David Chaum

Two interviews published by Centrum Wiskunde & Informatica (CWI) in 2019 and 2020 both give the year 1955 after his name. A Bitcoin Magazine article of April 2018 put his age at 62 or 63 and said he would not reveal his exact age. The article calls him “the bearded, ponytailed Chaum.”⁠[1][2][3]

In the CWI interview that appeared in CWI’s staff magazine on April 30, 2020, he recalled growing up in Los Angeles; he programmed his first computer by using toothpicks to push the pre-perforated holes out of Hollerith cards, which were submitted to a computer with a one-week turnaround; he taught programming at a local junior college while in high school and later, in his words, “kind of dropped out of high-school to sneak into UCLA computer science courses.”⁠[2]

On February 22, 1979, he issued the technical memorandum “Computer Systems Established, Maintained, and Trusted by Mutually Suspicious Groups” (UCB/ERL M79/10) at the Electronics Research Laboratory of 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.⁠[4][5]

A 2018 paper by Alan T. Sherman, Farid Javani, Haibin Zhang and Enis Golaszewski of the Cyber Defense Lab at UMBC summarizes the memorandum as describing a distributed computer system that mutually suspicious groups can establish, maintain and trust, built from physically secure “vaults,” symmetric and asymmetric encryption, cryptographic hash functions, digital signatures and threshold secret sharing; each vault signs, records and broadcasts every transaction it processes; membership changes such as adding or removing nodes require synchronization and agreement among the nodes, and consensus is reached by a majority vote of nodes based on the signed messages they observe entering and leaving vaults. The paper says threshold secret sharing was a new primitive that he introduced, and that Adi Shamir, after reading his February 1979 technical report describing “partial keys,” published an alternative method of secret sharing in November 1979.⁠[4]

In the 2020 CWI interview he said that Gene Lawler was his advisor at Berkeley for a while and got him interested in CWI.⁠[2]

In February 1981 he published the paper “Untraceable Electronic Mail, Return Addresses, and Digital Pseudonyms” in Communications of the ACM (vol. 24, no. 2, pp. 84–90). His personal website describes the mix networks the paper introduced: public-key cryptography hides who sends and who receives a message, which is encrypted in several layers and passed through a series of nodes, each of which shuffles the order of the messages and removes one layer of encryption.⁠[6][5]

A 2018 Bitcoin Magazine article says the paper laid the groundwork for research into encrypted Internet communication, which eventually led to privacy technologies such as Tor; a January 2016 Fortune article calls him “an inventor of key concepts undergirding identity-cloaking software such as the Tor web browser.”⁠[3][7]

In 1982 he organized the cryptography conference Crypto ’82 in Santa Barbara, 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 served as its general chair, with Ron Rivest as program chair and Alan Sherman as co-chair; his address at the time was the Department of Electrical and Computer Engineering of the University of California, Santa Barbara.⁠[8][9]

The page “Accounts of IACR Formation” on his personal website reproduces a report under David Kahn’s name from the January 1983 issue of Cryptologia, the announcement of Eurocrypt ’83 and an excerpt from the preface of the Crypto ’82 proceedings. The report records that on the last day of the conference some attendees met to begin organizing a group tentatively called the “International Association for Cryptologic Research,” which was to coordinate the timing, location and program of cryptology meetings and publish a bulletin giving notice of conferences; the planning committee consisted of Henry J. Beker of RACAL-Comsec, Ernest F. Brickell of Sandia National Laboratories, David Chaum, Whitfield DiffieWhitfield DiffieWhitfield Diffie (born 1944) is an American cryptographer who, with Martin Hellman, published the paper “New Directions in Cryptography” in 1976, introducing the ideas of public-key cryptography and digital signatures and the method of key exchange later named after the two, Diffie–Hellman key exchange, for which they received the 2015 A.M. Turing Award; he was chief security officer of Sun Microsystems and has long advocated the right of individuals and businesses to use encryption.Open the full entry of BNR, Robert R. Jueneman of Satellite Business Systems, Stephen Kent of Bolt, Beranek & Newman, and David Kahn, an editor of Cryptologia; the group had begun to draw up a charter, and he had begun planning the U.S. Crypto ’83 meeting and Henry J. Beker the European one. The preface records that the committee held its first meeting at the end of the conference, adopted the working title, and planned a meeting in Europe for March 1983 and Crypto ’83 for August 1983.⁠[9]

His personal website says that he founded the IACR by launching the conference at a time when the NSA was “bullying scientific societies to halt all events on crypto”; the background material it lists consists of Science coverage of NSA pressure on cryptography research (labeled Kolata, 1980), an article on the NSA’s demand for prepublication review months before Crypto ’82 (labeled Kolata, 1982), Martin HellmanMartin HellmanMartin Hellman (born 1945) is a cryptologist and professor emeritus of electrical engineering at Stanford University. In 1976 he and Whitfield Diffie published “New Directions in Cryptography,” which introduced public-key cryptography and digital signatures, and the two received the 2015 A.M. Turing Award for their contributions to modern cryptography; his later work has centered on the risk analysis of nuclear deterrence and on international security.Open the full entry’s copy of the Meyer letter with the IEEE forwarding correspondence, commentaries by Martin Hellman and Whitfield Diffie on the Meyer affair, and material on Bernstein v. DOJ and Bernstein v. U.S. Department of State (1996). In the 2020 CWI interview he said that he started the IACR at Berkeley when the NSA began trying to block cryptography conferences; CWI’s 2019 article dates the founding of the IACR to 1982. His personal website describes the IACR as the scientific society of academic cryptography, which sponsors three flagship conferences a year as well as workshops and a scholarly journal.⁠[8][2][1]

At Crypto ’82 he presented the paper “Blind Signatures for Untraceable Payments,” printed on pages 199–203 of the conference proceedings published by Plenum.⁠[5][10]

The Bitcoin Magazine article explains blind signatures as a way for a signer to sign data without seeing its contents; applied to money, a bank signs scrambled digital banknotes and can later verify them without learning who withdrew them, which is the basis of eCash. A 2019 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 article instead dates his creation of Ecash to 1983.⁠[3][11]

