Martin Hellman

Martin Hellman was born in New York City on October 2, 1945. In a 2017 oral history he said that he was born in the Bronx, where he lived for his first five years, and that his father returned from overseas service around March 1946, after his birth.⁠[1][2]

In the same interview he described the family’s origins: his father’s side came from what his grandfather called “Russia,” which he thought was probably today’s Lithuania or Belarus; his grandfather arrived around 1904 and worked as a tailor in New York; family lore had it that his grandmother bribed border guards to cross with two toddlers. His mother’s side came around 1910 from the Austro-Hungarian Empire, possibly from what is now Poland; his maternal grandfather started out with a pushcart, then ran a feather store, and eventually owned two apartment buildings in the Bronx.⁠[2]

In the interview he spoke of the family’s Jewish background: his grandfather called the old country “Russia” because, he explained, when the czar was in charge and one was Jewish it was “Russia,” and the czar did not like Jews. He said that in those days minority groups including Jews faced prejudice and it was harder for Jews to get teaching positions; his mother had also intended to become a teacher, but such jobs were very hard to get.⁠[2]

His father, Robert S. Hellman (born in New York City on June 29, 1908, to Abraham and Sarah Hellman), grew up in the Bronx, taught physics and chemistry in New York City high schools for more than thirty years, served as an officer in the U.S. Army during World War II, and remained in the Army Reserves, retiring with the rank of major. Martin Hellman said in the oral history that his father had studied physics and began teaching physics in the city’s high schools around 1939.⁠[3][2]

His mother, Adelaide Leifer Hellman, worked first as a secretary in private industry, then as a secretary in the school system and later as a substitute teacher; he said in the interview that it was his mother who taught him to save. His parents raised three sons in the Bronx: his older brother Howard, Martin, and his younger brother Stephen.⁠[3][2]

He recalled that in the summers of his childhood the family went tent camping at Rudd Pond in New York StateNew York (state)New York is a state in the eastern United States; its capital is Albany and its largest city is New York City. One of the original 13 states, it ratified the U.S. Constitution on July 26, 1788, becoming the 11th state to join the Union, and its population in the 2020 census was 20,201,249.Open the full entry, where Earl, a local farmer who delivered and sold ice to the campers, let him help take care of the cows; at about seven or eight he felt friendless and valued being allowed to tag along with his older brother. He also said that at eight, in third grade, he wanted to be an explorer, but knew that he could not be one and had to be a scientist.⁠[2]

As a boy, when he went to buy groceries for his mother, the grocer sometimes had him deliver orders for a small tip; in high school he did deliveries for a dry-cleaning store; and, he said, probably in 1961 he shelved books in a library for about 90 cents an hour. In a 2011 Computer History Museum interview he said that, by the standards of the San Francisco Peninsula, he had grown up in a relatively poor environment in the Bronx.⁠[2][4]

In the interview he named teachers he had liked: Mrs. Donovan in fourth and fifth grade, and, in junior high, Miss Blake, his mathematics and homeroom teacher, and Miss Martin in seventh grade; his favorite subject was science and later physics, his least favorite music.⁠[2]

From 1959 to 1962 he attended the Bronx High School of Science for grades 10 to 12, taking physics in his junior year so that he could take a physics elective as a senior. His physics teacher was his uncle Charles Hellman, his father’s younger brother, who also taught physics and lived to 106. He recalled using an 1898 edition of Ganot’s Physics for a science fair project, and said that ham radio in his senior year sparked his interest in electrical engineering.⁠[2]

He studied electrical engineering at New York UniversityNew York UniversityNew York University is a private university in New York City, founded in 1831, and one of the largest private universities in the United States.Open the full entry and received his Bachelor of Engineering (B.E.) degree in June 1966. He recalled that his electromagnetism professor, István Palócz, co-authored his first technical paper, and that in the summer of 1965 he worked at a microwave company that designed waveguides and switches for radars, his first technical job.⁠[5][2]

The undergraduate honors listed on his website are election to Tau Beta Pi and to Eta Kappa Nu in 1964 and, in 1966, the New York University Electrical Engineering Department’s Arnold Award, first prize (New York Section) and second prize (Region 1) in the IEEE Student Paper Contest, and an honorable mention in Eta Kappa Nu’s competition to name the most outstanding electrical engineering student in the United StatesUnited StatesThe United States is a federal country in North America made up of 50 states, the District of Columbia as the seat of government, and territories such as Puerto Rico and Guam; its capital is Washington, D.C. The Continental Congress adopted the Declaration of Independence on July 4, 1776. The 2020 census (April 1, 2020) counted a resident population of 331,449,281, and the 435 seats of the House of Representatives are apportioned among the states on the basis of the census.Open the full entry. He said in the interview that a senior-year paper on car driver systems won a first prize in the New York area.⁠[6][2]

As of November 2026, the NYU Tandon School of Engineering alumni page describes him as a Presidential Fellow of the school.⁠[5]

In the summer of 1966 he worked in the solid-state research laboratory of the Aerospace Corporation; that summer he met his future wife, Dorothie: he said that she would say they met on Catalina Island and he would say they met on a Girl Scout campout, and that both are true. He said in the interview that he married at 21.⁠[2]

He began graduate study at Stanford University in September 1966, held a National Science Foundation Graduate Fellowship from 1966 to 1968, and received an M.S. in electrical engineering in 1967 and a Ph.D. in electrical engineering in 1969. His doctoral adviser was Tom Cover, and his dissertation was titled “Learning with Finite Memory”; he said that it was more statistics than information theory.⁠[7][2][6][8]

