David Lee Chaum is an American computer scientist and cryptographer, a pioneer in fundamental ideas for digital privacy and cryptocurrency. His contributions include: Anonymous digital money: In the 1980s, Chaum developed concepts for anonymous electronic money, allowing transactions without revealing the identity of the parties involved. Blind signatures: A cryptographic technique invented by Chaum that allows a signer to approve a document without seeing its content. This technique is crucial for the functioning of anonymous digital money.