The rapid advance of the Internet of Things (IoT) has posed significant challenges for security and privacy because of its centralized architecture and resource-constrained devices. Moreover, since traditional security solutions require scaling and decentralized mechanisms immune to tampering, they cannot satisfy the requirements of IoT ecosystems. It is here that the distributed ledger technology in the form of blockchains fits the bill, with decentralized architecture, immutability, and cryptographic assurance. This review provides a thorough analysis of IoT security as augmented by blockchain, examining various security models based on blockchains, consensus protocols, and smart contracts. Blockchains are the basis for security architectures, access control models, and threat mitigation strategies proposed in 15 cutting-edge research papers reviewed. A comparative analysis of key features was carried out, contrasting blockchain architectures over several axes of performance: scalability, energy efficiency, latency, and security effectiveness. Finally, the challenges, future avenues for research, and barriers to the full-scale application of blockchains in IoT environments are discussed. It comprehensively surveys blockchain-enabled decentralized security for IoT applications and provides directions for developing robust security frameworks for IoT ecosystems for researchers and practitioners.
Reem Al-Maawali (2025) studied this question.