On August 22, 1983, he filed a U.S.United 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 patent application for “Blind signature systems,” which was granted on July 19, 1988, as US 4,759,063, with David L. Chaum named as inventor and an individual as original assignee; the legal events listed by Google Patents include an assignment from David Chaum to DigiCash Incorporated dated November 29, 1996, an assignment from DigiCash Inc. to DigiCash Acquisition Corporation dated July 19, 1999, that company’s change of name to eCash Technologies, Inc., dated October 13, 1999, and an assignment from eCash Technologies, Inc. to InfoSpace, Inc. dated June 24, 2002.⁠[12]

In April 1982 he completed his doctoral dissertation at the University of California, Berkeley, under the same title as the 1979 memorandum; his personal website states that he holds a Ph.D. in computer science from the university. Sherman and his co-authors write that the dissertation contains detailed specifications but went largely unnoticed, apparently because he never tried to publish it at a conference or in a journal and instead pursued other approaches to individual privacy.⁠[4][13]

The biography on his personal website says he taught at the NYUNew 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 Graduate School of Business and at the University of California; a 1998 American Banker article calls him a former University of California professor and expert on data encryption who was among the first to see a need for a cash-like payment mechanism on open networks, and a 1999 ForbesForbesForbes is an American business media brand that began with Forbes magazine, founded by B.C. Forbes in 1917. It is known for rankings such as the Forbes 400, the World’s Billionaires list and 30 Under 30, and operates Forbes.com, ForbesLive events and licensed editions in 81 countries. Since 2014 a majority stake has been held by the Hong Kong investment group Integrated Whale Media; a 2021 plan to list on the New York Stock Exchange through a special purpose acquisition company was terminated in 2022. It is headquartered in Jersey City, New Jersey.Open the full entry article says he worked at the Center for Mathematics & Science in Amsterdam. The 2018 Bitcoin Magazine article says he started his career as a computer science professor at Berkeley.⁠[13][14][15][3]

From March 21 to 25, 1983, the second European cryptology conference, Eurocrypt ’83, was held at the International Center for Mechanical Sciences in Udine, Italy, sponsored partly by the center and partly by the newly formed IACR, of whose organizing committee he was a leading member.⁠[9]

The Crypto ’82 proceedings, “Advances in Cryptology: Proceedings of Crypto 82,” which he edited with Ronald L. Rivest and Alan T. Sherman, were published by Plenum Press in 1983; the preface records that in the opening remarks of the conference he proposed forming an international organization to coordinate cryptology meetings and share news of relevant events and publications. The Crypto ’83 proceedings, which he edited alone, appeared in 1984.⁠[9][5]

CWI is the Dutch national research institute for mathematics and computer science, located in Amsterdam. CWI’s 2019 article says he joined the institute in the second half of the 1980s as head of its cryptography department; ERCIM News of January 2020 says he set up the Cryptology research group at CWI in the early 1980s, which brought modern cryptology to Europe. CWI’s 2019 article adds that by the time he arrived in Amsterdam his peers regarded him as one of the best cryptography experts in the world.⁠[1][16][17]

In the 2020 interview he said that Cor Baayen invited him to CWI and that he enjoyed helping Cor Baayen launch the European Research Consortium for Informatics and Mathematics (ERCIM); the Crypto Group he led ranged from students to professors and ran undergraduate conferences, graduate summer schools, monthly national crypto days and international conferences. He said, “Mokum, and CWI, gave me such a fantastic sense of freedom!”, a freedom from judgement in science that also came with the urban anonymity of an expatriate. He recalled Alfred Hofmann of Springer once remarking that the group had published more articles on cryptography than anyone, even five years after it stopped publishing; the “greats” he named in the interview were Andries Brouwer, Paul Vitányi, Gilles Brassard and Lambert Meertens. He said he often tells young academics that the life of a graduate student is as good as it gets for pursuing academic interests, “But being a group leader at CWI bests that everyday!”⁠[2]

His personal website says that he organized a two-week Crypto-Course at CWI that helped launch the careers of many leading cryptographers; some attendees and guest lecturers joined the CWI Crypto Group, and others returned as postdocs or during sabbaticals to work on fundamental results in multiparty computation. The website credits him with naming both the multiparty computation solution and the research area, and with leading work that proved fundamental theorems in three main models and in a combined model. A photo caption in the 2020 CWI interview dates the course to around 1986. In that interview he said the multiparty results “are at the same time like Maxwell’s equations and the Church-Turing thesis of cryptography” and that it was thrilling to lead in those breakthroughs.⁠[18][2]

His papers of this period include “Security Without Identification: Transaction Systems to Make Big Brother Obsolete” (Communications of the ACM, vol. 28, no. 10, 1985); “The Dining Cryptographers Problem: Unconditional Sender and Recipient Untraceability” (Journal of Cryptology, vol. 1, no. 1, 1988); “Untraceable Electronic Cash,” with A. Fiat and M. Naor (CRYPTO ’88, 1988); “Multiparty Unconditionally Secure Protocols,” with C. Crépeau and I. Damgård (20th ACM STOC, 1988); “Undeniable Signatures,” with H. van Antwerpen (CRYPTO ’89, 1989); and “Group Signatures,” with E. van Heyst (EUROCRYPT ’91, 1991).⁠[5]

He also edited the EUROCRYPT ’87 proceedings, published in 1988 (with W. L. Price), and two Smart Card 2000 volumes: one published in 1988, edited with I. Schaumüller-Bichl, and one published in 1991 covering the second Smart Card 2000 conference, held in Amsterdam in 1989.⁠[5]

The 1999 Forbes article says he started DigiCash in 1989 to build an online currency as secure and private as physical cash; CWI’s 2019 article instead gives 1990 as the founding year and says the company offered financial institutions secure, anonymous digital micropayments from a head office in the Matrix building at Amsterdam Science Park. Bitcoin Magazine says that by 1990 he had founded DigiCash in Amsterdam, where he had lived for a couple of years. ERCIM News calls DigiCash a spin-off from his research. The 1998 American Banker article calls DigiCash an “eight-year-old venture” that he created.⁠[15][1][3][16][14]

