Wireless Sensor Networks (WSN) have lot of interest in research due to their wide range of typical application areas such as environmental, military and commercial enterprises. Sensor network possesses unique challenges to protocol builders, because these tiny wireless devices are often deployed in unattended environment with limited capabilities. Hence these networks are vulnerable to different types of malicious attacks. This paper focused on secured communication in wireless sensor network. Security is a common concern for any network system, but security in WSN is of great importance to ensure its application success.