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News | March 13, 2020

The Legacy of Women in American Cryptology: Part 2

By The National Cryptologic Museum

As NSA continues to celebrate Women’s History Month, we’re pleased to share the second part in our series highlighting influential women in cryptology with five more groundbreaking pioneers in the field.

The first part of our series can be found here, and be sure to check back next Friday for part three.

The National Cryptologic Museum features a tribute to these influential women with their “Women in American Cryptology” exhibit, which honors those whose contributions in cryptology opened doors and raised ceilings for those in the field today and into the future. Few will have heard of most of the women named, but they deserve to have their stories told.

Barbara Clark

Barbara Clark began her cryptologic career in World War II assigned to the Pacific as part of the Women’s Army Corps. She returned to the business in early 1951 at Arlington Hall, the Army’s cryptologic headquarters. As a senior research analyst with foreign language capability, Mrs. Clark served in four different production elements as an analyst and reporter, briefer, manager, and special office-level assistant for manpower development. In 1990, she returned to the line as a senior analyst and continued until her death in 2003.

In addition to her cryptologic work, Mrs. Clark was best known for her efforts to help others. She was awarded the Women in NSA (WIN) Dorothy T. Blum Award for Excellence in the Employee Personal and Professional Arena in 1987 for her unsung and unselfish efforts to further the personal and professional goals of many people at NSA. WIN also named its undergraduate scholarship fund, the Barbara W. Clark Scholarship Fund, in honor of her tremendous contributions to its scholarship efforts.

Wilma Davis

After graduating from Bethany College with a degree in mathematics and teaching for four years, Wilma Zimmerman moved to Washington, D.C., with her husband. She became interested in cryptology after reading a newspaper article about William and Elizebeth Friedman. She took a Navy correspondence course on cryptology and did quite well. She followed that with the Civil Service exams and was hired by William Friedman in 1937 or 1938. Within six months, her husband passed away. Mrs. Davis managed to get through this hard time with the help of her new “family” at the Army’s cryptologic office.

Her first assignment was with Italian diplomatic codes, which she worked until 1942, when she was transferred to the Japanese problem. Within two years, Mrs. Davis was the head of the department responsible for solving and processing all addresses on all intercepted Japanese army code messages. At the end of the war, she moved on to the Chinese team and then to the Venona Project concerning Soviet diplomatic and KGB codes.

In 1949, Wilma married again and moved to Canada, leaving the cryptologic field. Unfortunately, her second husband died in 1952. William Friedman sent her a telegram and asked her to return to work again on Venona. She readily accepted. Before the decade ended, she remarried again. Lieutenant General John Davis was the assistant director for Production, which is equivalent to today’s signals intelligence aspect of NSA’s operations. Mrs. Davis left her cryptologic work again when they had children, but she couldn’t stay away.  She returned to work on codebreaking during the Vietnam War, finally retiring in 1973.

Wilma Davis passed away in December 2001.

Agnes Meyer Driscoll

Born in 1889, Agnes Meyer received her bachelor’s degree from Ohio State in mathematics and physics in 1911. She was also proficient in five languages: English, French, German, Latin, and Japanese.

She joined the U.S. Navy as a chief yeoman in 1918 and worked in the Code and Signal Section throughout World War I. Married in 1924, Mrs. Driscoll continued as a civilian with the Navy. She was instrumental in breaking Japanese naval systems between the wars, including their operational code known as the “Red Book.” The codebook (named after the color of the two volumes’ binding) contained over 100,000 code groups and she was responsible for the initial solutions and transposition. Her efforts were rewarded with a promotion and raise in 1925. Valuable information garnered from reading the Japanese Red Book included general knowledge of naval maneuvers and advances in naval aviation.

In 1930, the Japanese complicated the system, but Mrs. Driscoll solved it as well. Information learned from this new system came during the Japanese Grand Maneuvers. The Japanese exercise simulated combat operations against the United States. The decrypts indicated that the Japanese knew, quite accurately, American operational plans. This revelation secured signals intelligence importance within the Navy.

Late in 1930, the Japanese created a whole new code, the “Blue Book.” This new system required solving the code and the overlying cipher simultaneously. With 85,000 code groups and daily changes in the key, this task was assisted by the new IBM tabulating machines. The analytic work was done by the naval cryptanalysts, but the machines facilitated tracking of the codes and cipher. Breaking the “Red Book” had been helped with the photographic capture of a Japanese codebook, but the “Blue Book” would have to be recovered through pure analysis. Mrs. Driscoll made the first break, an accomplishment unequaled at the time and not repeated until the U.S. Army broke Purple nearly a decade later.

One of the most important pieces of information derived from the “Blue Book” involved the Japanese battleship Nagato. Messages revealed the ship’s top speed to be more than 26 knots. U.S. battleships, still in development stage, had a top speed of only 24 knots. Based on the information learned, the U.S. redesigned their battleships to achieve 28 knots.