In the written version of his Turing lecture he states that Gödel’s incompleteness theorem, which he learned in graduate school, shook his faith in logic, and that it took about ten more years, and nearly ruined his marriage, before he accepted the limits of logic: “Logic is just one way of knowing about the world, and an incomplete one at that.”⁠[9]

From 1968 to 1969 he worked at IBMIBMIBM (International Business Machines Corporation) is an American information technology company, renamed in 1924 from the Computing-Tabulating-Recording Company (C-T-R).Open the full entry’s Thomas J. Watson Research Center in Yorktown Heights, New York. Horst Feistel, who had been brought in from classified government work to seed IBM’s cryptography research, was hired in the same department; IBM’s work culminated in the Data Encryption Standard (DES) in 1975. His own work at IBM was not in cryptography, but he writes that his discussions with Feistel opened his eyes to new possibilities, and he learned about classical ciphers from Feistel.⁠[7][10][2]

He writes on his website that David Kahn’s best-selling book The Codebreakers was published in 1967 and that Kahn was the banquet speaker at his first IEEE International Symposium on Information Theory in January 1969.⁠[10]

From 1969 to 1971 he was an assistant professor of electrical engineering at the Massachusetts Institute of TechnologyMassachusetts Institute of TechnologyThe Massachusetts Institute of Technology (MIT) is a private research university in Cambridge, Massachusetts, United States. It received its charter from Massachusetts in 1861, admitted its first students in 1865 and moved from Boston to its present campus in 1916. As of October 2025 it had 11,816 students, and it counts 106 Nobel laureates among members of its community.Open the full entry. He writes that in 1970 Peter Elias gave him a copy of Claude Shannon’s 1949 paper relating cryptography to information theory, and that he noted how much information theory owed its birth to Shannon’s classified wartime cryptography research at Bell Labs.⁠[7][10]

In 1971 he returned to Stanford University, where he served on the regular faculty until he became professor emeritus in 1996. The Stanford School of Engineering’s profile states that he served as associate chairman of the Electrical Engineering Department, as chairman of electrical engineering graduate admissions, and as associate dean of graduate studies for minority student affairs.⁠[7][11]

He writes that in the early 1970s colleagues considered his interest in cryptography foolish for two reasons: the National Security Agency (NSA) had a multi-billion-dollar budget, which made new discoveries by outsiders seem unlikely, and any good work would be classified. His replies were that commercial encryption needs were unmet and that credit goes to the first to publish; he later called these counter-arguments “rationalizations.”⁠[10]

He said in the 2017 oral history: “Whit and I connected in the fall of 1974.” He also noted that Whitfield Diffie had technically been his student for a year or two.⁠[2]

In March 1975 the National Bureau of Standards published the proposed Data Encryption Standard in the Federal Register. In the written version of his Turing lecture he states that he and Whitfield Diffie judged its 56-bit key inadequate, estimating a cost of about $5,000 per recovered key, and writes: “While Diffie and I saw a 56-bit key as small, we now know it looked large from NSA’s perspective.” Their paper “Exhaustive Cryptanalysis of the NBS Data Encryption Standard” appeared in Computer in June 1977, pages 74–84.⁠[9][2][8]

A 2014 Stanford Magazine article states that the NSA tried to persuade IBM to cut the DES key from 64 bits to 48 and that the two sides compromised on a weakened 56-bit key; the public campaign Hellman and Diffie ran to strengthen DES was ultimately unsuccessful. In a 1979 speech NSA director Bobby Ray Inman said that the allegation that the NSA had tampered with DES was “totally false”; the article states that recently declassified documents show his statements to have been “misleading, if not incorrect.” CISAC’s profile states that he has taken part in the computer privacy debate since 1975, beginning with the DES key size.⁠[12][13]

In the written version of his Turing lecture he states that in January 1976 two high-level NSA employees flew to CaliforniaCaliforniaCalifornia is a U.S. state on the Pacific coast; its capital is Sacramento and its largest city is Los Angeles. California was admitted to the Union on September 9, 1850, as the 31st state. Its population at the 2020 Census (April 1, 2020) was 39,538,223, the largest of any state.Open the full entry to try to get him and Whitfield Diffie to stop; when he went home to decide what to do, the thought came to him to ignore right and wrong and seize the opportunity, and he believed that he had dismissed that “devil on my shoulder” and made a rational choice; five years later, trying to understand the motivation of the Manhattan ProjectManhattan ProjectThe Manhattan Project was the United States program that developed the atomic bomb during the Second World War, managed from 1942 by the Manhattan Engineer District of the Army Corps of Engineers with British and Canadian participation. It built plants and laboratories at Oak Ridge, Tennessee, Hanford, Washington, and Los Alamos, New Mexico, among other sites, carried out the first nuclear test in 1945, and produced the bombs dropped on Hiroshima and Nagasaki, Japan, later that year; after the war its functions passed to the civilian Atomic Energy Commission.Open the full entry scientists, he concluded that he had fooled himself, writing: “I vowed never to fool myself again.” The Stanford Magazine article states that after watching the documentary Day After Trinity he said he had “listened to his ego” and vowed never to do that again.⁠[9][12]

He said in the oral history that he came up with the key-exchange method in May 1976, when he had a talk on cryptography scheduled at an international symposium on information theory in Sweden, and quickly added the new result; the journal’s editor, Jim Massey, then agreed to publish the paper in the November issue of the IEEE Transactions on Information Theory. In the written version of his Turing lecture he credits Whitfield Diffie with the concept of the public-key cryptosystem and himself with what he calls the Diffie-Hellman-Merkle key exchange.⁠[2][9]

