Genevieve Marie Grotjan Feinstein (April 30, 1913 – August 10, 2006) was an American

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History On ...

and

cryptanalyst 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 sec ...

. She worked for the

Signals 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 th ...

throughout World War II, during which time she played an important role in deciphering the Japanese cryptography machine

Purple Purple is any of a variety of colors with hue between red and blue. In the RGB color model used in computer and television screens, purples are produced by mixing red and blue light. In the RYB color model historically used by painters, pu ...

, and later worked on the Cold War-era

Venona project The Venona project was a United States counterintelligence program initiated during World War II by the United States Army's Signal Intelligence Service (later absorbed by the National Security Agency), which ran from February 1, 1943, until Octob ...

Career

Feinstein discovered a passion for mathematics at a young age and aspired to become a math teacher. She graduated from the

University at Buffalo The State University of New York at Buffalo, commonly called the University at Buffalo (UB) and sometimes called SUNY Buffalo, is a public research university with campuses in Buffalo and Amherst, New York. The university was founded in 1846 ...

summa cum laude in February 1936 with a mathematics degree. Unable to find a teaching job, she took a position as a statistical clerk at the Railroad Retirement Board. Her high score on a civil service mathematics test in 1939 got the attention of

William F. Friedman William Frederick Friedman (September 24, 1891 – November 12, 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. ...

, who hired her to work as a junior cryptanalyst for the Army's

(SIS). For eighteen months, she worked with other SIS codebreakers to analyze the encryption system used in the Japanese

Type B Cipher Machine In the history of cryptography, the "System 97 Typewriter for European Characters" (九七式欧文印字機) or "Type B Cipher Machine", codenamed Purple by the United States, was an encryption machine used by the Japanese Foreign Office fr ...

, code named Purple by the SIS She played a key role in cracking the cipher, discovering cyclical behavior in the code on September 20, 1940. This enabled the construction of an equivalent machine by the SIS which in turn enabled the interception of almost all messages exchanged between the Japanese government and its embassies in foreign countries. Purple-encoded reports from

Hiroshi Oshima is a common masculine Japanese given name. It can also be transliterated as Hirosi. Possible writings Hiroshi can be written using different kanji characters and can mean: *浩, "meaning" *汎 *弘, *宏, *寛, *洋, *博, *博一, *博司, ...

, the Japanese ambassador in Berlin, were a main source of intelligence about Axis plans. In 1946, she was awarded the Exceptional Civilian Service Award from Brig. Gen. Paul Everton Peabody for her wartime service. She was later assigned to the

, trying to decode encrypted messages sent by the Soviet

KGB The KGB (russian: links=no, lit=Committee for State Security, Комитет государственной безопасности (КГБ), a=ru-KGB.ogg, p=kəmʲɪˈtʲet ɡəsʊˈdarstvʲɪn(ː)əj bʲɪzɐˈpasnəsʲtʲɪ, Komitet gosud ...

and

Main Intelligence Directorate Main Intelligence Directorate may refer to: * Main Directorate of Intelligence (Ukraine), the military intelligence service of Ukraine * GRU The Main Directorate of the General Staff of the Armed Forces of the Russian Federation, rus, Гла́� ...

(GRU). She made a significant breakthrough in November 1944, which allowed American cryptographers to recognize when an individual

one time pad In cryptography, the one-time pad (OTP) is an encryption technique that cannot be cracked, but requires the use of a single-use pre-shared key that is not smaller than the message being sent. In this technique, a plaintext is paired with a rand ...

cipher was (improperly) reused. After the conclusion of World War II, Feinstein continued to work at the SIS, as the

Cold War The Cold War is a term commonly used to refer to a period of geopolitical tension between the United States and the Soviet Union and their respective allies, the Western Bloc and the Eastern Bloc. The term '' cold war'' is used because the ...

began, but resigned in 1947. After resigning from government cryptanalysis, she joined the faculty of

George Mason University George Mason University (George Mason, Mason, or GMU) is a public research university in Fairfax County, Virginia with an independent City of Fairfax, Virginia postal address in the Washington, D.C. Metropolitan Area. The university was origin ...

, where she briefly served as a professor of mathematics.

Personal life

In 1943, Genevieve Grotjan married the

Manhattan Project The Manhattan Project was a research and development undertaking during World War II that produced the first nuclear weapons. It was led by the United States with the support of the United Kingdom and Canada. From 1942 to 1946, the project w ...

chemist Hyman Feinstein, who worked at the

National Bureau of Standards The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into physical sci ...

. They had a son named Ellis, who died of a heart condition at age 22. Grotjan died in 2006.

Legacy

Her husband established the annual Genevieve Feinstein Award in Cryptography at George Mason University in her honor. Her breakthrough in deciphering the Purple machine has been called, in the ''Encyclopedia of American Women at War'', "one of the greatest achievements in the history of U.S. codebreaking". NSA posthumously inducted her into the

NSA Hall of Honor The Hall of Honor is a memorial at the National Security Agency headquarters in Fort Meade, Maryland. It honors individuals who rendered distinguished service to American cryptology. The Hall of Honor The Hall of Honor is located on the grounds ...

in 2010. In 2018, the University at Buffalo's alumni magazine featured her as "An American Hero".

References

{{DEFAULTSORT:Feinstein, Genevieve Grotjan 1913 births 2006 deaths 20th-century American mathematicians Signals Intelligence Service cryptographers American women civilians in World War II George Mason University faculty American women mathematicians 20th-century American women scientists Scientists from Buffalo, New York 20th-century women mathematicians Mathematicians from New York (state) University at Buffalo alumni Women cryptographers 21st-century American women