical computer in its own right. They were the most important computing machines of the war, and their lineage traces directly to Rejewski’s 1938 design.

The Zygalski Sheets as Systematic Computation

The Zygalski sheets represent a different but equally important computational concept: a systematic, mechanical procedure for reducing a large search space to a single solution. The method of superimposing perforated sheets over a light source, shifting them according to a defined programme, and observing the decreasing number of visible apertures is functionally equivalent to a Boolean AND operation across multiple data sets. It is, in essence, a manual parallel filter – a physical algorithm.

The method is remarkably similar to what would later be called a “sieve” in computational number theory. The sheets were also independent of the plugboard settings, making them robust against procedural changes – a property that modern computer scientists would recognise as algorithmic generality.

From Bomba to Bombe to Colossus to ENIAC

The trajectory from Polish bomba to British Bombe to Colossus (built by Tommy Flowers in 1943 to crack the Lorenz cipher) to ENIAC forms a continuous thread in computing history. Each step moved from special-purpose to more general-purpose computation. The Polish contribution was the first step: the recognition that a cipher machine’s output could be modelled mathematically and that the mathematical model could be implemented in an electromechanical device that searched solutions faster than any human.

RUSI summarised: “It was the Polish use of electromechanical technology that moved cryptanalysis into the industrial age.” This statement applies equally to computing itself.

4. The Handover: The Pyry Conference (July 1939)

The Political Context

By mid-1939, the situation was desperate. Hitler had occupied Czechoslovakia in March. SS troops flooded Danzig. German forces massed on Poland’s borders. Britain had guaranteed to come to Poland’s aid if attacked. The head of Poland’s Signals Bureau sent a coded message on 30 June 1939: “there is a new development.”

At a previous meeting in January 1939, the Poles had been reticent about their achievements. But now, with war looming, the Polish General Staff decided to reveal everything.

The Meeting

On 25–26 July 1939 – five weeks before Germany invaded Poland – a conference was held at the Cipher Bureau’s facility in the Kabaty Woods at Pyry, south of Warsaw.

Polish delegation:

Lieutenant Colonel Gwido Langer (Cipher Bureau chief)
Major Maksymilian Ciezki (BS-4 chief)
Marian Rejewski, Jerzy Rozycki, Henryk Zygalski (civilian mathematician-cryptologists)
Colonel Stefan Mayer (chief of intelligence)

French delegation:

Major Gustave Bertrand (radio-intelligence chief)
Captain Henri Braquenie (Air Force staff)

British delegation:

Commander Alastair Denniston (head of the Government Code and Cypher School)
Alfred Dillwyn “Dilly” Knox (chief cryptanalyst)
Commander Humphrey Sandwith (Royal Navy)

What Was Revealed

The Poles revealed everything:

Their methods for breaking Enigma
The internal wiring of the rotors and reflector
The cyclometer and card catalog
The bomba kryptologiczna
The Zygalski sheets
They promised each delegation a Polish-reconstructed replica Enigma machine

Rejewski observed that Knox “grasped everything very quickly, almost quick as lightning.”

The Moment of Revelation

To the astonishment of the French and British delegations, the Poles announced almost immediately that they had broken Enigma some years earlier. The British and French had expected a technical discussion of approaches and difficulties. Instead, they were confronted with a fait accompli: the Poles had been reading German Enigma traffic since 1933.

The atmosphere was electric. Denniston’s own account of the meeting, published posthumously by Ralph Erskine in Cryptologia (2006), describes the British delegation’s shock at learning how much the Poles had achieved. The British had been working on Enigma for years with limited success; the Poles had solved it seven years earlier using methods that had never occurred to them.

Knox’s Reaction

Dilly Knox’s response was complex. He was “furious that the solution was one he had rejected” – specifically, the alphabetical wiring of the entry drum – yet he recognised the importance of the Polish achievement, which shortened the British attack on Enigma by at least a year. He was described as “chagrined – but grateful.”

Knox reportedly threw a tantrum at the meeting. His frustration was directed not at the Poles but at himself: he had considered and dismissed the possibility that the military Enigma wired its entry drum in simple alphabetical order. As Peter Twinn, Knox’s colleague at GC&CS, later said: “It was such an obvious thing to do, rather a silly thing to do, that nobody – not Dilly Knox or Tony Kendrick or Alan Turing – ever thought it worthwhile trying.”

Yet Knox grasped the implications instantly. Rejewski observed that Knox “grasped everything very quickly, almost quick as lightning.” Whatever his personal frustration, Knox immediately understood what the Polish methods meant for the British effort. He returned to Britain and threw himself into the work that would produce the first Bletchley Park breaks.

Significance

Gordon Welchman, the architect of Bletchley Park’s Hut 6 Ultra operation, later wrote:

“Hut 6 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 RUSI described the Pyry disclosure as “the most consequential intelligence-sharing arrangement of World War Two.”

How Turing Built on Polish Work

Alan Turing visited the Polish cryptologists at PC Bruno (Chateau de Vignolles, near Paris) in the first months of 1940 to confer about Enigma decryption. The British Bombe – Turing’s electromechanical device for breaking Enigma – was directly inspired by the Polish bomba, from which its name was derived.

