List of cryptographers
Encyclopedia
Pre twentieth century
- Al-KindiAl-Kindi' , known as "the Philosopher of the Arabs", was a Muslim Arab philosopher, mathematician, physician, and musician. Al-Kindi was the first of the Muslim peripatetic philosophers, and is unanimously hailed as the "father of Islamic or Arabic philosophy" for his synthesis, adaptation and promotion...
, 9th century Arabic polymath and originator of frequency analysisFrequency analysisIn cryptanalysis, frequency analysis is the study of the frequency of letters or groups of letters in a ciphertext. The method is used as an aid to breaking classical ciphers.... - Charles BabbageCharles BabbageCharles Babbage, FRS was an English mathematician, philosopher, inventor and mechanical engineer who originated the concept of a programmable computer...
, UKUnited KingdomThe 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...
, 19th century mathematicianMathematicianA mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....
who, about the time of the Crimean WarCrimean WarThe Crimean War was a conflict fought between the Russian Empire and an alliance of the French Empire, the British Empire, the Ottoman Empire, and the Kingdom of Sardinia. The war was part of a long-running contest between the major European powers for influence over territories of the declining...
, secretly developed an effective attack against polyalphabetic substitution ciphers. - Leone Battista AlbertiLeone Battista AlbertiLeon Battista Alberti was an Italian author, artist, architect, poet, priest, linguist, philosopher, cryptographer and general Renaissance humanist polymath...
, polymathPolymathA polymath is a person whose expertise spans a significant number of different subject areas. In less formal terms, a polymath may simply be someone who is very knowledgeable...
/universal geniusGeniusGenius is something or someone embodying exceptional intellectual ability, creativity, or originality, typically to a degree that is associated with the achievement of unprecedented insight....
, inventor of polyalphabetic substitution (more specifically, the Alberti cipherAlberti cipher- Leon Battista Alberti :Created in the 15th century , it was the peak of cryptography at that time. Its inventor was Leon Battista Alberti, an illegitimate son of an Italian nobleman. He was also interested in painting and writing, though he is probably best known for his architecture...
), and what may have been the first mechanical encryption aid. - Giovanni Battista della Porta, author of a seminal work on cryptanalysisCryptanalysisCryptanalysis 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...
. - Étienne BazeriesÉtienne BazeriesÉtienne Bazeries was a French military cryptanalyst active between 1890 and the First World War. He is best known for developing the "Bazeries Cylinder", an improved version of Thomas Jefferson's cipher cylinder. It was later refined into the US Army M-94 cipher device. Historian David Kahn...
, French, military, considered one of the greatest natural cryptanalysts. Best known for developing the "Bazeries CylinderJefferson diskThe Jefferson disk, or wheel cypher as Jefferson named it, also known as the Bazeries Cylinder, is a cipher system using a set of wheels or disks, each with the 26 letters of the alphabet arranged around their edge. The order of the letters is different for each disk and is usually scrambled in...
" and his influential 1901 text Les Chiffres secrets dévoilés ("Secret ciphers unveiled"). - Julius CaesarJulius CaesarGaius Julius Caesar was a Roman general and statesman and a distinguished writer of Latin prose. He played a critical role in the gradual transformation of the Roman Republic into the Roman Empire....
, Roman generalGeneralA general officer is an officer of high military rank, usually in the army, and in some nations, the air force. The term is widely used by many nations of the world, and when a country uses a different term, there is an equivalent title given....
/politicianPoliticianA politician, political leader, or political figure is an individual who is involved in influencing public policy and decision making...
, has the Caesar cipherCaesar cipherIn cryptography, a Caesar cipher, also known as a Caesar's cipher, the shift cipher, Caesar's code or Caesar shift, is one of the simplest and most widely known encryption techniques. It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number...
is named after him, and a lost workLost workA lost work is a document or literary work produced some time in the past of which no surviving copies are known to exist. Works may be lost to history either through the destruction of the original manuscript, or through the non-survival of any copies of the work. Deliberate destruction of works...
on cryptography by Probus (probably Valerius Probus) is claimed to have covered his use of military cryptography in some detail. It is likely that he did not invent the cipher named after him, as other substitution cipherSubstitution cipherIn cryptography, a substitution cipher is a method of encryption by which units of plaintext are replaced with ciphertext according to a regular system; the "units" may be single letters , pairs of letters, triplets of letters, mixtures of the above, and so forth...
s were in use well before his time. - Friedrich KasiskiFriedrich KasiskiMajor Friedrich Wilhelm Kasiski was a Prussian infantry officer, cryptographer and archeologist. Kasiski was born in Schlochau, West Prussia .-Military service:...
, author of the first published attack on the Vigenère cipherVigenère cipherThe Vigenère cipher is a method of encrypting alphabetic text by using a series of different Caesar ciphers based on the letters of a keyword. It is a simple form of polyalphabetic substitution....
, now known as the Kasiski test. - Auguste KerckhoffsAuguste KerckhoffsAuguste Kerckhoffs was a Dutch linguist and cryptographer who was professor of languages at the École des Hautes Études Commerciales in Paris in the late 19th century....
, known for contributing cipher design principles. - Johannes TrithemiusJohannes TrithemiusJohannes Trithemius , born Johann Heidenberg, was a German abbot, lexicographer, historian, cryptographer, polymath and occultist who had an influence on later occultism. The name by which he is more commonly known is derived from his native town of Trittenheim on the Mosel in Germany.-Life:He...
