Ralph Merkle

Ralph Merkle was born on February 2, 1952, in Berkeley, 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, and was raised in California.⁠[1][2]

His father, Theodore Charles Merkle, was a physicist. An obituary in Physics Today, November 1966 issue, records that Theodore Merkle was born in Toledo, OhioOhioOhio is a state in the Midwestern United States; its capital is Columbus. It joined the Union in 1803 as the 17th state, the first carved from the Northwest Territory, and its population in the 2020 census (April 1, 2020) was 11,799,448.Open the full entry, and educated at the University of MichiganUniversity of MichiganThe University of Michigan is a university founded in Detroit in 1817 that moved to Ann Arbor, Michigan, in 1837; it is governed by a statewide-elected Board of Regents and also has campuses in Dearborn and Flint.Open the full entry, and that after guided-missile research with the Navy during the Second World War he took his doctorate at the University of California at 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; he joined the Lawrence Radiation Laboratory as a physicist in 1953, became an associate director there in 1959 and worked as a reactor physicist on weapons and propulsion projects, and at his death he was the laboratory’s associate director for physics; the obituary records that he died of cancer on August 12. Ralph Merkle writes on his website that his father ran Project Pluto; the editor’s note to his 1995 interview includes an illustration of the nuclear-powered ramjet on which his father was then working in California.⁠[3][4][5]

On his website he writes that his sister, Judith Merkle Riley, wrote historical novels and that his great-uncle was Fred Merkle, “of baseball fame.”⁠[4]

Ralph Merkle studied computer science as an undergraduate at the University of California, Berkeley. In a 1995 interview he recalled taking a summer programming course on the CAL Time-sharing System and spending the rest of his education at Berkeley “basically learning about computers.”⁠[5][2]

In the fall of 1974 he took CS244, the computer security course taught by Lance Hoffman, and in his project proposal described a way for two parties to agree on a key over an insecure channel, the method later called Merkle’s Puzzles. Hoffman rejected his first, seven-page proposal; a rewritten two-page version also failed to interest Hoffman, and he dropped the course but kept working on the idea. In the 1995 interview he recalled that Hoffman advised him to work on data compression instead and that he had been “rather frustrated” at the time.⁠[6][2][5]

The National Inventors Hall of Fame’s profile states that he realized public key cryptography was possible in 1974 as an undergraduate and worked alone until he joined Whitfield Diffie and Martin Hellman in 1976.⁠[1]

The Computer History Museum records that he received a BS in computer science from the University of California, Berkeley in 1974; a 2003 news release of the Georgia Institute of Technology states instead that he holds a B.A. and an M.S. in computer science from UC Berkeley.⁠[2][7]

Bob Fabry, a member of the Berkeley faculty, read an early draft and commented: “Publish it, win fame and fortune!” In August 1975 he submitted the paper to Susan Graham, an editor of Communications of the Association for Computing Machinery. The referee, an “experienced cryptography expert” whose identity is still unknown, wrote that the paper “is not in the main stream of present cryptography thinking” and that “it is extremely dangerous to transmit key information in the clear”; in rejecting it, Graham wrote that she “was particularly bothered by the fact that there are no references to the literature.” On his website Merkle writes that he had failed to cite any prior work on public key cryptography and should have “looked up ‘public key cryptography’ on 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” before submitting, calling his defense “feeble”: the term did not yet exist. A revised version is dated December 7, 1975.⁠[6]

In the 1995 interview he recalled that Peter Blatman first put him in touch with Diffie and Hellman at Stanford UniversityStanford UniversityStanford University is a research university in California founded by Leland and Jane Stanford in 1885 and opened in 1891.Open the full entry; a letter he wrote to Hellman is dated February 7, 1976, at its end, from which he concludes that he first learned about Diffie and Hellman in early February 1976; Hellman made it clear that this was “a good and worthwhile problem.”⁠[5]

