A Blockchain Based Secure and Auditable Iot Data Marketplace for Smart Cities: an in-silico Prototype and Simulation Study

This study presents an in-silico prototype of a blockchain-based, secure, and auditable IoT data marketplace designed for smart city environments. Using harmonized datasets from ten global cities, the system models decentralized access to IoT-derived data streams\u2014such as temperature, pollution, and traffic\u2014secured via a blockchain ledger. Each data request was hashed and chained using SHA-256, creating a tamper-resistant log of transactions. Tampering scenarios were simulated and detected with over 96% accuracy, validating the robustness of the ledger mechanism. A marketplace simulation was implemented where buyers and sellers engaged in price-aware data transactions. Match efficiency increased with system load, peaking at 82%, while maintaining computational feasibility with logarithmic execution growth. A comparative analysis with a centralized broker system showed that while centralized models offered lower execution times, they lacked any tampering detection capability. The decentralized model provided critical advantages in integrity, transparency, and scalability. This research contributes to several UN Sustainable Development Goals (SDGs), including SDG 11 (Sustainable Cities), SDG 13 (Climate Action), and SDG 16 (Strong Institutions), by enabling secure and transparent data governance frameworks. The study concludes that decentralized data markets, underpinned by blockchain, are viable and desirable for future urban digital infrastructures.