Zhao, Yunlei2; Nielsen, Jesper Buus4; Deng, Robert H.2; Feng, Dengguo2
1 Department of Computer Science, Faculty of Science, Aarhus University, Aarhus University2 unknown3 Department of Computer Science, Science and Technology, Aarhus University4 Department of Computer Science, Science and Technology, Aarhus University
In this work, we present a generic yet practical transformation from any public-coin honest-verifier zero-knowledge (HVZK) protocols to normal zero-knowledge (ZK) arguments. By ``generic", we mean that the transformation is applicable to any public-coin HVZK protocol under any one-way function (OWF) admitting Sigma-protocols. By ``practical" we mean that the transformation does not go through general NP-reductions and only incurs additionally one round (for public-coin HVZK protocols of odd number of rounds that is the normal case in practice). In particular, if the starting public-coin HVZK protocols and the underlying Sigma-protocols are practical, the transformed ZK arguments are also practical. In addition, our transformation also preserves statistical/perfect zero-knowledge.To this end, we develop generic yet practical 3-round perfectly-hiding equivocal (string) commitment scheme under any OWF admitting Sigma-protocols, which is possibly of independent value. We also show that three rounds is the lower-bound of round-complexity for equivocal commitment schemes.
Electronic Colloquium on Computational Complexity, 2005, Issue TR05-162, p. 1-16