, mystic and first to describe tableaux (tables) for use in polyalphabetic substitution. Wrote an early work on steganographySteganographySteganography is the art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message, a form of security through obscurity...
and cryptography generally. - Philips van Marnix, lord of Sint-AldegondePhilips van Marnix, lord of Sint-AldegondePhilips of Marnix, Lord of Saint-Aldegonde, Lord of West-Souburg was a Flemish and Dutch writer and statesman, and the probable author of the text of the Dutch national anthem, the Wilhelmus.He was...
, deciphered Spanish messages for William the Silent during the Dutch revolt against the Spanish. - Sir Charles WheatstoneCharles WheatstoneSir Charles Wheatstone FRS , was an English scientist and inventor of many scientific breakthroughs of the Victorian era, including the English concertina, the stereoscope , and the Playfair cipher...
, inventor of the so-called Playfair cipherPlayfair cipherThe Playfair cipher or Playfair square is a manual symmetric encryption technique and was the first literal digraph substitution cipher. The scheme was invented in 1854 by Charles Wheatstone, but bears the name of Lord Playfair who promoted the use of the cipher.The technique encrypts pairs of...
and general polymath.
World War I and World War II Wartime Cryptographers
- Lambros D. CallimahosLambros D. CallimahosLambros Demetrios Callimahos was a US Army cryptologist. Born in Alexandria of Greek parents, the family emigrated to the United States when he was four...
, US, NSA, worked with William F. Friedman, taught NSA cryptanalysts - Ludomir Danielewicz, PolandPolandPoland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
, Biuro SzyfrowBiuro SzyfrówThe Biuro Szyfrów was the interwar Polish General Staff's agency charged with both cryptography and cryptology ....
, helped to construct the Enigma maschine copies to break the ciphers - Alastair DennistonAlastair DennistonCommander Alexander Guthrie Denniston CMG CBE RNVR was a British codebreaker in Room 40 and first head of the Government Code and Cypher School and field hockey player...
, UK, director of GC&CS at Bletchley ParkBletchley ParkBletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Museum of Computing...
during World War II - William F. FriedmanWilliam F. FriedmanWilliam Frederick Friedman was a US Army cryptographer who ran the research division of the Army's Signals Intelligence Service in the 1930s, and parts of its follow-on services into the 1950s...
, US, SISSignals Intelligence ServiceThe 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...
, introduced statistical methods into cryptographyCryptographyCryptography is the practice and study of techniques for secure communication in the presence of third parties... - Nigel de GreyNigel de GreyNigel de Grey , CMG, OBE, British codebreaker. Son of the rector of Copdock, Suffolk, and grandson of the 5th Lord Walsingham, he was educated at Eton College and became fluent in French and German. In 1907 he joined the publishing firm of William Heinemann. He married in 1910...
, UK, Room 40Room 40In the history of Cryptanalysis, Room 40 was the section in the Admiralty most identified with the British cryptoanalysis effort during the First World War.Room 40 was formed in October 1914, shortly after the start of the war...
, played an important role in the decryption of the Zimmermann TelegramZimmermann TelegramThe Zimmermann Telegram was a 1917 diplomatic proposal from the German Empire to Mexico to make war against the United States. The proposal was caught by the British before it could get to Mexico. The revelation angered the Americans and led in part to a U.S...
during World War I - Dillwyn Knox, UK, Room 40Room 40In the history of Cryptanalysis, Room 40 was the section in the Admiralty most identified with the British cryptoanalysis effort during the First World War.Room 40 was formed in October 1914, shortly after the start of the war...
and GC&CS, broke commercial Enigma cipher in various situations - Solomon KullbackSolomon KullbackSolomon 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...
, US, SISSignals Intelligence ServiceThe 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... - Frank W. LewisFrank W. LewisFrank Waring Lewis was an American cryptographer and cryptic crossword compiler. His puzzles were printed in The Nation for over 60 years, for a total of 2,962 puzzles...
, US, worked with William F. Friedman, puzzle master - William Hamilton Martin and Bernon F. MitchellMartin and Mitchell DefectionThe Martin and Mitchell Defection occurred in September 1960 when two National Security Agency cryptologists, William Hamilton Martin and Bernon F. Mitchell, defected to the Soviet Union...
, U.S. National Security AgencyNational Security AgencyThe 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...
cryptologists who defected to the Soviet Union in 1960 - Leo MarksLeo MarksLeopold Samuel Marks was an English cryptographer, screenwriter and playwright.-Early life:Born the son of an antiquarian bookseller in London, he was first introduced to cryptography when his father showed him a copy of Edgar Allan Poe's story, "The Gold-Bug"...
, UK, SOESpecial Operations ExecutiveThe Special Operations Executive was a World War II organisation of the United Kingdom. It was officially formed by Prime Minister Winston Churchill and Minister of Economic Warfare Hugh Dalton on 22 July 1940, to conduct guerrilla warfare against the Axis powers and to instruct and aid local...
cryptography director, author and playwright - Georges PainvinGeorges PainvinGeorges Jean Painvin was a French cryptanalyst during the First World War. His most notable achievement was the breaking of the ADFGVX cipher in June 1918.Before the First World War, Painvin taught paleontology and geology...
, broke the ADFGVX cipherADFGVX cipherIn cryptography, the ADFGVX cipher was a field cipher used by the German Army during World War I. ADFGVX was in fact an extension of an earlier cipher called ADFGX. Invented by Colonel Fritz Nebel and introduced in March 1918, the cipher was a fractionating transposition cipher which combined a...
during the First World War - Marian RejewskiMarian RejewskiMarian Adam Rejewski was a Polish mathematician and cryptologist who in 1932 solved the plugboard-equipped Enigma machine, the main cipher device used by Germany...
