Formal Verification of Permission Voucher

TL;DR

This paper conducts a formal security verification of the Permission Voucher Protocol using the Tamarin Prover, confirming its robustness and identifying areas for enhancement in distributed access control systems.

Contribution

It provides the first formal verification of the Permission Voucher Protocol, modeling trust, channels, and adversaries, and evaluates its security properties with detailed proofs.

Findings

Protocol is secure against message tampering, impersonation, and replay attacks.

Verification confirms voucher authenticity, data confidentiality, and key integrity.

Identifies potential improvements like timestamp checks and enhanced mutual authentication.

Abstract

Formal verification is a critical process in ensuring the security and correctness of cryptographic protocols, particularly in high-assurance domains. This paper presents a comprehensive formal analysis of the Permission Voucher Protocol, a system designed for secure and authenticated access control in distributed environments. The analysis employs the Tamarin Prover, a state-of-the-art tool for symbolic verification, to evaluate key security properties such as authentication, confidentiality, integrity, mutual authentication, and replay prevention. We model the protocol's components, including trust relationships, secure channels, and adversary capabilities under the Dolev-Yao model. Verification results confirm the protocol's robustness against common attacks such as message tampering, impersonation, and replay. Additionally, dependency graphs and detailed proofs demonstrate the successful enforcement of security properties like voucher authenticity, data confidentiality, and key integrity. The study identifies potential enhancements, such as incorporating timestamp-based validity checks and augmenting mutual authentication mechanisms to address insider threats and key management challenges. This work highlights the advantages and limitations of using the Tamarin Prover for formal security verification and proposes strategies to mitigate scalability and performance constraints in complex systems.