Abstract
To create a secure communication among the sensor nodes, a key establishment scheme is very important. Wireless sensor networks (WSN) are usually left unattended and thus may attract the adversary to launch several attacks to the network operation. The exposure of the key during a node capture may disturb a large part of network communication. If there is a reliable, efficient, and secure KMS, disruption in the network to such an extent may not occur during a node capture attack. Several researchers have presented several key agreement schemes, but still the area is open to design an efficient attack resistant KMS. Sometimes, during the design of security protocols, the assumptions taken for the adversary behavior in sensor field may not reflect their actual behavior of the adversary in sensor field making these schemes less feasible in many real-world WSN applications. This chapter first discusses the challenges and security requirements, node capture attacks, its impact on the network, and some open issues of KMS solutions to this problem.
Top2. Background
WSN is a extremely disseminated and unified network that can be abstracted in to two elements namely sensor nodes and base stations. Sensor nodes get the physical information from surrounding, process it and communicate it using wireless channel. It is a dynamic network of sensor nodes having the limited capabilities of computation to a central authority. A WSN may have huge number of sensor nodes that communicates over a small range of wireless network interface. For economic reasons, sensor nodes are made of highly resource constrained making public-key encryption difficult. The central authority or base station (BS) acts as a entry of forwarding the collected data to some higher authority. Individual sensors communicate locally with neighboring sensors and send readings in peer to peer network to BS. Data packets are broadcast over the air, so an adversary can easily eavesdrops the communication channel. The communication pattern within sensor network has three categories namely node to node communication (aggregation of sensor readings), BS to node communication (specific queries), node to BS (sensor readings) (Simplício, Barreto, Margi & Carvalho 2010). The architecture of WSN is depicted by Figure 1.
Figure 1. Architecture of a typical WSN
The sensors are equipped with three units namely sensing, processing and communication units. The sensing unit is dedicated for sensing the environment data and transfer to processing unit. The processed data is given to BS by communication unit. The sensor nodes are generally placed in a hostile environment so vulnerable to being physically tampered. There is an uncontrollable change in topology due to node failures.
Key Terms in this Chapter
Network Connectivity: Means the connection probability for two nodes have the same pre-distributed key or establishing a key path between them.
Node Capture Strategy: The strategy adopted by the adversary in the network to disrupt the complete traffic. It may be random or may be performed with intelligence.
Resilience Against Node Capture: Defines the security strength of KMS in presence of adversaries. It is the probability of key not getting compromised when x nodes are captured by the adversary in a network.
Key Management: It is set of different processes required to generate the cryptographic keys, distribute in the sensor nodes, and setup between the communicating nodes to carry out a secure information exchange.