, PolandPolandPoland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
, Biuro SzyfrówBiuro SzyfrówThe Biuro Szyfrów was the interwar Polish General Staff's agency charged with both cryptography and cryptology ....
, a Polish mathematician and cryptologist who, in 1932, solved the Enigma machineEnigma machineAn 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...
with plugboard, the main cipher device then in use by Germany. - John Joseph Rochefort, US, made major contributions to the break into JN-25JN-25The vulnerability of Japanese naval codes and ciphers was crucial to the conduct of World War II, and had an important influence on foreign relations between Japan and the west in the years leading up to the war as well...
after the attack on Pearl HarborAttack on Pearl HarborThe 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... - Frank RowlettFrank RowlettFrank 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...
, US, SISSignals Intelligence ServiceThe 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...
, leader of the team that broke PurplePurplePurple is a range of hues of color occurring between red and blue, and is classified as a secondary color as the colors are required to create the shade.... - Jerzy RóżyckiJerzy RózyckiJerzy Witold Różycki was a Polish mathematician and cryptologist who worked at breaking German Enigma-machine ciphers.-Life:Różycki was born in what is now Ukraine, the fourth and youngest child of Zygmunt Różycki, a pharmacist and graduate of Saint Petersburg University, and Wanda, née Benita. ...
, PolandPolandPoland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
, Biuro SzyfrówBiuro SzyfrówThe Biuro Szyfrów was the interwar Polish General Staff's agency charged with both cryptography and cryptology ....
, helped break German Enigma ciphers - Luigi SaccoLuigi SaccoLuigi Sacco was an Italian general and cryptanalyst.-References:...
, ItalyItalyItaly , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
, Italian General and author of the Manual of Cryptography - Laurance SaffordLaurance SaffordCaptain Laurance F. Safford was a U.S. Navy cryptologist. He established the Naval cryptologic organization after World War I, and headed the effort more or less constantly until shortly after the Japanese attack on Pearl Harbor. His identification with the Naval effort was so close that he was...
, US, chief cryptographer for the US Navy for 2 decades+, including World War II - Abraham SinkovAbraham SinkovDr. 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...
, US, SISSignals Intelligence ServiceThe 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... - John Tiltman, Brigadier, UK, GC&CS, Bletchley ParkBletchley ParkBletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Museum of Computing...
, GCHQ, NSA. Extraordinary length and range of cryptographic service - Alan Mathison TuringAlan TuringAlan Mathison Turing, OBE, FRS , was an English mathematician, logician, cryptanalyst, and computer scientist. He was highly influential in the development of computer science, providing a formalisation of the concepts of "algorithm" and "computation" with the Turing machine, which played a...
, UK, Bletchley ParkBletchley ParkBletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Museum of Computing...
, chief cryptographer Bletchley ParkBletchley ParkBletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Museum of Computing...
, pioneering logician, and renowned computer scientistComputer scienceComputer science or computing science is the study of the theoretical foundations of information and computation and of practical techniques for their implementation and application in computer systems...
, and pioneer - William Thomas TutteW. T. TutteWilliam Thomas Tutte, OC, FRS, known as Bill Tutte, was a British, later Canadian, codebreaker and mathematician. During World War II he made a brilliant and fundamental advance in Cryptanalysis of the Lorenz cipher, a major German code system, which had a significant impact on the Allied...
, UK, Bletchley ParkBletchley ParkBletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Museum of Computing...
, broke Lorenz SZ 40/42 encryption machine (codenamed Tunny) using theory carried out using the Colossus computerColossus computerNot to be confused with the fictional computer of the same name in the movie Colossus: The Forbin Project.Colossus was the world's first electronic, digital, programmable computer. Colossus and its successors were used by British codebreakers to help read encrypted German messages during World War II... - Gordon WelchmanGordon WelchmanGordon Welchman was a British-American mathematician, university professor, World War II codebreaker at Bletchley Park, and author.-Education and early career:...
, UK, head of Bletchley ParkBletchley ParkBletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Museum of Computing...
's Hut Six (German Army and Air Force cipherCipherIn 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...
decryption). - Herbert YardleyHerbert YardleyHerbert Osborne Yardley was an American cryptologist best known for his book The American Black Chamber . The title of the book refers to the Cipher Bureau, the cryptographic organization of which Yardley was the founder and head...
, US, MI8MI8MI8, or Military Intelligence, Section 8, was the cover designation for the Radio Security Service , a department of the British Directorate of Military Intelligence, part of the War Office...
, author "The American Black Chamber", worked in China as a cryptographer and briefly in Canada - Henryk ZygalskiHenryk ZygalskiHenryk Zygalski was a Polish mathematician and cryptologist who worked at breaking German Enigma ciphers before and during World War II.-Life:...
, PolandPolandPoland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
, Biuro SzyfrówBiuro SzyfrówThe Biuro Szyfrów was the interwar Polish General Staff's agency charged with both cryptography and cryptology ....
, helped break German EnigmaEnigma machineAn 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...
ciphers
Other pre-computer
- Rosario CandelaRosario CandelaRosario Candela was an Italian American architect who achieved renown through his apartment building designs in New York City, primarily during the boom years of the 1920s. He is credited with defining the city's characteristic terraced setbacks and signature penthouses. Over time, Candela's...
, US, Architect and notable amateur cryptologist who authored books and taught classes on the subject to civilians at Hunter CollegeHunter CollegeHunter College, established in 1870, is a public university and one of the constituent colleges of the City University of New York, located on Manhattan's Upper East Side. Hunter grants undergraduate, graduate, and post-graduate degrees in more than one hundred fields of study, and is recognized...
