Abraham Sinkov (August 22, 1907 – January 19, 1998) was a US
cryptanalyst
Cryptanalysis (from the Greek ''kryptós'', "hidden", and ''analýein'', "to analyze") refers to the process of analyzing information systems in order to understand hidden aspects of the systems. Cryptanalysis is used to breach cryptographic sec ...
. An early employee of the U.S. Army's
Signals Intelligence Service
The Signal Intelligence Service (SIS) was the United States Army codebreaking division through World War II. It was founded in 1930 to compile codes for the Army. It was renamed the Signal Security Agency in 1943, and in September 1945, became th ...
, he held several leadership positions during World War II, transitioning to the new
National Security Agency
The National Security Agency (NSA) is a national-level intelligence agency of the United States Department of Defense, under the authority of the Director of National Intelligence (DNI). The NSA is responsible for global monitoring, collecti ...
after the war, where he became a deputy director. After retiring in 1962, he taught mathematics at
Arizona State University
Arizona State University (Arizona State or ASU) is a public research university in the Phoenix metropolitan area. Founded in 1885 by the 13th Arizona Territorial Legislature, ASU is one of the largest public universities by enrollment in the ...
.
Biography
Sinkov was the son of Jewish immigrants Morris (Mordechai Eliezer) and Ethel (née Etel Constantinowsky) from Alexandria,
Russia
Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...
, which is now
Oleksandriya
Oleksandriia () is a city located in Oleksandriia Raion, Kirovohrad Oblast (region) in central Ukraine. Administratively, Oleksandriia serves as the administrative center of Oleksandriia Raion (district). Oleksandriia also hosts the administrat ...
,
Kirovohrad Oblast
Kirovohrad Oblast ( uk, Кіровоградська область, translit=Kirovohradska oblast; also referred to as #Nomenclature, Kirovohradschyna — uk, Кіровоградщина) is an administrative divisions of Ukraine, oblast (prov ...
,
Ukraine
Ukraine ( uk, Україна, Ukraïna, ) is a country in Eastern Europe. It is the second-largest European country after Russia, which it borders to the east and northeast. Ukraine covers approximately . Prior to the ongoing Russian inv ...
.
Sinkov was born in
Philadelphia
Philadelphia, often called Philly, is the largest city in the Commonwealth of Pennsylvania, the sixth-largest city in the U.S., the second-largest city in both the Northeast megalopolis and Mid-Atlantic regions after New York City. Sinc ...
, but grew up in
Brooklyn
Brooklyn () is a borough of New York City, coextensive with Kings County, in the U.S. state of New York. Kings County is the most populous county in the State of New York, and the second-most densely populated county in the United States, be ...
. After graduating from
Boys High School
Single-sex education, also known as single-gender education and gender-isolated education, is the practice of conducting education with male and female students attending separate classes, perhaps in separate buildings or schools. The practice of ...
he took his B.S. in
mathematics
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...
from
City College of New York
The City College of the City University of New York (also known as the City College of New York, or simply City College or CCNY) is a public university within the City University of New York (CUNY) system in New York City. Founded in 1847, Cit ...
. (By coincidence, one of his close friends at Boys High and CCNY was
Solomon Kullback
Solomon Kullback (April 3, 1907August 5, 1994) 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 (SIS) in the 1930s, along with Frank ...
). Mr. Sinkov taught in
New York City
New York, often called New York City or NYC, is the List of United States cities by population, most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the L ...
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 commonly refers to:
* Washington (state), United States
* Washington, D.C., the capital of the United States
** A metonym for the federal government of the United States
** Washington metropolitan area, the metropolitan area centered o ...
asking about their knowledge of foreign languages. Sinkov knew
French and Kullback,
Spanish
Spanish might refer to:
* Items from or related to Spain:
**Spaniards are a nation and ethnic group indigenous to Spain
**Spanish language, spoken in Spain and many Latin American countries
**Spanish cuisine
Other places
* Spanish, Ontario, Cana ...
. 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
The Signal Intelligence Service (SIS) was the United States Army codebreaking division through World War II. It was founded in 1930 to compile codes for the Army. It was renamed the Signal Security Agency in 1943, and in September 1945, became th ...
(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
The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cl ...
