David Chaum

David Lee Chaum (born 1955) is an American computer scientist, cryptographer, and inventor.

He is known as a pioneer in cryptography and privacy-preserving technologies, and widely recognized as the inventor of digital cash.

These ideas have been described as the technical roots of the vision of the Cypherpunk movement that began in the late 1980s.

Chaum's proposal allowed users to obtain digital currency from a bank and spend it in a manner that is untraceable by the bank or any other party.

His 1981 paper, "Untraceable Electronic Mail, Return Addresses, and Digital Pseudonyms", laid the groundwork for the field of anonymous communications research.

Chaum is Jewish and was born to a Jewish family in Los Angeles.

In 1981, Chaum proposed the idea of an anonymous communication network in a paper.

His proposal, called mix networks, allows a group of senders to submit an encryption of a message and its recipient to a server.

His 1982 dissertation "Computer Systems Established, Maintained, and Trusted by Mutually Suspicious Groups" is the first known proposal for a blockchain protocol.

Complete with the code to implement the protocol, Chaum's dissertation proposed all but one element of the blockchain later detailed in the Bitcoin whitepaper.

He has been referred to as "the father of online anonymity", and "the godfather of cryptocurrency".

He is also known for developing ecash, an electronic cash application that aims to preserve a user's anonymity, and inventing many cryptographic protocols like the blind signature, mix networks and the Dining cryptographers protocol.

He gained a doctorate in computer science from the University of California, Berkeley in 1982.

Also that year, he founded the International Association for Cryptologic Research (IACR), which currently organizes academic conferences in cryptography research.

Subsequently, he taught at the New York University Graduate School of Business Administration and at the University of California, Santa Barbara (UCSB).

He also formed a cryptography research group at CWI, the Dutch National Research Institute for Mathematics and Computer Science in Amsterdam.

Recently credited by Alan Sherman's "On the Origins and Variations of Blockchain Technologies", Chaum's 1982 Berkeley dissertation proposed every element of the blockchain found in Bitcoin except proof of work.

The proposed vault system lays out a plan for achieving consensus state between nodes, chaining the history of consensus in blocks, and immutably time-stamping the chained data.

The paper also lays out the specific code to implement such a protocol.

In the same 1982 paper that proposed digital cash, Chaum introduced blind signatures.

This form of digital signature blinds the content of a message before it is signed, so that the signer cannot determine the content.

The resulting blind signature can be publicly verified against the original, unblinded message in the manner of a regular digital signature.

Chaum is credited as the inventor of secure digital cash for his 1983 paper, which also introduced the cryptographic primitive of a blind signature.

In 1988, he extended this idea (with Amos Fiat and Moni Naor) to allow offline transactions that enable detection of double-spending.

In 1989, he (with Hans van Antwerpen) introduced undeniable signatures.

This form of digital signature uses a verification process that is interactive, so that the signatory can limit who can verify the signature.

Since signers may refuse to participate in the verification process, signatures are considered valid unless a signer specifically uses a disavowal protocol to prove that a given signature was not authentic.

He founded DigiCash, an electronic cash company, in 1990.

In 1990, he founded DigiCash, an electronic cash company, in Amsterdam to commercialize the ideas in his research.

In 1991, he (with Eugene van Heyst) introduced group signatures, which allow a member of a group to anonymously sign a message on behalf of the entire group.

However an appointed group manager holds the power to revoke the anonymity of any signer in the case of disputes.

The first electronic payment was sent in 1994.

In 1995 his company DigiCash created the first digital currency with eCash.

Chaum received the Information Technology European Award for 1995.

In 1998, DigiCash filed for bankruptcy, and in 1999 Chaum sold off DigiCash and ended his involvement with the company.

In 2004, he was named an IACR Fellow.

In 2010, at the RSA Conference, he was honored with the RSA Award for Excellence in Mathematics.

In 2019, he was awarded the honorary title of Dijkstra Fellow by CWI.

He received an honorary doctorate from the University of Lugano in 2021.

Chaum resides in Sherman Oaks, Los Angeles.