Instance-Dependent Verifiable Random Functions and Their Application to Simultaneous Resettability

Abstract. We introduce a notion of instance-dependent verifiable random functions (InstD-VRFs for short). Informally, an InstD-VRF is, in some sense, a verifiable random function [23] with a special public key, which is generated via a (possibly)interactive protocol and contains an instance y L {0, 1} for a specific NP language L, but the security requirements on such a function are relaxed: we only require the pseudorandomness property when y L and only require the uniqueness property when y / L, instead of requiring both pseudorandomness and uniqueness to hold simultaneously. We show that this notion can be realized under standard assumption. Our motivation is the conjecture posed by Barak et al.[2], which states there exist resettably-sound resettable zero knowledge arguments for NP. The instance-dependent verifiable random functions is a powerful tool to tackle this problem. We first use them to obtain two interesting instancedependent argument systems from the Barak's publ...

• Type: Conference
• Year: 2007
• Where: EUROCRYPT
• Authors: Yi Deng, Dongdai Lin
• Keywords: Cryptology, EUROCRYPT 2007, Knowledge Argument, Verifiable Random Functions, Zero Knowledge