Paper 2026/1036

Resettable Non-Interactive Zero-Knowledge: Attacks and Defenses

Abstract

As zero-knowledge proofs are used in real-world systems, they face threats such as resetting attacks, where an attacker manipulates the prover's randomness. While resettable security has been studied for interactive protocols, whether modern non-interactive systems such as zkSNARKs remain secure under resets is still unclear. This work provides the first systematic study of resettable security for NIZK arguments with three main contributions: - New Definition: We define strong resettable NIZK (srNIZK), which captures adversaries that can selectively reset the prover's randomness, so that some parts are reused while others are generated afresh. This goes beyond the whole-tape resets considered in standard rZK and is motivated by fault injection on secure hardware and incomplete state restoration in virtualized environments. - Concrete Attacks: We demonstrate that widely used NIZK constructions are vulnerable to resetting attacks. We show witness-recovery attacks against (i) Fiat-Shamir-compiled $\Sigma$-protocols (e.g., Schnorr), (ii) succinct proof systems using independently sampled masks (e.g., PLONK and Bulletproofs), and (iii) salted Fiat-Shamir compilations of a broad class of interactive arguments. - Generic Defense: Our simple compiler transforms any NIZK into an srNIZK by modifying only randomness generation, using a pseudorandom function (PRF) secure under partial key resets. This prevents resetting attacks without changing proof size or verification. Our results demonstrate that resetting attacks must be considered in NIZK systems, and provide a simple defense with minor prover overhead.