A Holistic Approach to Secure Sensor Networks

Wireless sensor networks (WSNs) form a unique class of ad hoc networks consisting of heterogeneous but highly resource-constrained devices that can sense their environment and report sensed data to designated nodes in the network. We present a holistic approach to improve the performance of wireless sensor networks with respect to security, longevity and connectivity under changing environmental conditions. Our approach is two-fold: We have created a framework for adaptability that detects, classifies and responds to environmental variations affecting WSN performance. We have also designed security mechanisms in our framework to demonstrate WSN adaptations. Our security mechanisms can be used as basic building blocks in WSN designs. The adaptability framework is generic and ensures that WSNs can respond to a variety of changes in environmental conditions, such as variations related to security and network topology, affecting their performance.

We have designed a two-tier adaptability component, SWANS, using a principled, ontological approach to ensure both local and global responses to environmental variations. Local responses are generated by individual sensor nodes. At node level, SWANS monitors a set of twenty-one low-level parameters (including those associated with secure WSN establishment) and employs a local knowledge base to compute the node's logical state. It employs a set of rules determine the most appropriate response corresponding to a logical state. At network level SWANS combines sensor node state information with user-defined constraints and sensor data. It employs a network-level knowledge base to compute the network's logical state and generate a global response to the observed environmental variation. Experimental evaluations show that WSNs employing SWANS are more secure, live longer and have better connectivity than their non-adaptive counterparts.

We also designed a set of three security protocol suites, SONETS, that secures a WSN against different classes of adversaries. P-SONETS is a centralized protocol suite that secures WSNs deployed to establish a perimeter around high value assets against adversaries who seek to breach the perimeter and attack the asset. C-SONETS is a scalable centralized protocol suite containing a novel topology discovery and key setup protocol to thwart adversaries with global presence in the area of interest capable of attacking the WSN before, during and after its formation. D-SONETS is a distributed protocol suite that ensures rapid establishment of a secure WSN for non-critical applications in which adversary presence is local. Experimental evaluations of P-SONETS, C-SONETS and D-SONETS show their feasibility to the associated application class and their ability to thwart adversaries corresponding to each class.