Edinburgh Napier University

  The blockchain has emerged as an innovative and powerful technology that shows the tremendous potential to enhance the smart industrial frameworks by providing encryption, immutable storage, and decentralization. In the past few years, several applications in the industrial Internet of Things (IIoT) have emerged and blockchain technologies gained great attention from academia and industry. To discover the great potential of blockchain technology for the IIoT, we present a comprehensive survey on security issues, blockchain architectures, and applications from the industrial perspective. This article starts with a comparison of exiting state-of-the-art surveys of blockchain technologies for IoT/IIoT applications. A four-layer reference architecture of IIoT is presented along with the functionalities and security issues of each layer. To address these challenges, we assess the potential of blockchain technology by considering the key characteristics, architectures, consensus algorithms, and implementation platforms. Furthermore, we also discussed some use cases of blockchain for the IIoT frameworks. Finally, this survey is concluded by highlighting some open issues and future research directions.