The Association for Computing Machinery’s biography of Whitfield Diffie states that Hellman and Diffie learned of Merkle’s work in 1975 and that their 1976 paper cited his work as a “submitted paper”; the Computer History Museum records that he joined their team in the summer of 1976 and became Hellman’s doctoral student that fall.⁠[8][2]

The Computer History Museum records that he received a master’s degree in electrical engineering from Stanford University in 1977.⁠[2]

On September 6, 1977, Martin E. Hellman, Bailey W. Diffie and Ralph C. Merkle filed the patent application “Cryptographic apparatus and method,” assigned to Leland Stanford Junior University; it was granted on April 29, 1980, as U.S. Patent 4,200,770. The Association for Computing Machinery’s biography of Diffie calls it the “Diffie-Hellman-Merkle patent (held by Stanford University)” and states that Stanford sublicensed it to 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.⁠[9][8]

On October 6, 1977, Martin E. Hellman and Ralph C. Merkle filed the patent application “Public key cryptographic apparatus and method,” also assigned to Leland Stanford Junior University; it was granted on August 19, 1980, as U.S. Patent 4,218,582. The example system in the specification makes use of the difficulty of the so-called “knapsack problem.”⁠[10]

At the symposium 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 on October 10, 1977, papers that student co-authors would normally have presented were read by Martin Hellman instead. Hellman writes on his website that there was a threat that they could be prosecuted under the International Traffic in Arms Regulations (ITAR); Stanford’s general counsel believed that the ITAR would be unconstitutional if interpreted broadly enough to cover the papers, but that a court case could last years and harm a new Ph.D.’s career, and advised that the students not present. Hellman left the decision to Merkle and Steve Pohlig, who at first said, “We need to give the papers, the hell with this,” but their parents’ concerns eventually prevailed; the two stood by the podium while Hellman gave the papers.⁠[11][12]

His paper “Secure Communications Over Insecure Channels” appeared in Communications of the Association for Computing Machinery, vol. 21, no. 4, April 1978, pp. 294–299, in the “Programming Techniques” section edited by S. L. Graham and R. L. Rivest, with the dates “Received August 1975; revised September 1977”; on his website he writes that it was published “only after almost three years of delay,” after others had published related work.⁠[13][6]

In September 1978 R. Merkle and M. Hellman published “Hiding information and signatures in trapdoor knapsacks” in IEEE Transactions on Information Theory, vol. 24, no. 5, pp. 525–530. In December of that year Adi Shamir and Richard E. Zippel showed, in a technical memo of the Massachusetts Institute of Technology’s Laboratory for Computer Science, that a simplified version of the Merkle-Hellman public-key system is breakable, while the full system “seems to be resistant” to the attack they proposed. The Association for Computing Machinery’s biography of Diffie states that Diffie wrote that the trap-door knapsack system did “not lend itself readily to the production of signatures.”⁠[14][15][8]

In 1979 he received his Ph.D. in electrical engineering from Stanford University.⁠[2][11]

Whitfield Diffie recalled in a 1992 interview that Merkle was working for him at Bell Northern Research “in 1980 or ’79” and left because “we didn’t get along very well”; Diffie said that Merkle wanted to move directly to producing public key systems and that he himself had been, in retrospect, “far too conservative.”⁠[16]

On September 5, 1979, Ralph C. Merkle, as sole inventor, filed the patent application “Method of providing digital signatures,” assigned to Leland Stanford Junior University; it was granted on January 5, 1982, as U.S. Patent 4,309,569. The abstract describes a method of providing a digital signature for the authentication of a message using an “authentication tree function” of a one-way function of a secret number, and the description sets out “tree authentication” with a binary authentication tree. CoinDeskCoinDeskCoinDesk is a cryptocurrency media, events, index, and data company founded in 2013 and headquartered in New York. Its businesses include the CoinDesk news website, the annual crypto industry conference Consensus, and the CoinDesk Indices index business. In November 2023, the digital asset exchange Bullish acquired CoinDesk from Digital Currency Group, and CoinDesk has since operated as an independent subsidiary of Bullish.Open the full entry’s 2016 article states that Merkle trees were called “certified digital signatures” by their inventor in his original 1979 paper.⁠[17][18]

