Wireless Sensor Networks (WSNs) are used in many applications in the area of tracking and monitoring. WSNs have many constraints like low computational power, small memory and limited energy resources. Most of the energy consumption is due to data transmission. For that the authors apply data aggregation approach on the sensed data by the deployed sensor nodes. This approach helps to reduce the number of transmissions and improves the life time of wireless sensor network with less energy usage of sensor nodes and also to protect data aggregation process from various kinds of attacks becomes extremely critical.