SemChain : A Blockchain-based semantic discovery on distributed resource directories for the Internet of Things

As the Web evolves towards Web 3.0, integrating the Internet of Things (IoT), the Semantic Web, and Blockchain (BC) technology, managing the growing number of IoT devices and ensuring their interoperability and trust becomes increasingly critical. Centralized solutions are prone to single points of failure, while distributed systems face synchronization and consensus issues. Although integrating BC into IoT has shown promise in addressing these challenges, existing approaches often overlook the resource limitations of IoT devices, the importance of standardized IoT protocols, and the impact of BC consensus mechanisms on network performance. To bridge these gaps, this paper presents SemChain: a framework integrating BC within the semantic web of things in a robust, resource-friendly, and trustworthy manner. Leveraging the CoAP standard, a distributed network of resource directories, and a permissioned BC with Smart Contracts (SC), SemChain strengthens the security and trust of semantic resource registration and discovery in IoT environments. Other key contributions include proposing two data storage approaches, namely SemChain-Full and SemChain-Hash, devising multiple SC transactions, and providing a detailed description of a prototype implementation. The framework’s performance is evaluated against state-of-the-art approaches within a smart hospital use case, demonstrating notable improvements, including an average precision of 92$\text{\%}$ and a recall of 88$\text{\%}$ in resource discovery.