David Chaum is an American computer scientist and cryptographer, known for his pioneering work in digital privacy and security. He introduced the concept of digital cash in the 1980s, which laid the groundwork for modern cryptocurrencies. Chaum's innovations include blind signatures, a technique that allows for secure and anonymous transactions. In addition to his contributions to digital currency, Chaum founded DigiCash, one of the first companies to implement electronic money. His research has significantly influenced the fields of cryptography and privacy technology, making him a key figure in the development of secure online communication and transactions.