He said in the oral history that when a professor asked Ralph MerkleRalph MerkleRalph Merkle (born 1952) is a cryptographer and nanotechnology researcher regarded as one of the inventors of public-key cryptography: as an undergraduate he devised Merkle’s Puzzles, a method of key exchange over a public channel, and he later worked with Whitfield Diffie and Martin Hellman, with whom he shares the public-key patent; the Merkle tree he proposed is used in the Bitcoin white paper. He has since worked for many years on molecular nanotechnology and is a director of the cryonics organization Alcor.Open the full entry to work on a different idea for a computer science class at the University of California, BerkeleyUniversity of California, BerkeleyThe University of California, Berkeley (UC Berkeley) is a campus of the University of California system; the University of California was founded in 1868 through a merger of two institutions and moved to Berkeley, California, in 1873.Open the full entry, Merkle quit the class and worked on public-key cryptography, and he joked that he “kidnapped” Merkle and brought him to Stanford University; he also discussed Merkle’s contribution and the paper Merkle submitted to the Communications of the Association for Computing Machinery, which rejected it.⁠[2]

“New Directions in Cryptography,” an invited paper by Whitfield Diffie and Martin Hellman, appeared in the IEEE Transactions on Information Theory, vol. IT-22, in November 1976, pages 644–654. A 2016 press release of the Association for Computing Machinery states that the paper introduced public-key cryptography and digital signatures, ideas that became the foundation of most widely used Internet security protocols, and that the Diffie-Hellman protocol protects everyday Internet communications and financial transactions worth trillions of dollars.⁠[8][14]

The National Inventors Hall of Fame’s profile explains that in traditional cryptography one key both encrypts and decrypts, so keys had to be delivered by couriers or other secure means, whereas public-key cryptography gives each person a pair of public and private keys, of which only the public key is shared: a message encrypted with someone’s public key can be read only with the private key, and a message signed with a private key can be verified with the matching public key.⁠[1]

The Stanford Magazine article states that in a 2004 oral history he recalled the reaction of the nonmilitary community to the paper as “ecstatic.” In 1978 the paper received the IEEE Information Theory Group Award for the best paper published in the preceding two years.⁠[12][6]

The Stanford Magazine article states that in July 1977, on the day Bobby Ray Inman took over as NSA director, the NSA employee J. A. Meyer wrote to the IEEE arguing that publishing cryptography papers could violate federal arms and secrecy laws, invoking the International Traffic in Arms Regulations (ITAR, Title 22 of the Code of Federal Regulations, parts 121–128) and concluding that the technology “could have more than academic effect”; Science magazine and the New York TimesThe New York TimesThe New York Times is an American morning daily newspaper published in New York City. Founded in 1851, it is published by The New York Times Company.Open the full entry covered the letter, and Science discovered that Meyer worked for the NSA.⁠[12]

Hellman sought advice from Stanford University counsel John Schwartz and wrote a memo arguing for public cryptographic research; The Stanford Daily wrote in 2016 that in the memo he argued that the NSA’s monopoly on cryptographic information was outdated and that commercial demand for cryptography had emerged, and warned that automated information processing could lead to economic problems and threats to privacy. Schwartz concluded that publishing cryptographic research would not by itself violate federal law, but that a lengthy court case would be harder on a young doctoral student than on a tenured faculty member.⁠[12][15]

On September 6, 1977, Martin E. Hellman, Bailey W. Diffie and Ralph C. Merkle filed a U.S. patent application titled “Cryptographic apparatus and method” (application no. 05/830,754), assigned to Leland Stanford Junior University, describing a way for two parties to agree on an encryption key over an insecure channel without sharing a key beforehand; it was granted as U.S. Patent No. 4,200,770 on April 29, 1980, with an anticipated expiration date of September 6, 1997. The National Inventors Hall of Fame inducted him in 2011 for public-key cryptography under this patent.⁠[16][1]

He said in the oral histories that under Stanford University’s generous patent policy the inventors were to receive a third of the royalties, but that the Stanford patents “made almost no money,” the first patent having been written by a summer intern who was a law student and not as well written as it should have been. He said that the Massachusetts Institute of Technology’s RSA patents became much more valuable, partly because the inventors built RSA Data Security around them; Ron Rivest, Adi Shamir and Leonard Adleman credited him and Diffie in their paper with inventing public-key cryptography, but on the patents he summed up the other side’s position as “Your patents are invalid. Sue us.” The written version of his Turing lecture mentions Stanford’s patent dispute with RSA Data Security without giving details.⁠[2][4][9]

He said in 2011 that he had once been unhappy with the RSA inventors and the company but now felt grateful, crediting Jim Bidzos, who ran RSA’s business, with building a public-key cryptography industry from which he himself had benefited economically. In a 2024 InfoWorldInfoWorldInfoWorld is a technology publication originating in 1978, serving enterprise developers, software architects and technology decision-makers as part of Foundry.Open the full entry interview he said that he had long been angry that RSA profited from work built on the Diffie-Hellman algorithm, but had come to rise above that anger.⁠[4][17]

