In TCC 2015, Lindell embarked on the challenging task of obtaining a similar transform with improved heuristic security. Lindell showed that, for several interesting and practical languages, there exists an efficient transform in the non-programmable random oracle (NPRO) model that also uses a common reference string (CRS). A major contribution of Lindell's transform is that zero knowledge is proved without random oracles and this is an important step towards achieving efficient NIZK arguments in the CRS model without random oracles.
In this work, we analyze the efficiency and generality of Lindell's transform and notice a significant gap when compared with the FS transform. We then propose a new transform that aims at filling this gap. Indeed our transform is almost as efficient as the FS transform and can be applied to a broad class of public-coin HVZK proof systems. Our transform requires a CRS and an NPRO in the proof of soundness, similarly to Lindell's transform.Category / Keywords: cryptographic protocols / NIZK, Fiat-Shamir Transform, NPRO, Sigma Protocols Original Publication (with minor differences): IACR-TCC-2016 Date: received 2 Aug 2015, last revised 20 Apr 2016 Contact author: ivan visconti at gmail com Available format(s): PDF | BibTeX Citation Note: This paper will appear in TCC 2016-A. Version: 20160420:233324 (All versions of this report) Short URL: ia.cr/2015/770 Discussion forum: Show discussion | Start new discussion