A behavior-based trust-gating framework for securing permissioned IoT blockchains using proof of authority

The integration of blockchain technology into Internet of Things (IoT) environments presents a fundamental conflict between the demand for robust, decentralized security and the severe computational constraints of IoT devices. While Proof-of-Authority (PoA) has emerged as an efficient consensus mechanism for permissioned networks, its inherent security model remains vulnerable to valid transactions from compromised or malicious nodes, a critical gap in existing protocols. This paper introduces PoA-TG Chain, a novel framework that enhances PoA with an integrated, lightweight Trust-Gating (PoA-TG) mechanism. This system assigns a dynamic, behavior-based trust score to each node, using it as a rapid pre-filter to reject transactions from untrusted actors before they enter the consensus process. Through a comprehensive simulation study, we conducted a rigorous comparative analysis of a standard PoA model against our proposed PoA-TG framework. The findings are definitive: the PoA-TG Chain framework reduced the success rate of malicious transactions from 25.35% in the standard PoA model to a mere 0.28%. This constitutes a 98.9% reduction in the remaining vulnerability, demonstrating the profound effectiveness of the trust-gating mechanism. This critical security hardening is achieved with remarkable efficiency, incurring only a 7.2% reduction in network throughput and a marginal 0.02% increase in average CPU load per transaction. Our work demonstrates that a dynamic, reputation-based security layer can provide near-total protection against the modeled threats at negligible performance cost, offering a viable, highly effective solution for securing resource-constrained IoT deployments.