On October 10, 1977, the International Symposium on Information Theory was held at Cornell UniversityCornell UniversityCornell University is a private research university in Ithaca, New York, and a member of the Ivy League. It is New York State's federal land-grant university, a distinction unique within the Ivy League. Ezra Cornell and Andrew Dickson White founded the university in 1865, and it opened in 1868. In addition to its Ithaca campus, Cornell operates Weill Cornell Medicine and Cornell Tech in New York City and a medical college in Qatar. It enrolled 26,793 students in fall 2024. Its president is Michael I. Kotlikoff.Open the full entry. He writes that on the advice of Stanford University’s general counsel he, rather than his student co-authors, presented two papers; the counsel believed a broad interpretation of ITAR would be unconstitutional, but a court case could harm a new Ph.D.’s career. His students Ralph Merkle and Steve Pohlig initially wanted to present, but their parents’ concerns won out, and the two stood mute by the podium so that they would receive recognition. The Stanford Magazine article states that the symposium proceeded without incident and signaled the end of U.S. government control of domestic cryptography research.⁠[10][12]

In the written version of his Turing lecture he states that in 1978 the NSA director, Admiral Bobby Ray Inman, asked to visit him and that the meeting grew into a friendship; he was then in his early thirties. He described the meeting in the oral history as making peace between him and the NSA, and the relationship as initially cautious before it became a friendship. The Stanford Magazine article states that Inman convened an NSA panel that offered three options and later organized a voluntary prepublication review system that was used for a decade.⁠[9][2][12]

In January 1978 he and his student Steve Pohlig published “An Improved Algorithm for Computing Logarithms Over GF(p) and its Cryptographic Significance” in the IEEE Transactions on Information Theory, vol. IT-24, pages 106–110; in September of that year he and Ralph Merkle published “Hiding Information and Signatures in Trap Door Knapsacks” in the same journal, pages 525–536. In the oral history he discussed the discrete logarithm problem and his work with John Gill and Steve Pohlig.⁠[8][2]

In the same year he received the California State Psychological Association Award for Distinguished Contributions to Consumer Protection.⁠[6]

In March 1979 he and Whitfield Diffie published the invited survey “Privacy and Authentication: An Introduction to Cryptography” in the Proceedings of the IEEE, vol. 67, pages 397–427; it received the 1981 IEEE Donald G. Fink Award for the outstanding tutorial or survey paper of 1979. In 1980 he was named an IEEE Fellow for contributions to cryptography.⁠[8][6]

He writes on his website that early in his career he focused on developing technology with little attention to its consequences and that events of the 1980s forced him to confront these issues; he saw the nuclear threat as the most visible symptom of the gap between technological and social development. He said in the oral history that he shifted toward international security and nuclear risk around 1980.⁠[18][2]

In July 1980 he published the single-author paper “A Cryptanalytic Time-Memory Tradeoff” in the IEEE Transactions on Information Theory, vol. 26, pages 401–406.⁠[8]

From 1982 to 1988 he worked with the Beyond War Foundation, which he writes was central to his life at the time. Beyond War concluded that a long-term solution required going beyond arms control and even complete nuclear disarmament to “a world beyond war.” He said in the oral history that the movement was organized with many Silicon Valley people involved and was founded by, among others, Harry Rathbun, a Stanford University business-law professor, and his wife; Harry Rathbun’s question “Why not assume the noble hypothesis?” shaped his optimism.⁠[18][2]

He said in the oral history that Dorothie left her career to work as a full-time volunteer, and that he was ready to resign his Stanford University professorship to do the same before taking unpaid leave to volunteer full-time instead. InfoWorld wrote in 2024 that it was Dorothie who found the Creative Initiative group and pushed him to attend its meetings.⁠[2][17]

He writes that in the 1970s, when Soviet-American relations had warmed, he and Dorothie befriended Russian information theorists they met through symposia and exchange programs. He said in the oral history that in September 1984 he went to the Soviet Union for an international symposium; on his website he writes that when he and Dorothie visited Moscow that year strict censorship was in force and their discussions with Russian friends were private and one-on-one, and that several of the scientists they talked with in 1984 later advised Mikhail GorbachevMikhail GorbachevMikhail Gorbachev (1931–2022) was a Soviet politician who served as general secretary of the Communist Party of the Soviet Union from 1985 to 1991 and as the Soviet Union’s only president from 1990 to 1991. He pursued the policies of perestroika (restructuring) and glasnost (openness) and received the Nobel Prize for Peace in 1990.Open the full entry directly; Gorbachev came to power in 1985 and lifted censorship in 1986.⁠[18][2]

He writes that in January 1986 he returned to campus after an eighteen-month leave spent as a full-time volunteer working to end war, and found the campus “in many ways at war along ethnic lines.” He developed a “no fault” approach to diversity: whereas the usual view treats prejudice as an illness of a few individuals, this approach treats prejudice as universal, its first step is changing oneself, and discussions of differences and conflicts become sources of understanding and learning. He writes that the approach is not universally applicable and should run in parallel with efforts against hate groups and with international tribunals for war criminals.⁠[19]

The work earned him three teaching awards from minority student organizations: the Stanford Society of Black Scientists and Engineers Outstanding Professor Award in 1987 and 1989 and the Stanford Society of Chicano and Latino Engineers and Scientists Outstanding Professor Award in 1989; in 1987 he also received the Stanford University Tau Beta Pi Award for Undergraduate Teaching.⁠[19][6]

In the 1980s he helped develop a dialogue between the Soviet and American scientific communities on how human thinking had to evolve for survival in the nuclear age; with Professor Anatoly Gromyko of Moscow he co-edited Breakthrough: Emerging New Thinking. His website states that it was published simultaneously in Russian and English in late 1987, while his publication list gives Walker and Co., New York, 1988. The Soviet sponsor was a committee of the Academy of Sciences headed by Evgeni Velikhov, Gorbachev’s chief science adviser; the book urged each nation to address its own actions, pointing to Soviet policy in Afghanistan and U.S. policy in Central America, and noted that the world had about 50,000 nuclear weapons. He writes that Mikhail Gorbachev praised the book as “a valuable experience in the promotion of new thinking.”⁠[18][8][7]

