Who first proposed blind signatures to build an untraceable digital currency?

David Chaumfirst proposed the concept ofblind signaturesin the early 1980s as a way to create an untraceable digital currency. Chaum’s work laid the groundwork for digital privacy in financial transactions by enabling transactions to be signed without revealing the actual content of the transaction, thus maintaining user privacy.

Key Details:

Blind Signatures: A blind signature is a form of digital signature in which the content of a message is hidden (or "blinded") before being signed. This allows for privacy-preserving digital transactions, as the signer cannot see the actual content they are signing.

Application in Digital Currency: Chaum’s idea was foundational for the development of anonymous electronic cash systems. His work led to the creation of DigiCash in 1989, one of the earliest forms of digital currency focused on user privacy.

Influence on Modern Cryptocurrencies: Although Chaum’s DigiCash was not a blockchain-based system, his concepts of privacy and anonymous transactions greatly influenced the development of later cryptographic currencies and protocols, including Bitcoin.

Therefore,A. David Chaumis the correct answer, as he pioneered the use of blind signatures for anonymous digital currency.