  A wireless sensor network (WSN) has important applications such as remote
environmental monitoring and target tracking. In addition, Wireless Sensor
networks is an emerging technology and have great potential to be employed in
critical situations like battlefields and commercial applications such as
building, traffic surveillance, habitat monitoring and smart homes and many
more scenarios. One of the major challenges wireless sensor networks face today
is security. This has been enabled by the availability for a kind of possible
attacks; the innate power and recall limit of sensor nodes earn customary
security solutions unfeasible. These sensors are equipped with wireless
interfaces with which they can communicate with one pther to form a network. In
this paper we present a survey of security issues in WSNs, address the state of
the art in research