He recalled in the oral history an event of about 200 people in Modesto shortly after the INF Treaty was signed in December 1987, and a speaking tour the following month on which he was paired with the Soviet rocket scientist Rauschenbach, who called Stalin “a murderer and a terrorist” in front of an audience.⁠[2]

From 1994 to 1996 he served on the National Research Council’s Committee to Study National Cryptographic Policy. He said in the oral history that its members included the former NSA deputy director Ann Caracristi and the former attorney general Benjamin Civiletti, that its conclusions were unanimous, and that it recommended making 56-bit DES almost freely exportable; in the written version of his Turing lecture he states that the study helped loosen encryption export restrictions.⁠[13][2][9]

In 1996 he became professor emeritus of electrical engineering at Stanford University. He said in the oral history that he had started teaching at 23 and retired at 50 after 27 years, that committee work and exam preparation had become burdensome, and that retirement let him teach and advise without pay.⁠[7][2]

He writes on his website that in December 1997 GCHQ, the British equivalent of the NSA, claimed to have invented public-key cryptography several years before his group; he writes that Cryptologia published the claim without a disclaimer although it could not be verified, and that a colleague at another university emailed people to look at it as “the true story.” He recommends Bruce Schneier’s May 1998 newsletter for a reasoned discussion of the claim.⁠[10]

On his website he recommends Simon Singh’s The Code Book and Steven LevySteven LevySteven Levy is an American technology journalist and author, editor at large at Wired, who has written about the digital revolution and the people behind it for almost four decades; his books include Hackers, Crypto and In the Plex.Open the full entry’s Crypto for readers who want to learn this history.⁠[10]

On November 22, 2004, in Palo Alto, he gave an oral history interview to Jeffrey R. Yost of the Charles Babbage Institute, covering his early interest in cryptography, his mid-1970s work on public-key cryptography at Stanford University with Whitfield Diffie and Ralph Merkle, his work with Steve Pohlig, his views on U.S. government cryptography policy (including NSA efforts to discourage academic research, export restrictions and the Clipper chip key-escrow proposal), the commercialization of cryptography through RSA Data Security and VeriSign, and contributors he felt had not received adequate recognition.⁠[20]

In spring 2008 he published “Risk Analysis of Nuclear Deterrence” in The Bent of Tau Beta Pi, vol. 99, no. 2; in March 2011 “How risky is nuclear optimism?” appeared in the Bulletin of the Atomic Scientists, vol. 67, no. 2; and in October 2012 the Federation of American Scientists and the Nuclear Age Peace Foundation issued his briefing paper “Fifty Years After the Cuban Missile Crisis: Time to Stop Bluffing at Nuclear Poker.”⁠[8]

The Federation of American Scientists’ profile describes him as its Adjunct Senior Fellow for Nuclear Risk Analysis, whose current project, “Defusing the Nuclear Threat,” applies quantitative risk analysis to a potential failure of nuclear deterrence. He writes on his website that the project argues that people have a right to know the risks of nuclear deterrence and that his preliminary analysis found that risk to be thousands of times greater than is prudent. In a Computer History Museum interview on March 11, 2011, he said: “The thing that I actually focus on these days is nuclear weapons.”⁠[21][18][4]

In the written version of his 2017 Turing lecture he states that he spent about ten years developing a risk framework for nuclear deterrence and concluded that the risk is unacceptable, likening it to “playing Russian roulette with the life of a child born today.” The Stanford School of Engineering’s profile states that he has campaigned for more than thirty years to raise awareness of the risks of nuclear weapons.⁠[9][11]

He said in the 2017 oral history that he serves on the board of advisors or trustees of the Daisy Alliance, a Georgia-based nongovernmental organization named after Lyndon JohnsonLyndon B. JohnsonLyndon B. Johnson (1908–1973) was an American politician who served Texas as a U.S. representative and senator and led the Senate Democrats, became vice president in 1961 and succeeded to the presidency on the assassination of John F. Kennedy in 1963, serving as the 36th president of the United States from 1963 to 1969. His administration enacted the Civil Rights Act of 1964 and other “Great Society” legislation while expanding the U.S. military commitment in the Vietnam War.Open the full entry’s 1964 “Daisy” advertisement, and has given talks for it.⁠[2]

In 2011 the Computer History Museum named him a Fellow “for his work, with Whitfield Diffie and Ralph Merkle, on public key cryptography”; the museum’s page quotes him: “When a lock icon appears at the bottom of your browser, it’s using public key cryptography.” On March 11, 2011, in Mountain View, California, he was interviewed for the Fellow Awards by Jon Plutte, covering his early work with Diffie and Merkle, his early explorations and influences, and his views on major problems facing the world.⁠[22][6][4][23]

In October 2012 he became an affiliated faculty member of Stanford University’s Center for International Security and Cooperation (CISAC). The Stanford Daily wrote in 2016 that at CISAC he mentors pre- and postdoctoral fellows working on cybersecurity.⁠[13][15]

That month CISAC announced that he and Whitfield Diffie were among the eleven inaugural inductees of the National Cyber Security Hall of Fame.⁠[24]

In 2016 he and his wife, Dorothie Hellman, published A New Map for Relationships: Creating True Love at Home & Peace on the Planet with New Map Publishing of Stanford, California; the whole book can be downloaded free as a PDF from his website, which also offers a Chinese version. He writes on his website that the book argues that the changes needed for a strong relationship are the same ones needed for “a more peaceful, sustainable world”; former Secretary of Defense William PerryWilliam J. PerryWilliam J. Perry is an American engineer, businessman and former secretary of defense whose tenure included acquisition reform and nuclear threat reduction.Open the full entry recommended it as a book that “should be read by married couples seeking peace at home.” In the oral history he also mentioned an endorsement by Karl Eikenberry.⁠[8][7][2]