In the 2020 interview he recalled that one day in his office at CWI he was contacted by Rijkswaterstaat, which wanted privacy-protecting road tolls; a team of students he put together demonstrated a solution in 10 days: an eCash payment completed within a meter of road travel at highway speeds of 100 kilometers per hour, with Amtech as partner for the radio link. Bitcoin Magazine says DigiCash had a government project to replace toll booths that was eventually cancelled, that the company also worked on smart cards, and that its flagship product was eCash. The patent list on his personal website includes one entitled “Automatic real-time highway toll collection from moving vehicles” (US 5,485,520).⁠[2][3][19]

In August 1992 he published the invited article “Achieving Electronic Privacy” in Scientific American (pages 96–101). Bitcoin Magazine relates that he wrote in it that the choice between individual and organizational control of information would shape the society of the next century. His personal website says that he invented the privacy technologies of untraceable communications, digital cash and credentials that are unlinkable but unforgeable, and that he predicted metadata would become a key privacy issue.⁠[5][3][20]

On May 27, 1994, DigiCash issued a press release announcing the world’s first electronic cash payment over computer networks. In the 2020 interview he said that DigiCash made the first payment over the Internet at the first WWW conference in Geneva.⁠[10][2]

His personal website says that he invented eCash and, as chief executive, oversaw its global rollout, and that eCash was the first digital bearer instrument and the first privacy-protected electronic payment system; it launched online as its own currency, CyberBucks, and was later licensed to banks around the world to issue in national currencies. DigiCash’s CyberBucks trial began in 1994, and on January 6, 1995, the company announced that the trial was now worldwide. On February 14, 1995, DigiCash announced a cost breakthrough in secure chip technology for smart cards. In the interview he said that Deutsche Bank issued Deutschmarks using eCash.⁠[10][2]

The eCash timeline on his personal website also lists press articles and papers of the period: “Attention Internet Shoppers - E-Cash Is Here” (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, October 19, 1994); “E-Money (That’s What I Want)” (Wired, December 1, 1994); the paper “Digital Cash & Monetary Freedom” (NYU Stern, April 1995); “INFORMATION TECHNOLOGY; Export Approved for Software To Aid Commerce on Internet” (The New York Times, May 8, 1995), “Today, Shoppers on Internet Get Access to Electronic Cash” (October 23, 1995) and “Regulators Turn Spotlight on Cybermoney” (September 19, 1996); and, from American Banker, “Digicash Eager to Reap Latent eCash Harvest” (December 11, 1997) and “Former Wells FargoWells FargoWells Fargo & Company is an American bank whose employees opened millions of unauthorized accounts, leading to regulatory penalties and a $1.95 trillion asset cap from the Federal Reserve that was lifted in June 2025.Open the full entry Exec Joins Digicash Board” (June 4, 1998).⁠[10]

On October 23, 1995, DigiCash announced a partnership with Mark Twain Bank of St. Louis, MissouriMissouriMissouri is a state of the United States bounded on the east by the Mississippi River; its capital is Jefferson City, its largest city is Kansas City, and its second-largest is St. Louis. It was admitted to the Union on August 10, 1821, as the 24th state, and its population in the 2020 census (April 1, 2020) was 6,154,913.Open the full entry, which its press release called the first bank to launch electronic cash.⁠[10]

The 1998 American Banker article says that Mercantile Bancorp had acquired Mark Twain Bank about 20 months earlier and ended the three-year eCash experiment that September; the bank had 5,000 eCash customers, about 20 percent of them in its eight-state Midwest territory and the rest on the two coasts, and they held “significantly less” than $100,000 in eCash accounts, in the words of Larry Kirschner, the bank’s senior vice president of foreign exchange. Bitcoin Magazine says that by 1998 the bank had enrolled only 300 merchants and 5,000 users. The Forbes article of November 1999 says Mercantile Bank had pulled the plug a year earlier after a three-year trial that signed up only 5,000 customers whose combined accounts totaled just $100,000.⁠[14][3][15]

The timeline of DigiCash press releases on his personal website lists the following: on March 13, 1996, DigiCash and EUnet opened online payments in Finland, which the release called the first European electronic cash system open for business on the Internet; on March 26, 1996, DigiCash opened an office in Australia and signed a worldwide smart card technology deal with Mars Electronics International; in 1996 DigiCash announced that Deutsche Bank would issue eCash, and a release of August 4, 1997, said Deutsche Bank was starting an eCash pilot with 1,500 clients; on October 24, 1996, Advance Bank became the first bank to provide eCash in Australia; on April 2, 1997, Nomura Research Institute licensed eCash technology for Japan, and on December 11 of that year the two announced an alliance in Japan; and on April 14, 1997, Bank Austria and Den norske Bank announced that they would issue eCash. The timeline also includes an American Banker article of June 16, 1998, on a test of DigiCash technology by Credit Suisse of Zurich.⁠[10]

The 2018 Bitcoin Magazine article relates several deals that DigiCash discussed, some of them in terms such as “are said to have” and “so the story goes”: ING and ABN Amro, two of the three major Dutch banks, are said to have made partnership deals with DigiCash worth tens of millions of dollars; VisaVisaVisa Inc. is one of the world’s leaders in digital payments, with roots going back to 1958, and is headquartered in San Francisco, California.Open the full entry is said to have offered a $40 million investment, and Netscape was interested as well; Bill GatesBill GatesBill Gates is an American entrepreneur, investor and philanthropist who cofounded Microsoft with Paul Allen in 1975 and served as its chief executive and chairman. He later shifted his focus toward global health, education and climate, chairs the Gates Foundation, and manages investments through arrangements including Cascade.Open the full entry is said to have wanted to integrate eCash into Windows 95, and Microsoft is said to have offered about $100 million, while he, so the story goes, asked for $2 for every copy of Windows 95 sold, and the deal was off; and a deal with Citibank came close before the bank walked away for unrelated reasons. A note at the end of the article says it is based in part on two articles of the 1990s, “E-Money (That’s What I Want)” by 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 for Wired and “Hoe DigiCash alles verknalde” (How DigiCash Blew Everything) by an unknown author for the Dutch Next! Magazine, and that chaum.com/ecash also holds a wealth of information.⁠[3]

