Trust Management and Security Analysis of Opportunistic Routing Protocols in Multihop Wireless Networks

Abstract

Routing in wireless sensor, mobile ad-hoc, and vehicular networks is a crucial operation having significantly attracted scientists' attention during the past years. Opportunistic routing, however, is a novel and promising approach, which is still an ongoing research paradigm. The purpose of opportunistic routing protocols is to increase the reliability of delivering data packets to their destination by utilizing the broadcast nature of wireless networks and selecting a set of nodes, instead of only one, as potential next-hop candidates. Apart from the reliability, security and trustworthiness of communications is also a challenging task. More specifically, almost all traditional and opportunistic routing protocols require cooperation of all network nodes to complete the routing process. However, some nodes in the network may be compromised and avoid collaboration with others due to various selfish or malicious motivations.

The focus of this thesis is on modeling security challenges and developing trust-based opportunistic routing protocols. This way, communication between nodes will not only benefit from the reliability of opportunistic routing methods, but also from the security of trust and reputation management schemes. For this purpose, a novel trust-based opportunistic routing protocol is proposed that introduces three different candidate selection metrics known as RTOR, TORDP, and GEOTOR. Such metrics have been designed to address specific characteristics of opportunistic routing protocols. In continue, a watchdog mechanism is proposed to assist nodes in monitoring their candidates, recalculating their trust value, and finally replacing malicious candidates with benign ones. Afterwards, an analytical approach is introduced using Discrete-Time Markov Chain to demonstrate the effect of malicious nodes on different parameters of a wireless network that uses opportunistic routing. In this model, a new method of calculating packet drop ratio is introduced to represent the effect of attackers. The model is then applied on different well-known opportunistic routing protocols and results of the model are verified by simulation. Finally, the proposed analytical model is extended to include a defensive mechanism against adversary nodes. In fact, a packet salvaging mechanism is developed through which backup candidates attempt to save some of the maliciously dropped data packets. Different related network parameters such as delivery ratio, salvage ratio, direct-delivery ratio, etc. are then introduced, calculated, and reported using the introduced model.