He said in the oral history that writing the book had been a powerful process and that by 2017 the couple had not had a fight in fifteen years. InfoWorld wrote in 2024 that their marriage nearly ended about ten years in and that Dorothie looked for catalysts to help them transform the relationship, while he dropped his resistance and opened up to seemingly crazy ideas; he said that “Get curious, not furious,” a principle from their book, was part of a major change in his approach to life and that they now see disagreements as opportunities to learn from one another.⁠[2][17]

On March 1, 2016, the Association for Computing Machinery announced that it was awarding the 2015 A.M. Turing Award to Whitfield Diffie and Martin E. Hellman for “critical contributions to modern cryptography,” with a prize of $1 million funded by GoogleGoogleGoogle is an American technology company founded by Larry Page and Sergey Brin and incorporated in 1998. It became an Alphabet subsidiary in 2015. Its businesses include internet search, advertising, software platforms, cloud computing, and artificial intelligence.Open the full entry. The release states that the award would be presented at the annual awards banquet in San Francisco, California, on June 11 of that year, and quotes Google Distinguished Scientist Andrei Broder: “Public-key cryptography is fundamental for our industry.”⁠[14]

The Stanford Daily wrote that he and Diffie sided with AppleAppleApple is a public technology company founded in 1976 and headquartered in Cupertino, California, United States. Its business includes the iPhone, Mac, iPad, wearables, and services such as digital content, payments, and cloud storage. The company builds its product system through in-house hardware, operating systems, and services.Open the full entry in its dispute with the FBIFederal Bureau of InvestigationThe Federal Bureau of Investigation (FBI) is the federal investigative agency of the U.S. Department of Justice. It grew out of a force of special agents organized by Attorney General Charles J. Bonaparte in 1908, has used its present name since 1935 and is headquartered in Washington, D.C.Open the full entry over unlocking an iPhone belonging to one of the San Bernardino attackers, and quoted Stanford University professor Dan BonehDan BonehDan Boneh is a professor of computer science and electrical engineering at Stanford University, where he heads the applied cryptography group and co-directs the computer security lab; his research applies cryptography to computer security. He received the 2013 Gödel Prize and serves as a senior research advisor at a16z.Open the full entry as saying that the paper “introduced number theory into the realm of cryptography.”⁠[15]

He said in the 2017 oral history that he had not realized the Turing Award came with a million dollars; on learning that his half was about half a million dollars, he and Dorothie “quickly agreed to use my half of the million to further our efforts to build a more peaceful, sustainable world.”⁠[2]

On May 19, 2017, in Palo Alto, California, he gave an oral history interview to Hugh Williams for the Association for Computing Machinery’s Turing Award project. He named public-key cryptography as his top contribution, together with securing researchers’ right to publish, and said that he had learned: “I could be 100% certain that I’m right and 100% wrong.” He also described measuring a television that drew about 20 watts in “Download Acquisition Mode,” which led to changes in the ENERGY STAR guidelines; he estimated that the change saved about a billion dollars in electricity.⁠[2]

In the interview he named as his role models his father, his mother, his uncle Charles, Professor István Palócz, Harry and Emilia Rathbun, and his adviser Tom Cover.⁠[2]

In December 2017 the written version of his Turing lecture, “Cybersecurity, Nuclear Security, Alan Turing, and Illogical Logic,” appeared in the Association for Computing Machinery’s Communications, vol. 60, no. 12, pages 52–59. In it he treats the chance of a breakthrough in factoring in each decade as a coin toss and argues for backup key-exchange and signature systems; he also writes that a course on computable real numbers based on Alan Turing’s 1936 paper left him “dumbfounded” and made him question whether mathematics rests on firm foundations.⁠[8][9]

In April 2019 the Federation of American Scientists published his special report Rethinking National Security. The Stanford Daily wrote on May 3, 2019, that the report argues that American national interests are closely tied to “global security” and that, as he put it, the nation’s security is becoming dependent on the security of all other nations, including its adversaries, quoting him: “Paradoxically, the more secure North Korea feels, the less threatened we are.” The report questions the view that nuclear weapons have preserved the peace, including the argument of John MearsheimerJohn MearsheimerJohn Mearsheimer is an American international relations scholar who has taught at the University of Chicago since 1982, where he is the R. Wendell Harrison Distinguished Service Professor of Political Science. He is known for the theory of “offensive realism” and books such as The Tragedy of Great Power Politics, and his views on the Israel lobby and the causes of the Ukraine crisis have drawn wide controversy.Open the full entry of the University of Chicago, and states that “society’s current complacency seems unjustified.”⁠[8][25]

The Stanford Daily wrote that the report’s supporters included former Stanford University president John HennessyJohn HennessyJohn Hennessy (John L. Hennessy) is a computer scientist who co-founded MIPS Computer Systems and Atheros Communications, served as the 10th president of Stanford University from 2000 to 2016, shared the 2017 ACM Turing Award and has chaired the board of Alphabet since 2018.Open the full entry and Admiral Bobby Ray Inman, NSA director from 1977 to 1981, who early in his tenure had tried to restrict publication of Hellman’s research; the two later came to appreciate each other’s perspectives. He writes on his website that former Secretary of Defense Leon Panetta and John Hennessy endorsed his Rethinking National Security approach.⁠[25][7]

