Resettable Zero-Knowledge.

摘要

We introduce the notion of Resettable Zero-Knowledge (rZK), a new security measure for cryptographic protocols which strengthens the classical notion of zero-knowledge. In essence, an rZK protocol is one that remains zero knowledge even if an adversary can interact with the prover many times, each time resetting the prover to its initial state and forcing it to use the same random tape. All known examples of zero-knowledge proofs and arguments are trivially breakable in this setting. Moreover, by definition, all zero-knowledge proofs of knowledge are breakable in this setting. Under general complexity assumptions, which hold for example if the Discrete Logarithm Problem is hard, we construct: rZK proof-systems for NP with non-constant number of rounds, five-round Resettable Witness-Indistinguishable proof-systems for NP, and constant-round rZK arguments for NP in the public key model where verifiers have fixed, public keys associated with them.