On April 28, 1997, DigiCash issued a press release announcing that it had appointed a chief executive, increased outside investment and moved its headquarters to California; the timeline on his personal website also lists, on the same day, the American Banker article “Digicash Puts ’Professional’ At the Helm” and, on May 6, 1997, the same paper’s “Digicash Sends Signal by Hiring Visa Veteran.” The 1998 American Banker article says that in 1997 DigiCash attracted venture capital interest from, among others, David Marquardt of August CapitalAugust CapitalAugust Capital is a San Francisco Bay Area venture capital firm co-founded in 1995 by David Marquardt and John Johnston. It primarily backs early-stage information technology businesses and makes selected later-stage investments. Its investment history includes Epinions, Shopping.com, Splunk, BILL and UpGuard. The firm’s brand, management services company and individual funds are distinct entities.Open the full entry, an early backer of Microsoft; the company reconstituted its board with the MITMassachusetts 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 professor Nicholas Negroponte as chairman and hired “professional management” led by the chief executive Michael Nash, a former American ExpressAmerican ExpressAmerican Express Company is a payments company headquartered in New York that issues credit and charge cards and operates its own payments network; founded in 1850, it is listed on the New York Stock Exchange.Open the full entry and Visa International executive; the headquarters moved from his base in Amsterdam to Silicon Valley, and he remained as chief technology officer; William Zuendt, a former president of Wells Fargo, joined the board in June 1998 alongside Nicholas Negroponte, David Marquardt, David Chaum and Toon den Heijer of Gilde Investment Funds. Forbes says he secured Nicholas Negroponte as chairman and raised more than $10 million from investors, David Marquardt among them.⁠[10][14][15]

In November 1998 DigiCash, then based in Palo Alto, California, filed for Chapter 11 bankruptcy protection. American Banker says that Scott Loftesness, who also had Visa in his background, had succeeded Michael Nash that August, was now interim chief executive and intended to see the Chapter 11 process through; staff had peaked at about 50 and had since been cut significantly, and the part of the operation that remained in Amsterdam had been closed; none of the licensees, Deutsche Bank, Den norske Bank, Bank Austria, Advance Bank of Australia and Mark Twain Bank of St. Louis, had got beyond the pilot stage. Scott Loftesness said he meant to find financing and forge strategic relationships and that the company had a significant “intellectual property portfolio” that could prove useful in other applications requiring privacy and anonymity, such as electronic voting; the article says DigiCash had never exploited the full potential of its patents to generate licensing income; he called eCash “important and inevitable.”⁠[15][14]

The same American Banker article records the views of peers and analysts: Richard Crone, vice president of CyberCashCyberCashCyberCash was an Internet payments company headquartered in Reston, Virginia, United States. Founded in 1994, it was one of the first companies to offer encrypted credit card payments on the Internet and later added CyberCoin micropayments, PayNow electronic checks and payment software; listed on Nasdaq from 1996, it filed for bankruptcy protection in 2001 and its operating assets were sold.Open the full entry and general manager of PayNow, its electronic check product, said, “You must match the payment type to the application that is being sold”; David Stewart, vice president of Global Concepts of Norcross, Georgia, said DigiCash needed to come up with an off-line electronic cash scheme and have the backing of a serious player in the payments world; and Larry Kirschner of Mercantile Bank said, “We didn’t see a strategic fit for eCash.” The article says credit cards had won the day in U.S. Internet consumer payments.⁠[14]

The Forbes article of November 1, 1999, says he had recently sold DigiCash’s patents. In it he explained why eCash had not succeeded: “It was hard to get enough merchants to accept it, so that you could get enough consumers to use it, or vice versa”; and as the Web grew and its average user became less sophisticated, “It was hard to explain the importance of privacy to them.” He said he intended to try electronic cash again, with better blind signatures, working with credit cards instead of replacing them, and described the new product as “a prophylactic for the credit card.” The article says the privacy would not be perfect this time and that he refused to offer details of the new venture.⁠[15]

Bitcoin Magazine says that after DigiCash he returned to Berkeley and produced many publications, often on digital elections and reputation systems.⁠[3]

In 2004 he published “Secret-Ballot Receipts: True Voter-Verifiable Elections” in IEEE Security & Privacy (vol. 2, no. 1); in 2008 he and his collaborators published “Scantegrity: End-to-End Voter-Verifiable Optical-Scan Voting” in the same magazine (vol. 6, no. 3).⁠[5]

His personal website says that Scantegrity is an optical-scan voting method in which voters reveal codes on the ballot with special pens and use the codes to verify their votes without compromising ballot secrecy, and that he invented the technology, including its chemistry and fabrication; its precursor was Punchscan, and before that “secret-ballot receipts.” Punchscan won the $10,000 first prize at VoComp, a university student voting competition, a prize that came from ES&S, which the website calls the largest election company.⁠[21]

On November 3, 2009, the city of Takoma Park, MarylandMarylandMaryland is a Middle Atlantic state of the United States, deeply indented by Chesapeake Bay and bordered by Pennsylvania, Delaware, Virginia, the District of Columbia and West Virginia; its capital is Annapolis and its largest city is Baltimore. One of the original 13 states, it ratified the U.S. Constitution on April 28, 1788, as the seventh state to do so, and had a population of 6,177,224 in the 2020 census (April 1, 2020).Open the full entry, used the Scantegrity II system to elect its mayor and city council members, with council races in six wards; 1,728 of 10,934 registered voters voted, a turnout of about 15.8 percent. The paper he wrote with Richard Carback, Jeremy Clark, Ronald L. Rivest, Alan T. Sherman, Poorvi L. Vora and others calls this “the first time any end-to-end (E2E) voting system with ballot privacy has been used in a binding governmental election”; it appeared at USENIX Security ’10. The Scantegrity website recorded 81 unique ballot ID verifications, about 66 of them before the deadline for complaints, almost 4 percent of the total votes.⁠[22][5]

Earlier, in April 2009, the Scantegrity team ran a mock election at Takoma Park’s Arbor Day celebration under its agreement with the city, in which volunteer voters chose their favorite tree.⁠[22]

His personal website says that he led the deployment of Scantegrity in two Takoma Park municipal elections, in 2009 and 2011, both by invitation; four graduate students earned Ph.D.s related to Scantegrity: Aleks Essex, Stefan Popoveniuc, Jeremy Clark and Richard Carback III.⁠[21][13][22]