Turing specified a machine that could break Enigma “more effectively than the Polish bomba kryptologiczna.” Gordon Welchman then added the “diagonal board,” an improvement that made the British Bombe immensely more powerful. Over 200 Bombes were eventually built.

But the foundations were Polish. As RUSI stated: “Enigma was broken at Bletchley Park because of the Polish decision in 1939 to share all they knew.”

Rejewski later wrote, with quiet understatement: “[I]t was not [as Harry Hinsley suggested, cryptological] difficulties of ours that prompted us to work with the British and French, but only the deteriorating political situation. If we had had no difficulties at all we would still, or even the more so, have shared our achievements with our allies as our contribution to the struggle against Germany.”

5. The Injustice

Wartime Mistreatment

After escaping Poland, the three mathematicians continued their work in France at PC Bruno (from October 1939) and later at Cadix, the Chateau des Fouzes near Uzes (from October 1940). Rejewski worked under the cover name “Pierre Ranaud,” a lycee professor from Nantes.

After Rozycki’s death in January 1942 and the German occupation of Vichy France in November 1942, Rejewski and Zygalski fled through southern France, crossed the Pyrenees on foot in January 1943 (their guide pulled a pistol and robbed them near the summit), were arrested in Spain, and spent three months in Spanish prisons before Polish Red Cross intervention secured their release. They reached London via Madrid, Portugal, and Gibraltar on 3 August 1943.

In Britain, the two men – who had cracked Enigma seven years before Bletchley Park existed – were inducted as privates in the Polish Armed Forces and assigned to a Polish signals unit at Stanmore Park. They were set to work cracking low-grade German SS and SD hand ciphers (the Doppelkassettenverfahren, or double Playfair system).

British cryptanalyst Alan Stripp’s verdict: “Setting them to work on the Doppelkassetten system was like using racehorses to pull wagons.”

They were never brought to Bletchley Park, apparently due to security considerations – though one suspects the British preferred not to have the original codebreakers looking over their shoulders.

Commissioned as second lieutenants in October 1943. Promoted to lieutenant in January 1945.

Decades of Silence: Why the Polish Contribution Was Hidden for 40+ Years

After the war, the Polish contribution was classified and suppressed for a convergence of reasons – British secrecy policy, Cold War politics, historiographic laziness, and the inability of the principals to speak.

Churchill’s ban (1945): In 1945, British Prime Minister Winston Churchill imposed secrecy on all Enigma-related intelligence (Ultra). The ban held for nearly three decades. At Bletchley Park itself, “very few even knew about the Polish contribution” because of the strict need-to-know principle. The British government had reason to maintain the secret: Enigma-type machines continued in use by former colonies and other nations after the war, and knowledge of Ultra’s methods remained operationally valuable to GCHQ.

The D-Notice system: The British ‘D-Notice Committee’ (which issues official ‘requests’ to the media not to publish on national security grounds) actively suppressed publication. When word reached the committee in the early 1970s that a book revealing the Ultra secret was about to be published in America, a D-Notice could not stop a US publication. The British response was to issue a controlled, authorised, and “with luck diversionary” version of the story first.

Winterbotham’s omission (1974): F.W. Winterbotham’s The Ultra Secret (1974) was the first major English-language disclosure of the Enigma story. But the book’s “most serious flaw” was “a complete elimination from the Enigma picture of what was prerequisite to its very existence: the mastering by Polish mathematicians of the German secret machine cipher.” Winterbotham attributed the original Enigma solution to information from a “Polish employee of the cipher machine factory” – a fiction that, as cryptographic historian David Kahn wrote in his 1974 New York Times review, “cheats the Poles of credit for one of the great cipher solutions of history.” At the end of the chapter, Winterbotham added a note saying that after writing the book he had learned about the contributions of “some Polish mathematicians,” but he stood by his account as it had been told to him. The book may have represented a controlled release by British authorities rather than an independent revelation.

Kozaczuk’s 1967 disclosure: The first public revelation of Poland’s role actually came in 1967, when Polish military historian Wladyslaw Kozaczuk published Bitwa o tajemnice (“Battle for Secrets”). But this was a Polish-language publication behind the Iron Curtain and attracted little international attention in the West.

Kozaczuk’s 1979 book: W kregu Enigmy (“In the Circle of Enigma”), published in Warsaw in 1979, was Kozaczuk’s comprehensive account. Its English translation by Christopher Kasparek, titled Enigma: How the German Machine Cipher Was Broken, and How It Was Read by the Allies in World War Two, did not appear until 1984 (University Publications of America).

Garlinski’s 1979 book: Jozef Garlinski published Intercept: The Enigma War (J.M. Dent & Sons, London, 1979), using first-hand documents, personal accounts, and interviews with surviving participants. This was the first detailed English-language book to tell the full story of the Polish contribution. It appeared in the same year as Kozaczuk’s Polish book – but too late for Zygalski (died August 1978) and just before Rejewski (died February 1980).

The Cold War factor: Poland’s position behind the Iron Curtain compounded the suppression. Polish scholars had limited access to Western publications and archives. Western scholars had limited access to Polish sources. Rejewski himself was silenced not only by British classification but by the practical danger of attracting the attention of Poland’s Soviet-controlled security services.

The standard narrative: For decades, the story was: “Alan Turing cracked Enigma.” The 2014 film The Imitation Game reduced the Polish contribution to a single line. Information Is Beautiful analysed the film and found it just 42.3% accurate. Poland responded by launching the exhibition “Enigma – Decipher Victory” to counter the misconceptions.

