William Friedman (1891-1969) was a United States Army cryptographer whose singular contribution was to run the research division of the Army’s Signal Intelligence Service (SIS) in the 1930s and who broke Japan’s PURPLE cipher, thus disclosing Japanese diplomatic secrets and significantly advancing America’s military victory in World War II.
Friedman was born as “Wolf Friedman” in Kishinev, then part of the Bessarabia Governorate of the Russian Empire (today Chișinău, Moldova) to his father, Frederic, a Romanian Jew from Bucharest who worked as a translator and linguist for the Tsarist postal service, and his mother, Rosa, the daughter of a wine-merchant family from Kishinev. As we shall see, his birthplace and family background place him firmly within the Jewish communities of Bessarabia under the Russian Empire, an environment that, at the time of his birth, was subject to severe antisemitic restrictions and violence.
Barely a year after William’s birth, the Friedman family decided to emigrate to the United States, part of the larger wave of Jewish migration fleeing the deteriorating conditions and rising anti-Jewish persecution, and they settled in Pittsburgh, Pennsylvania, arriving around 1892 (some sources suggest 1893). After his father became an American citizen a few years later, “Wolf” was formally renamed “William,” an Americanization that signaled the family’s transition to their new country. Although the family arrived in America under difficult economic circumstances – according to one account, his father eked out a living by selling sewing machines door-to-door – young William embraced education, matriculating at Cornell University and graduating in 1914 with a B.S. in genetics. While this academic training in biology, rather than in languages or mathematics, did not immediately suggest the distinguished cryptological career that would follow, it was at the threshold of that career that his life took the turn which history would remember.
Shortly after completing his studies, Friedman was hired by Riverbank Laboratories, a private think tank outside Chicago established by businessman-patron George Fabyan, where he worked initially in genetics and managed experiments such as how moonlight influenced crop growth. However, he soon became drawn to what then seemed a curious side interest, codes and ciphers, which was inspired in part by literary fascination, particularly by Edgar Allan Poe’s famous The Gold-Bug.
At Riverbank, William met Elizebeth Smith, then working in cryptanalytic research; they married in May 1917 and, over the following years, their lives became professionally and inextricably intertwined, as together they would lay much of the groundwork for what became modern American cryptology.
When the United States entered World War I, the Army lacked an official cryptographic service, and Riverbank’s Department of Codes and Ciphers, where the Friedmans worked, became the de facto center for American codebreaking. Friedman conducted three six-week courses in cryptanalysis for U.S. Army officers before receiving a commission to serve with General John J. Pershing in France, where he worked on decoding German codebooks and demonstrated an uncanny ability to apply analytical rigor and adapt to the demands of wartime intelligence. Back at Riverbank after the war, he completed what became a landmark in cryptologic science, his monograph The Index of Coincidence and Its Applications in Cryptography (1922), which remains widely regarded as the most important single publication in cryptology to that time and marked the emergence of cryptanalysis as a quantitative and systematic discipline.
Created during World War I, the “Black Chamber” (formally MI-8) was the first peacetime U.S. codebreaking agency. Operating from a New York City office disguised as a commercial cable company, it intercepted and solved foreign diplomatic communications, most famously cracking Japanese codes that shaped U.S. negotiating strategy at the 1921-22 Washington Naval Conference. Although influential, the Chamber’s work was controversial, and Secretary of State Henry Stimson abruptly shut it down in 1929, declaring that “gentlemen do not read each other’s mail.”
In 1921, the War Department had hired Friedman as a civilian cryptographer, the start of a protracted career that would span more than three decades in official U.S. service. As cryptanalysis became increasingly central to international diplomacy and security, his role evolved; with the closure of the “Black Chamber,” its functions and archives were quietly transferred to the Army; and, in 1930, the newly formed Signals Intelligence Service (SIS) was placed under Friedman’s leadership.
Friedman’s crucial contributions in World War II must be understood in the context of his previous decades of cryptologic experience. By 1930, after the closure of the Black Chamber, the U.S. Army re-organized codebreaking efforts under the newly formed Signal Intelligence Service (SIS) and appointed Friedman as its first head. Under his direction, SIS became the institutional home of U.S. Army cryptanalysis, fostering a cadre of cryptanalysts, training mathematicians and linguists, and shifting cryptanalysis from sporadic wartime work to systematic, peacetime preparation.
In the mid-1930s, Japan’s Foreign Office was using an older rotor-based cipher machine, which U.S. cryptanalysts codenamed “RED.” Under Friedman’s leadership, SIS had succeeded in breaking RED, but in 1939, the Japanese replaced it with a far more advanced system, which American cryptanalysts dubbed “PURPLE.” This new electromechanical machine (officially the “Type B Cipher Machine”) used stepping-switches (similar to those in automatic telephone exchanges) rather than rotors and it scrambled plaintext into ciphertext via a complex system of substitution tables and switch-based scrambling.