After his doctorate he went to work for Elxsi, a small computer company in Silicon Valley, serving as manager of compiler development at Elxsi Corporation from 1980 to 1988.⁠[2][7]

In April 1980 he published “Protocols for public key cryptosystems” in the proceedings of the 1980 Symposium on Security and Privacy of the IEEE Computer Society, pages 122–133. Writing in the Association for Computing Machinery’s magazine Queue in 2017, Arvind Narayanan and Jeremy Clark state that Merkle trees are named after Ralph Merkle, who proposed the idea in this 1980 paper, and that his intended application was to produce a digest for a public directory of digital certificates.⁠[19][20]

In 1982 UMI Research Press published his book Secrecy, Authentication, and Public Key Systems.⁠[7]

His wife is the video game designer Carol Shaw. In a 2011 interview Carol Shaw recalled that they met in 1976 at Berkeley in CS111 (Computer Science System Simulation), that he became interested after noticing that she had beaten him on the midterm, and that they lived together for a while before marrying in 1983.⁠[4][21]

From 1988 to 1999 he was a research scientist at Xerox PARC, and from 1988 he researched nanotechnology. Carol Shaw described the position in her 2011 interview as “this great job.”⁠[7][2][21]

He writes on his website that he and his wife joined Alcor, which he calls “the world’s leading cryonics organization,” in 1989.⁠[4]

On May 18, 1995, he was interviewed by Arnd Weber about how the idea of public key distribution arose, saying that he was then “primarily doing nanotechnology” and that “Nanotechnology is going to have a big impact on the future of the world.” On January 16, 2002, the Institute for Technology Assessment and Systems Analysis (ITAS) of the Karlsruhe Institute of Technology published the interview together with his 1974 paper and its early drafts.⁠[5]

The Association for Computing Machinery’s 2016 press release states that the association’s 1996 Paris Kanellakis Theory and Practice Award was shared by Leonard Adleman, Whitfield Diffie, Martin Hellman, Ralph Merkle, Ronald Rivest and Adi Shamir.⁠[22]

The Foresight Institute lists Ralph C. Merkle, Stephen Walch, M. Reza Ghadiri and Fotis Nifiatis as the 1998 Feynman Prize winners; Merkle states on his website that his was the prize for theory, and the Georgia Institute of Technology’s news release calls him a co-recipient of that year’s prize for theory.⁠[23][4][7]

He writes on his website that he has been a director of Alcor since May 21, 1998.⁠[4]

From 1999 he was a principal fellow at Zyvex LLC, a nanotechnology start-up near Dallas, where he led nanotechnology research. That year he, Whitfield Diffie and Martin Hellman received the IEEE Kobayashi Award.⁠[7][8]

In 2000 he received the RSA Award in Mathematics.⁠[2][7]

On July 15, 2003, the Georgia Institute of Technology announced his appointment as director of the Georgia Tech Information Security Center (GTISC), effective September 8, succeeding the interim director Richard A. DeMillo; he joined the College of Computing faculty as Professor of Computing and director of GTISC, reporting to the Office of the Provost. The release states that he then held 11 patents, including fundamental patents with Hellman and Diffie on public key distribution and public key cryptosystems, and was vice president for technology assessment at the Foresight Institute and a board member of the Alcor Life Extension Foundation; he was a member of the Association for Computing Machinery, the American Chemical Society, the American Physical Society and the IEEE, and had consulted for Xerox PARC, Securify and confidential clients. Provost Jean-Lou Chameau said: “His extensive research experience, credibility, and leadership will enhance GTISC’s successes.” The Computer History Museum records that he became a distinguished professor at Georgia Tech in 2003.⁠[24][7][2]

In 2006 he returned to California.⁠[2]