. 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
William Frederick Friedman (September 24, 1891 – November 12, 1969) was a US Army cryptographer who ran the research division of the Army's Signal Intelligence Service (SIS) in the 1930s, and parts of its follow-on services into the 1950s. In ...
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 PhD in mathematics in 1933 from The
George Washington University
, mottoeng = "God is Our Trust"
, established =
, type = Private federally chartered research university
, academic_affiliations =
, endowment = $2.8 billion (2022)
, preside ...
. In 1936, Sinkov was assigned to the
Panama Canal Zone
The Panama Canal Zone ( es, Zona del Canal de Panamá), also simply known as the Canal Zone, was an unincorporated territory of the United States, located in the Isthmus of Panama, that existed from 1903 to 1979. It was located within the terr ...
, where he established the U.S. Army's first permanent intercept site outside the
continental United States
The contiguous United States (officially the conterminous United States) consists of the 48 adjoining U.S. states and the Federal District of the United States of America. The term excludes the only two non-contiguous states, Alaska and Hawaii ...
.
World War II
SIS grew slowly throughout the early 1930s. However, successes against
Japanese diplomatic codes using 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
Britain most often refers to:
* The United Kingdom, a sovereign state in Europe comprising the island of Great Britain, the north-eastern part of the island of Ireland and many smaller islands
* Great Britain, the largest island in the United King ...
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 communication intelligence (
COMINT
Signals intelligence (SIGINT) is intelligence-gathering by interception of ''signals'', whether communications between people (communications intelligence—abbreviated to COMINT) or from electronic signals not directly used in communication ( ...
) between the two countries during the war, resulting in more personnel, bigger budgets, and a wider range of activities for the organization.
Sinkov mission
In January 1941, while Britain battled
Nazi Germany
Nazi Germany (lit. "National Socialist State"), ' (lit. "Nazi State") for short; also ' (lit. "National Socialist Germany") (officially known as the German Reich from 1933 until 1943, and the Greater German Reich from 1943 to 1945) was ...
but nearly a year before the United States entered the
Second World War
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
,
Captain
Captain is a title, an appellative for the commanding officer of a military unit; the supreme leader of a navy ship, merchant ship, aeroplane, spacecraft, or other vessel; or the commander of a port, fire or police department, election precinct, e ...
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 is an English country house and estate in Bletchley, Milton Keynes ( Buckinghamshire) that became the principal centre of Allied code-breaking during the Second World War. The mansion was constructed during the years following ...
, the secret headquarters for British cryptology, and exchanged information on
German
German(s) may refer to:
* Germany (of or related to)
**Germania (historical use)
* Germans, citizens of Germany, people of German ancestry, or native speakers of the German language
** For citizens of Germany, see also German nationality law
**Ger ...
and Japanese systems. It is still unclear how much the American delegation was told about British success against the German
Enigma machine, 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.
![Central Bureau of Intelligence directors](https://upload.wikimedia.org/wikipedia/commons/5/55/Central_Bureau_of_Intelligence_directors.jpg)
After the Japanese
attack on Pearl Harbor
The attack on Pearl HarborAlso known as the Battle of Pearl Harbor was a surprise military strike by the Imperial Japanese Navy Air Service upon the United States against the naval base at Pearl Harbor in Honolulu, Territory of Hawaii, j ...
on December 7, 1941, the Japanese also attacked the
Philippine Islands
The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no),
* bik, Republika kan Filipinas
* ceb, Republika sa Pilipinas
* cbk, República de Filipinas
* hil, Republ ...
.
General
A general officer is an Officer (armed forces), officer of highest military ranks, high rank in the army, armies, and in some nations' air forces, space forces, and marines or naval infantry.
In some usages the term "general officer" refers t ...
Douglas MacArthur
Douglas MacArthur (26 January 18805 April 1964) was an American military leader who served as General of the Army for the United States, as well as a field marshal to the Philippine Army. He had served with distinction in World War I, was C ...
had been ordered to leave the Philippines and re-establish U.S. Army headquarters in
Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
, from whence counterattacks might be launched. MacArthur recognized the need for cryptologic support, thus, on 15 April 1942, he established the
Central Bureau The Central Bureau was one of two Allied signals intelligence (SIGINT) organisations in the South West Pacific area (SWPA) during World War II. Central Bureau was attached to the headquarters of the Allied Commander of the South West Pacific area ...
