Practical zero-knowledge arguments from ∑-protocols

Abstract

Zero-knowledge (ZK) plays a central role in the field of modern cryptography and is a very powerful tool for constructing various cryptographic protocols, especially cryptographic protocols in E-commerce. Unfortunately, most ZK protocols are for general NP languages with going through general NP-reductions, and thus cannot be directly employed in practice. On the other hand, a large number of protocols, named ∑-protocols, are developed in industry and in the field of applied cryptography for specific number-theoretic languages (e.g. DLP and RSA), which preserves the ZK property only with respect to honest verifiers (i.e., they are not real ZK) but are highly practical. In this work, we show a generic yet practical transformation from ∑-protocols to practical (real) ZK arguments without general NP-reductions under either the DLP or RSA assumptions. © Springer-Verlag Berlin Heidelberg 2005.