Richard A. Leibler, a National Security Agency mathematician whose code-breaking work helped lead to the exposure and arrest of Soviet agents who spied on the United States during the height of the Cold War, has died. He was 89.
Leibler died of heart disease Oct. 25 at Reston Hospital Center in Reston, Va.
Leibler retired from the National Security Agency in 1980 as chief of the office of research in the agency's research and engineering organization. NSA officials said his theoretical work was critical to the development of a process that enabled cryptolinguists to decipher Soviet espionage messages in a project code-named VENONA. The 37-year project, which ended in 1980, employed hundreds of cryptanalysts, who sifted through a million Soviet messages, beginning in World War II, in what had been considered an unbreakable code.
Over the years, VENONA led to the unmaskings of Klaus Fuchs, the German-born scientist convicted of spying for the Soviets; Julius and Ethel Rosenberg, the New York couple who in 1953 were executed for espionage; and British intelligence officer Kim Philby, who, after defecting to Moscow in 1963, said he had been a Soviet spy for two decades.
Leibler was born in Chicago and graduated from Northwestern University, where he also received a master's in mathematics. He received a doctorate in math from the University of Illinois.
During World War II, he served in the Navy as an aviation ordnance officer. He participated in combat operations on aircraft carriers at Iwo Jima and Okinawa.
After the war, he worked for the Department of the Navy and spent a year at the Institute for Advanced Study at Princeton.
Leibler joined the NSA in 1953 and, in his early years with the agency, worked with pioneer computer scientists in the development of programs and applications. During that period, he also produced theories that helped cryptolinguists develop a process to decode the VENONA messages.
In the VENONA project, Leibler was dealing with numerical codes that changed every day, making it all but impossible for cryptolinguists to find patterns. But there were times when the codes did not change -- when the Soviets hastily relocated their wartime message-sending operation east from Moscow to escape advancing Nazi armies, for example. The lapses gave the code-breakers more to work with. Still, the decoding process was long, arduous work, and thousands of the VENONA messages were never deciphered.
Work on the VENONA project was halted in 1980, but the project remained classified until 1995, when it was unveiled by the Central Intelligence Agency as one of the major counterespionage feats of the Cold War.
In 1958, Leibler left the NSA to become deputy director of the Communications and Research Division of the Institute for Defense Analysis at Princeton.
Leibler became director in 1962 and continued to undertake NSA research projects. He returned to the NSA in 1977.
He is survived by his wife, Eleanor, and two children.