Rejewski’s Post-War Life: The Codebreaker as Accountant

Rejewski was discharged from the Polish Army on 15 November 1946. He returned to Poland on 21 November to reunite with his wife and children in Bydgoszcz. He chose not to return to his position at Poznan University (which was still open to him), unwilling to separate from his remaining family after the loss of his son Andrzej to polio.

Instead, he took a job as sales director at Kabel Polski (Polish Cable), a cable-manufacturing company in Bydgoszcz. Even in this modest role, his mathematician’s eye proved inconvenient: he discovered financial irregularities at the factory, which brought disfavour upon him rather than on the perpetrators. A man who had used abstract algebra to crack the most important cipher in history was now an unwelcome bookkeeper whose competence threatened the wrong people.

Between 1949 and 1958, Poland’s Office of Public Security repeatedly investigated Rejewski, suspecting him of membership in the Polish Armed Forces in the West. He never divulged that he had worked on Enigma. In 1950, the security services demanded he be fired from his employment. He then moved through a series of modest administrative positions: briefly director at the State Surveying Company, then the Association of Polish Surveyors. From 1951 to 1954 he worked at the Association of Timber and Varied Manufactures Cooperatives. From 1954 until his retirement on a disability pension in February 1967, he was director of the inspectorate of costs and prices at a Provincial Association of Labour Cooperatives.

The greatest cryptanalyst in Polish history spent his working life as a mid-level bureaucrat and cost inspector, harassed by secret police, unable to tell anyone what he had done. To appreciate the injustice: Rejewski’s application of permutation group theory to cryptanalysis has been called “one of the most important breakthroughs in cryptologic history.” Cipher A. Deavours, co-editor of Cryptologia, called the underlying theorem “the theorem that won World War II.” The man behind it spent two decades inspecting cooperative manufacturing costs in provincial Poland.

Breaking His Silence (1967–1980)

For two decades after returning to Poland, Rejewski remained silent about his prewar and wartime cryptological work to avoid the attention of Poland’s Soviet-dominated government. Before his retirement in early 1967, he began writing his memoirs, titled Wspomnienia z mej pracy w Biurze Szyfrow Oddzialu II Sztabu Glownego 1932–1945 (“Memoirs of My Work in the Cipher Bureau of Section II of the [Polish] General Staff”). The manuscript was purchased by Poland’s Military Historical Institute (Wojskowy Instytut Historyczny) in Warsaw.

The timing of his retirement coincided with Wladyslaw Kozaczuk’s 1967 publication of Bitwa o tajemnice (“Battle for Secrets”), the first public disclosure of Poland’s Enigma-breaking achievement. Rejewski then began publishing scholarly papers and correcting the historical record. He was interviewed by scholars, journalists, and television crews from Poland, East Germany, the United States, Britain, Sweden, Belgium, the Soviet Union, Yugoslavia, and Brazil.

On 12 August 1978, he received the Officer’s Cross of the Order of Polonia Restituta – the first formal Polish government recognition of his work, awarded when he was 72 years old.

The Final Publications

In his final years, Rejewski produced two landmark papers:

“An Application of the Theory of Permutations in Breaking the Enigma Cipher,” Applicationes Mathematicae, vol. 16, no. 4, pp. 543–559, 1980. Submitted on 13 May 1977, this was his formal mathematical treatment of the permutation theory he had used to crack Enigma in 1932. It was published the year of his death.
“How Polish Mathematicians Deciphered the Enigma,” IEEE Annals of the History of Computing, vol. 3, no. 3, pp. 213–234, July 1981. This personal account of the work at the Cipher Bureau from 1932 to 1939 was published posthumously – Rejewski died on 13 February 1980, more than a year before the paper appeared. It gives a first-person view of the successes and frustrations of the Enigma work and describes the mathematical principles, the cyclometer, and the bomba. It has been cited 29 times in academic literature and remains one of the most important primary sources on the Polish Enigma effort.

Did He Live to See Recognition?

Rejewski died of a heart attack on 13 February 1980, aged 74, while returning from shopping in Warsaw. He had received the Officer’s Cross in 1978 – a significant honour, but far short of what he deserved. The major recognitions all came after his death: the Grand Cross of the Order of Polonia Restituta (2000, posthumous), the British War Medal 1939–1945 (2005, received by his daughter), the Knowlton Award of the US Military Intelligence Corps Association (2012, posthumous), and the IEEE Milestone (2014). He saw partial recognition – but not the full reckoning. The dominant narrative during his lifetime remained “Alan Turing cracked Enigma.”

Zygalski’s Exile: The Master Cryptanalyst Teaching Undergraduates

Zygalski fared no better in recognition, though he avoided the hazards of communist Poland. After demobilisation from the Polish Signals Battalion in 1945, he chose to remain in Britain rather than return to Soviet-occupied Poland.

Teaching career: From 1947, Zygalski lectured in mathematics at the Polish University College in London, an institution established by the Polish Government-in-Exile to train displaced scientists and engineers. In 1951, he transferred to Battersea Polytechnic, where he taught mathematics and statistics. The institution was renamed Battersea College of Technology in 1957 and received a Royal Charter as the University of Surrey in September 1966. Zygalski continued teaching through all three incarnations of the institution until his stroke in 1968 forced early retirement.