In 2010 Springer published “Towards Trustworthy Elections: New Directions in Electronic Voting” (LNCS 6000), which he edited with M. Jakobsson, R. L. Rivest, P. Y. A. Ryan, J. Benaloh, M. Kutyłowski and B. Adida; in 2013 he and his collaborators published “Remotegrity: Design and Use of an End-to-End Verifiable Remote Voting System” at ACNS 2013.⁠[5]

On January 6, 2016, the IACR’s Cryptology ePrint Archive received report 2016/008; the report has had four revisions, the last on March 21, 2018, and its page carries the title “cMix: Mixing with Minimal Real-Time Asymmetric Cryptographic Operations” and lists as authors David Chaum, Debajyoti Das, Farid Javani, Aniket Kate, Anna Krasnova, Joeri de Ruiter and Alan T. Sherman; the list of papers on his personal website gives this ePrint report the title “cMix: Anonymization by High-Performance Scalable Mixing.” cMix is an anonymous communication system based on a mix network: a batch of messages is shuffled through a fixed chain of mix nodes to hide who is communicating with whom; it adds a precomputation step that moves the expensive public-key operations out of real time, so that the real-time phase needs only a few fast modular multiplications, and the authors call it the first mixing approach suitable for low-latency chat on lightweight devices. The paper entitled “cMix: Mixing with Minimal Real-Time Asymmetric Cryptographic Operations” was later published at ACNS 2017.⁠[23][5]

In the same week he unveiled PrivaTegrity, a plan built on cMix. A Fortune article of January 14, 2016, says PrivaTegrity was conceived as a social media system able to support features such as status update feeds, private chats, payments and pseudonymous interactions, and that the technology then existed only in a mostly untested alpha version; access to the system was split between ten contracting companies in as many countries, traffic passed through a cascade of ten mix servers, each server held only a sliver of identifying information, and interfering with or unmasking a user would require all the companies to cooperate; the article likens this to the two-man rule for nuclear missile launches, with added complexity and a greater division of power. Passages of news coverage quoted in a Techdirt article of January 6, 2016, instead say that the “backdoor” could strip anonymity from users whose activity is “generally recognized as evil,” that nine server administrators in nine countries would all have to cooperate to trace criminals and decrypt their communications, and that he planned to present PrivaTegrity for the first time that day at the Real World Crypto conference 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; Techdirt itself writes that the prototype ran entirely on AmazonAmazonAmazon is a publicly traded U.S. technology and retail company founded by Jeff Bezos in 1994, with its principal corporate offices in Seattle. Its businesses span e-commerce, logistics and fulfillment, digital advertising, membership and entertainment services, consumer electronics, and Amazon Web Services cloud computing.Open the full entry’s cloud computing infrastructure and that none of PrivaTegrity’s security claims had yet been checked or audited publicly.⁠[7][24]

The design drew criticism. The Techdirt article argues that “Chaum is both totally missing the point and playing right into 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’s hands,” and writes that, as Chris Soghoian, a security expert at the American Civil Liberties UnionAmerican Civil Liberties UnionThe American Civil Liberties Union (ACLU) is a nonprofit, nonpartisan civil liberties organization headquartered in New York City, founded in 1920 by Roger Nash Baldwin and others.Open the full entry, points out, the system is “little more than a huge political gift to the FBI.” The Fortune article reproduces several tweets: Jacob Appelbaum wrote on January 6, 2016, that the basic idea behind PrivaTegrity is that an adversary can never compromise nine groups or computer systems and that “That is not a serious suggestion”; the cryptographer Matt Blaze wrote that the claims should be greeted “with careful skepticism”; Matthew Green, an assistant professor of computer science at Johns Hopkins University, wrote, “I have no idea what Privategrity really does”; and Kevin Poulsen, a contributing editor at Wired (spelled “Kevin Paulsen” in the article, with the tweet under the handle kpoulsen), wrote, “FBI won’t back a plan that makes it run down key fragments around the world like Harry Potter collecting Horcruxes.”⁠[24][7]

In the same Fortune article he responded to the claim of a built-in backdoor, “It’s B.S.,” and said that “There unconditionally is no hidden weakening within PrivaTegrity”; of having let Wired use the word “backdoor” for access in general he said, “This probably was my big mistake”; and of the claim that the system could end the crypto wars he said, “I don’t want to retract it, but the sense that I meant it was misunderstood.” He added that the system was essentially a separate issue from end-to-end encryption, a technology that there is no way to deny to people; that critics should contrast his design with the only known alternative, saying, “Today, social media is absolutely insecure and is openly being manipulated and pressured by government”; and that the design would allow transparent, published policies for “extraordinary access,” without his advocating any particular policy.⁠[7]

His personal website says that he invented a new approach to elections, Random-Sample Voting, and led the technical project that implemented it, including decoy ballots meant to deter vote buying; the website compares it to the jury system and says he gave talks on it at a number of universities (Caltech, Berkeley, HarvardHarvard UniversityHarvard University is a private research university in Massachusetts, established by the Massachusetts Bay Colony legislature in 1636 and named in 1639 for early benefactor John Harvard. Its principal campuses are in Cambridge and the Allston and Longwood neighborhoods of Boston. It includes Harvard College, graduate and professional schools, and the Radcliffe Institute for Advanced Study. Two governing boards share oversight. Alan M. Garber was president as of October 2026, and the endowment stood at $56.9 billion at the end of fiscal 2025.Open the full entry) and at COMSOC 2018.⁠[25]

On November 9, 2017, the Random-Sample-Voting Project ran the system’s fourth public trial, and its first binding poll, at the World Forum for Democracy 2017 in Strasbourg, France: the Council of Europe put five conclusions to a vote, and the project sent the ballots to the Council of Europe’s printing service, and polls were open from 11 a.m. to 11:30 p.m. local time. The project’s report records that 834 real ballots were distributed and 120 ballots were cast, 117 of them real and 3 decoys; the share of votes in favor of the five conclusions ranged from 72.7 percent to 91.7 percent; the report says that, as far as the project was aware, no independent audit had yet been performed, and the full bulletin board data had been made public. He and Nicolas K. Blanchard represented the project there, gave talks and multiple interviews.⁠[26]

