Born: 30 April 1913, United States
Died: 10 August 2006
Country most active: United States
Also known as: Genevieve Marie Grotjan
The following is republished from the National Security Agency. This piece falls under under public domain, as copyright does not apply to “any work of the U.S. Government” where “a work prepared by an officer or employee of the U.S. Government as part of that person’s official duties” (See, 17 U.S.C. §§ 101, 105).
Genevieve Grotjan Feinstein was a skilled cryptanalyst whose discovery in September 1940 changed the course of history. Her successful breakthrough enabled the Army Signal Intelligence Service (SIS) to build an analog machine that solved the Japanese diplomatic system known as “Purple.” Exploitation of this system provided crucial intelligence in the Atlantic and Pacific theaters during World War II.
Ms. Grotjan Feinstein was hired by William Friedman for the SIS in 1939. By 1940 she made her discovery that led to breaking the “Purple” code, and by October 1943 she was assigned to the Soviet problem and worked on the project later known as “Venona.” She devised a process for recognizing the re-use of key, which, in turn, permitted the decryption of Russian KGB messages. The discovery was labeled “… the most important single cryptanalytic break in the whole history of Venona.”
Ms. Grotjan Feinstein’s brilliant findings in two instances enabled exploitation of communications that provided invaluable intelligence information to policymakers. This information was used by the most senior government officials for decisions in World War II and the Cold War.
In 1943, Ms. Grotjan married Hyman Feinstein, a chemist at the National Bureau of Standards. After serving as a cryptanalyst and as a research analyst for over seven years, on May 4, 1947, Genevieve Grotjan Feinstein resigned from the government and later became a professor of mathematics at George Mason University.
Genevieve Grotjan Feinstein died in 2006 at the age of 93. Before his death in 1995, Hyman Feinstein established an award in cryptology within the Department of Mathematical Sciences at George Mason in honor of his wife.
The following is republished from the National Park Service. This piece falls under under public domain, as copyright does not apply to “any work of the U.S. Government” where “a work prepared by an officer or employee of the U.S. Government as part of that person’s official duties” (See, 17 U.S.C. §§ 101, 105).
The Signal Intelligence Service (SIS) was first founded in 1930. For most of WWII it was a part of the US Army Signal Corps. SIS grew rapidly, but men were needed for fighting overseas. To meet operational demands, recruitment shifted toward young women. By the end of the war, approximately 7,000 of the 10,500 SIS staff were female. These women on the home front contributed to the Allied victory by successfully breaking codes and deciphering enemy messages. The women cryptologists were held to strict secrecy and would become one of the best-kept secrets of WWII.
Genevieve Grotjan was born in 1913. She graduated from the University of Buffalo with a mathematics degree and was hired in 1939 as a junior cryptologist after her high score on a civil service mathematics test was discovered. Grotjan discovered a correlation among intercepted messages in 1940 after analyzing the encryption system used in the Japanese Machine. The SIS named its code “Purple.” Because of her discovery, SIS and the US Navy were able to build a “Purple” analog machine to help decode Japanese messages. Genevieve Grotjan married the chemist Hyman Feinstein in 1943. Genevieve Grotjan Feinstein passed in 2006 and was posthumously inducted into the NSA Hall of Honor (2010).
Excerpt from: Frank B. Rowlett: A personal profile, by Theodore Hannah
“Finally, Genevieve Grotjan finds the evidence we are looking for. Time is about 2 p.m. Ferner, Small, and I are at table in working area discussing prospects and reviewing work. Grotjan enters room, obviously excited, politely interrupts, asks if she can show us what she has found. She takes us to her desk in next room, lays out worksheets, points to one example, then another, then a third. She stands back, with eyes tranced behind her rimless glasses. Al Small dashes around the room, hands clasped above his head like a victorious prizefighter. ‘Whoopee!’ he yells. Ferner, the quiet one, clasps his hands, shouting “Hooray, Hooray.” I jump up and down – “That’s it! That’s it!” The room gets crowded; everyone in section suddenly in room. Friedman comes in and asks, “What’s all the noise about?”
I settle down and say, “Look what Miss Grotjan has just discovered.” Gene wipes her eyes, tries to regain her composure. I point to the worksheets – “Gene’s found what we’ve been looking for. Look here, and here, and here.” Friedman examines each one and understands what he sees; he looks suddenly tired. We take a break and send out for Cokes. The excitement gradually wears off and we look ahead to the next step.” – Frank Rowlett
That next step would soon lead to the solution of Japan’s highest level diplomatic cipher system, the so-called Type “B” machine, better known as “Purple.” What young, studious Genevieve Grotjan had discovered on that warm Friday afternoon in September 1940 represented the decisive breakthrough into a highly sophisticated machine system that for 18 months had stubbornly resisted the concerted attack by some of the best cryptanalysts in the world. Its solution has been called “the greatest feat of cryptanalysis the world had yet known,” one which, in the words of another author, “involved a unique intellectual effort of heroic proportions.”