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William Frederick Friedman (September 24, 1891 – November 2, 1969) was a
US Army The United States Army (USA) is the primary land service branch of the United States Department of Defense. It is designated as the Army of the United States in the United States Constitution.Article II, section 2, clause 1 of the United Stat ...
cryptographer Cryptography, or cryptology (from "hidden, secret"; and ''graphein'', "to write", or '' -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adversarial behavior. More gen ...
who ran the research division of the Army's
Signal Intelligence Service The Signal Intelligence Service (SIS) was the United States Army codebreaking division through World War II. It was founded in 1930 to compile codes for the Army. It was renamed the Signal Security Agency in 1943, and in September 1945, became ...
(SIS) in the 1930s, and parts of its follow-on services into the 1950s. In 1940, subordinates of his led by Frank Rowlett broke
Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...
's PURPLE cipher, thus disclosing Japanese diplomatic secrets before America's entrance into
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 ...
.


Early life

Friedman was born Wolf Friedman (, ), in Kishinev,
Bessarabia Bessarabia () is a historical region in Eastern Europe, bounded by the Dniester river on the east and the Prut river on the west. About two thirds of Bessarabia lies within modern-day Moldova, with the Budjak region covering the southern coa ...
, the son of Frederick Friedman, a Jew from
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 ...
who worked as a
translator Translation is the communication of the meaning of a source-language text by means of an equivalent target-language text. The English language draws a terminological distinction (which does not exist in every language) between ''trans ...
and
linguist Linguistics is the scientific study of language. The areas of linguistic analysis are syntax (rules governing the structure of sentences), semantics (meaning), Morphology (linguistics), morphology (structure of words), phonetics (speech sounds ...
for the Russian Postal Service, and the daughter of a well-to-do wine merchant. Friedman's family left Kishinev in 1892 on account of anti-Semitic persecution, ending up in
Pittsburgh, Pennsylvania Pittsburgh ( ) is a city in Allegheny County, Pennsylvania, United States, and its county seat. It is the List of municipalities in Pennsylvania#Municipalities, second-most populous city in Pennsylvania (after Philadelphia) and the List of Un ...
. Three years later, his first name was changed to William. As a child, Friedman was introduced to cryptography in the short story "
The Gold-Bug "The Gold-Bug" is a short story by American writer Edgar Allan Poe published in 1843. The plot follows William Legrand, who becomes fixated on an unusual gold-colored bug he has discovered. His servant Jupiter fears that Legrand is going insan ...
" by
Edgar Allan Poe Edgar Allan Poe (; January 19, 1809 – October 7, 1849) was an American writer, poet, editor, and literary critic who is best known for his poetry and short stories, particularly his tales involving mystery and the macabre. He is widely re ...
. He studied at the Michigan Agricultural College (known today as
Michigan State University Michigan State University (Michigan State or MSU) is a public university, public Land-grant university, land-grant research university in East Lansing, Michigan, United States. It was founded in 1855 as the Agricultural College of the State o ...
) in
East Lansing East Lansing is a city in the U.S. state of Michigan. Most of the city lies within Ingham County, Michigan, Ingham County, although a small portion extends north into Clinton County, Michigan, Clinton County. At the 2020 United States census, 2020 ...
and received a scholarship to work on
genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinians, Augustinian ...
at
Cornell University Cornell University is a Private university, private Ivy League research university based in Ithaca, New York, United States. The university was co-founded by American philanthropist Ezra Cornell and historian and educator Andrew Dickson W ...
. Meanwhile, George Fabyan, who ran a private research laboratory to study any personally interesting project, decided to set up his own genetics project and was referred to Friedman. Friedman joined Fabyan's Riverbank Laboratories outside
Chicago Chicago is the List of municipalities in Illinois, most populous city in the U.S. state of Illinois and in the Midwestern United States. With a population of 2,746,388, as of the 2020 United States census, 2020 census, it is the List of Unite ...
in September 1915. As head of the Department of Genetics, one of the projects he ran studied the effects of moonlight on crop growth, and so he experimented with the planting of
wheat Wheat is a group of wild and crop domestication, domesticated Poaceae, grasses of the genus ''Triticum'' (). They are Agriculture, cultivated for their cereal grains, which are staple foods around the world. Well-known Taxonomy of wheat, whe ...
during various phases of the
moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...
.