The Official Secrets Act constraint: Zygalski’s wartime expertise in cryptanalysis remained classified under the Official Secrets Act, preventing him from leveraging it in academic publications or career advancement. His colleagues at Battersea Polytechnic and later the University of Surrey were entirely unaware of his pioneering role. He had signed an oath of confidentiality that prohibited discussion of his wartime work even with family, and he adhered to it lifelong, rarely speaking of his contributions. A man who had invented one of the most elegant cryptanalytic techniques in history – the perforated sheets that bore his name – spent his days teaching elementary statistics to undergraduates who had no idea who he was.

The stroke and final years: In 1968 Zygalski suffered a stroke that ended his teaching career. He lived quietly in retirement in Liss, Hampshire, in modest circumstances.

The honorary doctorate: In 1977, the Polish University in Exile (Polski Uniwersytet na Obczyznie, PUNO) awarded Zygalski an honorary doctorate for his role in breaking Enigma – the first formal academic recognition of his achievement.

The cruel timing: Zygalski died on 30 August 1978 in Liss. He was 70 years old. Kozaczuk’s comprehensive Polish-language book W kregu Enigmy (“In the Circle of Enigma”) was published in 1979 – just months after Zygalski’s death. Jozef Garlinski’s Intercept: The Enigma War (1979), the first detailed English-language account of the Polish Enigma work, also appeared after he died. Zygalski never saw the full story reach the English-speaking world. He never saw his name in a major international publication. The man who cracked Enigma died in a village in Hampshire, and almost nobody knew.

Ciezki’s Destitution

Maksymilian Ciezki – the man who had the vision to recruit mathematicians, who ran the day-to-day Enigma operation, who withstood German interrogation without breaking – died on 9 November 1951 in London, “after living the last three years on subsidies from the Assistance Board.” He died in poverty, forgotten.

Belated Recognition

The recognition came, but too late for the men themselves:

Date	Recognition
1967	Kozaczuk’s Bitwa o tajemnice first publicly discloses Polish Enigma breaking
1974	Winterbotham’s The Ultra Secret lifts the British secrecy ban, but omits Polish role
1978	Rejewski receives Officer’s Cross of the Order of Polonia Restituta
1978	Zygalski receives honorary doctorate from the Polish University in Exile
2000	Poland’s President Kwasniewski posthumously awards Grand Cross of the Order of Polonia Restituta to Rejewski and Zygalski
2005	Rejewski’s daughter receives the British War Medal 1939–1945 on his behalf
2007	Three-sided bronze monument unveiled before the Imperial Castle in Poznan
2009	Polish Post issues commemorative stamps featuring all three cryptologists
2012	Rejewski posthumously receives the Knowlton Award of the US Military Intelligence Corps Association
2014	IEEE Milestone Award for “the first breaking of Enigma ciphers by the Polish Cipher Bureau, in 1932–1939”
2021	Enigma Cipher Centre opens in Poznan, dedicated to the Polish Enigma breakers

6. Quotes and Anecdotes

Rejewski’s Own Words

On solving the rotor wiring:

“From my pencil, as by magic, began to issue numbers designating the connections in rotor N.”

On the challenge after reconstructing the machine:

“Now we had the machine, but we didn’t have the keys and we couldn’t very well require Bertrand to keep on supplying us with the keys every month… The situation had reversed itself: before, we’d had the keys but we hadn’t had the machine – we solved the machine; now we had the machine but we didn’t have the keys. We had to work out methods to find the daily keys.”

On the French intelligence material:

“The intelligence material furnished to us should be regarded as having been decisive to solution of the machine.”

On sharing secrets with the Allies:

“[I]t was not [as Harry Hinsley suggested, cryptological] difficulties of ours that prompted us to work with the British and French, but only the deteriorating political situation. If we had had no difficulties at all we would still, or even the more so, have shared our achievements with our allies as our contribution to the struggle against Germany.”

The Hans-Thilo Schmidt Story (“Asche”)

Hans-Thilo Schmidt (1888–1943) was the unlikely catalyst. A German civil servant and former military officer (forced out of active service after gas exposure in World War I), Schmidt was the younger brother of Wehrmacht general Rudolf Schmidt. His brother secured him a civilian post at the German Armed Forces’ Cipher Office.

Driven by financial need, Schmidt contacted French intelligence and offered to sell information about the new Enigma machine. Captain Gustave Bertrand of French Intelligence accepted and gave him the codename “Asche” (also “Source D”). His French handler was a German-born agent named Rodolphe Lemoine, codename “Rex.”

Over several years, Schmidt photographed and delivered highly classified documents including Enigma operating manuals, wiring diagrams, and monthly key settings. In December 1932, Bertrand shared these materials with the Polish Cipher Bureau. The key-settings lists helped fill in enough unknowns in Rejewski’s equations to enable the breakthrough.

The French had previously offered the same materials to the British, but Dilly Knox and the Government Code and Cypher School had been unable to make use of them.

Schmidt’s fate was grim. After France fell, his handler Lemoine was arrested by the Gestapo and betrayed Schmidt. Schmidt was arrested on 1 April 1943. In September 1943, his daughter identified his body; evidence suggests he committed suicide rather than face execution.

