Blockchain-Based Security Architecture For Smart City Data Exchange

Abstract

Today, the number of sensors, edge devices, and municipal informatics systems that produce data, along with the Internet of Things (IoT) more broadly, is creating an increasing number of data sources in cities, turning urban governance into a data-driven business. The transition to this smart city paradigm enables real-time monitoring of traffic, energy, water, waste, public safety, and health services, but it also exposes cities to significant cybersecurity and data governance issues. Centralized data exchange systems remain vulnerable to single points of failure, unauthorized access, data tampering, and privacy violations. This paper proposes a blockchain-based security architecture for data exchange between departments and across organizations within a smart city blockchain ecosystem. The proposed architecture involves integrating a 6-layer architecture, namely the perception layer, edge gateway/fog gateway, security/cryptography layer, blockchain ledger, consensus layer, and smart contract layer, with an application layer. Hybrid Practical Byzantine Fault Tolerance (PBFT) and Proof-of-Authority (PoA) consensus mechanisms are used, along with elliptic-curve cryptography, attribute-based access control, and off-chain InterPlanetary File System (IPFS) storage, to meet widely varying security, scalability, and performance requirements. The selected architecture was assessed against existing consensus systems and traditional centralized security models and compared in terms of throughput, latency, energy consumption, and resilience. Results show that the proposed hybrid consensus model strikes a good balance among decentralization, transaction throughput, and energy consumption compared to PoW and pure PoS models, while the proposed attribute-based smart contracts effectively minimize the risk of unauthorized data access. The study's conclusions establish that blockchain-based architectures, alongside edge computing and cryptographic access control, represent a valid option for achieving certified, non-repudiable data exchange in smart cities, but also highlight other limitations, such as energy-related and/or regulatory considerations, that warrant further exploration.