David Chaum

David Chaum is an American computer scientist and cryptographer. He is known as a pioneer in cryptography and privacy-preserving technologies, and widely recognized as the inventor of digital cash. 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 - except proof of workproof-of-work) element of the blockchain later detailed in the Bitcoin whitepaper.