This transition from RED to PURPLE raised an immediate alarm in Washington because the shift risked cutting off a vital source of information. According to accounts preserved by the George C. Marshall Foundation, which now holds much of Friedman’s papers, the Army’s Chief Signal Officer, Joseph Mauborgne, summoned Friedman and charged him personally with leading the renewal of efforts to break the new cipher.
At the outset, Friedman and his team lacked many of the tools typical for cryptanalysis. For one thing, they did not have access to an actual PURPLE machine or to internal hardware or wiring plans; rather, all they had were intercepts, encrypted diplomatic messages exchanged globally between Tokyo and its embassies. According to Elizabeth’s later recollection, when the team first began working on the new cipher, they didn’t even know that it had been created by a machine.
What made the task more tractable, though still incredibly difficult, was that the initial switch from RED to PURPLE had been gradual, which meant that, for a time, the United States had both old-system (RED) messages and new-system (PURPLE) messages, giving cryptanalysts “cribs,” plaintext/ciphertext correspondences that allowed them to compare patterns across encryption systems. This slow rollout provided rare cross-system parallels that vastly aided analysis.
Beginning in mid-to-late 1938 and, over the next roughly eighteen 18 months, Friedman and his team engaged in intensive, round-the-clock cryptanalytic work, collecting intercepted messages, cataloguing them, and searching for statistical irregularities, repeated patterns, anomalies and clues. In a September 20, 1940 breakthrough, he discovered repeating sequences in the ciphertext messages, a “first glimmer of light” after many months of darkness, as he later recalled. Once those repeating sequences (also called “repeating keys/indicators”) were identified, the team leveraged them to reverse-engineer how the machine must be working and they deduced a plausible wiring and switch architecture that could reproduce the same ciphertext transformations as the Japanese machine. (Incredibly, Friedman accomplished this without ever physically seeing a PURPLE machine.) After verifying and refining their design using sample ciphertexts, he proceeded to build a functional analog, a replica cipher machine using roughly $700 worth of commercial parts, and, by late September 1940, that reconstruction produced its first successful decryptions of Japanese diplomatic messages.
Upon decoding the Japanese diplomatic traffic, the Friedman-led SIS delivered the plaintext to the U.S. War Department and later, during the war, to relevant military and civilian leadership. These decrypted Japanese diplomatic messages, with their insight into Japanese intentions, alliances, diplomatic negotiations, and strategic planning, were classified under the codename “MAGIC” and, from then through much of WWII, these intercepts provided the U.S. with an unprecedented intelligence advantage.
Because Japanese diplomats regularly communicated with embassies around the world, including in Berlin and other Axis capitals, MAGIC decrypts often contained reports about Japanese observations of Axis strategy, German-Japanese cooperation, diplomatic negotiations, and global political developments. That meant U.S. intelligence could read not only Japanese diplomatic planning, but potentially get a window into the Axis coordination as well.
The importance of PURPLE/MAGIC decrypts cannot be overstated, as the ability to anticipate Japanese diplomatic moves provided strategic forewarning. For example, intelligence gleaned from PURPLE intercepts was cited among the critical factors that helped the Allied forces win crucial engagements in the Pacific, including the Battle of Midway, and in operations against Japanese and Axis diplomatic and intelligence networks.
However, it is also important to highlight what PURPLE did not provide. While Japanese diplomatic traffic included high-level communications, such as negotiations, declarations, and embassy-level intelligence, it generally did not carry direct Japanese naval or military operational orders, such as fleet movements, battle plans, carrier strike orders, etc. As a result, for example, while PURPLE decrypts often showed when Tokyo severed diplomatic relations or sent final demands – as indeed happened in the lead-up to the attack on Pearl Harbor in December 1941 – they did not deliver the actual military orders directing the attack. As such, while MAGIC/PURPLE gave the United States important diplomatic and strategic intelligence, it did not foresee the “when” and “where” of many military actions.
The scale, intensity, and psychological toll of the PURPLE-breaking effort were profound and, according to post-war accounts, Friedman endured extraordinarily long hours, often working late into the night over many months. One source indicates that the strain contributed to what contemporaries described as a nervous breakdown, after which he was honorably discharged from his commissioned reserve (1941), though he continued to serve as a civilian cryptologic expert.
Even after his breakdown, his influence remained. During the war years and after, Friedman played a critical role in organizing, guiding, and supervising cryptanalytic and cryptographic development. Notably, he is credited with influencing the joint Army-Navy adoption of a secure cipher machine designed under his conceptual guidance, known as SIGABA, a machine whose encryption, by many accounts, remained unbroken through WWII and beyond. Taken collectively, his wartime accomplishments helped to lay the groundwork for modern American signals intelligence and cryptographic security.