On July 3, 2019, at the 69th Lindau Nobel Laureate Meeting in Lindau, Germany, he gave the Heidelberg Lecture, titled “The Technological Imperative for Ethical Evolution.”⁠[8][5]

On September 1, 2020, he submitted comments on the National Research Council study mandated by Section 1674 of the FY2020 National Defense Authorization Act; on April 21, 2021, he gave a briefing for the National Research Council study on risk analysis methods for nuclear war and nuclear terrorism; in 2021 he wrote Chapter 4, “Probabilistic Risk Assessment,” of On Assessing the Risk of Nuclear War, edited by James Scouras and published by the Johns Hopkins University Applied Physics Laboratory; and on October 14, 2022, he published “Sixty Years After the Cuban Missile Crisis: Time to Stop Playing Russian Roulette.”⁠[8]

On March 18, 2021, the Bulletin of the Atomic Scientists published “An existential discussion: What is the probability of nuclear war?” by him and Vint CerfVint CerfVint Cerf (born 1943) is an American computer scientist who co-designed the TCP/IP protocols and the basic architecture of the Internet with Bob Kahn and is widely known as one of the “Fathers of the Internet”; he worked at Stanford University, DARPA, MCI and the Corporation for National Research Initiatives, and was vice president and Chief Internet Evangelist at Google from 2005 to 2026.Open the full entry, in which the two friends took opposing sides on whether the risk of nuclear war should be quantified: Hellman argued that a number is needed, used 10% and 0.1% per year as upper and lower bounds, and gave an order-of-magnitude estimate of about 1% per year (roughly 0.3% to 3%), calculating that 1% per year gives worse-than-even odds over a child’s lifetime; Cerf held that any positive risk of a global nuclear exchange is unacceptable.⁠[26]

On February 7, 2024, InfoWorld published Matthew Tyson’s interview with him. He said that before the war in Ukraine he estimated the risk of a major nuclear war at roughly one pull of the trigger in “nuclear roulette” every fifteen years, and that while the wars in Ukraine and between Israel and Gaza continue it had risen to roughly one pull per year; he said: “If we keep fighting wars, it’s only a matter of time before one blows up.” He also said that true cybersecurity is hard to achieve while nations plan and carry out cyberattacks on one another, and asked how artificial intelligence can be used only for good when nations are building it into weapons systems.⁠[17]

In the interview he argued that the dominant narrative about the Ukraine conflict is overly simplified and tends to make the United States look good and its adversaries bad, referring to a University of Chicago poll taken four months after the invasion in which 85% of Ukrainians blamed Russia, 70% their own government and 58% the United States; drawing on a researcher’s finding, he noted a sampling bias, since the Ukrainian cell numbers used tend not to work in the occupied territories, making the results more pro-Ukrainian than average. He also referred to Carl Jung’s idea of the “shadow,” and said that his second career focuses on world peace and personal development, with talks such as his Stanford Engineering Hero lecture, “The Wisdom of Foolishness.”⁠[17]

As of November 2026, his Stanford University profile lists him as professor of electrical engineering, emeritus, as an affiliate of the Stanford Woods Institute for the Environment, and in the Science, Technology and Society program; it states that his most recent work, “Rethinking National Security,” identifies “questionable assumptions that are largely taken as axiomatic truths.” The CISAC website lists him as affiliated faculty, “Not in residence.”⁠[27][13]

His father, Robert S. Hellman, and his mother, Adelaide Leifer Hellman, were married for 47 years; his mother died in 1984. His parents moved to Yorktown Heights, New York, in 1978, where his father edited the Yorktown Senior Sentinel for many years and was a member of the Yorktown Rotary Club; he lived independently there until December 2006, when declining health led him to move to an assisted-living facility in Cortland Manor, where he died peacefully on March 15, 2007, at the age of 98. The memorial describes him as outgoing, with a large circle of friends, often entertaining the staff by singing his favorite song, “You Are My Sunshine”; he was survived by his three sons and their wives, seven grandchildren, eleven great-grandchildren and his brothers Charles and Benjamin.⁠[3]

He said in the oral history that his older brother, Howard, born in 1942, became a science teacher in New York City high schools, and that his younger brother, Steve, studied nuclear engineering, worked at the patent office and later in pharmaceutical research and business.⁠[2]

His wife, Dorothie Hellman, worked as a certified public accountant at Touche Ross (now DeloitteDeloitteDeloitte is a global professional services network made up of Deloitte Touche Tohmatsu Limited and its member firms, providing audit and assurance, consulting, tax and legal services. It reported aggregate revenue of $74.5 billion for fiscal 2026 and has nearly 500,000 people.Open the full entry). On the length of their marriage, his Stanford University profile calls her his “wife of fifty years” in describing their 2016 book, The Stanford Daily wrote in 2019 that they had been married 52 years, and InfoWorld wrote in 2024 that they had been married 56 years.⁠[17][27][25]

He said in the oral history that the couple had planned to wait five years before having children but that this changed; their daughters, Sonja and Gretchen, were born in 1969 and 1971. In 2017 Sonja was a psychologist, and Gretchen had worked in information security for about twenty years before becoming a career coach.⁠[2]

He said in the 2011 interview that he lived on the Stanford University campus; his father’s memorial likewise lists him and Dorothie as living in Stanford, California.⁠[4][3]