In September 2018 he unveiled Elixxir, a distributed messaging platform that removes metadata to protect users’ privacy. A CoinDesk article of October 2019 says Elixxir then had a public alpha for iOS and Android and that he said 700 people were already on the wait-list to run new Elixxir software and that several messaging services were discussing white-label use of the messenger. The biography on the Electronic Privacy Information Center’s website calls him the chief executive and founder of Elixxir.⁠[11][27]

In August 2019 he unveiled Praxxis, his second digital currency. CoinDesk says Praxxis had two goals: a new consensus algorithm suited to the Elixxir network, and a “quantum-resistant” cryptocurrency for anonymous payments on Elixxir that hide the identities of both sender and receiver; interviewed at Devcon in Osaka, Japan, in October 2019, he said that Elixxir “is waiting for Praxxis” and called combined vertical and horizontal privacy “the holy grail.”⁠[11]

A Praxxis press release of November 2019 says Praxxis was designed and developed by WBM Corp., a company led by the computer scientist William Carter and one of the first based in Cayman Enterprise City, and that early work on the Praxxis chain was done at Privategrity Corporation in the Los Angeles area.⁠[28]

CWI’s article of November 18, 2019, says CWI would award him the Dijkstra Fellowship on November 21, 2019; in it he calls himself “one of the inaugural Dijkstra Fellows” and says CWI feels like “a homecoming.” ERCIM News of January 2020 says CWI awarded the newly established honorary title for the first time, to him and to Guido van RossumGuido van RossumGuido van Rossum is a programmer who grew up in the Netherlands and the creator of the Python programming language, which he began writing in 1989 and led for decades as its “BDFL” (Benevolent Dictator For Life) until stepping down in 2018; he worked at CWI, CNRI, Google, Dropbox and Microsoft.Open the full entry; the title is named after the former CWI researcher Edsger W. Dijkstra, and with it CWI recognizes the impact of the two men’s groundbreaking work on mathematics and computer science; Guido van Rossum created the Python programming language while working at CWI; a photo caption there describes David Chaum as a mathematician and computer scientist, and the article says he is internationally recognized as the founder of digital currencies and blockchain technology. The introduction to CWI’s 2020 interview says he received the fellowship for his groundbreaking work in privacy and cryptology and for the development of digital currency.⁠[1][16][2]

A press release datelined Amsterdam, November 22, says that in a lecture at CWI he announced the forthcoming release of the xx network whitepaper and a Praxxis technical brief; the xx network and its xx coin are a blockchain and cryptocurrency built on Elixxir and Praxxis technology, and its consensus protocol includes quantum-secure trustless initialization, an unmanipulatable random seed, constant-sized endorser sampling and compact quantum-secure group signatures. The release adds that the xx collective, a global community supporting his projects, had more than 4,800 members. The release says the lecture was part of a two-day event at which he was also honored with the Dijkstra Fellowship.⁠[28]

In the interview published in April 2020 he said the main net of the xx network was planned to launch that year as an autonomous blockchain, a platform using metadata shredding, quantum-resistant cryptography and “one user, one vote” governance through sample voting. The speaker biography for a 2022 KuppingerCole conference says the xx network, which he founded, launched in the fall of 2021 as a blockchain platform for secure, private, decentralized messaging and payments; it gives his titles as founder of the xx network and chief executive of Elixxir.io and says he was developing technology to decentralize market making and asset exchange, using cryptography and shared keys so that buyers and sellers can transact without centralized exchanges; on May 10, 2022, he gave a talk at that European Identity and Cloud Conference entitled “Credentials and Privacy - History and New Kinds of Cards.” In the 2020 interview he predicted a major breakthrough in direct democracy within ten years, built on metadata shredding and sample voting.⁠[2][17]

On February 23, 2021, the Swiss National Bank published working paper 2021-03, “How to issue a central bank digital currency,” by him, Christian Grothoff and Thomas Moser, an alternate member of the Swiss National Bank’s Governing Board. The paper does not discuss whether a central bank should issue a digital currency but explains how one could if it wished: the authors propose a token-based design without distributed ledger technology that improves on earlier software-only electronic cash to protect transaction privacy, meet regulatory requirements and “offer a level of quantum-resistant protection against systemic privacy risk”; they argue that because the design would function like physical cash and not like bank deposits, monetary policy and financial stability would not be materially affected.⁠[29]

In 2022 he and his collaborators posted “VoteXX: A Solution to Improper Influence in Voter-Verifiable Elections” on the IACR ePrint archive (2022/1212), followed in 2024 by “VoteXX: Extreme Coercion Resistance” (2024/1354). His personal website says VoteXX is a joint project of the xx network and an international academic team, which he invented and led, a project meant to solve vote buying and voter coercion without polling places and aiming at a massively scalable, end-to-end voter-verifiable, coercion-resistant remote election system: inalienable registration is separated from vote casting, and voters can flip their votes through what it calls “hedgehogs,” which vote buyers and coercers can neither detect nor prevent. The team consists of David Chaum, Richard Carback and Mario Yaksetig of the xx network in Los Angeles, Jeremy Clark and Mahdi Nejadgholi of Concordia University, Alan T. Sherman and Chao Liu of UMBC, Filip Zagórski of Wroclaw University of Science and Technology, and Bart Preneel of the Katholieke Universiteit in Leuven, Belgium.⁠[5][30]

Also in 2022 he wrote two unpublished white papers: “eCash 2.0: Inalienably Private and Quantum-Resistant to Counterfeiting,” with T. Moser, and “Offline eCash 2.0: Robust In-Person Payments, Later Onlineable.”⁠[5]

