An energy efficient key management scheme is an important aspect to ensure secure services in resource constrained Wireless Sensor Networks (WSNs). There are two parts of key management scheme, i.e. key distribution and key revocation. Key distribution is the task to manage the key in such a way that if two or more sensors want to communicate with each other for the purpose of sharing the data or control messages, the key is to be made available to them only. The scheme should be energy efficient, as the sensor nodes in the network are resource constrained.