Blockchain-Enabled Zero Trust Architectures for Securing 6G-Connected Smart Cities

Abstract

The emergence of 6G-connected smart cities introduces unprecedented challenges in ensuring security, privacy, and scalability for billions of heterogeneous devices and mission-critical services. Traditional Zero Trust Architectures (ZTA) provide continuous verification but rely on centralized control, making them vulnerable to insider threats and single points of failure. Conversely, blockchain-based frameworks ensure immutability and decentralized trust but suffer from high latency and limited scalability. This paper proposes a novel Blockchain-Enabled Zero Trust Architecture (BZTA) that integrates blockchain’s distributed trust management with Zero Trust’s continuous authentication and micro-segmentation, optimized for 6G urban infrastructures.The contributions of this work are fourfold. First, we design a four-layer BZTA model incorporating decentralized identity management, Zero Trust Gateways (ZTGs), blockchain-based ledgers, and smart contracts for adaptive access control. Second, we formalize the methodological foundations of the framework, including trust computation, Zero-Knowledge Proof (ZKP)-based authentication, authorization logic, and Proof-of-Authority consensus mechanisms. Third, we present a comprehensive evaluation using analytical models and simulations. Results show that BZTA achieves 95% trust classification accuracy, sub-20 ms authentication latency compliant with 6G URLLC, revocation within 3 s, and throughput up to 50,000 transactions per second, while reducing authentication energy costs by 35–40% compared to blockchain-only systems. Fourth, we demonstrate that BZTA provides robust defense against spoofing, replay, insider, lateral, and location spoofing attacks, significantly outperforming both ZTA-only and blockchain-only approaches.The findings highlight BZTA as a scalable, resilient, and privacy-preserving security paradigm for 6G smart cities. By merging blockchain immutability with Zero Trust’s dynamic verification, BZTA enables secure and transparent deployment of critical urban services such as healthcare, transportation, and energy management. This work positions BZTA as a foundational step toward building resilient, citizen-centric, and quantum-ready smart city infrastructures.