This document proposes a structureless and efficient data aggregation technique for wireless sensor networks that ensures data integrity with low transmission overhead. It introduces a concept where the base station can recover individual sensor data even after aggregation by cluster heads. This allows the base station to verify data integrity and authenticity, as well as perform any desired aggregation functions. It then proposes a structure-free scheme using intracluster and intercluster encryption and aggregation procedures. This scheme aims to address limitations of previous work such as high transmission costs and inability to query individual data values, while maintaining security and scalability. The document analyzes security and scalability aspects and argues the proposed scheme offers improved performance and efficiency for data aggregation in wireless sensor networks.