Abstract

The exponential growth of the Internet of Things (IoT) ecosystem has amplified concerns regarding data privacy, trust management, and cyber resilience in decentralized environments. Traditional perimeter-based security models are inadequate for heterogeneous IoT networks that operate across multiple domains. To address these challenges, this paper proposes a Blockchain-Augmented Zero Trust Architecture (BZTA) integrated with a hybrid intrusion detection mechanism for achieving secure, verifiable, and adaptive threat mitigation in decentralized IoT frameworks. The proposed BZTA employs blockchain-based identity verification to ensure device authenticity and policy-driven Zero Trust enforcement to validate every access request dynamically. A federated intrusion detection model built using Long Short-Term Memory (LSTM) and Graph Attention Networks (GAT) identifies anomalous communication patterns, while smart contracts facilitate tamper-proof logging and automated response coordination. The integration of Proof-of-Trust (PoT) consensus enhances scalability by minimizing latency during transaction validation. Experimental evaluations conducted on simulated IoT network datasets demonstrate a detection accuracy of 98.6%, false positive rate of 1.8%, and an average latency reduction of 22% compared to traditional IDS and standalone blockchain systems. The proposed BZTA framework effectively balances security, scalability, and interoperability, providing a resilient foundation for next-generation decentralized IoT infrastructures.