In 2008 he was named a Fellow of the International Association for Cryptologic Research (IACR), with the citation “For the invention of public-key cryptography.”⁠[25]

In 2010 the IEEE awarded its Richard W. Hamming Medal to Martin Hellman, Whitfield Diffie and Ralph Merkle. A Foresight Institute post of February 16, 2010, quotes the Stanford News announcement: “Thirty-five years ago, Martin Hellman, Whitfield Diffie and Ralph Merkle developed an easy method” for sending secure messages over insecure channels.⁠[26][22]

In 2011 he was inducted into the National Inventors Hall of Fame for U.S. Patent 4,200,770 and was made a Fellow of the Computer History Museum, “For his work, with Whitfield Diffie and Martin Hellman, on public key cryptography.”⁠[1][2]

On March 11, 2011, Jon Plutte of the Computer History Museum recorded an interview with him; the 10-page transcript covers how his early research at Berkeley led to a distinctive method of key exchange, how his contribution relates to the subsequent work of Martin Hellman and Whitfield Diffie at Stanford University, and his views on emerging technologies.⁠[27]

CoinDesk’s 2016 article states that in May 2014 he joined the EthereumEthereumEthereum is an open, general-purpose smart contract blockchain that launched in 2015, and its native asset is ether (ETH). The project was proposed by Vitalik Buterin and advanced jointly by eight co-founders; the network now uses proof of stake and centers on the EVM, the account model, a rollup scaling roadmap, and the open EIP process.Open the full entry project as an adviser and was then drawn to an article by Vitalik ButerinVitalik ButerinVitalik Buterin is the originator of Ethereum, the author of its whitepaper, and one of its eight co-founders, as well as a co-founder of Bitcoin Magazine. The Ethereum Foundation calls him the inventor of Ethereum; he has long been involved in protocol research and public discussion, but does not control the network as a CEO.Open the full entry on futarchy, a model of governance based on prediction markets that Robin HansonRobin HansonRobin Hanson is an American economist and associate professor of economics at George Mason University, known for pioneering work on prediction markets, for advocating futarchy, a form of governance based on prediction markets, and for writing The Age of Em and co-writing The Elephant in the Brain.Open the full entry proposed in 2000.⁠[18]

In May 2016 he published the 27-page paper “DAOs, Democracy, and Governance,” proposing that prediction markets be used for matters such as determining citizenship, assessing collective welfare, passing bills, electing leaders and preventing war; the paper treats Bitcoin itself as the first DAO prototype. CoinDesk’s article of June 28, 2016, quotes him as saying that technology is enhancing the ability of smaller and smaller groups to do more and more damage, that “we have to pay greater attention to dealing with the governance issues,” and that “people don’t fight wars if they know what the outcome is going to be.”⁠[18]

The same article states that The DAO, the first large-scale DAO, had been depleted of a large portion of what was once over $150 million worth of resources after someone figured out how to manipulate parts of its governance model; Merkle holds that a DAO democracy must be able to automatically improve its core software, envisages DAOs evolving through Darwinian competition with one another, and suggested testing DAO democracy first in small groups such as student organizations and then in “bankrupt cities or lawless states”; he presented the paper to the Decentralized Autonomous Society in Palo Alto, California. On his website he also writes that concepts related to Bitcoin can improve governance through a “DAO Democracy.”⁠[18][4]

As of November 2026 his website lists him as a Senior Research Fellow of the Institute for Molecular Manufacturing, president of Nanofactory Corporation and of Nanofactory CBN (NFCBN), co-founder of the Nanofactory Collaboration and a director of Alcor, and gives his motto as “Life is good. More is better.” The National Inventors Hall of Fame’s profile also describes him as a member of the faculty of Singularity UniversitySingularity UniversitySingularity University is a technology and leadership education organization founded by Peter H. Diamandis and Ray Kurzweil. It offers short executive programs, organizational training and support for entrepreneurs, focusing on rapidly developing technologies and their social and business implications.Open the full entry.⁠[4][1]

