Wireless sensor networks can be applied in various applications ranging from the battlefield monitoring, trespass alert systems at high security zones, remote medical diagnosis, fitness monitoring, home sentry systems, digital homes, to agriculture. Moreover, the evolution of Internet of things (IoT) has greatly increased the usage of sensor nodes in real-time applications. The rapid growth of IoT leads to generating large quantity of data, generally referred as big data, thereby it has growing demand to apply various analytics on the data to uncover hidden patterns, correlations, and other insights. [1][2][3][4][5] The sensor nodes, which work on battery power, are generally deployed in an unattended environment to monitor natural phenomena such as sound, pressure, light, temperature, and sensing information (eg, movement of soldiers of the opponent sides in case of battlefield scenario and monitoring of pH level, blood sugar, and blood pressure in case of healthcare application). The sensors then transmit the sensed data to the nearby base station(s) or gateway nodes (GWNs), which analyze the received data and take the appropriate actions on the target environment.Secure communication along with mutual authentication among the user, sensor nodes and the GWN becomes necessary for WSN. This raises security challenges such as eavesdropping, replay and man-in-the-middle attacks, impersonation attacks, denial-of-service (DoS) attack and physical compromise of sensor nodes. Consider critical applications such as healthcare application and battlefield scenario where the live information of patients' vital information and important information about the opponent side need to be analyzed by the hospital staffs (eg, doctors and nurses) and commanders. This could be achieved when we provide access to the real-time live information directly to the external entities those who are permitted to access the information. In this case, after mutual authentication between a user (external party) and an accessed sensor node, a session key is established for secure communications among them. This paper focuses on this important research topic in WSNs, which attracts much attention to the research community in recent years.
Network modelThe network model associated to the proposed scheme presented in Figure 1 is the hierarchical wireless sensor network (HWSN) or multigateway-based WSN. This model has 3 participants: (1) sensors, (2) GWNs or base stations, and (3) users who wish to use the services of the WSN. The sensor nodes sense the real-time data and transmit to the nearest GWN or the authenticated user. The GWNs act as authentication servers and facilitate in establishing mutual authentication and shared session key between a user and a sensor node in its vicinity. Upon successful authentication and shared key establishment with the desired sensor node, users interact with the sensor node to access the necessary data. It is assumed that the sensor nodes and base stations are stationary after their deployment in the target field....