Cryptology ePrint Archive: Report 1998/015

More on Proofs of Knowledge

Shai Halevi and Silvio Micali

Abstract: The notion of proofs of knowledge is central to cryptographic protocols, and many definitions for it have been proposed. In this work we explore a different facet of this notion, not addressed by prior definitions. Specifically, prior definitions concentrate on capturing the properties of the verifier, and do not pay much attention to the properties of the prover.

Our new definition is strictly stronger than previous ones, and captures new and desirable properties. In particular, it guarantees prover feasibility, that is, it guarantees that the time spent by the prover in a proof of knowledge is comparable to that it spends in an "extraction" of this knowledge. Our definition also enables one to consider meaningfully the case of a single, specific prover.

Category / Keywords: Proofs of knowledge, knowledge extractor, prover feasibility.

Publication Info: Appeared in the THEORY OF CRYPTOGRAPHY LIBRARY and has been included in the ePrint Archive.

Date: received May 4, 1998.

Contact author: shaih at watson ibm com

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