Knox’s Fury and Gratitude

At Pyry, when the Poles revealed that the Enigma’s entry drum was wired in simple alphabetical order, Knox was “furious that the solution was one he had rejected” – he had considered and dismissed this possibility. Yet he immediately grasped the implications. He was “chagrined – but grateful.”

Rejewski’s observation of Knox at the meeting: “Knox grasped everything very quickly, almost quick as lightning.”

Racehorses Pulling Wagons

When Rejewski and Zygalski finally reached Britain in August 1943, after their harrowing escape through France, Spain, and Portugal, the British assigned them to crack low-grade German hand ciphers at a Polish Army unit. They were never brought to Bletchley Park. Alan Stripp commented: “Setting them to work on the Doppelkassetten system was like using racehorses to pull wagons.”

The Guide Who Robbed Them

On 29 January 1943, Rejewski and Zygalski, accompanied by a guide, climbed the Pyrenees toward Spain to escape German-occupied France. Near midnight, at high altitude, the guide pulled a pistol and robbed them. The two mathematicians who had cracked the most important cipher of the twentieth century were left in the freezing mountains, stripped of their valuables, with nothing but their knowledge.

7. Comparison with Beurling

The Polish codebreakers and Arne Beurling represent parallel stories of extraordinary mathematical achievement from small countries, overshadowed by the larger Anglo-American narrative of World War II cryptanalysis.

	Polish Trio	Arne Beurling
Country	Poland (occupied)	Sweden (neutral)
Target cipher	Enigma (3-rotor electromechanical)	Geheimschreiber / T52 (10-wheel teleprinter cipher)
Date of breakthrough	December 1932	Summer 1940
Method	Permutation group theory, systematic mathematical analysis	Intuitive-mathematical hypothesis testing (“A magician does not reveal his secrets”)
Team vs. individual	Three mathematicians (Rejewski primary)	Single individual
Tools	Pen and paper initially; later cyclometer, bomba, Zygalski sheets	Pen and paper only
Time to crack	Weeks (for initial rotor wiring recovery)	Two weeks
Captured machine?	No – reconstructed from mathematical analysis and documents	No – reconstructed from intercepted traffic only
Complexity	Enigma: ~158962555217826360000 settings (with plugboard)	T52: ~893622318929520960 cipher variations (10 wheels)
Strategic impact	Enabled Ultra intelligence – possibly shortened the war by two years	Advance knowledge of Operation Barbarossa; maintained Swedish neutrality
Post-war recognition	Suppressed for decades; Rejewski worked as accountant	Classified; Beurling moved to Princeton, took Einstein’s office
When recognised	1967 (Kozaczuk); 1974 (Ultra secret lifted); 2000s (honours)	2002 (Beckman’s book Codebreakers)
Famous quote	“From my pencil, as by magic, began to issue numbers…”	“A magician does not reveal his secrets.”

Key Parallels

Mathematical genius applied to cipher machines. Both Rejewski and Beurling understood that machine ciphers were fundamentally mathematical problems, not linguistic ones. Both used abstract mathematical reasoning – group theory in Rejewski’s case, a combination of linguistic-mathematical hypothesis testing in Beurling’s – to crack machines they had never seen.
Small countries punching above their weight. Poland and Sweden, both facing the existential threat of Nazi Germany (one invaded, one precariously neutral), produced cryptanalytic achievements that rivalled or exceeded those of the great powers. The transition to “searching for cryptanalytical talents among mathematics graduates probably started in Poland” (Beckman).
No captured machines. Both worked without access to the physical cipher device. Rejewski reconstructed the Enigma from mathematical analysis plus French-supplied documents. Beurling reconstructed the Geheimschreiber from intercepted teleprinter tapes alone – arguably the more extraordinary feat, though Rejewski’s systematic mathematical framework was more rigorous and replicable.
Overshadowed by larger narratives. The dominant story of wartime cryptanalysis centres on Bletchley Park, Alan Turing, and (to a lesser extent) the American effort. The Polish contribution was actively suppressed; the Swedish contribution was simply unknown. Both stories were casualties of Cold War secrecy and Anglo-American historiographic dominance.
Personal cost. Rejewski returned to communist Poland and spent decades as a cost inspector, harassed by secret police. Beurling left for Princeton and occupied Einstein’s office. Zygalski taught statistics in Surrey under the Official Secrets Act. Ciezki died in poverty in London. Rozycki died at sea at 32. The human costs were distributed unevenly, but all paid a price for work they could not discuss.

Timeline Comparison

1932: Rejewski cracks Enigma in Warsaw
1938: Rejewski builds the bomba; Zygalski designs perforated sheets
July 1939: Poles share everything with Britain and France at Pyry
September 1939: Germany invades Poland; Cipher Bureau evacuates
Summer 1940: Beurling cracks the Geheimschreiber in two weeks at FRA
1940–1943: FRA reads German traffic through Sweden; Bletchley Park reads Enigma traffic
1942: Rozycki dies at sea; Turing’s improved Bombe operational
1943: Rejewski and Zygalski reach Britain; assigned to low-grade ciphers
1945: War ends; Ultra classified; Beurling’s work classified
1954: Beurling joins Institute for Advanced Study, Princeton
1967: Kozaczuk first discloses Polish Enigma role publicly
1974: Winterbotham’s The Ultra Secret lifts secrecy (but omits Poles)
1978: Zygalski dies in Liss, Hampshire, just before full story breaks in English
1979: Kozaczuk’s W kregu Enigmy and Garlinski’s Intercept published
1980: Rejewski dies; his mathematical paper published posthumously
1981: Rejewski’s IEEE Annals paper published posthumously
2002: Beckman’s Codebreakers tells Beurling’s story

