Multiphase deployment models for fast self healing in wireless sensor networks

The majority of studies on security in resource limited wireless sensor networks (WSN) focus on finding an efficient balance among energy consumption, computational speed and memory usage. Besides these resources, time is a relatively immature aspect that can be considered in system design and performance evaluations. In a recent study(Castelluccia and Spognardi, 2007), the time dimension is used to lower the ratio of compromised links, thus, improving resiliency in key distribution in WSNs. This is achieved by making the old and possibly compromised keys useful only for a limited amount of time. In this way, the effect of compromised keys diminish in time, so the WSN selfheals. In this study we further manipulate the time dimension and propose a deployment model that speeds up the resilience improvement process with a tradeoff between connectivity and resiliency. In our method, self healing speeds up by introducing nodes that belong to future generations in the time scale. In this way, the duration that the adversary can make use of compromised keys become smaller

The effect of time dimension and network dynamics on key distribution in wireless sensor networks

The majority of studies on security in resource limited wireless sensor networks (WSN) focus on finding an efficient balance among energy consumption, computational speed and memory usage. Besides these resources, time, network dynamics (e.g. routing), and implementation and integration issues of the security solutions are relatively immature aspects that can be considered in system design and performance evaluations. In the first part of this thesis, we develop and analyze different implementation options of a Random Key Predistribution scheme in a real network simulation environment. Implementation options include Proactive Key Establishment and Reactive Key Establishment. In Proactive Key Establishment, pairwise keys are established at the beginning, prior to start of application. In Reactive Key Establishment, keys are established only whenever needed by the application during its execution. In literature the latter is known to preserve energy since it reduces useless key establishments; however, it also introduces delay in application traffic. We implement the reactive key establishment in such a way that key establishment traffic and energy consumption are reduced. As a result our reactive key establishment implementation has similar throughput performance with proactive scenarios despite the longer lifetime of reactive scenario. We also simulate an attack scenario and measure different metrics including a novel one. This new metric, the packet compromise ratio, reflects the harm caused by the adversary in a more realistic way. In our simulations, we show that packet compromise ratios are very high as compared to link compromise ratios for a long period. However, when the majority of nodes die, link compromise ratios exceed packet compromise ratios. This is an indication to the fact that link compromise ratios seem high even though there is no high amount of traffic in network to be compromised by adversary. Due to the results showing that classical key distribution schemes in WSNs have actually low resiliency, in the second part of this thesis, we propose new deployment models that improve resiliency. In a recent study by Castelluccia and Spognardi, the time dimension is used to lower the ratio of compromised links, thus, improving resiliency in key distribution in WSNs. This is achieved by making the old and possibly compromised keys useful only for a limited amount of time. In this way, the effect of compromised keys diminishes in time, so the WSN selfheals. We further manipulate the time dimension and propose a deployment model that speeds up the resiliency improvement process with a tradeo between connectivity and resiliency. In our method, self healing speeds up by introducing nodes that belong to future generations in the time scale. In this way, the duration that the adversary can make use of compromised keys becomes smaller

A highly resilient and zone-based key predistribution protocol for multiphase wireless sensor networks

Pairwise key distribution among the sensor nodes is an essential problem for providing security in Wireless Sensor Networks (WSNs). The common approach for this problem is random key predistribution, which suffers from resiliency issues in case of node captures by adversaries. In the literature, the resiliency problem is addressed by zone-based deployment models that use prior deployment knowledge. Another remedy in the literature, which is for multiphase WSNs, aims to provide self-healing property via periodic deployments of sensor nodes with fresh keys over the sensor field. However, to the best of our knowledge, these two approaches have never been combined before in the literature. In this paper, we propose a zone-based key predistribution approach for multiphase WSNs. Our approach combines the best parts of these approaches and provides self-healing property with up to 9-fold more resiliency as compared to an existing scheme. Moreover, our scheme ensures almost 100% secure connectivity, which means a sensor node shares at least one key with almost all of its neighbors

Achieving fast self healing in wireless sensor networks using multi-generation deployment schemes

The majority of studies on security in resource limited wireless sensor networks (WSN) focus on finding an efficient balance among energy consumption, computational speed and memory usage. Besides these resources, time is a relatively immature aspect that can be considered in system design and performance evaluations. In a recent study by Castelluccia and Spognardi[5], the time dimension is used to lower the ratio of compromised links, thus, improving resiliency in key distribution in WSNs. This is achieved by making the old and possibly compromised keys useful only for a limited amount of time. In this way, the effect of compromised keys diminish in time, so the WSN selfheals. In this study we further manipulate the time dimension and propose a deployment model that speeds up the resilience improvement process with a tradeoff between connectivity and resiliency. In our method, self healing speeds up by introducing nodes that belong to future generations in the time scale. In this way, the duration that the adversary can make use of compromised keys become smaller