The wireless sensor network appears as an emerging technology which consists of thousands of small and low cost sensors. These sensors have limited power, computation, storage and communication capabilities. The data aggregation framework process is required which combines the data coming from various sensors, remove the redundancies in those data and then enroot them. In this paper, the authors have proposed a secure data aggregation protocol for Wireless Sensor Networks (WSNs) that is robust to deceitful nodes. This protocol is to guarantee the essential security needs (like authentication, data confidentiality & data integrity) as well as to achieve the low communication overhead and be fitted with various aggregation functions.