  Traditional approach of providing network security has been to borrow tools
and mechanisms from cryptography. However, the conventional view of security
based on cryptography alone is not sufficient for the defending against unique
and novel types of misbehavior exhibited by nodes in wireless self-organizing
networks such as mobile ad hoc networks and wireless sensor networks.
Reputation-based frameworks, where nodes maintain reputation of other nodes and
use it to evaluate their trustworthiness, are deployed to provide scalable,
diverse and a generalized approach for countering different types of
misbehavior resulting form malicious and selfish nodes in these networks. In
this chapter, we present a comprehensive discussion on reputation and
trust-based systems for wireless self-organizing networks. Different classes of
reputation system are described along with their unique characteristics and
working principles. A number of currently used reputation systems are
critically reviewed and compared with respect to their effectiveness and
efficiency of performance. Some open problems in the area of reputation and
trust-based system within the domain of wireless self-organizing networks are
also discussed.