. - Elizebeth FriedmanElizebeth FriedmanElizebeth Smith Friedman was a cryptanalyst and author, and a pioneer in U.S. cryptography. The special spelling of her name is attributed to her mother, who disliked the prospect of Elizebeth ever being called "Eliza." She has been dubbed "America's first female cryptanalyst".Although she is...
, US, Coast GuardUnited States Coast GuardThe United States Coast Guard is a branch of the United States Armed Forces and one of the seven U.S. uniformed services. The Coast Guard is a maritime, military, multi-mission service unique among the military branches for having a maritime law enforcement mission and a federal regulatory agency...
and US Treasury DepartmentUnited States Department of the TreasuryThe Department of the Treasury is an executive department and the treasury of the United States federal government. It was established by an Act of Congress in 1789 to manage government revenue...
cryptographer. - Claude Elwood ShannonClaude Elwood ShannonClaude Elwood Shannon was an American mathematician, electronic engineer, and cryptographer known as "the father of information theory"....
, US, founder of information theoryInformation theoryInformation theory is a branch of applied mathematics and electrical engineering involving the quantification of information. Information theory was developed by Claude E. Shannon to find fundamental limits on signal processing operations such as compressing data and on reliably storing and...
, proved the one-time padOne-time padIn cryptography, the one-time pad is a type of encryption, which has been proven to be impossible to crack if used correctly. Each bit or character from the plaintext is encrypted by a modular addition with a bit or character from a secret random key of the same length as the plaintext, resulting...
to be unbreakable.
Modern
See also: Category:Modern cryptographers for an exhaustive list.Symmetric-key algorithm inventors
- Ross Anderson, UK, University of CambridgeUniversity of CambridgeThe University of Cambridge is a public research university located in Cambridge, United Kingdom. It is the second-oldest university in both the United Kingdom and the English-speaking world , and the seventh-oldest globally...
, co-inventor of the SerpentSerpent (cipher)Serpent is a symmetric key block cipher which was a finalist in the Advanced Encryption Standard contest, where it came second to Rijndael. Serpent was designed by Ross Anderson, Eli Biham, and Lars Knudsen....
cipher. - Paulo S. L. M. BarretoPaulo S. L. M. BarretoPaulo S. L. M. Barreto is a Brazilian cryptographer and one of the designers of the Whirlpool hash function and the block ciphers Anubis and KHAZAD, together with Vincent Rijmen...
, BrazilBrazilBrazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
ian, University of São PauloUniversity of São PauloUniversidade de São Paulo is a public university in the Brazilian state of São Paulo. It is the largest Brazilian university and one of the country's most prestigious...
, co-inventor of the Whirlpool hash function. - George BlakleyGeorge BlakleyGeorge Robert Blakley Jr. is an American cryptographer and a professor of mathematics at Texas A&M University, best known for inventing a secret sharing scheme in 1979.-Biography:...
, US, independent inventor of secret sharingSecret sharingSecret sharing refers to method for distributing a secret amongst a group of participants, each of whom is allocated a share of the secret. The secret can be reconstructed only when a sufficient number of shares are combined together; individual shares are of no use on their own.More formally, in a...
. - Eli BihamEli BihamEli Biham is an Israeli cryptographer and cryptanalyst, currently a professor at the Technion Israeli Institute of Technology Computer Science department. Starting from October 2008, Biham is the dean of the Technion Computer Science department, after serving for two years as chief of CS graduate...
, Israel, co-inventor of the SerpentSerpent (cipher)Serpent is a symmetric key block cipher which was a finalist in the Advanced Encryption Standard contest, where it came second to Rijndael. Serpent was designed by Ross Anderson, Eli Biham, and Lars Knudsen....
cipher. - Don CoppersmithDon CoppersmithDon Coppersmith is a cryptographer and mathematician. He was involved in the design of the Data Encryption Standard block cipher at IBM, particularly the design of the S-boxes, strengthening them against differential cryptanalysis...
, co-inventor of DESData Encryption StandardThe Data Encryption Standard is a block cipher that uses shared secret encryption. It was selected by the National Bureau of Standards as an official Federal Information Processing Standard for the United States in 1976 and which has subsequently enjoyed widespread use internationally. It is...
and MARS ciphers. - Joan DaemenJoan DaemenJoan Daemen |Limburg]], Belgium) is a Belgian cryptographer and one of the designers of Rijndael, the Advanced Encryption Standard , together with Vincent Rijmen. He has also designed or co-designed the MMB, Square, SHARK, NOEKEON, 3-Way, and BaseKing block ciphers...
, BelgianBelgiumBelgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...
, co-developer of Rijndael which became the Advanced Encryption StandardAdvanced Encryption StandardAdvanced Encryption Standard is a specification for the encryption of electronic data. It has been adopted by the U.S. government and is now used worldwide. It supersedes DES...
(AES). - Horst FeistelHorst FeistelHorst Feistel was a German-born cryptographer who worked on the design of ciphers at IBM, initiating research that would culminate in the development of the Data Encryption Standard in the 1970s....
, US, IBMIBMInternational Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
, namesake of Feistel networks. - Lars KnudsenLars KnudsenLars Ramkilde Knudsen is a Danish researcher in cryptography, particularly interested in the design and analysis of block ciphers, hash functions and message authentication codes .-Academic:...
, DenmarkDenmarkDenmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
, co-inventor of the SerpentSerpent (cipher)Serpent is a symmetric key block cipher which was a finalist in the Advanced Encryption Standard contest, where it came second to Rijndael. Serpent was designed by Ross Anderson, Eli Biham, and Lars Knudsen....
cipher. - Ralph MerkleRalph MerkleRalph C. Merkle is a researcher in public key cryptography, and more recently a researcher and speaker on molecular nanotechnology and cryonics...
, US, inventor of Merkle treesHash treeIn cryptography and computer science Hash trees or Merkle trees are a type of data structure which contains a tree of summary information about a larger piece of data – for instance a file – used to verify its contents. Hash trees are a combination of hash lists and hash chaining, which in turn are...
. - Bart PreneelBart PreneelBart Preneel is a Belgian cryptographer and cryptanalyst. He is a professor at Katholieke Universiteit Leuven, in the COSIC group, president of the International Association for Cryptologic Research, and project manager of ECRYPT....
, BelgianBelgiumBelgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...
, co-inventor of RIPEMD-160. - Vincent RijmenVincent RijmenVincent Rijmen is a Belgian cryptographer and one of the two designers of the Rijndael, the Advanced Encryption Standard. Rijmen is also the co-designer of the WHIRLPOOL cryptographic hash function, and the block ciphers Anubis, KHAZAD, Square, NOEKEON and SHARK.In 1993, Rijmen obtained a degree...
, BelgianBelgiumBelgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...
, co-developer of Rijndael which became the Advanced Encryption StandardAdvanced Encryption StandardAdvanced Encryption Standard is a specification for the encryption of electronic data. It has been adopted by the U.S. government and is now used worldwide. It supersedes DES...
(AES). - Ronald L. RivestRon RivestRonald Linn Rivest is a cryptographer. He is the Andrew and Erna Viterbi Professor of Computer Science at MIT's Department of Electrical Engineering and Computer Science and a member of MIT's Computer Science and Artificial Intelligence Laboratory...
, US, MIT, inventor of RC cipher seriesRC5In cryptography, RC5 is a block cipher notable for its simplicity. Designed by Ronald Rivest in 1994, RC stands for "Rivest Cipher", or alternatively, "Ron's Code"...
and MD algorithm seriesMD5The MD5 Message-Digest Algorithm is a widely used cryptographic hash function that produces a 128-bit hash value. Specified in RFC 1321, MD5 has been employed in a wide variety of security applications, and is also commonly used to check data integrity...
. - Bruce SchneierBruce SchneierBruce Schneier is an American cryptographer, computer security specialist, and writer. He is the author of several books on general security topics, computer security and cryptography, and is the founder and chief technology officer of BT Managed Security Solutions, formerly Counterpane Internet...
, US, inventor of BlowfishBlowfish (cipher)Blowfish is a keyed, symmetric block cipher, designed in 1993 by Bruce Schneier and included in a large number of cipher suites and encryption products. Blowfish provides a good encryption rate in software and no effective cryptanalysis of it has been found to date...
and co-inventor of TwofishTwofishIn cryptography, Twofish is a symmetric key block cipher with a block size of 128 bits and key sizes up to 256 bits. It was one of the five finalists of the Advanced Encryption Standard contest, but was not selected for standardisation...
. - Adi ShamirAdi ShamirAdi Shamir is an Israeli cryptographer. He is a co-inventor of the RSA algorithm , a co-inventor of the Feige–Fiat–Shamir identification scheme , one of the inventors of differential cryptanalysis and has made numerous contributions to the fields of cryptography and computer...
, Israel, Weizmann Institute, inventor of secret sharingSecret sharingSecret sharing refers to method for distributing a secret amongst a group of participants, each of whom is allocated a share of the secret. The secret can be reconstructed only when a sufficient number of shares are combined together; individual shares are of no use on their own.More formally, in a...
.
Asymmetric-key algorithm inventors
- Leonard AdlemanLeonard AdlemanLeonard Max Adleman is an American theoretical computer scientist and professor of computer science and molecular biology at the University of Southern California. He is known for being a co-inventor of the RSA cryptosystem in 1977, and of DNA computing...
, US, USCUniversity of Southern CaliforniaThe University of Southern California is a private, not-for-profit, nonsectarian, research university located in Los Angeles, California, United States. USC was founded in 1880, making it California's oldest private research university...
, the 'A' in RSA. - David ChaumDavid ChaumDavid Chaum is the inventor of many cryptographic protocols, including blind signature schemes, commitment schemes, and digital cash. In 1982, Chaum founded the International Association for Cryptologic Research , which currently organizes academic conferences in cryptography research...
, US, inventor of blind signatureBlind signatureIn cryptography a blind signature as introduced by David Chaum is a form of digital signature in which the content of a message is disguised before it is signed. The resulting blind signature can be publicly verified against the original, unblinded message in the manner of a regular digital...
s. - Whitfield DiffieWhitfield DiffieBailey Whitfield 'Whit' Diffie is an American cryptographer and one of the pioneers of public-key cryptography.Diffie and Martin Hellman's paper New Directions in Cryptography was published in 1976...
, US, (public) co-inventor of the Diffie-Hellman key-exchange protocol. - Taher ElgamalTaher ElgamalDr. Taher Elgamal is an Egyptian cryptographer. Elgamal is sometimes written as El Gamal or ElGamal, but Elgamal is now preferred...
, US (born EgyptEgyptEgypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...
ian), inventor of the Elgamal discrete log cryptosystemElGamal encryptionIn cryptography, the ElGamal encryption system is an asymmetric key encryption algorithm for public-key cryptography which is based on the Diffie–Hellman key exchange. It was described by Taher Elgamal in 1984. ElGamal encryption is used in the free GNU Privacy Guard software, recent versions of...
