Frank Byron Rowlett was an American cryptologist.

Rowlett was born in Rose Hill, Virginia

Rose Hill, Virginia

Rose Hill is the name of some places in the U.S. state of Virginia:*Rose Hill, Albemarle County, Virginia*Rose Hill, Fairfax County, Virginia*Rose Hill, Lee County, Virginia*Rose Hill, Rappahannock County, Virginia...

 and attended Emory & Henry College in Emory, Virginia

Emory, Virginia

Emory is a census-designated place in Washington County, Virginia, United States. The population was 1,251 at the 2010 census. It is part of the Kingsport–Bristol –Bristol Metropolitan Statistical Area, which is a component of the Johnson City–Kingsport–Bristol, TN-VA...

, where he was a member of the Beta Lambda Zeta fraternity. In 1929 he received a bachelor's degree in mathematics and chemistry. He was hired by William Friedman as a "junior cryptanalyst" for the Signals Intelligence Service

Signals Intelligence Service

The Signals Intelligence Service was the United States Army codebreaking division, headquartered at Arlington Hall. It was a part of the Signal Corps so secret that outside the office of the Chief Signal officer, it did not officially exist. William Friedman began the division with three "junior...

 (SIS) on April Fool’s Day, 1930; shortly after, he was followed into SIS by Abraham Sinkov

Abraham Sinkov

Dr. Abraham Sinkov was a US cryptanalyst.-Biography:Sinkov, the son of immigrants from Russia, was born in Philadelphia, but grew up in Brooklyn. After graduating from Boys High School—what today would be called a "magnet school" -- he took his B.S. in mathematics from City College of New York...

 and Solomon Kullback

Solomon Kullback

Solomon Kullback was an American cryptanalyst and mathematician, who was one of the first three employees hired by William F. Friedman at the US Army's Signal Intelligence Service in the 1930s, along with Frank Rowlett and Abraham Sinkov. He went on to a long and distinguished career at SIS and...

.

During the 1930s, after a lengthy period of training, Rowlett and his colleagues compiled code

Code (cryptography)

In cryptography, a code is a method used to transform a message into an obscured form, preventing those who do not possess special information, or key, required to apply the transform from understanding what is actually transmitted. The usual method is to use a codebook with a list of common...

s and cipher

Cipher

In cryptography, a cipher is an algorithm for performing encryption or decryption — a series of well-defined steps that can be followed as a procedure. An alternative, less common term is encipherment. In non-technical usage, a “cipher” is the same thing as a “code”; however, the concepts...

s for use by the U.S. Army and began solving a number of foreign, notably Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

ese, systems. In the mid-1930s, they solved the first Japanese machine for encipherment of diplomatic

Diplomacy

Diplomacy is the art and practice of conducting negotiations between representatives of groups or states...

 communications, known to the Americans as RED

Red (cipher machine)

In the history of cryptography, 91-shiki injiki or Angōki Taipu-A , codenamed Red by the United States, was a diplomatic cryptographic machine used by the Japanese Foreign Office before and during World War II. A relatively simple device, it was quickly broken by western cryptographers...

. In 1939-40, Rowlett led the SIS

Signals Intelligence Service

The Signals Intelligence Service was the United States Army codebreaking division, headquartered at Arlington Hall. It was a part of the Signal Corps so secret that outside the office of the Chief Signal officer, it did not officially exist. William Friedman began the division with three "junior...

 effort that solved a more sophisticated Japanese diplomatic machine cipher, codenamed PURPLE

PURPLE

In the history of cryptography, 97-shiki ōbun inji-ki or Angōki Taipu-B , codenamed Purple by the United States, was a diplomatic cryptographic machine used by the Japanese Foreign Office just before and during World War II...

 by the U.S. Once, when asked what his greatest contribution to that effort had been, Rowlett said, "I was the one who believed it could be done."

Rowlett also played a crucial role in protecting American communications during World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, making fundamental and innovative contributions to the design of the SIGABA

SIGABA

In the history of cryptography, the ECM Mark II was a cipher machine used by the United States for message encryption from World War II until the 1950s...

  cipher machine

Cipher

In cryptography, a cipher is an algorithm for performing encryption or decryption — a series of well-defined steps that can be followed as a procedure. An alternative, less common term is encipherment. In non-technical usage, a “cipher” is the same thing as a “code”; however, the concepts...

. Its security was an important factor in saving American lives in combat. (In 1964, Congress awarded Rowlett US$100,000 as partial compensation for his classified cryptologic inventions).

In addition to having highly-developed cryptanalytic skills, Rowlett was a good manager, and he rose quickly within the organization. In 1943-1945 he was chief of the General Cryptanalytic Branch, and in 1945-1947 chief of the Intelligence Division. From 1949 to 1952, he was technical director in the Office of Operations of the Armed Forces Security Agency, predecessor to the National Security Agency

National Security Agency

The National Security Agency/Central Security Service is a cryptologic intelligence agency of the United States Department of Defense responsible for the collection and analysis of foreign communications and foreign signals intelligence, as well as protecting U.S...

 (NSA).

Rowlett differed with General Ralph J. Canine, the first director of NSA, over personnel movements, including his own. Acting on his differences, he transferred to the Central Intelligence Agency

Central Intelligence Agency

The Central Intelligence Agency is a civilian intelligence agency of the United States government. It is an executive agency and reports directly to the Director of National Intelligence, responsible for providing national security intelligence assessment to senior United States policymakers...

 (CIA) in 1952 and worked there until 1958. At that time he returned to NSA as a Special Assistant to the Director. In 1965 Rowlett became commandant of the National Cryptologic School

National Cryptologic School

The National Cryptologic School is a school within the National Security Agency that provides training to members of the Agency.The National Cryptologic School is a Cryptologic Training School within the National Security Agency...

. He retired from federal service in 1966. In 1965 he was awarded the National Security Medal

National Security Medal

The National Security Medal was a decoration of the United States of America officially established by President Harry S. Truman in Executive Order 10431 of January 19, 1953...

 by President Lyndon B. Johnson

Lyndon B. Johnson

Lyndon Baines Johnson , often referred to as LBJ, was the 36th President of the United States after his service as the 37th Vice President of the United States...

 for his work on breaking the Japanese Purple

PURPLE

In the history of cryptography, 97-shiki ōbun inji-ki or Angōki Taipu-B , codenamed Purple by the United States, was a diplomatic cryptographic machine used by the Japanese Foreign Office just before and during World War II...

 cipher.

Rowlett has been inducted into the Military Intelligence Hall of Fame

Military Intelligence Hall of Fame

The Military Intelligence Hall of Fame is a Hall of Fame established by the Military Intelligence Corps of the United States Army in 1988 to honor soldiers and civilians who have made exceptional contributions to Military Intelligence...

.

Because of his importance in the protection of American communications, the Information Systems Security Organization has named its highest award the Frank Byron Rowlett Award

Frank Byron Rowlett Award

The Frank Byron Rowlett Award is an award given by the National Security Agency to recognize outstanding organizational and individual excellence in the field of information systems security...

.

Frank Rowlett died June 29, 1998, at age 90.