13 profiles
People
Short, factual profiles of the people who appear most often in our essays. We describe what they published and built, and we do not speculate about anyone’s identity.
Luca Pacioli
Born in Sansepolcro in Tuscany, Pacioli worked as a young man as a tutor in the household of a Venetian merchant, then joined the Franciscan order and taught mathematics in several Italian cities, including Perugia. His Summa de arithmetica, geometria, proportioni et proportionalita, printed in Venice in 1494, gathered the mathematics of his time in the Italian used by merchants. A short section of it described the Venetian method of double-entry bookkeeping, and it became the first printed account of the method. Pacioli did not invent double entry and did not claim to. At the court of Milan he befriended Leonardo da Vinci, who drew the geometric illustrations for his later book De divina proportione, printed in 1509.
Appears in: Double-Entry Bookkeeping and the Merchants of Venice
Whitfield Diffie
Diffie spent the early 1970s travelling around the United States in search of anyone working on cryptography outside the government, eventually joining Martin Hellman at Stanford. Their 1976 paper, New Directions in Cryptography, introduced public-key cryptography to the open literature: a method for two parties to agree on a secret key over a public channel, and the idea of digital signatures that anyone could verify. He later worked in industry, including many years at Sun Microsystems, where he became its chief security officer. With Susan Landau he wrote Privacy on the Line (1998) about the politics of encryption. Diffie and Hellman shared the 2015 ACM Turing Award.
Appears in: The Cypherpunks and the Dream of Private Money
Martin Hellman
A professor of electrical engineering at Stanford University, Hellman co-authored with Whitfield Diffie the 1976 paper that opened public-key cryptography to academic research. In the 1970s he also argued publicly that the key length of the new US Data Encryption Standard was too short, an early instance of academic cryptographers challenging government choices. With Ralph Merkle, his doctoral student, he devised the Merkle–Hellman knapsack cryptosystem. In later decades Hellman turned much of his attention to the risks of nuclear deterrence. He and Diffie received the 2015 ACM Turing Award for their contributions to modern cryptography.
Appears in: The Cypherpunks and the Dream of Private Money
Ralph Merkle
As an undergraduate at the University of California, Berkeley, in 1974, Merkle devised a scheme for two parties to establish a shared secret over an insecure channel, now known as Merkle’s puzzles; it was eventually published in 1978. He completed his doctorate at Stanford under Martin Hellman in 1979. His hash trees, in which many items are summarised by a single hash at the root, became a basic tool of computer security. Merkle trees appear in the Bitcoin whitepaper, which cites his 1980 paper on public-key protocols, and in many other systems that need to prove that an item belongs to a large set. He later turned to work on molecular nanotechnology.
Appears in: Hashcash, b-money and Bit Gold: the Precursors, Reading the Bitcoin Whitepaper, Section by Section
David Chaum
Chaum completed his doctorate at the University of California, Berkeley, in 1982. His 1981 paper on untraceable electronic mail introduced mix networks, and in 1982 he presented blind signatures, the basis of his design for private electronic cash. In a 1985 article he argued that computerised transactions would create unprecedented surveillance unless systems were designed for privacy from the start. After moving to Amsterdam, he founded DigiCash in 1989; its eCash was offered by Mark Twain Bank in St. Louis from 1995, but the company filed for bankruptcy in 1998. Chaum later worked on verifiable voting systems and other privacy technologies.
Appears in: Chaum, DigiCash and the First Digital Cash
Leslie Lamport
Lamport’s 1978 paper on time, clocks and the ordering of events in a distributed system showed how computers without a shared clock can agree on the order in which things happened. In 1979 he described a one-time digital signature built only from hash functions. In 1982, with Robert Shostak and Marshall Pease, he published “The Byzantine Generals Problem”, which defined the challenge of reaching agreement when some participants may be faulty or dishonest. He later designed the Paxos consensus algorithm and created LaTeX, the document system used for much scientific writing. He worked at SRI International, Digital Equipment Corporation and Microsoft Research, and received the 2013 ACM Turing Award.
Appears in: Hashcash, b-money and Bit Gold: the Precursors
Stuart Haber and W. Scott Stornetta
Working at Bellcore, the research arm of the American regional telephone companies, Haber and Stornetta asked how to prove when a digital document was created, in a way that not even the timestamping service could falsify. Their 1991 paper in the Journal of Cryptology linked each timestamp to the previous one with a hash, forming a chain. A 1993 paper with Dave Bayer used Merkle trees to timestamp many documents at once. In 1994 they founded a company, Surety, which from 1995 published a hash of its timestamp chain every week in the classified section of The New York Times. Three of the eight references in the Bitcoin whitepaper are to their work.
