  Conventional cryptography methods alone are not adequate for secure routing
in Wireless Sensor Networks (WSNs). These networks are more vulnerable to
security attacks due to their diverse applications, lack of supervision and
limitations in view of resource, processing and storage. To mitigate these
problems, trust is widely used as a tool to provide better security by aiding
routing protocols. In recent years, numerous researchers have proposed wide
variety of solutions based on trust. However, all these solutions carry their
own design. In this paper, we attempt to present steps for a systematic design
of trust management systems for WSNs. In addition, we address the techniques
followed by scholars in implementing trust frameworks. Furthermore, we provide
discussion on state-of-the-art research in designing trust systems with summary
and comparisons.
