Philip Michael Asuquo

Privacy-Enhanced Group Communication for Vehicular Delay Tolerant Networks

Vehicular Delay Tolerant Networking (VDTN) is a special instance of Vehicular Ad hoc Networking (VANET) and in particular Delay Tolerant Networking (DTN) that utilizes infrastructure to enhance connectivity in challenged environments. While VANETs assume end-to-end connectivity, DTNs and VDTNs do not. Such networks are characterized by dynamic topology, partitioning due to lack of end-to-end connectivity, and opportunistic encounters between nodes. Notably, VDTNs enhances the capabilities DTNs to provide support for delay and intermittent connectivity. Hence, they can easily find applicability in the early stages of the deployment of vehicular networks characterized by low infrastructure deployment as is obtainable in rural areas and in military communications. Privacy implementation and evaluation is a major challenge in VDTNs. Group communication has become one of the well discussed means for achieving effective privacy and packet routing in ad hoc networks including VDTNs. However, most existing privacy schemes lack flexibility in terms of the dynamics of group formation and the level of privacy achievable. Again, it is difficult to evaluate privacy for sparse VDTNs for rural area and early stages of deployment. This paper reports on an improved privacy scheme based on group communication scheme in VDTNs. We analyze the performance of our model in terms of trade-off between privacy and performance based on delivery overhead and message delivery ratio using simulations. While this is a work in progress, we report that our scheme has considerable improvement compared to other similar schemes described in literature.

A collaborative trust management scheme for emergency communication using delay tolerant networks

Delay Tolerant Network (DTN) comprises of nodes with small and limited resources including power and memory capacity. We propose the use of DTN as an alternate means of communication for the dissemination of emergency information in a post-disaster evacuation operation. We investigate the performance of DTN in providing emergency communication support services under packet dropping attacks. We consider internally motivated attacks where the nodes that are part of the emergency rescue team are compromised with malicious behaviours thereby dropping packets to disrupt the message dissemination during the evacuation operation. A way to mitigating malicious behaviour and improve network performance of DTN is to use incentives in exchanging information between nodes. Unlike existing schemes, we consider the Basic Watchdog Detection System which detects and acts against misbehaving nodes to reduce their overall impact on the network performance. We design a Collaborative Trust Management Scheme (CTMS) which is based on the Bayesian detection watchdog approach to detect selfish and malicious behaviour in DTN nodes. We have evaluated our proposed CTMS through extensive simulations and compared our results with the other existing schemes. Our evaluations show that the use of adequate collaborative strategies between well behaved nodes could improve the performance of Watchdog schemes taking into account the delivery ratio, routing cost and the message delay from the source node to the destination node.

Analysis of DoS Attacks in Delay Tolerant Networks for Emergency Evacuation

In the event of a disaster, there is a severe damage/destruction to physical infrastructures such as telecommunication and power lines which result in the disruption of communication in this areas. For such scenarios, Delay Tolerant Network (DTN) provides an alternative means of communication. In Delay Tolerant Networks (DTNs), a message from a source node may be delivered to the destination node despite the non-existence of an infrastructure and an end-to-end connectivity. However DTNs are susceptible to security threats such as DoS attacks targeted at disrupting relayed packets or dropping critical packets during a disaster rescue operation. DoS attacks consist of blackhole, grayhole, wormhole, packet flooding attacks etc. The scope of this paper is to study the impacts of blackhole and packet flooding attacks in a post disaster communication network using DTN. Various performance metrics in DTN have been used to study the impacts of different DoS attacks in DTN and a comprehensive analysis is presented.

A Mobility-Aware Trust Management Scheme for Emergency Communication Networks Using DTN

In the aftermath of a disaster, collecting and disseminating critical information is very challenging. The damage to telecommunication infrastructures makes its extremely difficult to have an effective recovery and relief operation. In this paper, we consider the use of DTN as an alternative measure to temporarily disseminate emergency information in a post disaster scenario using the Post Disaster Model recommended by IETF. We consider internally motivated attacks where responder nodes are compromised thereby dropping packets forwarded to them. We design a Mobility-Aware Trust Management Scheme (MATMS) to mitigate this routing misbehaviour. We evaluate our proposed scheme through extensive simulations and compare our results with existing benchmarks schemes. Our results show that the use of adequate collaborative strategies can improve the performance of DTNs under attack taking into consideration the delivery probability and message delay from source node to the destination node.

Delay Tolerant Revocation Scheme for Delay Tolerant VANETs (DTRvS)

This article discusses an effective revocation scheme for disconnected Delay Tolerant Vehicular Ad hoc Networks (VANETs). Malicious vehicles can exhibit various misbehaviour such as dropping packets due to selfish reasons. Selfishness can be due to the need to conserve limited resources such as energy and bandwidth. This forces vehicles to either drop all or some of the packets they receive. This is particularly obtainable in multi-hop forwarding networks where packets are routed from one vehicle to another towards their destination. When some packets are dropped, the usefulness of the system is not fully realised since it affects the quality of information available to vehicles for making driving decisions such as road manoeuvres. Additionally, packet dropping can degrade the routing efficiency of the system. In extreme cases of misbehaviour, it is important to stop such vehicles from further participation in network communication. One way of achieving this is through revocation. However, it is important to establish mechanisms for identifying such vehicles before blacklisting them for revocation. Our objective here is to address the question of how much we can use a trust-based scheme where vehicles cannot always be expected to follow normal protocols for revocation. Revocation or suspension of misbehaving vehicles is essential to avoid havoc and possible economic damage.

Experimental Privacy Analysis and Characterization for Disconnected VANETs

Intelligent Transport Systems (ITS) are special applications of Vehicular Ad-hoc Networks (VANETs) for road safety and efficient traffic management. A major challenge for ITS and VANETs in all its flavours is ensuring the privacy of vehicle drivers and the transmitted location information. One attribute of ITS during its early roll-out stage especially in rural areas and challenged environments is low vehicle density and lack of end-to-end connectivity akin to the attribute of Vehicular Delay Tolerant Networks (VDTNs). This means that contact duration between network entities such as vehicles and road-side units (RSUs) are short-lived. Three popular solutions are the use of pseudonyms, mix-zones, and group communication. Privacy schemes based on the mix-zone technique abound for more conventional VANETs. A critical privacy analysis of such scenarios will be key to the design of privacy techniques for intermittent networks. We are not aware of any work that analyse the privacy problem in intermittent VANTEs. In this paper, we add our voice to efforts to characterize the privacy problem in disconnected VANETs.