A Multi-Factor Quantum-Resistant and Privacy-Preserving Authentication Protocol for Decentralized Systems

This paper presents a Quantum-Resistant and Privacy-Preserving Authentication Protocol (PPAP) designed for decentralized systems. PPAP integrates lattice-based cryptographic primitives, particularly Module-Lattice Key Encapsulation Mechanisms (ML-KEM), addressing both quantum computing threats and stringent privacy requirements. The protocol introduces advanced identity masking techniques and a multi-factor authentication layer employing Cheon-Kim-Kim-Song (CKKS) homomorphic encryption, enabling secure and privacy-aware authentication that supports approximate knowledge-based factors such as biometrics and handwritten signatures. Rigorous formal analysis, including cryptographic proofs and automated verification using the Tamarin Prover, validates PPAP's resilience against classical and quantum adversaries, as well as common security threats such as replay attacks, impersonation, and credential linkage. Performance evaluations demonstrate the practical feasibility of PPAP, highlighting its computational efficiency and minimized communication overhead, suitable for diverse scenarios ranging from Internet of Things (IoT) and mobile environments to high-security infrastructure. Furthermore, the Time-Aware Predictive Access Model (TAPM) significantly optimizes authentication lookup complexity, demonstrating substantial empirical improvement. Future work will focus on further performance enhancements, integration of additional biometric modalities, and deployment in practical decentralized applications.