Employment at the Signals Intelligence Service began for Frank Rowlett on April 1, 1930, when he joined the organization as a junior cryptanalyst. His entry into the field followed his 1929 graduation from Emory & Henry College, where he focused his academic studies on the disciplines of mathematics and chemistry before beginning his lifelong tenure in government service.
Cryptanalytic Achievements
During his early years with the Signals Intelligence Service, Rowlett focused on breaking foreign communications systems. His team successfully identified the structure of the Japanese RED machine in the mid-1930s. By 1939, he led the effort to decrypt the Japanese diplomatic machine cipher known as PURPLE. His career also involved supervising Virginia Dare Aderholdt, who decrypted the official Japanese surrender message on August 14, 1945.
Twenty questions, eight minutes on the clock, and a percentile measured against everyone who has taken it. No sign-up.
Take the IQ test →Security Systems and Compensation
Beyond his work in decryption, Rowlett contributed to the design of the SIGABA cipher machine to protect American communications. His inventions in this area were significant enough that in 1964, the United States Congress awarded him $100,000 as partial compensation for his classified work. This amount was estimated to be equivalent to $1,040,000 by 2025.
Administrative Leadership
Rowlett moved through several high-level management positions during his career. He served as chief of the General Cryptanalytic Branch from 1943 to 1945, and later as chief of the Intelligence Division until 1947. Between 1949 and 1952, he acted as technical director for the Armed Forces Security Agency. Following a disagreement with General Ralph J. Canine, he transferred to the Central Intelligence Agency, where he remained until 1958 before returning to the National Security Agency as a Special Assistant to the Director.
Honors and Final Service
In 1965, Rowlett assumed the role of commandant for the National Cryptologic School. That same year, President Lyndon B. Johnson presented him with the National Security Medal for his role in breaking the PURPLE cipher. He also received the President’s Award for Distinguished Federal Civilian Service. Rowlett retired in 1966 and was eventually inducted into the Military Intelligence Hall of Fame.
Fast facts
- Born: 1908, Rose Hill, Virginia
- Died: June 29, 1998, age 90
- Education: Emory & Henry College
- Primary Fields: Mathematics, Cryptography
- Key Decryption: PURPLE cipher
- Notable Machine Contribution: SIGABA
- Retirement Year: 1966
Questions readers ask
What was Rowlett's contribution to the PURPLE cipher?
He led the Signals Intelligence Service team that successfully solved the machine in 1939.
Did Rowlett ever leave the National Security Agency?
Yes, he transferred to the Central Intelligence Agency in 1952 due to professional differences with the NSA director and returned to the NSA in 1958.
Achievements
- Fields: cryptography
