Generic yet Practical ZK Arguments from any Public-Coin HVZK

Generic yet Practical (Statistical) Zero-Knowledge from any Public-Coin HVZK

In this work, we present a generic yet practical transformation from any public-coin honestverifier 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 Σ-protocols. By “practical” we mean that the transformation does not go through general ...

Zero-Knowledge Proofs and String Commitments Withstanding Quantum Attacks

The concept of zero-knowledge (ZK) has become of fundamental importance in cryptography. However, in a setting where entities are modeled by quantum computers, classical arguments for proving ZK fail to hold since, in the quantum setting, the concept of rewinding is not generally applicable. Moreover, known classical techniques that avoid rewinding have various shortcomings in the quantum setti...

Efficient and Concurrent Zero-Knowledge from any public coin HVZK protocol

A Transform for NIZK Almost as Efficient and General as the Fiat-Shamir Transform Without Programmable Random Oracles

The Fiat-Shamir (FS) transform uses a hash function to generate, without any further overhead, non-interactive zero-knowledge (NIZK) argument systems from constant-round publiccoin honest-verifier zero-knowledge (public-coin HVZK) proof systems. In the proof of zero knowledge, the hash function is modeled as a programmable random oracle (PRO). In TCC 2015, Lindell embarked on the challenging ta...

On the Implausibility of Constant-Round Public-Coin Zero-Knowledge Proofs

We consider the problem of whether there exist non-trivial constant-round public-coin zero-knowledge (ZK) proofs. To date, in spite of high interest in the above, there is no definite answer to the question. We focus on the type of ZK proofs that admit a universal simulator (which handles all malicious verifiers), and show a connection between the existence of such proof systems and a seemingly...