We are witnessing an exponential growth of the Internet of Things (IoT) market. Across the globe, wherever there is internet connectivity, each individual owns multiple devices which are connected to the internet. Further, there are “things” which are directly connected to each other through the internet and act independent of human intervention by participating in automated business processes to provide business value. A wide range of IoT applications have been developed and deployed in the recent past. However, the IoT technologies have some inherent drawbacks and challenges, for e.g. security and scalability issues. On the other hand the use of blockchain technologies is also experiencing an exponential growth, even beyond the financial applications. As both IoT and blockchain technologies are finding widespread acceptance, researchers and practitioners have experimented with the adoption of blockchain technologies for IoT based applications with a view to build robust and state of the art systems. Such initiatives have been quite successful. This paper reviews the current research status of IoT and blockchain technologies and discusses how the blockchain technologies are leveraged to address some of the challenges faced during the development of IoT based applications. It identifies research trends and future scope to build IoT architectures based on blockchain technologies.

IOT, Blockchain, Security, Distributed Ledger, Sensors, Actuators, SOA, Reference Architecture, Ethereum, Raspberry Pi, Scalability, Digital Transformation

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