Initial work in cryptology

Another of Fabyan's pet projects was research into secret messages which Sir
Francis Bacon Francis Bacon, 1st Viscount St Alban (; 22 January 1561 – 9 April 1626) was an English philosopher and statesman who served as Attorney General and Lord Chancellor of England under King James I. Bacon argued for the importance of nat ...
had allegedly hidden in various texts during the reigns of
Elizabeth I Elizabeth I (7 September 153324 March 1603) was List of English monarchs, Queen of England and List of Irish monarchs, Ireland from 17 November 1558 until her death in 1603. She was the last and longest reigning monarch of the House of Tudo ...
and
James I James I may refer to: People *James I of Aragon (1208–1276) * James I of Sicily or James II of Aragon (1267–1327) * James I, Count of La Marche (1319–1362), Count of Ponthieu * James I, Count of Urgell (1321–1347) *James I of Cyprus (1334� ...
. The research was carried out by Elizabeth Wells Gallup. She believed that she had discovered many such messages in the works of
William Shakespeare William Shakespeare ( 23 April 1564 – 23 April 1616) was an English playwright, poet and actor. He is widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. He is often called England's nation ...
, and convinced herself that Bacon had written many, if not all, of
Shakespeare William Shakespeare ( 23 April 1564 – 23 April 1616) was an English playwright, poet and actor. He is widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. He is often called England's natio ...
's works. Friedman had become something of an expert photographer while working on his other projects, and was asked to travel to England on several occasions to help Gallup photograph historical manuscripts during her research. He became fascinated with the work as he courted Elizebeth Smith, Gallup's assistant and an accomplished cryptographer. They married, and he soon became director of Riverbank's Department of Codes and Ciphers as well as its Department of Genetics. During this time, Friedman wrote a series of eight papers on cryptography, collectively known as the " Riverbank Publications", including the first description of the
index of coincidence In cryptography, coincidence counting is the technique (invented by William F. Friedman) of putting two texts side-by-side and counting the number of times that identical letters appear in the same position in both texts. This count, either as a r ...
, an important mathematical tool in cryptanalysis. With the entry of the United States into
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 ...
, Fabyan offered the services of his Department of Codes and Ciphers to the government. No Federal department existed for this kind of work (although both the Army and Navy had had embryonic departments at various times), and soon Riverbank became the unofficial cryptographic center for the US Government. During this period, the Friedmans broke a code used by
German German(s) may refer to: * Germany, the country of the Germans and German things **Germania (Roman era) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizenship in Germany, see also Ge ...
-funded
India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...
n radicals in the US who planned to ship arms to
India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...
to gain independence from Britain. Analyzing the format of the messages, Riverbank realized that the code was based on a dictionary of some sort, a cryptographic technique common at the time. The Friedmans soon managed to decrypt most of the messages, but only long after the case had come to trial did the book itself come to light: a German-English dictionary published in 1880.


