Dr. Abraham Sinkov was a US cryptanalyst

Cryptanalysis

Cryptanalysis is the study of methods for obtaining the meaning of encrypted information, without access to the secret information that is normally required to do so. Typically, this involves knowing how the system works and finding a secret key...

.

Biography

Sinkov, the son of immigrants from Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

, was born in Philadelphia, but grew up in Brooklyn

Brooklyn

Brooklyn is the most populous of New York City's five boroughs, with nearly 2.6 million residents, and the second-largest in area. Since 1896, Brooklyn has had the same boundaries as Kings County, which is now the most populous county in New York State and the second-most densely populated...

. After graduating from Boys High School—what today would be called a "magnet school

Magnet school

In education in the United States, magnet schools are public schools with specialized courses or curricula. "Magnet" refers to how the schools draw students from across the normal boundaries defined by authorities as school zones that feed into certain schools.There are magnet schools at the...

" -- he took his B.S. in mathematics

Mathematics

Mathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...

 from City College of New York

City College of New York

The City College of the City University of New York is a senior college of the City University of New York , in New York City. It is also the oldest of the City University's twenty-three institutions of higher learning...

. (By coincidence, one of his close friends at Boys High and CCNY was 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...

). Mr. Sinkov taught in New York City

New York City

New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...

 schools but was unhappy with the working conditions and anxious to use his mathematics knowledge in practical ways.

Early career

The opportunity for a career change came in 1930. Sinkov and Kullback took the Civil Service examination and placed high. Both received mysterious letters from Washington

Washington, D.C.

Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....

 asking about their knowledge of foreign languages. Sinkov knew French

French language

French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...

 and Kullback, Spanish

Spanish language

Spanish , also known as Castilian , is a Romance language in the Ibero-Romance group that evolved from several languages and dialects in central-northern Iberia around the 9th century and gradually spread with the expansion of the Kingdom of Castile into central and southern Iberia during the...

. This was acceptable to their prospective employer, and they were offered positions as junior cryptanalysts. Although neither was quite certain what a cryptanalyst did, they accepted.

The small 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) organization (Sinkov and Kullback were the third and fourth employees there) had the primary mission of compiling codes and ciphers for use by the U.S. Army. Its secondary task was to attempt to solve selected foreign codes and ciphers—this was not necessarily done for intelligence purposes but to keep the cryptanalysts abreast of new developments in the field.

William Friedman put his new employees through a rigorous course of study of his own design in cryptology, bringing them to high levels of skill in making and breaking codes and ciphers. Friedman also encouraged other self-improvement endeavors: his employees trained summers at a camp at Ft. Meade to earn commissions in the military reserves. Both Sinkov and Kullback also went on to receive doctorates in mathematics. Sinkov received his in mathematics in 1933 from The George Washington University

George Washington University

The George Washington University is a private, coeducational comprehensive university located in Washington, D.C. in the United States...

. In 1936, Dr. Sinkov was assigned to the Panama Canal Zone

Panama Canal Zone

The Panama Canal Zone was a unorganized U.S. territory located within the Republic of Panama, consisting of the Panama Canal and an area generally extending 5 miles on each side of the centerline, but excluding Panama City and Colón, which otherwise would have been partly within the limits of...

, where he established the U.S. Army's first permanent intercept site outside the continental United States.

WWII

SIS grew slowly throughout the early 1930s. However, successes against 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 diplomatic machine systems after 1935 provided the U.S. government with critical information during a series of crises. This success had practical consequences for SIS, as well. For the first time, SIS began to garner respect from its military superiors. Once the military understood that this small organization could read sensitive messages from a potential adversary, the Signal Corps increased the SIS budget and authorized increased hiring of cryptanalysts.

In 1940, even though the United States was not officially a combatant, the U.S. and Britain

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 initiated exchanges of technical material. Included in this was a cautious sharing of cryptologic information: the British in stages revealed the extent of their considerable success against high-level German systems, the U.S. its equivalent success against Japanese. This led to an unprecedented level of cooperation in COMINT between the two countries during the war, resulting in more personnel, bigger budgets, and a wider range of activities for the organization.
In January 1941, while Britain battled Nazi Germany

Nazi Germany

Nazi Germany , also known as the Third Reich , but officially called German Reich from 1933 to 1943 and Greater German Reich from 26 June 1943 onward, is the name commonly used to refer to the state of Germany from 1933 to 1945, when it was a totalitarian dictatorship ruled by...

 but nearly a year before the United States entered the Second World War, Captain Sinkov was selected as a member of a delegation to the United Kingdom for initial sharing of information about the two countries' respective cryptologic programs. The delegation returned in April with mixed results to report. Sinkov and his colleagues had been shown Bletchley Park

Bletchley Park

Bletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Museum of Computing...

, the secret headquarters for British cryptology, and exchanged information on German

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 and Japanese systems. It is still unclear how much the American delegation was told about British success against the German Enigma machine

Enigma machine

An Enigma machine is any of a family of related electro-mechanical rotor cipher machines used for the encryption and decryption of secret messages. Enigma was invented by German engineer Arthur Scherbius at the end of World War I...

, but Sinkov later recalled that they were told about the Enigma problem only a short while before the delegation was to leave, and that details were sketchy. Nevertheless, the mission to the UK was a success overall and helped give US-UK cryptologic relations a strong practical foundation.