. - Shafi GoldwasserShafi GoldwasserShafrira Goldwasser is the RSA Professor of electrical engineering and computer science at MIT, and a professor of mathematical sciences at the Weizmann Institute of Science, Israel.-Biography:...
, US and Israel, MIT and Weizmann Institute, co-discoverer of zero-knowledge proofs. - Martin HellmanMartin HellmanMartin Edward Hellman is an American cryptologist, and is best known for his invention of public key cryptography in cooperation with Whitfield Diffie and Ralph Merkle...
, US, (public) co-inventor of the Diffie-Hellman key-exchange protocol. - Neal KoblitzNeal KoblitzNeal I. Koblitz is a Professor of Mathematics at the University of Washington in the Department of Mathematics. He is also an adjunct professor with the Centre for Applied Cryptographic Research at the University of Waterloo. He is the creator of hyperelliptic curve cryptography and the...
, independent co-creator of elliptic curve cryptographyElliptic curve cryptographyElliptic curve cryptography is an approach to public-key cryptography based on the algebraic structure of elliptic curves over finite fields. The use of elliptic curves in cryptography was suggested independently by Neal Koblitz and Victor S...
. - Alfred MenezesAlfred MenezesAlfred Menezes is co-author of several books on cryptography, most notably the Handbook of Applied Cryptography.Menezes is a professor in the Department of Combinatorics & Optimization at the University of Waterloo. He is also the Managing Director of the Centre for Applied Cryptographic...
, co-inventor of MQVMQVMQV is an authenticated protocol for key agreement based on the Diffie–Hellman scheme. Like other authenticated Diffie-Hellman schemes, MQV provides protection against an active attacker...
, an elliptic curveElliptic curve cryptographyElliptic curve cryptography is an approach to public-key cryptography based on the algebraic structure of elliptic curves over finite fields. The use of elliptic curves in cryptography was suggested independently by Neal Koblitz and Victor S...
technique. - Silvio MicaliSilvio MicaliSilvio Micali is an Italian-born computer scientist at MIT Computer Science and Artificial Intelligence Laboratory and a professor of computer science in MIT's Department of Electrical Engineering and Computer Science since 1983. His research centers on the theory of cryptography and information...
, US (born Italian), MIT, co-discoverer of zero-knowledge proofs. - Victor MillerVictor S. MillerVictor Saul Miller is an American mathematician at the Center for Communications Research of the Institute for Defense Analyses in Princeton, New Jersey, US. He received his A.B. in mathematics from Columbia University in 1968, and his Ph.D. in mathematics from Harvard University in 1975...
, independent co-creator of elliptic curve cryptographyElliptic curve cryptographyElliptic curve cryptography is an approach to public-key cryptography based on the algebraic structure of elliptic curves over finite fields. The use of elliptic curves in cryptography was suggested independently by Neal Koblitz and Victor S...
. - Pascal Paillier, inventor of Paillier encryption.
- Michael O. RabinMichael O. RabinMichael Oser Rabin , is an Israeli computer scientist and a recipient of the Turing Award.- Biography :Rabin was born in 1931 in Breslau, Germany, , the son of a rabbi. In 1935, he emigrated with his family to Mandate Palestine...
, inventor of Rabin encryption. - Ronald L. RivestRon RivestRonald Linn Rivest is a cryptographer. He is the Andrew and Erna Viterbi Professor of Computer Science at MIT's Department of Electrical Engineering and Computer Science and a member of MIT's Computer Science and Artificial Intelligence Laboratory...
, US, MIT, the 'R' in RSA. - Adi ShamirAdi ShamirAdi Shamir is an Israeli cryptographer. He is a co-inventor of the RSA algorithm , a co-inventor of the Feige–Fiat–Shamir identification scheme , one of the inventors of differential cryptanalysis and has made numerous contributions to the fields of cryptography and computer...
, Israel, Weizmann Institute, the 'S' in RSA.
Cryptanalysts
- [(Rev. Robert M. Dailey)], Ohio, US
- Ross Anderson, UK
- Eli BihamEli BihamEli Biham is an Israeli cryptographer and cryptanalyst, currently a professor at the Technion Israeli Institute of Technology Computer Science department. Starting from October 2008, Biham is the dean of the Technion Computer Science department, after serving for two years as chief of CS graduate...
, Israel, co-discoverer of differential cryptanalysisDifferential cryptanalysisDifferential cryptanalysis is a general form of cryptanalysis applicable primarily to block ciphers, but also to stream ciphers and cryptographic hash functions. In the broadest sense, it is the study of how differences in an input can affect the resultant difference at the output...
and Related-key attackRelated-key attackIn cryptography, a related-key attack is any form of cryptanalysis where the attacker can observe the operation of a cipher under several different keys whose values are initially unknown, but where some mathematical relationship connecting the keys is known to the attacker...
. - Matt BlazeMatt BlazeMatt Blaze is a researcher in the areas of secure systems, cryptography, and trust management. He is currently an Associate Professor of Computer and Information Science at the University of Pennsylvania; he received his PhD in Computer Science from Princeton University.In 1992, while working for...
, US - Dan BonehDan BonehDan Boneh is a Professor of Computer Science and Electrical Engineering atStanford University. He is a well-known researcher in the areas of applied cryptographyand computer security.-Education:...
