A Bronx boyhood
Martin Edward Hellman was born in New York City on October 2, 1945, into a Jewish family; his grandparents had immigrated to the United States from Eastern Europe. He grew up in the Bronx, which was then sharply divided along ethnic lines. For his first few years the family lived in a neighbourhood that he has recalled as almost entirely Jewish; around 1950 they moved to the West Bronx, where, as a Jewish boy in a largely Catholic neighbourhood, he experienced prejudice. He later drew on those memories in his thinking about how to overcome prejudice and conflict.
He showed an early gift for mathematics and science, became a ham radio enthusiast who hunted for surplus parts in Manhattan’s old radio district, and went to the Bronx High School of Science, graduating in 1962. A scholarship took him to New York University, where he studied electrical engineering and earned his bachelor’s degree in 1966.
Stanford, IBM and a first look at codes
Hellman wanted to go west for graduate school, and with a National Science Foundation fellowship he went to Stanford University, earning his master’s degree in 1967 and his doctorate in 1969 under the information theorist Thomas Cover. In 1966, on Catalina Island, he met Dorothie, who became his wife.
He completed his doctoral research while working at IBM’s Thomas J. Watson Research Center in Yorktown Heights, New York, in 1968 and 1969. There he met Horst Feistel, who was designing the ciphers that would lead to the U.S. Data Encryption Standard, and he first encountered serious cryptographic research. He taught at the Massachusetts Institute of Technology from 1969 to 1971, read Claude Shannon’s wartime work linking information theory and cryptography, and then returned to Stanford as an assistant professor in 1971.
The wisdom of foolishness
At Stanford, Hellman decided to work on cryptography. Colleagues warned him that it was foolish: the U.S. National Security Agency had a huge budget and decades of secret knowledge, so anything an academic discovered would either already be known or be classified. Hellman later called his choice the wisdom of foolishness, arguing that it can pay to pursue a problem others think hopeless.
The central problem he wanted to solve was key distribution. For all of history, two people who wanted to communicate in secret first had to share a secret key, delivered by a courier or agreed face to face. That was workable for armies and embassies, but as computers began to be linked by networks, Hellman foresaw a world in which millions of people and businesses would need to communicate securely with strangers. The old approach could never scale to that.
New Directions in Cryptography
In 1974 a young, self-taught cryptographer named Whitfield Diffie arrived at Stanford to work with Hellman, and they were soon joined in thinking about the problem by Ralph Merkle, a Berkeley student who had independently been exploring similar ideas. In November 1976 Diffie and Hellman published a paper in the IEEE Transactions on Information Theory titled New Directions in Cryptography. It proposed public-key cryptography, in which each user has two related keys: a public key that can be published openly, and a private key kept secret. It also described digital signatures, a way to sign electronic documents that anyone can verify but no one can forge.
The paper gave a concrete method, now known as Diffie–Hellman key exchange, by which two people communicating over a public channel can agree on a shared secret key without any eavesdropper being able to learn it, relying on mathematics that is easy to do in one direction and very hard to reverse. Hellman has long argued that it should be called Diffie–Hellman–Merkle key exchange, in recognition of Merkle’s contribution. With his student Stephen Pohlig he also developed the Pohlig–Hellman algorithm, an important result on the security of such systems.
The paper opened with a confident prediction that the world stood on the brink of a revolution in cryptography. Within a few years that prediction came true, as public-key methods moved from academic journals into products.
Why it matters every day
The 1976 paper launched modern cryptography as an open science and led directly to the RSA system invented at MIT the following year. Its ideas are now built into almost every secure connection on the internet. When a browser shows a padlock beside a web address, the connection has been set up with public-key methods, and versions of Diffie–Hellman key exchange are used in that process, in secure messaging apps, in virtual private networks and in remote login systems.
The Turing Award citation said that Diffie and Hellman’s paper introduced the ideas of public-key cryptography and digital signatures, which are the foundation for most regularly used security protocols on the internet today. A Stanford profile notes that the technology is used to transfer literally trillions of dollars every day. Online banking, online shopping and private communication at global scale all rest on the idea that strangers can create a shared secret in public.