After the Japanese attack on Pearl Harbor

Attack on Pearl Harbor

The attack on Pearl Harbor was a surprise military strike conducted by the Imperial Japanese Navy against the United States naval base at Pearl Harbor, Hawaii, on the morning of December 7, 1941...

 on December 7, 1941, the Japanese also attacked the Philippine Islands. General Douglas MacArthur

Douglas MacArthur

General of the Army Douglas MacArthur was an American general and field marshal of the Philippine Army. He was a Chief of Staff of the United States Army during the 1930s and played a prominent role in the Pacific theater during World War II. He received the Medal of Honor for his service in the...

 had been ordered to leave the Philippines and re-establish U.S. Army headquarters in Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, from whence counterattacks might be launched. MacArthur recognized the need for cryptologic support, thus, on 15 April 1942, he established the Central Bureau

Central Bureau

The Central Bureau was one of two Allied Sigint organisations in the South West Pacific area during World War II. Central Bureau was attached to the HQ of the Allied Commander of the South West Pacific area, Douglas MacArthur. The other unit was the joint RAN/USN Fleet Radio Unit, Melbourne ,...

 (CBB), cobbling it together from refugee elements of American cryptologists evacuated from the Philippines, Australian cryptologists, and other Allied contingents. CBB began in Melbourne

Melbourne

Melbourne is the capital and most populous city in the state of Victoria, and the second most populous city in Australia. The Melbourne City Centre is the hub of the greater metropolitan area and the Census statistical division—of which "Melbourne" is the common name. As of June 2009, the greater...

, then moved to Brisbane

Brisbane

Brisbane is the capital and most populous city in the Australian state of Queensland and the third most populous city in Australia. Brisbane's metropolitan area has a population of over 2 million, and the South East Queensland urban conurbation, centred around Brisbane, encompasses a population of...

.

In July 1942, by now major

Major (United States)

In the United States Army, Air Force, and Marine Corps, major is a field grade military officer rank just above the rank of captain and just below the rank of lieutenant colonel...

 Sinkov arrived in Melbourne as commander of the American detachment at Central Bureau

Central Bureau

The Central Bureau was one of two Allied Sigint organisations in the South West Pacific area during World War II. Central Bureau was attached to the HQ of the Allied Commander of the South West Pacific area, Douglas MacArthur. The other unit was the joint RAN/USN Fleet Radio Unit, Melbourne ,...

. The Director of CBB on paper was General Spencer B. Akin, MacArthur's chief signal officer, but General Akin in practice seldom visited the organization. He had worked with Sinkov in Washington and in Panama

Panama

Panama , officially the Republic of Panama , is the southernmost country of Central America. Situated on the isthmus connecting North and South America, it is bordered by Costa Rica to the northwest, Colombia to the southeast, the Caribbean Sea to the north and the Pacific Ocean to the south. The...

, and confidently left CBB operations under his control.

Dr. Sinkov, who demonstrated strong organizational and leadership qualities in addition to his mathematics skills, brought this group of Americans and Australians—representing also different military services from their countries—into a cohesive unit. CBB quickly became a trusted producer of Signals Intelligence (SIGINT) for MacArthur and his senior commanders. This SIGINT enabled consistent success in the air war against the Japanese and allowed MacArthur to win some stunning victories in the ground campaign in New Guinea

New Guinea

New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...

 and the Philippines.

Post-war

After the war, Sinkov rejoined SIS, now renamed the Army Security Agency, and, in 1949, when the Armed Forces Security Agency (AFSA) -- the first centralized cryptologic organization in the United States—was formed, Sinkov became chief of the Communications Security program. He remained in this position as AFSA made the transition into 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...

.

In 1954, Dr. Sinkov became the second NSA official to attend the National War College

National War College

The National War College of the United States is a school in the National Defense University. It is housed in Roosevelt Hall on Fort Lesley J. McNair, Washington, D.C., the third-oldest Army post still active. It was officially established on July 1, 1946, as an upgraded replacement for the...

 (the first was Dr. Louis Tordella). Upon his return, he became Deputy Director for Production, effectively swapping jobs with his old colleague Frank Rowlett

Frank Rowlett

Frank Byron Rowlett was an American cryptologist.Rowlett was born in Rose Hill, Virginia and attended Emory & Henry College in Emory, Virginia, where he was a member of the Beta Lambda Zeta fraternity. In 1929 he received a bachelor's degree in mathematics and chemistry...

. Dr. Sinkov retired from NSA in 1962.

In 1966, he wrote Elementary Cryptanalysis: A Mathematical Approach. Published by the Mathematical Association of America, it was one of the first books on the subject available to the general public.

Retirement

Dr. Abraham Sinkov lived in retirement in Arizona

Arizona

Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...

 after two careers, 32 years in NSA (and its predecessors), followed by an appointment as a professor of mathematics at Arizona State University

Arizona State University

Arizona State University is a public research university located in the Phoenix Metropolitan Area of the State of Arizona...

.

Books written

• Sinkov, Abraham. Elementary cryptanalysis :a mathematical approach, Mathematical Association of America, Washington, D.C. ISBN 0-88385-622-0