He writes on his website that he enjoys people, soaring, speed skating and hiking, the last three infrequently in recent years, and that he has a deep interest in the ethics of technological development. He said in the oral history that he also rode bicycles and sailed, and that he had logged about 2,700 hours in gliders, flying most intensively from 1994 to about 2010. He writes that he owned and flew a Super Dimona motorglider from 1995 to 1998 and a Stemme S10VT from 1998 until he sold it in 2010; both were based in the San Francisco Bay Area with Hayward, California, as home field, and his trips took him to the Grand Canyon, Telluride in ColoradoColoradoColorado is a U.S. state classified as one of the Mountain states, with Denver as its capital. It was admitted to the Union on August 1, 1876, as the 38th state, and its population in the 2020 census (April 1, 2020) was 5,773,714.Open the full entry and the Grand Tetons, and more usually to Yosemite and the Sierra Nevada.⁠[7][2][28]

On his website he maintains a project called the “Mathematical Playground” to make advanced mathematics accessible to motivated high school students.⁠[7]

He said in the oral history that he worked as a consultant and then decided to build a company rather than remain an individual consultant: Hellman Associates, which started out as a continuing-education short-course company. His website states that he has been involved with several high-tech start-ups as a founder, adviser and investor.⁠[2][7]

The Stanford Magazine article states that Ralph Merkle was his student and received his Ph.D. in 1979, and that Steve Pohlig, also his student, received an M.S. in 1975 and a Ph.D. in 1978. In the 2017 oral history he described where several students went: Merkle turned to nanotechnology; Pohlig worked on government projects at Lincoln Laboratory; Aydano Carleial, from Brazil, went to a government research center; Justin Reyneri built a DES board and later worked in computer-aided design at companies including SynopsysSynopsysSynopsys is an American electronic design automation (EDA) and semiconductor IP company founded in 1986 as Optimal Solutions by Aart de Geus and others. It went public in 1992, trades on Nasdaq as SNPS and is headquartered in Sunnyvale, California. It completed its acquisition of Ansys in July 2025. NVIDIA board chair Harvey C. Jones led the company from 1987 to 1998.Open the full entry; and Susan Langford, his last Ph.D. student, worked at HP Labs.⁠[12][2]

Other honors listed on his website are the IEEE Centennial Medal (1984), the Electronic Frontier Foundation Pioneer Award (1994), the National Computer Systems Security Award (1996), the Franklin Institute’s Levy Medal (1997), the IEEE Information Theory Society Golden Jubilee Award and International Engineering Consortium Fellow (1998), the IEEE Kobayashi Computers and Communications Award (1999), and the Marconi International Fellow Award (2000).⁠[6]

For the Paris Kanellakis Theory and Practice Award, his website gives the year 1997, while the Association for Computing Machinery’s 2016 press release gives 1996 and states that he shared it with five others.⁠[6][14]

In 2002 he was elected to the National Academy of Engineering for contributions to the theory and practice of cryptography; in 2006 he was named a Fellow of the International Association for Cryptologic Research (IACR) for the invention of public-key cryptography and for pioneering open research in cryptology; and in 2010 he received the IEEE Hamming Medal “for the invention of public key cryptography and its application to secure communications,” shared with Whitfield Diffie and Ralph Merkle.⁠[6][14]

His website also lists Stanford Engineering Hero, the National Academy of Inventors Hall of Fame and the RSA Lifetime Achievement Award in 2012, and the Silicon Valley Hall of Fame and the Information Systems Security Association Hall of Fame in 2013. The Stanford School of Engineering website places his profile in its “2013 Heroes” section.⁠[6][11]

His website and the NYU Tandon School of Engineering profile state that he has written more than seventy technical papers and holds twelve U.S. patents plus a number of foreign equivalents; the Association for Computing Machinery’s 2016 press release likewise gives twelve U.S. patents; the CISAC profile gives six U.S. patents, and the Federation of American Scientists profile ten.⁠[7][5][14][13][21]

In the 2024 InfoWorld interview he said: “The original ideas behind blockchain go way back, at least as far as Digital Time Stamp Inc.’s plan to use Merkle trees”; on cryptocurrencies he said: “I don’t know very much about cryptocurrencies, so I will defer to others on that.”⁠[17]

In the BitcoinBitcoinBitcoin (common symbol BTC) is an open peer-to-peer electronic cash protocol, network, and native digital asset. Full nodes independently verify transactions and blocks according to the consensus rules; transactions are recorded as UTXOs, and blocks are organized into a public ledger through proof of work. Bitcoin is not issued or managed by any single institution, but using, holding in custody, and trading it still involve key, privacy, market, and legal risks.Open the full entry white paper, Bitcoin: A Peer-to-Peer Electronic Cash System, Satoshi NakamotoSatoshi NakamotoSatoshi Nakamoto is the pseudonymous creator of Bitcoin, who published the Bitcoin white paper in 2008, released the first Bitcoin software and launched the blockchain in 2009, and stopped public activity around 2011; the person’s true identity has never been confirmed.Open the full entry writes: “We define an electronic coin as a chain of digital signatures.” The paper’s eight references include Ralph Merkle’s 1980 paper “Protocols for public key cryptosystems” but not the 1976 paper by Whitfield Diffie and Martin Hellman.⁠[29]

Personal website: https://ee.stanford.edu/~hellman/ (opens in a new window).⁠[7]

IBM: Official website: https://www.ibm.com/ (opens in a new window).⁠[30]

Massachusetts Institute of Technology: Official website: https://www.mit.edu/ (opens in a new window).⁠[31]

Stanford University: Official website: https://www.stanford.edu/ (opens in a new window).⁠[27]

Center for International Security and Cooperation: Official website: https://cisac.fsi.stanford.edu/ (opens in a new window).⁠[32]

Federation of American Scientists: Official website: https://fas.org/ (opens in a new window).⁠[33]