Mrs. Driscoll’s efforts were not solely cryptanalytic; she also assisted in the development of one of the Navy’s early cipher machines. In 1937, she received $15,000 for her part in the creation of the Navy’s CM (Cipher Machine or Communications Machine), built in the early 1920s. She also worked briefly in 1923 with Edward Hebern at his laboratory in California, improving his designs for cipher machines.

Although Mrs. Driscoll’s greatest achievements came between the World Wars, she continued with the Navy’s cryptologic offices and its successors for the rest of her career. Agnes Driscoll retired from NSA in 1959.

Genevieve Grotjan Feinstein

Genevieve Grotjan attended the University of Buffalo, hoping to become a math teacher. With no teaching positions available during the Great Depression, she took a job as a statistical clerk with the Railroad Retirement Board in Washington, D.C. She later took the tests required to become a professional government mathematician and was offered a job with the Army’s Signal Intelligence Service (SIS). In 1939, Miss Grotjan was a member of a team of cryptanalysts involved in the decryption and reading of Japanese secret messages. The team struggled for eighteen months with this difficult Japanese diplomatic cipher, codenamed Purple. In September 1940, Genevieve Grotjan made a discovery that changed the course of history. By analyzing and studying the intercepted encrypted messages, she found a correlation that no one else had yet detected. Her successful breakthrough enabled other cryptanalysts to find other links. SIS built a Purple analog machine to decrypt the Japanese diplomatic messages. Additional analog machines decrypted Purple messages throughout WWII.

Genevieve Grotjan followed her success with work on other Japanese ciphers systems. She was also “an instructor in machine cryptanalysis” and “a mainstay of the small cryptanalytic research section, where she worked on a variety of machine cipher systems.” In 1944, she was assigned to the Soviet problem working on the project that later became known as Venona. Once again she identified previously unnoticed characteristics in the messages that contributed significantly to successful exploitation. She continued her cryptanalytic career with the Armed Forces Security Agency and the NSA.

Genevieve Grotjan, by now Genevieve Feinstein, left the cryptologic business in 1947.

Elizebeth Friedman

Elizebeth Smith, an English literature graduate of Hillsdale College in Michigan, began her cryptologic career in 1916 at Riverbank Laboratory, a research lab outside Chicago. Her task was to assist in the decryption of the works of Shakespeare. A relatively well-known theory at the time stated that Francis Bacon authored the works of Shakespeare. It was believed he used his biliteral cipher in the original folios and, with careful analysis, it could be proven. Miss Smith worked under the direction of Elizabeth Gallup, who had written a book in 1899 on the subject and claimed she had deciphered some of the work.

The biliteral system used slight changes in font to distinguish the cipher letter from the plain text. Team members analyzed the fonts and indicated which were believed to be cipher. Miss Smith was then expected to determine the decipherment. Only able to decipher a word or two, Elizebeth took the work to Mrs. Gallup who, with relative ease, translated complete sentences. Confused, Elizebeth reexamined the font selections. Eventually she came to doubt Mrs. Gallup’s ability. Following years of study, Elizebeth and her husband, William Friedman, would write a book refuting the notion that a cipher was contained in the works of Shakespeare.

In 1921, Mrs. Friedman moved with her husband to Washington, D.C., and spent several months with him in the Army’s new cryptologic service. She also worked for a short time in the Navy’s service.  However, her skill as a cryptanalyst following World War I proved invaluable to the United States during the Prohibition years. She almost single-handedly broke over 12,000 coded messages from the rumrunners and smugglers who used codes to conduct their illicit business. Her efforts, and her testimony at their trials, broke up smuggling rings and saved the government hundreds of thousands of dollars.

One of her most celebrated cases involved the I’m Alone, a Canadian-built rumrunning ship. In 1929, a Coast Guard cutter spotted the I’m Alone off the Louisiana coast and ordered it to “heave to and be boarded.” Refusing to do so, it took to open waters. Days later the Coast Guard sank the ship in international waters while it was flying the Canadian flag. The Canadian government sued the United States for more than $300,000 for the loss of the ship and its cargo. The U.S. claimed the ship was owned by American citizens and that the pursuit had begun in U.S. territorial waters, justifying the attack. Mrs. Friedman was able to prove the U.S. case after decrypting 23 messages from Belize (at the time, British Honduras) to a New York address. The decrypts exactly matched the shipping dates and contents of the I’m Alone and the New York address belonged to one of the owners of the ship. In the end, the United States paid the Canadians only $50,000 and apologized for the insult to the Canadian flag.

Following WWII, Mrs. Friedman created the communications security systems for the International Monetary Fund.

Visit the National Cryptologic Museum to see this impressive “Women in American Cryptology” exhibit in person, among the many other exhibits that explore the expansive history of American cryptology. The National Cryptologic Museum is located at the intersection of Maryland Route 32 and the Baltimore-Washington Parkway (I-295), adjacent to the headquarters of the National Security Agency. Admission and parking are free! Click here for hours, directions, and other information. You can also follow the museum on Facebook.