ABSTRACT
Recently, there has been a flurry of cross-layer design schemes being proposed in WSN. As the fusion of secure networking and wireless communication occupies the center stage in sensor networks, the traditional layered protocol architecture upon which most of the networks form their basis is under scrutiny. Although, the layered approach has been repeatedly used in wired networks, it has been argued that the same approach cannot be directly applied in resource-constraint, wireless ad-hoc networks such as WSN. Hence, to combat this approach, security researchers have proposed several cross-layer design schemes in an ad-hoc environment (Shakkottai et al. 2003). Unlike the layering approach, where protocols at each layer are designed independently, cross-layer designs aim at exploiting the dependence between different protocol layers to achieve maximum performance gains. In the current state of the art in the paradigm of cross-layer design schemes in ad-hoc wireless networks, several diverse interpretations exist. One of the main reasons for such varied explanations is that the design effort is largely dominated
by researchers who have made independent contributions in designing different layers of the stack. Many of the cross-layer designs depend on other cross-layer designs and hence raise the fundamental question of the coexistence of different cross-layer design proposals. In addition, the question of time synchronization between various cross-layer schemes and the roles each layer of the stack plays is an active area of research. In addition, the wireless medium allows richer modalities of communication than wired networks. For example, nodes can make use of the inherent broadcast nature of the wireless medium and cooperate with each other. Employing modalities such as node cooperation in protocol design also calls for cross-layer design. The goal of designing security solutions with a cross-layer design approach takes us to a new paradigm of security research. The main objective of security solutions in a network is to provide security services such as authentication, integrity, confidentiality, and availability to the users. In wireless adhoc networks, due to the unreliable nature of the shared radio medium, attackers can launch varying attacks, ranging from passive reconnaissance attacks to active man-inthe-middle attacks (Chapter 2). Routing in WSN is hop by hop and assumes a trusted, cooperative environment as intermediate nodes act as relays. However, compromised intermediate nodes can launch varying routing attacks, such as blackhole, wormhole, flood rushing, and selective-forwarding attacks (Chapter 2). In this chapter, we review the existing state of the art in the cross-layer design from a security perspective. In addition, as an example, we look at a cross-layer key-distribution mechanism.