Appears in: Hashcash, b-money and Bit Gold: the Precursors, Reading the Bitcoin Whitepaper, Section by Section
Phil Zimmermann
In 1991 Zimmermann released Pretty Good Privacy, a program that let anyone encrypt e-mail and files with public-key cryptography. Copies spread worldwide, and he became the subject of a US federal investigation over the export of encryption software. In 1995 MIT Press published PGP’s source code as a printed book, emphasising that code could be treated as protected speech. The investigation was dropped in 1996 without charges. PGP’s web of trust, in which users vouch for one another’s keys without a central authority, was an early practical model of decentralised trust. The OpenPGP standard that grew out of his work remains in use.
Appears in: The Cypherpunks and the Dream of Private Money
Timothy C. May
As a physicist at Intel in the 1970s, May identified alpha particles from trace radioactivity in chip packaging as a cause of random errors in memory chips, a finding of real importance to the industry. He retired from Intel in 1986. In 1988 he wrote “The Crypto Anarchist Manifesto”, predicting that cryptography would allow anonymous communication and commerce and would change the nature of government. In 1992 he co-founded the cypherpunks with Eric Hughes and John Gilmore, and in 1994 compiled the Cyphernomicon, a long FAQ on the group’s ideas. His views were deliberately provocative and often controversial, even among the cypherpunks themselves.
Appears in: The Cypherpunks and the Dream of Private Money
Adam Back
A British cryptographer with a doctorate in computer science, Back was an active member of the cypherpunks mailing list in the 1990s, where he was known for work on encryption tools and for campaigning against export controls. In 1997 he announced Hashcash, a scheme in which the sender of an e-mail attaches a stamp that is costly to compute but easy for the recipient to check, intended to make sending junk mail in bulk expensive. He described the scheme fully in a 2002 paper. Hashcash’s method of searching for a hash with a required number of leading zero bits is the proof-of-work design adopted in the Bitcoin whitepaper, which cites his paper.
Appears in: Hashcash, b-money and Bit Gold: the Precursors, Reading the Bitcoin Whitepaper, Section by Section
Wei Dai
Wei Dai is known in cryptography as the original author of Crypto++, a widely used open-source library of cryptographic algorithms. In November 1998 he published b-money, a short proposal for an anonymous, distributed system of money and contracts among participants known only by their public keys. In its first version, every participant would keep a copy of the ledger, and new money would be created by solving computational problems, with the amount linked to the cost of the effort. Dai himself pointed out the practical difficulties of his proposal, and it was never built. B-money is the first reference cited in the Bitcoin whitepaper.
Appears in: Hashcash, b-money and Bit Gold: the Precursors
Nick Szabo
Szabo worked at DigiCash in the 1990s and is known above all for introducing the idea of smart contracts: agreements whose terms are embedded in software and hardware so that breaking them is costly. He set out the concept in essays from 1994 onwards, including a 1997 article in the journal First Monday. In 1998 he proposed bit gold, a scheme for creating costly digital tokens through proof of work, chaining them together and recording their ownership in a registry run by a group of servers; he described it publicly in 2005. His 2002 essay “Shelling Out” explores the origins of money in collectibles such as shells and beads.
Appears in: Hashcash, b-money and Bit Gold: the Precursors
Hal Finney
Finney was an early contributor to PGP and later worked for many years at PGP Corporation. A member of the cypherpunks from the beginning, he wrote one of the first anonymous remailers in 1992. In 2004 he released RPOW, a system for passing proof-of-work tokens from person to person, using secure hardware to show that the server ran its published code. When the Bitcoin software was released in January 2009, Finney was among the first to run it, and on 12 January 2009 he received the first transaction between two people. Diagnosed with amyotrophic lateral sclerosis in 2009, he continued programming as long as he could. He died on 28 August 2014.
Appears in: Hashcash, b-money and Bit Gold: the Precursors, Reading the Bitcoin Whitepaper, Section by Section, The Cypherpunks and the Dream of Private Money
Profiles describe published work and documented events only. Portraits are not shown; we do not use stock photographs or generated likenesses of real people.