"A Wireless Sensor Network (WSN) is generally a vast network with large number of sensors nodes. It suffers from several constraints, like low computation capability, less storage capability, restricted energy resources, liability to physical capture, and therefore the use of insecure wireless communication channels. As the size and the density increases over the network, there are more chances of penetration of security in such network. These constraints build ""Security"" in WSNs a challenge. Most of the protocols designed for wireless sensor networks consider energy efficiency but not security as a goal."