Connected devices are increasingly deployed across diverse domains, including industrial monitoring and e health. A persistent challenge common to all sensor-based applications lies in the inherent limitations of these devices, particularly their restricted hardware resources, with energy representing the most critical constraint. Within such Internet of Things (IoT) environments, notably in medical monitoring, sensors must undergo authentication prior to transmitting data to a gateway; consequently, secure authentication between communicating entities constitutes a fundamental requirement. As many IoT devices operate on battery power and transmit data periodically, it is imperative that they adopt lightweight authentication protocols to mitigate energy consumption. Although several approaches such as static and dynamic authentication have been proposed, they remain inadequate when confronted with the stringent energy and storage constraints of sensors. Continuous authentication has emerged as a promising alternative, complementing static methods by ensuring the legitimacy of a sender without reliance on computationally intensive cryptographic operations. In this paper, we enhance a continuous authentication protocol with the objective of optimising energy expenditure associated with security mechanisms. Our proposed solution demonstrates reduced energy consumption and fewer computational operations through the adoption of a query-based model. Finally, the protocol is vali dated using the AVISPA formal verification tool.

Sensor node; Internet of things, Cryptography, Data authentication, RFID, AVISPA