Abstract
Internet of Things (IoT) is a new computing paradigm that refers to interconnected physical devices or IoT devices that contain sensors, actuators and connectivity to enable these IoT devices to connect, interact and exchange data. With the growing number of IoT devices, many security issues have been exposed especially when sensitive data is exchanged. One of these security issues is authentication. In IoT environments, authentication is a big challenge because of the heterogeneity in protocols, devices, and topologies. IoT devices that communicate with each other need to be authentic, in order to avoid different types of attacks that are related to the negligence of authentication. Also, authentication is the basis of access control and accountability. Existing authentication schemes are not suitable anymore for IoT devices. They need to be modified to consider the limitations of the capabilities of these devices, for example, limited memory and energy, and low processing abilities. This paper mainly focuses on reviewing and comparing several recent authentication techniques that have been proposed for IoT environments.