A Lightweight Blockchain Framework for secure transaction in resource constrained IoT devices

Internet of Things (IoT)-based applications are making a big impact in various sectors of our daily life, like smart cities, smart healthcare, smart industries, etc. IoT networks usually require a centralized server or certain authorities to manage and control devices scattered over the network. As a result of centralized management, IoT network security is put at risk. By integrating blockchain technology with IoT, we can create a decentralized and secure network. However, traditional blockchain implementation on IoT devices is not the best solution. It requires high computational capacity to achieve consensus over data communicated among devices, which is not feasible for resource constraint IoT devices. Furthermore, the data generated by IoT devices is massive, making it impossible to keep in blockchain after a certain point. Several models have been proposed in the literature to address these challenges. In 2021, Fusion Chain was proposed as a lightweight blockchain framework that was shown to be the lightest of all models. However, this model is not secure. In this paper, we highlight the various security issues within this framework. We then propose a secure version of Fusion chain, termed Fusion Chain-S, that overcomes these security issues and also provides enhanced storage and access policies for every data element. Also, to make it fault-tolerant, we have used COAP (Constrained Application Protocol) as an integrity channel. We provide a comprehensive security analysis of our framework and prove it using BAN logic. To the best of our knowledge, our improved model is the most lightweight and secure among the other peer models.