Trust-based fog-blockchain model for scalable authentication in smart cities

In smart cities, ensuring robust authentication, security, and scalability of infrastructure presents significant challenges. Traditional centralized authentication methods expose vulnerabilities and increase energy consumption, particularly in resource-constrained IoT nodes. Moreover, existing blockchain-based authentication systems encounter substantial overhead, delays, and complexities, compromising their effectiveness in diverse environments. A critical issue in real-time smart systems is the significant authentication delays caused by the high volume of requests processed by the blockchain. To address these challenges, we propose an innovative blockchain architecture that connects distributed fog servers for seamless IoT node authentication within smart-city networks. Our model integrates trust-based analyses, encompassing the behavior and data trust evaluations of the IoT at fog servers, to fortify security by detecting malicious nodes and tampered data early in the process. This process streamlines verification by reducing the influx of untrusted data during consensus, ensuring only the most reliable data advances for blockchain operations, and enhancing efficiency and reliability. This architecture guarantees data confidentiality and integrity through lightweight encryption and digital certification. It fosters scalability, seamless communication, and information sharing among smart city entities, facilitating internetwork node identification across a spectrum of smart systems. Performance assessment of the proposed model revealed notable improvements in computation cost, execution time, and power consumption. Our findings revealed a network lifetime enhancement of up to 35 % compared with centralized and blockchain schemes. Furthermore, a security assessment confirmed the effectiveness of the model in preventing tampering and various attacks, thereby satisfying the stringent security requirements of smart cities.