Abstract
IoT environment merges the digital and physical universes and enabling them to communicate real-time data It is crucial to constantly ensure that the user is not impersonated which brings a particular type of authentication known as continuous authentication. Therefore, this survey is primary attempt to present an overview about continuous authentication methods in IoT environment, where Blockchain-related solutions provided in this context is also discussed. Subsequently, we overview IoT environment and classify IoT attacks based on its layers with the corresponding proposed countermeasures. Next, we identify a number of open issues that must be taken into account when developing authentication schemes for IoT. We further contribute to this survey by providing a comprehensive analysis of designing continuous authentication process. Besides, we highlight the primary advantages of continuous authentication over the static authentication scheme. In this context, we review relevant works that have proposed Blockchain-based solution to strength the security of IoT systems. We further contribute to present, analyze, and compare user-related IoT-based continuous authentication solutions. Also, we present the solutions that integrate Blockchain. Finally, several research directions and open challenges are identified.