Resettably-Sound Resettable Zero Knowledge Arguments for NP.
Yi Deng · 2008
Abstract. We construct resettably-sound resettable zero knowledge arguments for NP based on standard hardness assumption (the existence of claw-free permutations) in the plain model. This proves the simultaneous resettability conjecture posed by Barak et al. in [FOCS 2001]. Our construction, inspired by the paradigm for designing concurrent zero knowledge protocols, makes crucial use of a tool called instance-dependent resettably-sound resettable WI argument of knowledge (IDWIAOK (and a special-purpose variant), introduced recently by Deng and Lin in [Eurocrypt 2007]). Roughly speaking, for a NP statement of the form x0 ∨ x1, IDWIAOK is an argument for which resettable WI property holds when both x0 and x1 are YES instances, and resettably-sound argument of knowledge property holds when x0 is a NO instance. The heart of the simulator for our protocol is a new technique that allows us to embed the (non-black-box) straight-line simulation strategy in the (black-box) recursive rewinding simulation strategy. 1 The problem and our result It is well known that randomness is essential to zero knowledge proofs/arguments[17]. Moreover,