Connection to the Blog Series: NWP, Computing, and Cryptanalysis

This post fits the blog series arc as a pivot from the ENIAC/IAS computing story into the parallel world of wartime cryptanalysis. The connections are structural:

1. Mathematics as weapon. The blog series traces how mathematics moved from theory to applied computation – from Richardson’s dream of numerical weather prediction, through the ENIAC and IAS machine, to operational NWP. The Polish codebreakers represent the same transition in a different domain: abstract algebra (permutation group theory) applied to a concrete, urgent problem. Both stories are about mathematicians whose theoretical tools proved unexpectedly decisive in the real world.

2. The bomba-to-Bombe-to-Colossus-to-ENIAC trajectory. The computing history arc of the blog passes through the IAS machine and von Neumann. But the wartime computing arc that made the IAS machine possible runs through Bletchley Park: Turing’s Bombe, Flowers’ Colossus, and the intellectual milieu that produced the first electronic computers. The Polish bomba is the first link in that chain. Without the Polish handoff at Pyry, the British Bombe would have been delayed by “at least a year” (multiple sources), and the entire trajectory of wartime computing shifts.

3. The Beurling parallel (Post 11). The Beurling/Geheimschreiber story is the Swedish mirror of the Polish/Enigma story. Both involve a small neutral/occupied country’s mathematician(s) cracking a major German cipher machine without possessing the physical device. Both achievements were suppressed for decades. Both men paid personal costs for work they could not discuss. The structural parallel is exact:

Beurling cracked T-52 in two weeks using intuitive-mathematical hypothesis testing
Rejewski cracked Enigma using formal permutation group theory
Both reconstructed the machine’s internal wiring sight-unseen
Both stories were overshadowed by the Anglo-American narrative
Both were recognised only decades later (Beurling in 2002, Rejewski partially in 1967/1974, fully posthumously)

4. The personal angle. The blog author is Polish. This is the most personal post in the series. The injustice of Rejewski’s post-war life – a Fields-Medal-calibre mathematician doing cost accounting in provincial Poland while being investigated by the secret police – resonates with the series’ recurring theme of genius constrained by politics and circumstance (Richardson’s pacifism, Charney’s Cold War funding, Beurling’s secrecy).

5. The suppression theme. Every post in the series touches on how history gets written. The Polish Enigma story is the most egregious case: an achievement that changed the course of the war was actively erased from the historical record for political and institutional reasons. The blog’s NWP history thread deals with the same dynamic in miniature – the marginalisation of Richardson’s 1922 experiment, the amnesia about European contributions to computing.

8. The Poznan Monument and the Enigma Cipher Centre

The Monument (2007)

In 2007, on the 75th anniversary of the first decryption of Enigma, a three-sided bronze monument was unveiled before the Imperial Castle in Poznan. Designed by artists Grazyna Bielska-Kozakiewicz and Mariusz Krzysztof Kozakiewicz and initiated by the Poznan Society of Friends of Science, the stele is a triangular prism, 1.20 metres wide and 3.10 metres tall on each face. The surfaces are inscribed with seemingly random sequences of numbers – reminiscent of the cipher output of the Enigma machine. Among these numbers, the names MARIAN REJEWSKI, JERZY ROZYCKI, and HENRYK ZYGALSKI stand out in bold.

The Enigma Cipher Centre (2021)

The Enigma Cipher Centre (Centrum Szyfrow Enigma) opened on 25 September 2021 in the former Collegium Martineum building in Poznan. A joint venture of the city of Poznan and Adam Mickiewicz University, the interactive multimedia centre tells the story of the Polish codebreakers through historical objects – including an original Enigma machine – and interactive exhibits. The exhibition covers the history of cryptography from antiquity to the present day, showing how the Polish cryptologists’ work contributed to the digital revolution.

Sources

Primary and Scholarly Sources

Marian Rejewski, “An Application of the Theory of Permutations in Breaking the Enigma Cipher,” Applicationes Mathematicae 16, no. 4 (1980): 543–559. Submitted 13 May 1977; published the year of Rejewski’s death. https://cryptocellar.org/enigma/files/rew80.pdf Accessed: 2026-04-03
Marian Rejewski, “How Polish Mathematicians Deciphered the Enigma,” IEEE Annals of the History of Computing 3, no. 3 (July 1981): 213–234. Published posthumously. https://ieeexplore.ieee.org/document/4640685/ Accessed: 2026-04-08
Ralph Erskine, “The Poles Reveal their Secrets: Alastair Denniston’s Account of the July 1939 Meeting at Pyry,” Cryptologia 30, no. 4 (2006). https://www.tandfonline.com/doi/abs/10.1080/01611190600920944 Accessed: 2026-04-03
“The Theorem That Won the War,” Convergence, Mathematical Association of America. https://old.maa.org/press/periodicals/convergence/the-theorem-that-won-the-war Accessed: 2026-04-03
“Marian Rejewski and the First Break into Enigma,” AMS Feature Column. https://www.ams.org/publicoutreach/feature-column/fcarc-enigma Accessed: 2026-04-08
“Resurrecting Bomba Kryptologiczna: Archaeology of Algorithmic Artefacts, I,” Cryptologia 33, no. 2 (2009). https://www.tandfonline.com/doi/full/10.1080/01611190802562809 Accessed: 2026-04-08