, US, Stanford UniversityStanford UniversityThe Leland Stanford Junior University, commonly referred to as Stanford University or Stanford, is a private research university on an campus located near Palo Alto, California. It is situated in the northwestern Santa Clara Valley on the San Francisco Peninsula, approximately northwest of San... - Niels FergusonNiels FergusonNiels T. Ferguson is a Dutch cryptographer and consultant who currently works for Microsoft. He has worked with others, including Bruce Schneier, designing cryptographic algorithms, testing algorithms and protocols, and writing papers and books...
, Holland, co-inventor of Twofish and Fortuna - Ian GoldbergIan GoldbergIan Avrum Goldberg is a cryptographer and cypherpunk. He is best known for breaking Netscape's implementation of SSL , and for his role as Chief Scientist of Radialpoint , a Canadian software company...
, US - Lars KnudsenLars KnudsenLars Ramkilde Knudsen is a Danish researcher in cryptography, particularly interested in the design and analysis of block ciphers, hash functions and message authentication codes .-Academic:...
, Denmark, DTUTechnical University of DenmarkThe Technical University of Denmark , often simply referred to as DTU, is a university just north of Copenhagen, Denmark. It was founded in 1829 at the initiative of Hans Christian Ørsted as Denmark's first polytechnic, and is today ranked among Europe's leading engineering institutions, and the...
, discovered integral cryptanalysisIntegral cryptanalysisIn cryptography, integral cryptanalysis is a cryptanalytic attack that is particularly applicable to block ciphers based on substitution-permutation networks. It was originally designed by Lars Knudsen as a dedicated attack against Square, so is commonly known as the Square attack. It was also... - Paul KocherPaul KocherPaul Carl Kocher is an American cryptographer and cryptography consultant, currently the president and chief scientist of Cryptography Research, Inc....
, US, discovered differential power analysis - Mitsuru MatsuiMitsuru Matsuiis a Japanese cryptographer and senior researcher for Mitsubishi Electric Company. While researching error-correcting codes in 1990, Matsui was inspired by Biham and Shamir's differential cryptanalysis, and discovered the technique of linear cryptanalysis, published in 1993. Differential and linear...
, Japan, discoverer of linear cryptanalysisLinear cryptanalysisIn cryptography, linear cryptanalysis is a general form of cryptanalysis based on finding affine approximations to the action of a cipher. Attacks have been developed for block ciphers and stream ciphers... - David Wagner, US, UC Berkeley, co-discoverer of the slideSlide attackThe slide attack is a form of cryptanalysis designed to deal with the prevailing idea that even weak ciphers can become very strong by increasing the number of rounds, which can ward off a differential attack. The slide attack works in such a way as to make the number of rounds in a cipher irrelevant...
and boomerang attackBoomerang attackIn cryptography, the boomerang attack is a method for the cryptanalysis of block ciphers based on differential cryptanalysis. The attack was published in 1999 by David Wagner, who used it to break the COCONUT98 cipher....
s. - Xiaoyun WangXiaoyun WangWang Xiaoyun is a researcher and professor in the Department of Mathematics and System Science, Shandong University, Shandong, China....
, the People's Republic of ChinaPeople's Republic of ChinaChina , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
, known for MD5MD5The MD5 Message-Digest Algorithm is a widely used cryptographic hash function that produces a 128-bit hash value. Specified in RFC 1321, MD5 has been employed in a wide variety of security applications, and is also commonly used to check data integrity...
and SHA-1 hash functionCryptographic hash functionA cryptographic hash function is a deterministic procedure that takes an arbitrary block of data and returns a fixed-size bit string, the hash value, such that an accidental or intentional change to the data will change the hash value...
attacks. - Willi Meier, SwitzerlandSwitzerlandSwitzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
, known for correlation attackCorrelation attackIn cryptography, correlation attacks are a class of known plaintext attacks for breaking stream ciphers whose keystream is generated by combining the output of several linear feedback shift registers using a Boolean function...
, algebraic attack stream cipherStream cipherIn cryptography, a stream cipher is a symmetric key cipher where plaintext digits are combined with a pseudorandom cipher digit stream . In a stream cipher the plaintext digits are encrypted one at a time, and the transformation of successive digits varies during the encryption...
and hash functionHash functionA hash function is any algorithm or subroutine that maps large data sets to smaller data sets, called keys. For example, a single integer can serve as an index to an array...
.
Algorithmic number theorists
- Daniel J. BernsteinDaniel J. BernsteinDaniel Julius Bernstein is a mathematician, cryptologist, programmer, and professor of mathematics at the University of Illinois at Chicago...
, US, known for battle with US government in Bernstein v. United StatesBernstein v. United StatesBernstein v. United States is a set of court cases brought by Daniel J. Bernstein challenging restrictions on the export of cryptography from the United States....
. - Don CoppersmithDon CoppersmithDon Coppersmith is a cryptographer and mathematician. He was involved in the design of the Data Encryption Standard block cipher at IBM, particularly the design of the S-boxes, strengthening them against differential cryptanalysis...
, US
Theoreticians
- Mihir BellareMihir BellareMihir Bellare is a cryptographer and professor at the University of California, San Diego. He has published several seminal papers in the field of cryptography , many coauthored with Phillip Rogaway. Bellare has published a number of papers in the field of Format-Preserving Encryption...
, US, UCSD, co-proposer of the Random oracleRandom oracleIn cryptography, a random oracle is an oracle that responds to every query with a random response chosen uniformly from its output domain, except that for any specific query, it responds the same way every time it receives that query...
model - Gilles BrassardGilles BrassardGilles Brassard was born in Montreal, Canada, in 1955. He received a Masters degree from the Université de Montréal in 1975, and obtained his Ph.D. in Computer Science from Cornell University in 1979, working in the field of cryptography with John Hopcroft as his advisor...