In her 2011 interview Carol Shaw mentioned that she lived with her husband, Ralph Merkle, in Mountain View, and recalled a homemade terminal that he had built from a kit. Among his other interests his website lists medical applications of nanotechnology, computational chemistry, reversible computing and the extropians.⁠[21][4]

In the same interview Carol Shaw also recalled that, when she was writing 3D Tic-Tac-Toe for Atari, Ralph found a paper in which someone had proven, with the aid of a computer, that the first player could always win with perfect play; that he proposed for the Atari 800 version of her River Raid a river that would keep branching depending on whether the player went left or right, which she did not have time to build; that years later he duplicated at Xerox PARC the EPROM holding the prototype of Polo, her first, unreleased game, to extract its binary file; and that her later MASS project (Molecular Assembler Sequence Software) was related to his nanotechnology work but was never finished.⁠[21]

On his website he writes that the central objective of molecular manufacturing is the design, modeling and manufacture of systems that can inexpensively make products specified in molecular detail; his work covers positional devices such as molecular robotic arms and Stewart platforms, self-replication and convergent assembly. He chaired both the Fourth and the Fifth Foresight Conferences on Molecular Nanotechnology and served for several years as an executive editor of the journal Nanotechnology.⁠[4]

On his website he presents cryonics as a bridge to the future for people who might not live long enough to benefit from future nanomedicine: “cryonics offers a bridge to the future in case we wouldn’t otherwise make it.”⁠[4]

In a 1992 interview Whitfield Diffie said, “The most original person I can identify in this case is Merkle,” and “Merkle had the earliest claim,” calling Merkle’s Puzzles “the first thing which is really any sort of a solution to the problem” and “a fantastic discovery”; he also judged that the system’s work factor could not be improved to the point of being useful on most channels. Diffie added that part of the reason the work was not appreciated sooner was that Merkle “didn’t write very well,” and that it was “very very hard to read”; the editor of the interview notes that Diffie apparently does not mean Merkle’s early papers but later ones.⁠[16]

The Foresight Institute’s 2010 post on the Hamming Medal states that Martin Hellman was especially happy that Merkle was recognized, since his early public-key work had not received the acknowledgement it deserved, and quotes him: “Ralph really deserves equal credit with us.” The Association for Computing Machinery’s biography of Diffie states that Hellman later argued that public-key credit should go to “Diffie-Hellman-Merkle.” In 2003 Richard A. DeMillo said that Merkle, together with Martin Hellman and Whitfield Diffie, “invented modern cryptography”; the Georgia Institute of Technology’s release also quotes 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 describing him as an inventor of the encryption technology that allows secure transactions over the Internet.⁠[26][8][7]

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’s Bitcoin white paper, “Bitcoin: A Peer-to-Peer Electronic Cash System,” states in Section 7, “Reclaiming Disk Space,” that transactions “are hashed in a Merkle Tree,” with only the root included in the block’s hash, and lists Merkle’s 1980 paper as reference [7]; in Section 8, “Simplified Payment Verification,” a user verifies a payment by obtaining the “Merkle branch” linking the transaction to the block in which it is timestamped. Arvind Narayanan and Jeremy Clark write that in each block’s Merkle tree the leaf nodes are transactions.⁠[19][20]

CoinDesk’s 2016 article states that hashing methods based on the Merkle tree are central to both Bitcoin and Ethereum; on his own website he writes: “Merkle trees are central to Bitcoin.”⁠[18][4]

On his website he argues that the quantum computers likely to be built would compromise widely used public-key systems such as RSA and ECC, recommends that organizations with high security needs deploy cryptographic systems based on conventional algorithms until quantum-resistant ones are available, and points to the post-quantum cryptography project of the National Institute of Standards and Technology (NIST).⁠[4]

Personal website: https://ralphmerkle.com/ (opens in a new window).⁠[4]