Quantum-Safe Identity Verification using Relativistic Zero-Knowledge Proof Systems

TL;DR

This paper advances quantum-safe identity verification by improving relativistic zero-knowledge proof protocols, making them more practical and secure against malicious entangled provers, with enhanced scalability and relaxed constraints.

Contribution

It introduces a more scalable and stable implementation of relativistic zero-knowledge proofs and extends the protocol to a three-prover setup for increased security.

Findings

Relaxed relativistic constraints from 60m to 30m.

Enhanced stability and scalability of the proof protocol.

Extended security to three-prover configurations.

Abstract

Identity verification is the process of confirming an individual's claimed identity, which is essential in sectors like finance, healthcare, and online services to ensure security and prevent fraud. However, current password/PIN-based identity solutions are susceptible to phishing or skimming attacks, where malicious intermediaries attempt to steal credentials using fake identification portals. Alikhani et al. [Nature, 2021] began exploring identity verification through graph coloring-based relativistic zero-knowledge proofs (RZKPs), a key cryptographic primitive that enables a prover to demonstrate knowledge of secret credentials to a verifier without disclosing any information about the secret. Our work advances this field and addresses unresolved issues: From an engineering perspective, we relax further the relativistic constraints from 60m to 30m, and significantly enhance the stability and scalability of the experimental demonstration of the 2-prover graph coloring-based RZKP protocol for near-term use cases. At the same time, for long-term security against entangled malicious provers, we propose a modified protocol with comparable computation and communication costs, we establish an upper bound on the soundness parameter for this modified protocol. On the other hand, we extend the two-prover, two-verifier setup to a three-prover configuration, demonstrating the security of such relativistic protocols against entangled malicious provers.