Abstract—Privacy protection in Wireless Sensor Networks (WSN) constitutes a big challenge for the adoption of WSNs in data sensitive applications like health monitoring or tracking and surveillance of borders. Privacy protection require additional controls and communications overloads, which impact the overall network lifetime. Research community has proposed several scenarios to minimize the impact of data protection generally based on secure aggregation and encryption to meet the practical requirements of energy constraints imposed by WSN. However, efficiency of privacy protection must be assessed before deployment. The privacy protection mechanisms are evaluated based on their hackability and network performance using four main metrics:  Control Packet Overhead, delay, Throughput, Packet delivery ratio. The purpose of this paper is to propose a secure aggregation scheme based on homomorphic encryption. The new scheme will be will be compared to another scheme based on network metric and attack detection accuracy to have full view on the scheme performance for both network and security metrics. The proposed scheme named “Cluster-based Semi-Homomophic Encryption Aggregated Data” (CSHEAD) offer better performance as it reduces the controls overhead with higher detection accuracy. The conducted simulations confirm the expected results.