Decentralized AI-Driven Zero-Trust Architecture: Leveraging Blockchain for Immutable Policy Enforcement and Autonomous Anomaly Response in Critical Infrastructure Systems

As critical infrastructure systems transition toward hyper-connectivity, the risk of catastrophic cyber-physical attacks increases. This paper introduces a Decentralized AI-Driven Zero-Trust Architecture (D-AI-ZTA) that mitigates the risks of centralized authority failure. By leveraging Blockchain technology, the framework ensures that security policies are immutable and transparently enforced through Smart Contracts. Simultaneously, an integrated Artificial Intelligence layer provides autonomous anomaly detection, allowing the system to identify and isolate threats in millisecond timeframes without human intervention. The study demonstrates that decentralizing the Policy Decision Point (PDP) reduces the attack surface and ensures system continuity even under persistent threat conditions.