William Frederick Friedman (September 24, 1891 – November 2, 1969) was a US Army cryptographer who ran the research division of the Army's Signal Intelligence Service (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's PURPLE cipher, thus disclosing Japanese diplomatic secrets before America's entrance into World War II.
Early life Friedman was born Wolf Friedman (Yiddish: װאָלף פֿרידמאַן, Russian: Вольф Ф. Фридман), in Kishinev, Bessarabia, the son of Frederick Friedman, a Jew from Bucharest who worked as a translator and linguist 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. 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" by Edgar Allan Poe. He studied at the Michigan Agricultural College (known today as Michigan State University) in East Lansing and received a scholarship to work on genetics at Cornell University. 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 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 during various phases of the moon.
Initial work in cryptology
Another of Fabyan's pet projects was research into secret messages which Sir Francis Bacon had allegedly hidden in various texts during the reigns of Elizabeth I and James I. The research was carried out by Elizabeth Wells Gallup. She believed that she had discovered many such messages in the works of William Shakespeare, and convinced herself that Bacon had written many, if not all, of Shakespeare'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, an important mathematical tool in cryptanalysis.
With the entry of the United States into World War I, 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-funded Indian radicals in the US who planned to ship arms to India 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 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 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", 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 Smith Friedman continued her own work in cryptology, and became famous in a number of trials involving rum-runners and the Coast Guard and FBI during Prohibition.
Solution of cipher machines
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