In this very rare February 2, 1949 correspondence to lawyer Ashley C. Cole, in which he evidences the extreme modesty that marked his life, Friedman writes:
No doubt you have felt that either your letter of 15 October had gone astray or that the recipient is a stuffed shirt. Neither of these contingencies is true.
The fact of the matter is that your letter arrived at a time when I was quite ill and was concentrating what energy I had on the matter of getting better. Now I am better and hence this letter of apology for the delay.
Before acceding to your request, which I would be pleased to grant, I would like to know the basis on which you reached the conclusion that I am one of those “persons who are distinguished in the Second World War.” Upon receipt of this information I will be glad to send you a letter which I hope will be worthy of addition to your notable collection.
Cole (1876-1965) was a prominent early-to-mid 20th‑century New York lawyer, corporate counsel, public‑service official, and horse‑racing commissioner. He served as legal counsel for the Union Carbide and Carbon Corporation (1916); as a delegate to the New York State Constitutional Convention (1933); and as a member of the New York State World’s Fair Commission (1936 – 1941). He also served as Chair of the New York State Racing Commission (1945 – 1965) and was commemorated by the naming of the Ashley T. Cole Handicap, a thoroughbred horse race run annually at Belmont Park. He was also known as a serious collector, to which Friedman refers at the end of our letter; the New York Public Library notes that he “assembled one of the most impressive collections of [military and other] autographs . . . at the time.”
Following the war, as U.S. intelligence was reorganized, Friedman continued to serve in senior positions. When the Armed Forces Security Agency (AFSA) replaced SIS in 1949, he became head of its cryptographic division and, later, with the founding of the National Security Agency (NSA) in 1952, he became its chief cryptologist. During this period he authored a series of definitive textbooks, known collectively as Military Cryptanalysis (Parts I–IV), which became foundational reference works for generations of American cryptanalysts. Beyond these textual works, his influence extended to institution-building as, under his leadership, cryptology in the United States was transformed from an ad-hoc wartime craft into a structured, professional, and bureaucratically embedded discipline, a legacy that continues to this day.
After a long career, Friedman retired in 1955 but, even in retirement, he and Elizebeth planned ahead. Aware that much of their work was classified and that others in the government feared that it would never again see the light of day, they decided to donate their private library and papers to the George C. Marshall Foundation. This archive, now known as the “Friedman Collection,” is one of the most complete collections of cryptologic historical materials in the world, comprising books, correspondence, technical documents, manuscripts, photographs, and artifacts. In April 2015, more than 7,600 documents (over 52,000 pages) from this collection were declassified and made publicly accessible through NSA and the Marshall Foundation, significantly enriching what scholars now know about Friedman’s work, contributions, and influence.
One of the more interesting projects undertaken by William and Elizebeth after their retirement was The Shakespearean Ciphers Examined (1957), a meticulous, often witty demolition of the long-running belief that hidden codes in Shakespeare’s plays prove that he did not write them. For decades, “cipher hunters” had claimed that numerical patterns, acrostics, or secret messages embedded in the texts pointed instead to Francis Bacon, the Earl of Oxford, or other supposed authors. The Friedmans, two of the most accomplished cryptologists of the twentieth century, approached these theories with the same rigor they brought to breaking wartime military codes, and their essential conclusion was simple and devastating: none of the alleged ciphers were real. What enthusiasts mistook for sophisticated cryptography were either coincidences, misreadings, or methods so subjective that anyone could force them to say anything. The Friedmans showed that genuine ciphers follow strict, reproducible rules, whereas the claimed “Shakespeare codes” relied entirely on arbitrary choices by their discoverers.
The book’s tone is accessible, sometimes playful, and aimed at showing a general reader why true codebreaking is a disciplined science rather than a creative game. The Friedmans patiently reconstruct the reasoning of cipher theorists, demonstrate its flaws, and then compare it to how actual ciphers work, and they also devise clever “counter-examples” proving that with the same loose methods one could “discover” messages crediting Shakespeare’s works to anyone, from Queen Elizabeth to the Friedmans themselves. The result is both an introduction to cryptologic thinking and a sustained argument that extraordinary claims require rigorous, testable evidence.
The durability of such claims echoes in later controversies, most famously the contemporary enthusiasm for “Bible Codes.” Proponents of that idea argue that equidistant letter sequences hidden in the Hebrew Bible reveal prophecies, historical events, or theological secrets. To professional cryptologists, however, the methods used in Bible-code hunting suffer from the same flaws the Friedmans exposed in the Shakespeare case: enormous freedom in choosing the starting point, the interval, and the direction, all of which allow the searcher to extract almost any desired message. In genuine cryptography, by contrast, the rules are fixed and reproducible; change them and the cipher collapses. Although the Friedmans did not write directly about Bible Codes, their principles make their verdict easy to predict: they would almost certainly have regarded Bible-code research as another example of pattern-seeking unconstrained by disciplined method, a psychological phenomenon rather than a cryptologic one, and a reminder that if you give yourself enough leeway, even sacred scripture can be made to “say” anything at all.