(CB), cobbling it together from refugee elements of American cryptologists evacuated from the Philippines, Australian cryptologists, and other
Allied
An alliance is a relationship among people, groups, or states that have joined together for mutual benefit or to achieve some common purpose, whether or not explicit agreement has been worked out among them. Members of an alliance are called ...
contingents. CB began in
Melbourne
Melbourne ( ; Boonwurrung/Woiwurrung: ''Narrm'' or ''Naarm'') is the capital and most populous city of the Australian state of Victoria, and the second-most populous city in both Australia and Oceania. Its name generally refers to a met ...
, then moved to
Brisbane
Brisbane ( ) is the capital and most populous city of the states and territories of Australia, Australian state of Queensland, and the list of cities in Australia by population, third-most populous city in Australia and Oceania, with a populati ...
.
In July 1942, by now
Major
Major (commandant in certain jurisdictions) is a military rank of commissioned officer status, with corresponding ranks existing in many military forces throughout the world. When used unhyphenated and in conjunction with no other indicators ...
Sinkov arrived in Melbourne as commander of the American detachment at
Central Bureau The Central Bureau was one of two Allied signals intelligence (SIGINT) organisations in the South West Pacific area (SWPA) during World War II. Central Bureau was attached to the headquarters of the Allied Commander of the South West Pacific area ...
. The Director of CB 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 ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Cos ...
, and confidently left CB operations under his control.
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. CB quickly became a trusted producer of
Signals Intelligence
Signals intelligence (SIGINT) is intelligence-gathering by interception of ''signals'', whether communications between people (communications intelligence—abbreviated to COMINT) or from electronic signals not directly used in communication ( ...
(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 (; Hiri Motu
Hiri Motu, also known as Police Motu, Pidgin Motu, or just Hiri, is a language of Papua New Guinea, which is spoken in surrounding areas of Port Moresby (Capital of Papua New Guinea).
It is a simplified version of ...
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
The National Security Agency (NSA) is a national-level intelligence agency of the United States Department of Defense, under the authority of the Director of National Intelligence (DNI). The NSA is responsible for global monitoring, collectio ...
(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
The National Security Agency (NSA) is a national-level intelligence agency of the United States Department of Defense, under the authority of the Director of National Intelligence (DNI). The NSA is responsible for global monitoring, collecti ...
.
In 1954, Sinkov became the second NSA official to attend the
National War College
The National War College (NWC) 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.
History
The National War Colle ...
(the first was
Louis Tordella). Upon his return, he became deputy director for production, effectively swapping jobs with his old colleague
Frank Rowlett
Frank Byron Rowlett (May 2, 1908 – June 29, 1998) was an American cryptologist.
Life and career
Rowlett was born in Rose Hill, Lee County, Virginia and attended Emory & Henry College in Emory, Virginia. In 1929 he received a bachelor's d ...
. Sinkov retired from NSA in 1962.
In 1966, he wrote ''Elementary Cryptanalysis: A Mathematical Approach'', one of the first books on the subject, directed at high school students and available to the general public.
Retirement
Abraham Sinkov lived in retirement in
Arizona
Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...
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 or ASU) is a public research university in the Phoenix metropolitan area. Founded in 1885 by the 13th Arizona Territorial Legislature, ASU is one of the largest public universities by enrollment in the ...
.
Hall of fame
Colonel Sinkov is a member of the
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. The hall is ...
.
Books written
* Abraham Sinkov (1966), ''Elementary Cryptanalysis: A Mathematical Approach'', Mathematical Association of America, Washington, D.C. . 2nd edition, revised and updated by Todd Feil (2009), Mathematical Association of America, Washington, D.C. (print), (electronic).
References
NSA Hall of Honor entry for Sinkov(public domain; a previous version of this article was derived from this NSA work)
{{DEFAULTSORT:Sinkov, Abraham
1907 births
1998 deaths
Arizona State University faculty
National Security Agency cryptographers
Signals Intelligence Service cryptographers
City College of New York alumni
Columbian College of Arts and Sciences alumni
20th-century American mathematicians
United States Army colonels
United States Army personnel of World War II
Boys High School (Brooklyn) alumni
Military personnel from Philadelphia
Mathematicians from New York (state)