Architecting a Blockchain-Based Framework for the Internet of Things

Traditionally, Internet-of-Things (IoT) solutions are based on centralized infrastructures, which necessitate high-end servers for handling and transferring data. Centralized solutions incur high costs associated to maintaining centralized servers, and do not provide built-in guarantees against security threats and trust issues. Therefore, it is an essential research problem to mitigate the aforementioned problems by developing new methods for IoT decentralisation. In recent years, blockchain technology, the underlying technology of Bitcoin, has attracted research interest as the potential missing link towards building a truly decentralized, trustless and secure environment for the IoT. Nevertheless, employing blockchain in the IoT has significant issues and challenges, related to scalability since all transactions logged in a blockchain undergo a decentralized consensus process. This thesis presents the design and implementation of a blockchain-based decentralized IoT framework that can leverage the inherent security characteristics of blockchains, while addressing the challenges associated with developing such a framework. This decentralized IoT framework aims to employ blockchains in combination with other peer-to-peer mechanisms to provide: access control; secure IoT data transfer; peer-to-peer data-sharing business models; and secure end-to-end IoT communications, without depending upon a centralized intermediary for authentication or data handling. This framework uses a multi-tiered blockchain architecture with a control-plane/data-plane split, in that the bulk data is transferred through peer-to-peer data transfer mechanisms, and blockchains are used to enforce terms and conditions and store relevant timestamped metadata. Implementations of the blockchain-based framework have been presented in a multitude of use-cases, to observe the framework's viability and adaptability in real-world scenarios. These scenarios involved traceability in supply chains, IoT data monetization and security in end-to-end communications.With all the potential applications of the blockchain-based framework within the IoT, this thesis takes a step towards the goal of a truly decentralized IoT.