Encyclopaedic Sources

“Marian Rejewski,” Wikipedia. https://en.wikipedia.org/wiki/Marian_Rejewski Accessed: 2026-04-03
“Jerzy Rozycki,” Wikipedia. https://en.wikipedia.org/wiki/Jerzy_R%C3%B3%C5%BCycki Accessed: 2026-04-03
“Henryk Zygalski,” Wikipedia. https://en.wikipedia.org/wiki/Henryk_Zygalski Accessed: 2026-04-03
“Cipher Bureau (Poland),” Wikipedia. https://en.wikipedia.org/wiki/Cipher_Bureau_(Poland) Accessed: 2026-04-03
“Bomba (cryptography),” Wikipedia. https://en.wikipedia.org/wiki/Bomba_(cryptography) Accessed: 2026-04-03
“Bombe,” Wikipedia. https://en.wikipedia.org/wiki/Bombe Accessed: 2026-04-03
“Zygalski sheets,” Wikipedia. https://en.wikipedia.org/wiki/Zygalski_sheets Accessed: 2026-04-03
“Cyclometer,” Wikipedia. https://en.wikipedia.org/wiki/Cyclometer Accessed: 2026-04-03
“Cryptanalysis of the Enigma,” Wikipedia. https://en.wikipedia.org/wiki/Cryptanalysis_of_the_Enigma Accessed: 2026-04-03
“Hans-Thilo Schmidt,” Wikipedia. https://en.wikipedia.org/wiki/Hans-Thilo_Schmidt Accessed: 2026-04-03
“Maksymilian Ciezki,” Wikipedia. https://en.wikipedia.org/wiki/Maksymilian_Ci%C4%99%C5%BCki Accessed: 2026-04-03
“Gwido Langer,” Wikipedia. https://en.wikipedia.org/wiki/Gwido_Langer Accessed: 2026-04-03
“Dilly Knox,” Wikipedia. https://en.wikipedia.org/wiki/Dilly_Knox Accessed: 2026-04-03
“Marian Rejewski,” Britannica. https://www.britannica.com/biography/Marian-Rejewski Accessed: 2026-04-03
“Bombe,” Britannica. https://www.britannica.com/topic/Bombe Accessed: 2026-04-03

Biographical and Historical Sources

“Marian Rejewski (1905–1980),” MacTutor History of Mathematics. https://mathshistory.st-andrews.ac.uk/Biographies/Rejewski/ Accessed: 2026-04-03
“Henryk Zygalski (1908–1978),” MacTutor History of Mathematics. https://mathshistory.st-andrews.ac.uk/Biographies/Zygalski/ Accessed: 2026-04-03
“Rejewski,” Polish Contributions to Computing. https://polishcomputing.org/contributions/rejewski/ Accessed: 2026-04-03

Institutional Sources

“First Breaking of Enigma Code by the Team of Polish Cipher Bureau, 1932–1939,” IEEE Engineering and Technology History Wiki (Milestone). https://ethw.org/Milestones:First_Breaking_of_Enigma_Code_by_the_Team_of_Polish_Cipher_Bureau,_1932-1939 Accessed: 2026-04-03
“The History Column: The Polish Cryptographers Marian Rejewski, Jerzy Rozycki and Henryk Zygalski,” IEEE AESS. https://ieee-aess.org/post/blog/history-column-polish-cryptographers-marian-rejewski-jerzy-rozycki-and-henryk-zygalski Accessed: 2026-04-03
“Poland’s Decisive Role in Cracking Enigma and Transforming the UK’s SIGINT Operations,” RUSI. https://www.rusi.org/explore-our-research/publications/commentary/polands-decisive-role-cracking-enigma-and-transforming-uks-sigint-operations Accessed: 2026-04-03
“What’s the context? Polish cryptologists reveal they have cracked the Enigma code, 26 July 1939,” UK Government History Blog. https://history.blog.gov.uk/2019/07/26/whats-the-context-polish-cryptologists-reveal-they-have-cracked-the-enigma-code-26-july-1939/ Accessed: 2026-04-03

Museum and Memorial Sources

Enigma Cipher Centre, Poznan. https://csenigma.pl/en/ Accessed: 2026-04-03
“Centre dedicated to Polish Enigma codebreakers opens,” Notes From Poland, 21 September 2021. https://notesfrompoland.com/2021/09/21/centre-dedicated-to-polish-enigma-codebreakers-opens/ Accessed: 2026-04-03
“Enigma cryptologist monument in Poznan.” https://www.mycityhunt.com/cities/poznan-pl-10306/poi/enigma-cryptologist-monument-in-poznan-64923 Accessed: 2026-04-03

