Short answers, pulled from the story.
David Lee Chaum, born in 1955, is an American computer scientist and cryptographer widely recognized as the inventor of digital cash and a pioneer of privacy-preserving technologies. He is called "the father of online anonymity" and "the godfather of cryptocurrency" for contributions including blind signatures, mix networks, and a 1982 blockchain protocol proposal that preceded Bitcoin.
Chaum's 1982 Berkeley dissertation proposed every element of the blockchain found in Bitcoin except proof of work. The dissertation described achieving consensus between untrusting nodes, chaining consensus history in blocks, and immutably time-stamping that chain, and included code to implement the protocol.
DigiCash was an electronic cash company Chaum founded in Amsterdam in 1990 to commercialize his research on digital currency. It sent the first electronic payment in 1994 and issued eCash, the first digital currency from a company. DigiCash filed for bankruptcy in 1998, and Chaum sold off the company in 1999.
A blind signature is a cryptographic technique introduced by David Chaum in 1983 that allows a signer to sign a message without seeing its contents. The resulting signature can still be publicly verified against the original unblinded message, enabling untraceable digital payments.
David Chaum invented mix networks in a 1981 paper. The system routes encrypted messages through a chain of servers that shuffle and re-encode them, preventing any observer from linking senders to recipients. Mix networks are the conceptual ancestor of Tor, the modern anonymous web browsing tool.
The city of Takoma Park, Maryland, used a system called Scantegrity in its November 2009 election, making it the first public sector election run using any cryptographically verifiable voting system. Scantegrity was one of several cryptographic paper-ballot systems proposed by Chaum.