Zero-Trust Security Frameworks for Heterogeneous IoT Networks in Industrial Environments: A Lightweight Continuous-Authentication Protocol

The convergence of Information Technology (IT) and Operational Technology (OT) in Industry 4.0 smart manufacturing floors introduces dense, heterogeneous Industrial Internet of Things (IIoT) networks. Traditional perimeter-based security architectures fail to protect these networks against lateral threat movement, device cloning, and session hijacking. While Zero-Trust Architecture (ZTA) enforces the core principle of “never trust, always verify,” implementing continuous authentication on resource-constrained, low-power field devices (e.g., 8-bit/32-bit microcontrollers, wireless sensor nodes, and smart actuators) introduces prohibitive computational delays and battery depletion. This paper proposes the Lightweight Continuous PUF-ECC Re-Authentication Protocol (LCP-RAP) designed specifically for low-power IIoT field assets. LCP-RAP combines SRAM-based Physical Unclonable Functions (PUF) for keyless hardware identity generation, lightweight Elliptic Curve Cryptography over Curve25519, and a dynamic context-aware trust scoring mechanism. Evaluating 500 heterogeneous IIoT field nodes across a simulated factory testbed over 100,000 continuous communication sessions, empirical results show that LCP-RAP reduces initial handshake latency by 92.5% (from 245 ms under X.509 PKI to 18.4 ms) and cuts continuous packet re-verification time to 1.12 ms. Furthermore, energy consumption is reduced by 74.2% relative to standard TLS 1.3 setups, consuming less than 3.2% of the daily power budget of battery-operated field sensors while defending against 99.8% of impersonation, physical cloning, and replay attacks.