On November 29, 2023, the Bank for International Settlements (BIS) published the report of Project Tourbillon. The project, run by the Swiss Centre of the BIS Innovation Hub with the Swiss National Bank, studied privacy for retail central bank digital currencies around the concept of “payer anonymity”: a consumer who pays discloses no personal information to the merchant, the banks or the central bank, while the merchant’s identity is known to, and kept confidential by, the merchant’s bank. Both of the project’s prototypes are based on the eCash design: eCash 1.0 (EC1) is a cash-like digital payment instrument, and eCash 2.0 (EC2) explores stronger protection against, and detection of, counterfeiting. The project implemented quantum-safe cryptography and explored both current and quantum-safe blind signatures; its scalability tests found that with quantum-safe cryptography the duration of payments increased by a factor of five and throughput fell by a factor of 200. The description of the video “Reflections on project Tourbillon” on the BIS page calls him “Cryptographer and inventor of eCash.”⁠[31]

His personal website says that eCash 2.0 shows a central bank digital currency can be private, that its protection against counterfeiting is stronger than that of quantum-secure designs, that it is fully scalable, and that it was demonstrated with smartphone payments in the BIS’s Project Tourbillon.⁠[32]

As of November 2026 his personal website says he is leading the xx network, which it describes as a high-speed, privacy-protected blockchain with quantum-resistant consensus and a currency that removes metadata through mixing, with both messaging and payments encrypted. The xx network’s own website describes it as a quantum-resistant decentralized mixnet and blockchain; the copyright holder named in its footer is the xx Foundation.⁠[13][33][34]

The Bitcoin white paper by 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 lists eight references, among them Wei DaiWei DaiWei Dai is a computer engineer and the original author of the open-source cryptography library Crypto++. In 1998 he proposed b-money, a scheme for anonymous digital money that the Bitcoin paper lists as its first reference, and the smallest unit of ether, the wei, is named after him. He also writes on LessWrong about decision theory and AI safety, and proposed the decision theory that came to be called Updateless Decision Theory.Open the full entry’s b-money, Adam BackAdam BackAdam Back is a British cryptographer and computer scientist, the inventor of the proof-of-work system Hashcash, and a co-founder and the chief executive of the Bitcoin technology company Blockstream.Open the full entry’s Hashcash and a 1980 paper by 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; none is a work by David Chaum, and neither Chaum, DigiCash nor ecash is mentioned anywhere in the paper. Section 2 of the white paper says that a common solution to double spending is to introduce a trusted central authority, or “mint,” that checks every transaction.⁠[35]

A Bitcoin.com News article of February 11, 2022, says Satoshi Nakamoto first announced 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 project publicly through the P2P Foundation forum on February 11, 2009; others in the thread talked about “old Chaumian central stuff” and e-currency projects such as e-golde-golde-gold was a digital currency, described by its issuer as fully backed by physical gold, whose value could be transferred between accounts over the internet; it began operating in 1996 and ceased operations in 2009. Its issuer E-Gold, Ltd., its operator Gold & Silver Reserve, Inc. and three directors were indicted by a U.S. federal grand jury in 2007 on charges including money laundering conspiracy and operating an unlicensed money transmitting business, and pleaded guilty in 2008.Open the full entry that had failed in the past, and Satoshi Nakamoto noted in his replies that the “old Chaumian central mint stuff” was the only thing available at the time. The article quotes his reply of February 15, 2009: “A lot of people automatically dismiss e-currency as a lost cause because of all the companies that failed since the 1990’s,” “I hope it’s obvious it was only the centrally controlled nature of those systems that doomed them,” and “I think this is the first time we’re trying a decentralized, non-trust-based system.”⁠[36]

The 2018 Bitcoin Magazine article says his work inspired the group later known as the cypherpunks, among whom Nick SzaboNick SzaboNick Szabo is an American computer scientist, legal scholar and cryptographer who developed the term and concept of smart contracts and in 1998 conceived bit gold, a design for digital money often described as a precursor of Bitcoin; he has repeatedly denied being Satoshi Nakamoto, and in January 2025 he became chief scientist of JAN3.Open the full entry and Zooko Wilcox-O’HearnZooko WilcoxZooko Wilcox is a computer security expert, an early cypherpunk, the founder of the Electric Coin Company (ECC), and the principal initiator of Zcash; his early papers were also signed Zooko Wilcox-O’Hearn. He worked on DigiCash, Mojo Nation, Tahoe-LAFS, and cryptographic software research, and led ECC in bringing Zcash to mainnet in 2016. After stepping down as ECC’s chief executive officer in 2023, he joined Shielded Labs in 2024 as head of product and a board member, and in 2025 was appointed a strategic advisor to Cypherpunk Technologies.Open the full entry had both contributed to DigiCash; the group kept the idea of electronic cash alive through the 1990s and early 2000s, and in 2008 Satoshi Nakamoto sent the Bitcoin proposal to the successor of the cypherpunks mailing list. The article holds that Bitcoin and eCash have little in common in design: eCash was centralized around DigiCash and could not be a currency of its own, and banks were still needed for balances and transaction confirmation, so it was less censorship resistant; Bitcoin itself does not use blind signatures, though layers built on Bitcoin could. The article describes the cypherpunks as “a bit more radical than Chaum himself ever was.”⁠[3]

The 2018 paper by Alan T. Sherman and his co-authors argues that “Arguably, many of the elements of blockchains are embodied in David Chaum’s 1979 vault system,” including a chained cryptographic checksum through the consensus history, membership consistency and private distributed computation; what the system lacks is proof of work, dynamic throttling of work difficulty and explicit smart contracts, and its communication model is “best effort” broadcast with no mechanism for reaching consensus over unreliable communication. The paper also notes that Satoshi Nakamoto’s 2008 paper cites Adam Back’s 2002 Hashcash and that most of the underlying ideas of blockchains arose years earlier.⁠[4]

The introduction to CWI’s 2020 interview says the digital currency he developed laid the technological basis for blockchain and Bitcoin; CWI’s 2019 article says he is called the “Godfather of Cryptocurrency” and that his 1982 dissertation described a blockchain-like technology for digital transactions without an authority such as a bank or credit card company; ERCIM News calls DigiCash’s eCash the precursor of Bitcoin and calls him a “forefather of blockchain.” The 2019 Praxxis press release says he has recently been “credited with proposing the first decentralized blockchain” as his 1982 doctoral dissertation at Berkeley.⁠[2][1][16][28]