Journalistic and Popular Sources

“Cracking Enigma: The Polish Connection,” JSTOR Daily. https://daily.jstor.org/polish-codebreakers/ Accessed: 2026-04-03
“The Polish cryptographers who cracked the Enigma code,” Sky History. https://www.history.co.uk/articles/the-polish-cryptographers-who-cracked-the-enigma-code Accessed: 2026-04-03
“Marian Rejewski – Meet the Polish Cryptographer Who Cracked Germany’s Top-Secret Enigma Code Seven Years Before WW2,” MilitaryHistoryNow.com. https://militaryhistorynow.com/2018/10/04/marian-rejewski-meet-the-polish-cryptographer-who-cracked-germanys-top-secret-enigma-code-seven-years-before-ww2/ Accessed: 2026-04-03
“Polish mathematicians were the first to decipher the German Enigma Machine,” Katrina Shawver. https://katrinashawver.com/polish-mathematicians-german-enigma-machine/ Accessed: 2026-04-03
“80 years ago Polish intelligence handed over the Enigma code to French and British allies,” Science in Poland. https://scienceinpoland.pl/en/news/news,78071,80-years-ago-polish-intelligence-handed-over-enigma-code-french-and-british-allies Accessed: 2026-04-03
“Forgotten Pioneers: How Polish Codebreakers Cracked Enigma Before Turing,” Polish Sue. https://polishsue.com/2025/06/24/forgotten-pioneers-how-polish-codebreakers-cracked-enigma-before-turing/ Accessed: 2026-04-03
“Rare Interviews with Enigma Cryptanalyst Marian Rejewski,” Schneier on Security. https://www.schneier.com/blog/archives/2024/05/rare-interviews-with-enigma-cryptanalyst-marian-rejewski.html Accessed: 2026-04-03

Museum and Exhibition Sources

“Zygalski sheets: Polish codebreaking and the role of reconstruction in the Top Secret exhibition at the Science Museum,” Science Museum Group Journal. https://journal.sciencemuseum.ac.uk/article/zygalski-sheets-polish-codebreaking-and-the-role-of-reconstruction-in-the-top-secret-exhibition-at-the-science-museum/ Accessed: 2026-04-03

Books (Referenced but not directly consulted online)

Wladyslaw Kozaczuk, Bitwa o tajemnice (“Battle for Secrets”), Warsaw, 1967. First public disclosure of Polish Enigma breaking.
Wladyslaw Kozaczuk, W kregu Enigmy (“In the Circle of Enigma”), Warsaw, 1979. Comprehensive Polish-language account.
Wladyslaw Kozaczuk, Enigma: How the German Machine Cipher Was Broken, and How It Was Read by the Allies in World War Two (translated and edited by Christopher Kasparek), University Publications of America, 1984. English translation of the 1979 book.
Jozef Garlinski, Intercept: The Enigma War, J.M. Dent & Sons, London, 1979. First detailed English-language account using first-hand documents and interviews.
F.W. Winterbotham, The Ultra Secret, Weidenfeld & Nicolson, 1974. First major English-language Ultra disclosure; omits Polish contribution.
David Kahn, Seizing the Enigma: The Race to Break the German U-Boat Codes, 1939–1943, Houghton Mifflin, 1991.
Gordon Welchman, The Hut Six Story: Breaking the Enigma Codes, McGraw-Hill, 1982.
Dermot Turing, X, Y & Z: The Real Story of How Enigma Was Broken, The History Press, 2018.
Bengt Beckman, Codebreakers: Arne Beurling and the Swedish Crypto Program During World War II, AMS, 2002.

Additional Sources (Consulted 2026-04-08)

“SS Lamoriciere,” Wikipedia. https://en.wikipedia.org/wiki/SS_Lamorici%C3%A8re Accessed: 2026-04-08
“Jerzy Rozycki – the man who broke Enigma and died in mysterious circumstances,” Polish Sue. https://polishsue.com/2025/07/24/jerzy-rozycki-the-man-who-broke-enigma-and-died-in-mysterious-circumstances/ Accessed: 2026-04-08
“Henryk Zygalski celebrated in Chichester,” Dermot Turing. https://dermotturing.com/2018/09/13/henryk-zygalski-celebrated-in-chichester/ Accessed: 2026-04-08
“Henryk Zygalski in comparison with Polish emigration in post-war Great Britain,” Enigma Cipher Centre. https://csenigma.pl/en/enigma/henryk-zyglaski-in-comparison-with-polish-emigration-in-post-war-great-britain/ Accessed: 2026-04-08
“The Pyry Forest Meeting,” GCHQ. https://www.gchq.gov.uk/information/the-pyry-forest-meeting Accessed: 2026-04-08
“Henryk Zygalski: The Code Breaker who helped win the war,” Petersfield Museum. https://www.petersfieldmuseum.co.uk/explore/wartime/people_of_the_second_world_war/henryk_zygalski Accessed: 2026-04-08
“Gustave Bertrand,” Wikipedia. https://en.wikipedia.org/wiki/Gustave_Bertrand Accessed: 2026-04-08
“F. W. Winterbotham,” Wikipedia. https://en.wikipedia.org/wiki/F._W._Winterbotham Accessed: 2026-04-08
“Dilly Knox,” Wikipedia. https://en.wikipedia.org/wiki/Dilly_Knox Accessed: 2026-04-08
David Kahn, review of The Ultra Secret, New York Times, 1974 (referenced in secondary sources). Accessed: 2026-04-08

Michał Brennek