Signals Intelligence Service

The United States government decided to set up its own cryptological service, and sent Army officers to Riverbank to train under Friedman. To support the program, Friedman wrote a series of technical monographs, completing seven by early 1918. He then enlisted in the Army and went to France to serve as the personal cryptographer for General John J. Pershing. He returned to the US in 1920 and published an eighth monograph, "The
Index of Coincidence In cryptography, coincidence counting is the technique (invented by William F. Friedman) of putting two texts side-by-side and counting the number of times that identical letters appear in the same position in both texts. This count, either as a r ...
and its Applications in Cryptography", considered by some to be the most important publication in modern cryptography to that time. His texts for Army cryptographic training were well thought of and remained classified for several decades. In 1921 he became chief cryptanalyst for the War Department and later led the Signals Intelligence Service (SIS)—a position he kept for a quarter century. In 1929, after the American
Black Chamber The Black Chamber, officially the Cable and Telegraph Section and also known as the Cipher Bureau, was the first peacetime cryptanalytic organization in the United States, operating from 1917 to 1929. It was a forerunner of the National Security ...
in New York City was disbanded, its files were entrusted to SIS, and the cryptographic and intelligence services was reorganized to suit its new position at the War Department. Friedman coined several terms, including "
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 ...
", and wrote many monographs on cryptography. One of these (written mostly in his spare time) was the first draft of his ''Elements of cryptanalysis'', which later was expanded to four volumes and became the U.S. Army's cryptographic main textbook and reference. Realizing that mathematical and language skills were essential to SIS's work, Friedman managed to get authority to hire three men with both mathematical training and language knowledge. They were Solomon Kullback, Frank Rowlett and Abraham Sinkov, each of whom went on to distinguished service for decades. In addition he also was finally able to hire a man fluent in Japanese, John Hurt. During this period Elizebeth Friedman continued her own work in cryptology, and became famous in a number of trials involving rum-runners and the
Coast Guard A coast guard or coastguard is a Maritime Security Regimes, maritime security organization of a particular country. The term embraces wide range of responsibilities in different countries, from being a heavily armed military force with cust ...
and
FBI The Federal Bureau of Investigation (FBI) is the domestic Intelligence agency, intelligence and Security agency, security service of the United States and Federal law enforcement in the United States, its principal federal law enforcement ag ...
during
Prohibition Prohibition is the act or practice of forbidding something by law; more particularly the term refers to the banning of the manufacture, storage (whether in barrels or in bottles), transportation, sale, possession, and consumption of alcoholic b ...
.


Solution of cipher machines

During the 1920s, several new cipher machines were developed generally based on using
typewriter A typewriter is a Machine, mechanical or electromechanical machine for typing characters. Typically, a typewriter has an array of Button (control), keys, and each one causes a different single character to be produced on paper by striking an i ...
mechanics and basic electrical circuitry. An early example was the
Hebern Rotor Machine The Hebern Rotor Machine was an electro-mechanical encryption machine built by combining the mechanical parts of a standard typewriter with the electrical parts of an electric typewriter, connecting the two through a scrambler. It is the first e ...
, designed in the US in 1915 by Edward Hebern. This system offered such security and simplicity of use that Hebern heavily promoted it to investors. Friedman realized that the new rotor machines would be important, and devoted some time to analyzing Hebern's design. Over a period of years, he developed principles of analysis and discovered several problems common to most rotor-machine designs. Examples of some dangerous features which allowed cracking of the generated code included having rotors step one position with each keypress, and putting the fastest rotor (the one that turns with every keypress) at either end of the rotor series. In this case, by collecting enough
ciphertext In cryptography, ciphertext or cyphertext is the result of encryption performed on plaintext using an algorithm, called a cipher. Ciphertext is also known as encrypted or encoded information because it contains a form of the original plaintext ...
and applying a standard statistical method known as the kappa test, he showed that he could, albeit with great difficulty, crack any cipher generated by such a machine. Friedman used his understanding of rotor machines to develop several that were immune to his own attacks. The best of the lot was the SIGABA—which was destined to become the US's highest-security cipher machine in
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 ...
after improvements by Frank Rowlett and Laurance Safford. Just over 10,000 were built. A patent on SIGABA was filed at the end of 1944, but kept secret until 2001, long after Friedman had died, when it was finally issued as . In 1939, the Japanese introduced a new cipher machine for their most sensitive diplomatic traffic, replacing an earlier system that SIS referred to as "RED." The new cipher, which SIS called "
PURPLE Purple is a color similar in appearance to violet light. In the RYB color model historically used in the arts, purple is a secondary color created by combining red and blue pigments. In the CMYK color model used in modern printing, purple is ...
", was different and much more difficult. The Navy's cryptological unit (
OP-20-G OP-20-G or "Office of Chief Of Naval Operations (OPNAV), 20th Division of the Office of Naval Communications, G Section / Communications Security", was the U.S. Navy's signals intelligence and cryptanalysis group during World War II. Its mission ...
) and the SIS thought it might be related to earlier Japanese cipher machines, and agreed that SIS would handle the attack on the system. After several months trying to discover underlying patterns in PURPLE ciphertexts, an SIS team led by Friedman and Rowlett, in an extraordinary achievement, figured it out. PURPLE, unlike the German Enigma or the Hebern design, did not use
rotor ROTOR was an elaborate air defence radar system built by the British Government in the early 1950s to counter possible attack by Soviet bombers. To get it operational as quickly as possible, it was initially made up primarily of WWII-era syst ...
s but stepper switches like those in automated
telephone exchange A telephone exchange, telephone switch, or central office is a central component of a telecommunications system in the public switched telephone network (PSTN) or in large enterprises. It facilitates the establishment of communication circuits ...
s. Leo Rosen of SIS built a machine using—as was later discovered—the identical model of switch that the Japanese designer had chosen. Thus, by the end of 1940, SIS had constructed an exact analog of the PURPLE machine without ever having seen one. With the duplicate machines and an understanding of PURPLE, SIS could decrypt increasing amounts of Japanese traffic. One such intercept was the message to the Japanese Embassy in Washington, D.C., ordering an end (on December 7, 1941) to negotiations with the US. The message gave a clear indication of impending
war War is an armed conflict between the armed forces of states, or between governmental forces and armed groups that are organized under a certain command structure and have the capacity to sustain military operations, or between such organi ...
, and was to have been delivered to the US State Department only hours prior to the
attack on Pearl Harbor The attack on Pearl HarborAlso known as the Battle of Pearl Harbor was a surprise military strike by the Empire of Japan on the United States Pacific Fleet at Naval Station Pearl Harbor, its naval base at Pearl Harbor on Oahu, Territory of ...
. The controversy over whether the US had foreknowledge of the Pearl Harbor attack has roiled well into the 21st century. In 1941, Friedman was hospitalized with a "
nervous breakdown A mental disorder, also referred to as a mental illness, a mental health condition, or a psychiatric disability, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. A mental disorder is ...
", widely attributed to the mental strain of his work on PURPLE. While he remained in hospital, a four-man team— Abraham Sinkov and Leo Rosen from SIS, and Lt. Prescott Currier and Lt. Robert Weeks from the U.S. Navy's OP-20-G—visited the British establishment at the "
Government Code and Cypher School The Government Code and Cypher School (GC&CS) was a British signals intelligence agency set up in 1919. During the First World War, the British Army and Royal Navy had separate signals intelligence agencies, MI1b and NID25 (initially known as R ...
" 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 ...
. They gave the British a PURPLE machine, in exchange for details on the design of the
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 ...
and on how the British decrypted the Enigma cipher. However Friedman visited Bletchley Park in April 1943 and played a key role in drawing up the 1943 BRUSA Agreement.


