Paper 2026/1036

Resettable Non-Interactive Zero-Knowledge: Attacks and Defenses

Abstract

As zero-knowledge proofs are increasingly deployed in real-world systems, they face new security threats beyond traditional theoretical guarantees. One important threat is resetting attacks, where an adversary exploits side-channel vulnerabilities or fault injection to manipulate a prover's randomness generation. While resettable zero-knowledge has been extensively studied for interactive protocols, it remains unclear whether modern non-interactive arguments (e.g., zkSNARKs) are secure against resetting attacks. We present the first systematic study of resettable security for non-interactive zero-knowledge (NIZK) arguments. We make three contributions: - New Definition: We formalize strong resettable zero-knowledge (srZK), which captures adversaries that can selectively reset portions of the prover's randomness while leaving other parts unchanged. This models practical attacks such as fault injection on secure hardware or partial state corruption in virtualized environments, which are not captured by the standard rZK definition. - Concrete Attacks: We demonstrate that widely-used NIZK constructions are vulnerable to resetting attacks. We show witness-recovery attacks against Fiat-Shamir-compiled versions of (i) $\Sigma$-protocols (e.g., Schnorr), (ii) PIOP-based SNARKs (e.g., PlonK), and (iii) salted Fiat-Shamir compilation of rewindable protocols. - Generic Defense: We present a simple compiler that transforms any NIZK into one satisfying srZK by modifying only the randomness generation. The prover now derives all necessary randomness by applying a pseudorandom function (PRF) to the public parameters, the statement, and the witness, using a short secret seed as the PRF key, i.e., $\tilde r = \mathsf{F}_r(\mathsf{pp}, x, w)$. This approach prevents resetting attacks without increasing proof size and with only negligible proving overhead. Our results demonstrate that resetting attacks must be considered in NIZK systems, and provide a practical defense with negligible overhead.