A Taxonomy and Review of Lightweight Blockchain Solutions for Internet of Things Networks

Internet of things networks have spread to most digital applications in the past years. Examples of these networks include smart home networks, wireless sensor networks, Internet of Flying Things, and many others. One of the main difficulties that confront these networks is the security of their information and communications. A large number of solutions have been proposed to safeguard these networks from various types of cyberattacks. Among these solutions is the blockchain, which gained popularity in the last few years due to its strong security characteristics, such as immutability, cryptography, and distributed consensus. However, implementing the blockchain framework within the devices of these networks is very challenging, due to the limited resources of these devices and the resource-demanding requirements of the blockchain. For this reason, a large number of researchers proposed various types of lightweight blockchain solutions for resource-constrained networks. The "lightweight" aspect can be related to the blockchain architecture, device authentication, cryptography model, consensus algorithm, or storage method. In this paper, we present a taxonomy of the lightweight blockchain solutions that have been proposed in the literature and discuss the different methods that have been applied so far in each "lightweight" category. Our review highlights the missing points in existing systems and paves the way to building a complete lightweight blockchain solution for resource-constrained networks.