NTN-PQ-AKE: A Lightweight Transcript-Bound and Explicitly Authenticated Post-Quantum Key Exchange for IoT

Abstract

Post-quantum authenticated key exchange is needed for Internet of Things (IoT) systems facing quantum-enabled adversaries, but signature-heavy post-quantum handshakes remain costly for constrained devices and long-delay non-terrestrial network (NTN) links. This paper proposes NTN-PQ-AKE, a lightweight, transcript-bound authenticated key exchange for managed IoT/NTN deployments. The protocol avoids online post-quantum signatures by combining the Module-Lattice-Based Key-Encapsulation Mechanism (ML-KEM) with provisioned symmetric token material, replay-window checking, transcript-bound derivation using the HMAC-based Key Derivation Function (HKDF), and two-way confirmation tags. Its principal novelty relative to the KEM-based baselines considered here is the joint provision of pair-scoped pre-authentication before ML-KEM processing, complete binding of the key-establishing transcript, and fail-closed two-way key confirmation for managed IoT/NTN deployments. Its “authenticate first, compute later” design rejects forged initiations before expensive KEM processing, while each endpoint releases local session keys only after verifying the role-specific peer confirmation for the same transcript-derived state. Security analysis under a Dolev–Yao adversarial model shows that, within the stated freshness and provisioning assumptions, NTN-PQ-AKE supports mutual authentication, KEM-derived session-key freshness for uncompromised sessions, replay and man-in-the-middle resistance, transcript integrity, and scoped resource-exhaustion mitigation; it does not claim full perfect forward secrecy after later endpoint-key compromise. Across 100 measured runs after five warm-up runs, hardware profiling on an STM32F407G-DISC1 Cortex-M4 gives a mean combined Alice-and-Bob handshake cost of 3,812,967 cycles (SD 13,420; 95% CI half-width 2,662), or 22.70 ms at 168 MHz, with 52,356 B of text, 136 B of data, and 68,664 B of bss. OMNeT++ evaluation shows that NTN-PQ-AKE transmits 2,472 bytes and completes in approximately 524.67 ms on the modeled NTN channel.