Toward 6G Authentication and Key Agreement Protocol: A Survey on Hybrid Post Quantum Cryptography

The evolution of 6G networks necessitates robust authentication and key agreement (AKA) protocols to counter emerging security challenges, particularly the threat posed by quantum computing. Existing 5G-AKA protocols remain vulnerable to user tracking, replay attacks, and false base station impersonation, while Elliptic Curve Cryptography (ECC) and RSA-based key exchanges face imminent obsolescence due to quantum attacks. This study examines the vulnerabilities of 5G-AKA and explores hybrid post-quantum cryptography (PQC) as a transitional security solution for 6G networks. We evaluate NIST-standardized PQC algorithms, focusing on their computational overhead, key size efficiency, and adaptability to heterogeneous network environments, including IoT and ultra-low latency applications. A comparative analysis of hybrid cryptographic schemes demonstrates that lattice-based (Kyber, Dilithium), hash-based (SPHINCS+), and code-based (BIKE, Classic McEliece) PQC techniques provide varying trade-offs between security, efficiency, and deployment feasibility. Furthermore, we propose a quantum-resistant 6G-AKA framework, integrating hybrid PQC, AI-driven trust mechanisms, and decentralized authentication to ensure scalability and interoperability. Experimental benchmarks highlight potential performance constraints, including latency in PQC-based key exchange and resource limitations in edge computing. Addressing these challenges requires the optimization of lightweight PQC implementations, formal security validation, and global standardization efforts. Our findings provide a roadmap for the secure transition to 6G authentication protocols, ensuring resilience against both classical and quantum threats.