  Wireless sensor networks (WSNs) have attracted a lot of interest in the
research community due to their potential applicability in a wide range of
real-world practical applications. However, due to the distributed nature and
their deployments in critical applications without human interventions and
sensitivity and criticality of data communicated, these networks are vulnerable
to numerous security and privacy threats that can adversely affect their
performance. These issues become even more critical in cognitive wireless
sensor networks (CWSNs) in which the sensor nodes have the capabilities of
changing their transmission and reception parameters according to the radio
environment under which they operate in order to achieve reliable and efficient
communication and optimum utilization of the network resources. This chapter
presents a comprehensive discussion on the security and privacy issues in CWSNs
by identifying various security threats in these networks and various defense
mechanisms to counter these vulnerabilities. Various types of attacks on CWSNs
are categorized under different classes based on their natures and targets, and
corresponding to each attack class, appropriate security mechanisms are also
discussed. Some critical research issues on security and privacy in CWSNs are
also identified.