National Security Agency

Following World War II, Friedman remained in government signals intelligence. In 1949 he became head of the cryptographic division of the newly formed Armed Forces Security Agency (AFSA) and in 1952 became chief cryptologist for the
National Security Agency The National Security Agency (NSA) is an intelligence agency of the United States Department of Defense, under the authority of the director of national intelligence (DNI). The NSA is responsible for global monitoring, collection, and proces ...
(NSA) when it was formed to take over from AFSA. Friedman produced a classic series of textbooks, " Military Cryptanalysis", which was used to train NSA students. (These were revised and extended, under the title " Military Cryptanalytics", by Friedman's assistant and successor
Lambros D. Callimahos Lambros Demetrios Callimahos (December 16, 1910 – October 28, 1977) was a United States Army, US Army cryptography, cryptologist and a flute player. Early life and education Callimahos was born in Alexandria of Greek people, Greek parents; t ...
, and used to train many additional cryptanalysts.) During his early years at NSA, he encouraged it to develop what were probably the first super-computers, although he was never convinced a machine could have the "insight" of a human mind. Friedman spent much of his free time trying to decipher the famous Voynich Manuscript, said to be written sometime between 1403–1437. However, after four decades of study he finally had to admit defeat, contributing no more than an educated guess as to its origins and meaning. In 1955, Friedman initiated, on behalf of the NSA, a secret agreement with
Crypto AG Crypto AG was a Swiss company specialising in communications and information security founded by Boris Hagelin in 1952. The company was secretly purchased in 1970 by the US Central Intelligence Agency (CIA) and West German Federal Intelligence Se ...
, a Swiss manufacturer of encryption machines. The agreement resulted in many of the company's machines being compromised, so that the messages produced by them became crackable by the NSA. Friedman retired in 1956 and, with his wife, turned his attention to the problem that had originally brought them together: examining Bacon's supposed codes. Together they wrote a book entitled ''The Cryptologist Looks at Shakespeare'', which won a prize from the Folger Library and was published under the title ''The Shakespearean Ciphers Examined.'' The book demonstrated flaws in Gallup's work and in that of others who sought hidden ciphers in Shakespeare's work. At NSA's request Friedman prepared ''Six Lectures Concerning Cryptography and Cryptanalysis'', which he delivered at NSA. But later the Agency, concerned about security, confiscated the reference materials from Friedman's home.


