Node misbehavior detection and secure trust metadata management in mobile networks

The topic of study of this dissertation is node misbehavior detection and secure trust metadata management in mobile networks. For concreteness, two classic mobile networks, delay-tolerant networks and mobile ad-hoc networks, are chosen as the context of this study.;In a Delay-Tolerant Network (DTN), data originating from a source node may be delivered to the destination node, despite the non-existence of end-to-end connectivity between them at all times. In an adversarial environment such as a battlefield, DTN nodes could be compromised to launch Denial-of-Service (DoS) attacks by generating excess data, to cause an overflow of the limited resources of the legitimate nodes, hence decreasing the network throughput. A node may also display selfish behavior by generating more data than allowed, to increase its throughput and to decrease the latency of its data packets. In this dissertation, such a DoS attack and selfish data generation behavior is termed a resource-misuse attack. Two types of resource-misuse attacks are studied, breadth attacks and depth attacks. Accordingly, different schemes to detect these attacks are proposed. Trace-driven simulations using both a synthetic and a real-world trace show that the detection schemes have low average detection latency and additionally, probabilistic detection of the depth attack has low false positive and false negative rates.;Nodes may also display selfish or malicious behavior in a mobile ad-hoc network (MANET). Since the nodes in a MANET are generally resource limited, some nodes could refuse service to other nodes to conserve their resources, thereby exhibiting selfish behavior. Also, since a MANET is often deployed in uncontrolled environments, some nodes could be compromised by an adversary and directed to act maliciously. A trust management framework in a MANET is useful to infer if nodes behave in a selfish or malicious manner, so that appropriate action could be taken, in order to maximize network performance. In this dissertation, a scalable semantics-aware trust metadata management scheme to partition and store an information network of trust metadata of nodes in a MANET is proposed. In this scheme, trust metadata created by individual nodes is propagated to and stored at certain geographic locations in the network itself, based on its semantics. A network entity, such as a trust authority (TA) (e.g., the network administrator), could then send queries of various types in the network to obtain the trust metadata of its interest, and thereby evaluate the behavior of nodes and make prompt decisions (e.g., revoking malicious nodes). The simplicity of this scheme for trust metadata propagation and retrieval, and its robustness to node failures, membership changes and mobility, make it a promising choice for trust metadata management in a MANET. Simulation results that evaluate this scheme based on some trust management metrics demonstrate its performance benefits.;A trust metadata management scheme for a MANET is also required to be secure. Misbehaving nodes could attempt to prevent trust metadata from eventually reaching the concerned network entity (e.g., a TA), to escape detection of their misbehavior. In this dissertation, a secure and scalable trust metadata management scheme for a MANET is designed. This scheme is robust to several security attacks that attempt to disrupt the availability of trust metadata in the network. Analysis of the proposed scheme shows that it provides desirable security and functionality properties with low query overhead.