, Canada, Université de MontréalUniversité de MontréalThe Université de Montréal is a public francophone research university in Montreal, Quebec, Canada. It comprises thirteen faculties, more than sixty departments and two affiliated schools: the École Polytechnique and HEC Montréal...
. Co-inventor of quantum cryptographyQuantum cryptographyQuantum key distribution uses quantum mechanics to guarantee secure communication. It enables two parties to produce a shared random secret key known only to them, which can then be used to encrypt and decrypt messages...
. - Claude CrépeauClaude CrépeauDr. Claude Crépeau is a professor in the School of Computer Science at McGill University. Ηe was born in Montreal, Quebec, Canada, in 1962. He received a Masters degree from the Université de Montréal in 1986, and obtained his Ph.D. in Computer Science from MIT in 1990, working in the field of...
, Canada, McGill UniversityMcGill UniversityMohammed Fathy is a public research university located in Montreal, Quebec, Canada. The university bears the name of James McGill, a prominent Montreal merchant from Glasgow, Scotland, whose bequest formed the beginning of the university...
. - Oded GoldreichOded GoldreichOded Goldreich is a professor of Computer Science at the Faculty of Mathematics and Computer Science of Weizmann Institute of Science, Israel. His research interests lie within the theory of computation...
, Israel, Weizmann Institute, author of Foundations of Cryptography. - Shafi GoldwasserShafi GoldwasserShafrira Goldwasser is the RSA Professor of electrical engineering and computer science at MIT, and a professor of mathematical sciences at the Weizmann Institute of Science, Israel.-Biography:...
, US and Israel - Silvio MicaliSilvio MicaliSilvio Micali is an Italian-born computer scientist at MIT Computer Science and Artificial Intelligence Laboratory and a professor of computer science in MIT's Department of Electrical Engineering and Computer Science since 1983. His research centers on the theory of cryptography and information...
, US - Rafail OstrovskyRafail OstrovskyRafail Ostrovsky is a professor of computer science and mathematics at UCLA and a well-known researcher in algorithms and cryptography. Prof. Ostrovsky received his Ph.D. from MIT in 1992...
, US, UCLA. - Charles RackoffCharles RackoffCharles Weill Rackoff is an American cryptologist. Born and raised in New York City, Rackoff attended MIT as both an undergraduate and graduate student, and earned a Ph.D. degree in Computer Science in 1974. He spent a year as a postdoctoral scholar at INRIA in France.He currently works at the...
, co-discoverer of zero-knowledge proofZero-knowledge proofIn cryptography, a zero-knowledge proof or zero-knowledge protocol is an interactive method for one party to prove to another that a statement is true, without revealing anything other than the veracity of the statement....
s. - Phillip RogawayPhillip RogawayPhillip Rogaway is a professor of computer science at the University of California, Davis. He graduated with an BA in computer science from UC Berkeley and completed his PhD in cryptography at MIT, in the Theory of Computation group. He has taught at UC Davis since 1994.Dr...
, US, UC Davis, co-proposer of the Random oracleRandom oracleIn cryptography, a random oracle is an oracle that responds to every query with a random response chosen uniformly from its output domain, except that for any specific query, it responds the same way every time it receives that query...
model. - Gustavus SimmonsGustavus SimmonsGustavus J. Simmons is a retired cryptographer and former manager of the applied mathematics Department and Senior Fellow at Sandia National Laboratories...
, US, SandiaSandia National LaboratoriesThe Sandia National Laboratories, managed and operated by the Sandia Corporation , are two major United States Department of Energy research and development national laboratories....
, authenticationAuthenticationAuthentication is the act of confirming the truth of an attribute of a datum or entity...
theory
Government cryptographers
- Clifford CocksClifford CocksClifford Christopher Cocks, CB, is a British mathematician and cryptographer at GCHQ.He invented the widely-used encryption algorithm now commonly known as RSA, about three years before it was independently developed by Rivest, Shamir, and Adleman at MIT...
, UK, GCHQ, secret inventor of the algorithm later known as RSA. - James H. EllisJames H. EllisJames Henry Ellis was a British engineer and mathematician. In 1970, while working at the Government Communications Headquarters in Cheltenham he conceived of the possibility of "non-secret encryption", more commonly termed public-key cryptography.-Early life, education and career:Ellis was born...
, UK, GCHQ, secretly proved the possibility of asymmetric encryption. - Malcolm Williamson, UK, GCHQ, secret inventor of the protocol later known as Diffie-Hellman.
Cryptographer businesspeople
- Bruce SchneierBruce SchneierBruce Schneier is an American cryptographer, computer security specialist, and writer. He is the author of several books on general security topics, computer security and cryptography, and is the founder and chief technology officer of BT Managed Security Solutions, formerly Counterpane Internet...
, US, CTO and founder of Counterpane Internet Security, Inc. and cryptography author. - Scott VanstoneScott VanstoneScott A. Vanstone is a cryptographer who co-authored the Handbook of Applied Cryptography. He is currently on faculty at the University of Waterloo's Faculty of Mathematics and a member of the school's Centre for Applied Cryptographic Research. He is also the founder of Certicom. In 1998, he was...
, Canada, founder of Certicom and elliptic curve cryptographyElliptic curve cryptographyElliptic curve cryptography is an approach to public-key cryptography based on the algebraic structure of elliptic curves over finite fields. The use of elliptic curves in cryptography was suggested independently by Neal Koblitz and Victor S...
proponent.