Death and legacy

Friedman's health began to fail in the late 1960s, and he died in 1969.  Friedman and his wife Elizebeth are buried in
Arlington National Cemetery Arlington National Cemetery is the largest cemetery in the United States National Cemetery System, one of two maintained by the United States Army. More than 400,000 people are buried in its 639 acres (259 ha) in Arlington County, Virginia. ...
. Friedman and his wife donated their archives to the library of the George C. Marshall Foundation, which also has had material reclassified and removed by the NSA. Friedman has been inducted into the Military Intelligence Hall of Fame and there is a building named after William and Elizebeth at the NSA complex at
Fort Meade Fort George G. Meade is a United States Army installation located in Maryland, that includes the Defense Information School, the Defense Media Activity, the United States military bands#Army Field Band, United States Army Field Band, and the head ...
in Maryland. He was also presented the
Medal for Merit The Medal for Merit was the highest civilian decoration of the United States in the gift of the president. Created during World War II, it was awarded by the president of the United States to civilians who "distinguished themselves by exceptiona ...
by President
Harry Truman Harry S. Truman (May 8, 1884December 26, 1972) was the 33rd president of the United States, serving from 1945 to 1953. As the 34th vice president in 1945, he assumed the presidency upon the death of Franklin D. Roosevelt that year. Subsequen ...
, and the
National Security Medal The National Security Medal is a decoration of the United States of America officially established by President Harry S. Truman in Executive Order 10431 of January 19, 1953. The medal was originally awarded to any person, without regard to natio ...
by
Dwight Eisenhower Dwight David "Ike" Eisenhower (born David Dwight Eisenhower; October 14, 1890 – March 28, 1969) was the 34th president of the United States, serving from 1953 to 1961. During World War II, he was Supreme Commander of the Allied Expeditionar ...
. Friedman has the distinction of having one of the longest known suppressed patent applications, for , a patent for a "cryptographic system". It was filed on July 25, 1933, issued on August 1, 2000. Friedman Hall, located on
Fort Huachuca Fort Huachuca is a United States Army military base, installation, in Cochise County, Arizona, Cochise County in southeast Arizona, approximately north of the Mexico–United States border, border with Mexico and at the northern end of the Huac ...
,
Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...
, is named in his honor.


Children

Friedman had two children with his wife, Elizebeth: Barbara Friedman (later Atchison), and John Ramsay Friedman.


In popular culture

Commander Schoen, a character appearing in
Neal Stephenson Neal Town Stephenson (born October 31, 1959) is an American writer known for his works of speculative fiction. His novels have been categorized as science fiction, historical fiction, cyberpunk, and baroque. Stephenson's work explores mathemati ...
's novel ''
Cryptonomicon ''Cryptonomicon'' is a 1999 novel by American author Neal Stephenson, set in two different time periods. One group of characters are World War II–era Allied codebreakers and tactical-deception operatives affiliated with the British Govern ...
'', is to a large extent inspired by Friedman. Schoen shares a significant background and personality traits with Friedman, including being one of the top cryptanalysts of the U.S. Army, breaking Japanese codes prior to Japan's involvement in World War II, and the psychological problems that he suffered from as a result. In his acknowledgements, Stephenson writes "Among all these great wartime hackers, some kind of special recognition must go to William Friedman, who sacrificed his health to break the Japanese machine cipher called Purple before the war even began."


