PRCash: Fast, Private and Regulated Transactions for Digital Currencies

Fiat currency implemented as a blockchain can enable multiple benefits such as reduced cost compared to expensive handling of cash and better transparency for increased public trust. However, such deployments have conflicting requirements including fast payments, strong user privacy and regulatory oversight. None of the existing blockchain transaction techniques supports all of these three requirements. In this paper we design a new blockchain currency, called PRCash, that addresses the above challenge. The primary technical contribution of our work is a novel regulation mechanism for transactions that use cryptographic commitments. We enable regulation of spending limits using zero-knowledge proofs. PRCash is the first blockchain currency that provides fast payments, good level of user privacy and regulatory control at the same time.

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