LETM-IoT: A lightweight and efficient trust mechanism for Sybil attacks in Internet of Things networks

The Internet of Things (IoT) has recently gained significance as a means of connecting various physical devices to the Internet, enabling various innovative applications. However, the security of IoT networks is a significant concern due to the large volume of data generated and transmitted over them. The limited resources of IoT devices, along with their mobility and diverse characteristics, pose significant challenges for maintaining security in routing protocols, such as the Routing Protocol for Low-Power and Lossy Networks (RPL). This lacks effective defense mechanisms against routing attacks, including Sybil and rank attacks. Various techniques have been proposed to address this issue, including cryptography and intrusion-detection systems. The use of these techniques on IoT nodes is limited by their low power and lossy nature, primarily due to the significant computational overhead they involve. In addition, conventional trust-management systems for addressing security concerns need to be improved due to their high computation, memory, and energy costs. Therefore, this paper presents a novel, Lightweight, and Efficient Trust-based Mechanism (LETM-IoT) for resource-limited IoT networks to mitigate Sybil attacks. We conducted extensive simulations in Cooja, the Contiki OS simulator, to assess the efficacy of the proposed LETM-IoT against three types of Sybil attack (A, B, and C). A comparison was also made with standard RPL and state-of-the-art approaches. The experimental findings show that LETM-IoT outperforms both of these in terms of average packet-delivery ratio by 0.20 percentage points, true-positive ratio by 1.34 percentage points, energy consumption by 2.5%, and memory utilization by 19.42%. The obtained results also show that LETM-IoT consumes increased storage by 5.02% compared to the standard RPL due to the existence of an embedded security module.