Promoting trust between strangers in ad hoc networks
In ad hoc networking technology, mobile nodes equipped with wireless network interfaces dynamically self-organise into temporary networks, allowing people and devices to communicate without any pre-existing infrastructure. Aiming to enhance network performance by stimulating node participation to the network operation, the impact of several threats that have often been neglected when designing ad hoc routing protocols was investigated. The simulation-based analysis conducted in the laboratories of the Eurécom Institute in France was focused on the lack of a-priori trust relationship between the members of these networks. Network nodes typically do not belong to the same organisational structure nor are they governed by the same authority, and more importantly they do not pursue a common goal. The network thus relies on the cooperation of individual users whose devices provide relaying functions. Moreover, the network performance can be severely degraded even when a small fraction of nodes deny participation due to scarce resources. Research pointed out the novelty of cooperation requirements and the difficulty of providing secure associations without the support of external infrastructure. Based on the basic design requirements drawn, reputation based cooperation enforcement was suggested as a generic mechanism that can be integrated with any network function like packet forwarding, route discovery and network management. The CORE mechanism follows a distributed approach and does not depend on a centralised service to coordinate the activity of the network nodes. Each network entity in monitors other entities collaboration to identify the trustworthiness of peers by comparing the observations collected with the expected results. Nodes denying cooperation or deviating from a legitimate behaviour are gradually refused communication services. Throughout the simulation study, the CORE mechanism introduced significant power saving with respect to other cooperation enforcement mechanism available in literature, especially for legitimate nodes. A detailed analysis of the security features of this mechanism under different networking scenarios defined the lower bound on the number of legitimate nodes in an ad hoc network. Future work, taking into account both static and dynamic networks as well as different traffic patterns, will test the effectiveness of the mechanism under heavy load conditions.
