GridTrust: A Secure and Scalable IoT Framework for Vehicle-to-Grid (V2G) Communication

The integration of electric vehicles into the power grid through Vehicle-to-Grid technology offers significant potential for sustainable energy management, but it is hindered by persistent security vulnerabilities and scalability limitations. Existing communication frameworks often rely on heavy cryptographic mechanisms that increase authentication latency and fail to maintain efficiency under large-scale deployments. To address these shortcomings, this paper proposes GridTrust, a hierarchical Internet of Things framework that combines multi-layered security with scalable communication for V2G networks. The framework integrates Physically Unclonable Functions for tamper-resistant authentication, a lightweight authenticated key agreement protocol for secure and efficient session establishment, and a permissioned blockchain to ensure immutable transaction logging and transparent auditing. A large-scale simulation was conducted to evaluate the system under diverse load conditions. Results show that GridTrust reduces authentication latency by $35 \%$ compared to conventional PKI models, achieves a throughput of 150 transactions per second with 5,000 concurrent EVs, and mitigates over $\mathbf{9 8 \%}$ of replay and man-in-the-middle attacks. These findings demonstrate that GridTrust effectively addresses the dual challenge of security and scalability in V2G communication. The study concludes with a discussion on current limitations, such as real-world deployment constraints, and highlights opportunities for future integration with AIdriven intrusion detection and $5 \mathrm{G} / 6 \mathrm{G}$-enabled V2G ecosystems.