I. Introduction
Wireless Sensor Network (WSN), refers to the heteroge-neous system of many tiny sensor devices with the dedicated purpose of processing field data unattended. Hence, power management is vital to the environment sensing missions. Typical sensors are powered by batteries, which can run out in a few weeks of continuous operation. To save energy, sensing data may be merged at one of many aggregators. The data aggregation process must be entrusted to protect aggregated data as well as to reduce wireless communication. Hence, we require the use of an encryption technique to secure the data aggregation process. However, if an aggregator node is captured or becomes faulty, it can easily allow an adversary to interfere with the sensing mission by means of injecting faulty data or modifying the aggregated data, making the results of the whole mission unreliahle