Genevieve Grotjan was a mathematician and cryptanalyst just prior to the war, and part of a secretive effort within the US Army Signal Intelligence Service to decipher coded messages transmitted by the Japanese diplomatic corps. In late 1940, the 27-year-old Grotjan was responsible for a seismic breakthrough that enabled her team to unlock the Japanese diplomatic codes and translate confidential intercepts. For years, the ability of American intelligence to read these messages provided early warning and pivotal insights into Tokyo’s foreign policy intentions.
Grotjan later turned her attention to a trove of intercepts from the Soviet Union, then a US ally, and her efforts led to the unmasking of a massive network of Soviet spies that had infiltrated US government agencies and industries for years. Grotjan died in 2006, and four years later, she was inducted into the National Security Agency’s Cryptologic Hall of Honor.