Speaking about Bitcoin in the CWI interview of November 2019, he said that Bitcoin’s limitations, particularly in calculation speed and energy expenditure, sometimes affect how observers see blockchain as a whole, but that it launched a worldwide movement and attracted millions of people to the promise and importance of digital currency; blockchain, he said, is not moving in a single direction, and new approaches keep appearing. He argued that blockchain can decentralize power and that it is essential not to cede “quantum supremacy” to 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 or whoever else has the fastest computer; Facebook’s Libra project he regarded as a compliment to the blockchain community, adding that what people want is an open, decentralized network. He said that new ways of communicating often necessitate new ways of understanding money, that once there are banks, branches and networks there will be checks and eventually credit cards, and that this is why he felt the Internet would need a currency of its own, and that proper use of encryption can make communications secure, commerce reliable and voting trustworthy. In the same interview he called Praxxis “our forthcoming high performance digital currency and blockchain technology,” which would introduce quantum-resistant vertical and horizontal privacy.⁠[1]

The list of papers on his personal website also includes “How to Keep a Secret Alive: Extensible Partial Key, Key Safeguarding, and Threshold Systems” (1984); “Multiparty Computations Ensuring Privacy of Each Party’s Input and Correctness of the Result,” with I. B. Damgård and J. van de Graaf (1987); “Elections with Unconditionally-Secret Ballots and Disruption Equivalent to Breaking RSA” (1988); “Convertible Undeniable Signatures,” with I. Damgård and T. Pedersen (1990); “Wallet Databases with Observers,” with T. P. Pedersen (1992); and the DigiCash technical note “Prepaid Smart Card Techniques: A Brief Introduction and Comparison” (1993).⁠[5]

His papers from 2021 onward include “W-OTS+ Up My Sleeve! A Hidden Secure Fallback for Cryptocurrency Wallets,” with M. Larangeira, M. Yaksetig and W. Carter (ACNS 2021); “UDM: Private User Discovery with Minimal Information Disclosure,” with M. Yaksetig, A. T. Sherman and J. de Ruiter (Cryptologia, vol. 46, no. 4, 2022); “Phoenixx: Linear Consensus with Random Sampling,” with B. Cardoso, W. Carter, M. Yaksetig and B. Aroso (IACR ePrint 2023/1262, 2023); and “Revisiting Silent Coercion,” with co-authors (E-VOTE-ID 2025, 2025).⁠[5]

His personal website lists 30 patents and patent applications, among them “Cryptographic identification, financial transaction, and credential device” (US 4,529,870), “Blind unanticipated signature systems” (US 4,759,064), “One-show blind signature systems” (US 4,914,698 and US 4,987,593), “Undeniable signature systems” (US 4,947,430), “Electronic lock that can learn to recognize any ordinary key” (US 6,318,137), “Secret-ballot systems with voter-verifiable integrity” (US 7,210,617), “Scan-integrity election systems” (US 8,162,215), “Near to eye display system and appliance” (US 2010/0149073) and “Random sample elections” (US 2014/0172517).⁠[19]

The biography on the Electronic Privacy Information Center’s website says that, besides the IACR, the cryptography group at CWI and DigiCash, he founded the Voting Systems Institute and the Perspectiva Fund.⁠[27]

His personal website also presents the following projects: Perspectiva, a proposed optical architecture in the form factor of ordinary prescription eyeglasses that uses multiple facets with adaptive foveation and focus, whose page has one photo caption saying that RGB holograms were being made in 2012 at “our Lab in Tucson” and another identifying one of the third-party groups of experts that validated the eyewear system design; Liquifinity, a cryptographic technology he invented for direct peer-to-peer trading of cryptocurrencies and other financial instruments with no trusted intermediaries and no smart contracts; “Better Than Money,” a new medium of exchange he invented in which each user has a portfolio of assets from which value can be sent or received, with an app that keeps all of a user’s assets, including what would have been cash, invested at all times, accompanied by the white paper “Better Than Money: Interfungible, asset-backed, transparent yet private”; 7th Estate, also called “Guerrilla Democracy,” a way for anyone to prove that a majority of a population supports a statement, needing only a mailing list, postage for 1,000 letters, the Internet and simple materials such as envelopes, stickers and cardboard boxes; AstroCool, a four-phase proposal to reverse global warming with shade from moon dust placed in space by near-term technologies, democratized through competition and a secure global referendum; and, on the homepage, an item headed “Democracy Jiu-Jitsu” with the line “DEMOCRACY CAN PREVAIL— BY REINVENTING ITSELF.”⁠[37][38][39][40][13]

The awards page of his personal website lists the Information Technology European Award for 1995, a $250,000 prize that the text reproduced on the page says was given for DigiCash’s ecash technology; the RSA Excellence in Mathematics prize of 2010; the Honorary Consensus 2022 MetaGala Award, presented at the 2022 ConsensusConsensusConsensus is an annual cryptocurrency, blockchain, and Web3 industry conference hosted by the crypto media outlet CoinDesk (not the consensus mechanism of a blockchain). It was first held in New York in 2015 and later moved to Austin and Toronto; a Hong Kong edition was added from 2025, and since 2026 the main conference has been held in Miami.Open the full entry conference; and an item headed “Honorary Doctorate,” under which the page reproduces the opening of a letter to him from the dean of the Faculty of Informatics of the Università della Svizzera italiana (USI) about the announcement of his honorary doctorate.⁠[41]

In 2004 the IACR named him an IACR Fellow, with the citation “For numerous seminal contributions to security and privacy research and for visionary leadership in the role of IACR founder.”⁠[42]

In 2021 the 30-year STOC Test of Time Award went to his 1988 paper with Claude Crépeau and Ivan Damgård, “Multiparty Unconditionally Secure Protocols,” together with a 1988 paper by Michael Ben-Or, Shafi Goldwasser and Avi Wigderson and a 1989 paper by Tal Rabin and Michael Ben-Or.⁠[43][41]

Personal website: https://chaum.com/ (opens in a new window).⁠[13]

International Association for Cryptologic Research: Official website: https://www.iacr.org/ (opens in a new window).⁠[42]

Centrum Wiskunde & Informatica: Official website: https://www.cwi.nl/ (opens in a new window).⁠[1]

xx network: Official website: https://xx.network/ (opens in a new window).⁠[34]