Public-key methods also made possible the digital signatures that protect software updates, electronic contracts and the certificates that prove a website is genuine. Without them, anyone could impersonate a bank or slip malicious code into an update, and the trust on which online life depends would collapse.
The first crypto war
Hellman and Diffie also became the leading academic critics of the government’s Data Encryption Standard. In 1975 they argued that its 56-bit key was too short and that a machine built to try every key could break it. They reviewed the standard publicly at Stanford in 1976 with officials of the National Bureau of Standards and representatives of the NSA. Later history proved them right: it emerged that the NSA had pressed for the shorter key, and in the late 1990s special-purpose machines did break DES, which was then replaced.
The NSA in those years tried to discourage and control academic work on cryptography, and Hellman and his students faced warnings that publishing could be illegal under export rules. They kept publishing. Hellman later served from 1994 to 1996 on the National Research Council’s committee to study national cryptographic policy, whose main recommendations were later implemented.
The dispute over who could study and publish cryptography was later called the first crypto war. In his Stanford oral history Hellman recalls a memorable conversation with Admiral Bobby Ray Inman, who directed the NSA from 1977 to 1981. In the end, open academic research in cryptography prevailed, and it is now taught at universities around the world.
From codes to peace
From the 1980s Hellman turned much of his energy to international security. Working with his wife Dorothie and the Beyond War movement, he was the principal editor of its booklet Beyond War: A New Way of Thinking, and in 1987 he and Anatoly Gromyko of the Soviet Academy of Sciences were chief editors of Breakthrough: Emerging New Thinking, a book by more than thirty Soviet and Western scholars published in Russian and English on how to move beyond the Cold War. He has since applied the tools of risk analysis to the danger of nuclear war, arguing that the risk is far higher than most people assume, through his project NuclearRisk.org.
In 2016 he and Dorothie published A New Map for Relationships: Creating True Love at Home and Peace on the Planet, linking the work of healing a marriage to the work of reducing conflict between nations. They used his share of the Turing Award to further that work. At Stanford he also served as an associate dean working to recruit and support minority graduate students in engineering.
Jewish roots and honours
Hellman grew up in a Jewish family in the Bronx, the grandson of Eastern European Jewish immigrants, and he has spoken in his Stanford oral history about facing discrimination as a Jew in a Catholic neighbourhood as a child. He has drawn from that experience a no-fault approach to prejudice that seeks understanding rather than blame. Sources describe his background and experience rather than any religious practice.
He became an IEEE Fellow in 1980 and received the Marconi Prize with Diffie in 2000, the IEEE Richard W. Hamming Medal in 2010 and induction into the National Inventors Hall of Fame in 2011, the same year he was made a Fellow of the Computer History Museum with Diffie and Merkle. He was elected to the National Academy of Engineering in 2002. In 2016 he and Diffie received the 2015 A.M. Turing Award, the highest honour in computer science.
Legacy
Martin Hellman took on a problem that powerful people told him was not worth an academic’s time, and with Diffie and Merkle he changed the world’s communications. Public-key cryptography protects the passwords, payments, medical records and private messages of billions of people every day, and it made possible the commercial internet.
He did all this as a teacher at Stanford, where he spent his full-time career and where, as emeritus professor, he has continued to write and speak about both privacy and peace.
He then took on an even harder problem, the risk of nuclear war, with the same conviction that clear thinking and openness can make the world safer. Few engineers have done more to protect ordinary people’s privacy, and few have worked so hard to persuade the world to take the next step toward peace.
Sources & further reading
Martin Hellman, Wikipedia · Martin E. Hellman: An Oral History, Stanford Historical Society, Stanford Digital Repository · Leonard Adleman, RSA Cryptography, National Inventors Hall of Fame · Jewish Computer and Information Scientists, jinfo.org · Researched from the sources above and checked against them. Spotted an error? Tell us.
A life of tikkun olam. This is part of tikkun olam, the Jewish idea of repairing the world, and every one of us can add to it.