Precise Concurrent Zero Knowledge
- Cite this paper as:
- Pandey O., Pass R., Sahai A., Tseng WL.D., Venkitasubramaniam M. (2008) Precise Concurrent Zero Knowledge. In: Smart N. (eds) Advances in Cryptology – EUROCRYPT 2008. EUROCRYPT 2008. Lecture Notes in Computer Science, vol 4965. Springer, Berlin, Heidelberg
Precise zero knowledge introduced by Micali and Pass (STOC’06) guarantees that the view of any verifier V can be simulated in time closely related to the actual (as opposed to worst-case) time spent by V in the generated view. We provide the first constructions of precise concurrent zero-knowledge protocols. Our constructions have essentially optimal precision; consequently this improves also upon the previously tightest non-precise concurrent zero-knowledge protocols by Kilian and Petrank (STOC’01) and Prabhakaran, Rosen and Sahai (FOCS’02) whose simulators have a quadratic worst-case overhead. Additionally, we achieve a statistically-precise concurrent zero-knowledge property—which requires simulation of unbounded verifiers participating in an unbounded number of concurrent executions; as such we obtain the first (even non-precise) concurrent zero-knowledge protocols which handle verifiers participating in a super-polynomial number of concurrent executions.