Awards and honors

* 1944: Commendation for Exceptional Civilian Service * 1946:
Medal for Merit The Medal for Merit was the highest civilian decoration of the United States in the gift of the president. Created during World War II, it was awarded by the president of the United States to civilians who "distinguished themselves by exceptiona ...
* 1955:
National Security Medal The National Security Medal is a decoration of the United States of America officially established by President Harry S. Truman in Executive Order 10431 of January 19, 1953. The medal was originally awarded to any person, without regard to natio ...
.


Publications

* "The index of coincidence and its applications in cryptography" (1922). Department of Ciphers. Publ 22. Geneva, Illinois: Riverbank Laboratories. . *
2nd ed.
(1935). Washington, D.C.: Signals Office, War Department.
"Preliminary Historical Report on the Solution of the 'B' Machine"
(Oct. 14, 1960).


See also

*
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), ...
*
Elizebeth Smith Friedman Elizebeth Smith Friedman (August 26, 1892 – October 31, 1980) was an Americans, American cryptanalyst and author who deciphered enemy codes in both World Wars and helped to solve international smuggling cases during Prohibition in the United S ...
* Magic (cryptography) * Riverbank Publications


Further reading

* Goldman, Irwin L. (May 3, 2017)
"William Friedman, Geneticist Turned Cryptographer."
''Genetics'', vol. 206, no. 1. pp. 1–8. Madison, Wis.:
Genetics Society of America The Genetics Society of America (GSA) is a scholarly membership society of more than 5,500 genetics researchers and educators, established in 1931. The Society was formed from the reorganization of the Joint Genetics Sections of the American Soc ...
. .


References


Bibliography

* Clark, Ronald W. (1977). ''The Man Who Broke Purple: the Life of Colonel William F. Friedman, Who Deciphered the Japanese Code in World War II''. Boston: Little Brown & Co. . . * Friedman, William F. (1984). Six Lectures on Cryptology. U.S. National Security Agency, 1965, declassified 1977. * Gannon, James (2001). ''Stealing Secrets, Telling Lies: How Spies and Codebreakers Helped Shape the Twentieth Century''. Washington, D.C.: Brassey's. . . * Kahn, David (1966). ''The Codebreakers: the Story of Secret Writing''. London: Weidenfeld and Nicolson. . * Rowlett, Frank B. (1999). ''The Story of Magic: Memoirs of an American Cryptologic Pioneer''. Laguna Hills, Calif.: Aegean Park Press. . . * Jensen, Cora J. (apparently William Friedman) (Oct. 28, 1920)
"'Saying It' in Cipher."
''The Florists’ Review'', vol. XLVI, no. 1196. p. 17. * ''Methods for the Reconstruction of Primary Alphabets'', with Elizebeth S. Friedman. Riverbank Publication, no. 21 (1918). In
''Methods for the Solution of Ciphers, Publications 15-22 ''.
Rufus A. Long Digital Library of Cryptography, George C. Marshall Library. * For references to other material, se
''The Friedman Collection: An Analytical Guide''.


External links


William F. Friedman Papers
at George C. Marshall Foundation
Friedman Cryptologic Collection
at George C. Marshall Foundation
NSA Hall of Honor page on Friedman

NSA William F. Friedman Collection of Official Papers

Colonel William F. Friedman (the Godfather of Cryptology)
by Robert A. Reeves

of Friedman's work were available through Aegean Park Press {{DEFAULTSORT:Friedman, William F. 1891 births 1969 deaths People from Chișinău People from Kishinyovsky Uyezd Moldovan Jews Bessarabian Jews Emigrants from the Russian Empire to the United States American cryptographers American people of Moldovan-Jewish descent Riverbank Laboratories Baconian theory of Shakespeare authorship Mathematicians from Illinois People from Kane County, Illinois 20th-century people from Washington, D.C. Cornell University alumni Michigan State University alumni United States Army personnel of World War I American people of World War II Military personnel from Pittsburgh National Security Agency cryptographers Signals Intelligence Service cryptographers Medal for Merit recipients Burials at Arlington National Cemetery