Throughout his life, Friedman’s reputation among peers and successors was titanic, and was widely regarded as the “Dean of American Cryptology,” a title that reflected not just his technical genius, but his role in conceptualizing and institutionalizing cryptanalysis in the United States. After his death in 1969, the NSA renamed one of its buildings in his and his wife’s honor, and the Friedman Collection remains a vital resource for historians.
Friedman’s career and legacy are well-established and broadly recognized, but what remains much more delicate – and, in fact, elusive – is with respect to any documented trace of a religious or communal Jewish life extending into his adulthood. His marriage to Elizabeth Smith is sometimes cited as having been officiated by a rabbi; for example, a history of the Riverbank cryptography program notes that William and Elizabeth, were “married by a rabbi in Chicago.” However, no public source names the officiating rabbi, the synagogue (if any), or confirms whether the ceremony included standard Jewish matrimonial rites such as ketubah, chuppah, witnesses, etc. In any event, a Jewish wedding is highly dubious at best, given that Elizebeth was born in Huntington, Indiana (1892) to Quaker parents, was raised as a Quaker, and there is no credible source that even suggests that she ever converted to Judaism. According to the biographical sketch from U.S. cryptologic history, William and Elizebeth had two children – a son, John, and a daughter, Barbara – but there is no publicly available information that I could find about how these children were raised, whether they were brought up Jewishly, educated in Jewish institutions, or participated in Jewish communal life.
Nonetheless, there is substantive evidence that Friedman did not forget his Jewish heritage and that his early childhood was shaped by his parents’ immigrant experience: fleeing pogroms and antisemitic persecution in Bessarabia and Russia, arriving in the United States hoping for a better and safer life. According to his U.S. Army biography, news that “their hometown was destroyed and the hundreds of Jews that remained there were killed in 1902” haunted Friedman through his life, and that traumatic legacy of antisemitic violence played a psychological role in his identity. In a biographical sketch associated with the Marshall-NSA release of his papers, his daughter reportedly recalled her father’s “deep ties to his early Jewish upbringing, especially his great love and respect for his own father, the ‘Talmudic Scholar’ who spoke nine languages.”
However, and this is crucial, the publicly available archival record, including the voluminous Friedman Collection, does not appear to contain materials that reflect active religious practice, synagogue membership, holiday observance, or sustained involvement in Jewish communal life. Rather, the catalog description of the Friedman Collection’s holdings, including manuscripts, correspondence, technical reports, photographs, speeches, and writings, focuses almost exclusively on his cryptologic work, government employment, and personal intellectual interests. Moreover, in his extensive public biographies, whether in institutional histories (e.g., at NSA) or general-interest media, nothing suggests that he maintained visible connections to Jewish religious institutions. Even in Jewish-community oriented retrospectives – e.g., articles listing Jewish codebreakers – his background is invoked as heritage, “a Jewish immigrant from Russia,” but not as evidence of any observant Jewish religious life.
These silences in the archival and biographical record pose fundamental challenges to reconstructing any fully credible “Jewish life” biography of Friedman, but several interpretive explanations may account for the absence of such material. First, like many children of immigrant Jewish families in early-20th-century America, Friedman may have rapidly assimilated, focusing on education, professional opportunities, and socioeconomic stability, common priorities among immigrant families seeking to establish themselves in a new society. Second, as a high-level government employee working in intelligence and cryptography, fields heavily burdened by secrecy and security concerns, he may have deliberately downplayed or compartmentalized any personal religious identity, considering it private and irrelevant to his public duties. Third, it is possible, and perhaps even likely, that any private religious observance or communal involvement was never documented or, if documented, was not preserved or transferred into the collection now housed at the Marshall Foundation. Recall that the Collection’s contents reflect what Friedman and his wife chose to preserve: a private selection shaped by their assessment of what was historically important. The bottom line is that one can assert with confidence his Jewish birth, family history, and immigrant identity, but one cannot, with current publicly available evidence, assert that he maintained or practiced Judaism in adulthood in any visible or institutionally traceable way.
In recognition of his extraordinary contributions, the NSA later inducted Friedman into its Hall of Honor, and in 2002, it dedicated the “William and Elizebeth Friedman Building” on the NSA campus. However, no honors by Jewish organizations are recorded, and the accolades he received, including Congressional commendations, awards for service, and later institutional honors by cryptologic organizations, were secular, government- or profession-oriented.
Friedman was buried at Arlington National Cemetery in 1969 and, when Elizabeth died in 1980, she was interred with him under a gravestone that bears the epitaph “Knowledge is Power,” a phrase they had used previously in a 1918 code‑breakers class photo.