Wireless sensor networks (WSNs) are widely used in many different number of applications, like border surveillance, under water sensor networks etc. In a large WSN, there is significant reduction in the amount of communication overhead and energy consumption when in network data aggregation is performed. Various methods available for data aggregation are: hierarchy aggregation, averaging. Different algorithms which performs secured data aggregation considered are ESPDA (Energy efficient and secure pattern based data aggregation), SRDA (Secure reference based data aggregation). However in all these approaches the algorithms do not allow intermediate nodes to perform data aggregation thus limits the benefit of data aggregation. In this paper the new approach i.e. built in self test (BIST) is considered which will perform secured data aggregation.