Data fusion or information collection is one of the fundamental functions in the future cyber-physical systems. But, privacy concerns must be addressed and security must be assured in such systems. It is very challenging to achieve the synergy of privacy and integrity, because privacy preserving schemes try to hide or interfere with data, while integrity protection usually needs to enable peer monitoring or public access of the data. Therefore, privacy and integrity can be the conflicting requirements, one may barricade the implementation of the other.In this paper, we address both privacy of individual sensory data and integrity of aggregation result simultaneously by proposing a protocol called iCPDA, which piggybacks on a cluster-based privacy-preserving data aggregation protocol(CPDA). We implement the add-on feature to protect integrity of aggregation result. To show the efficacy and efficiency of the proposed scheme, we present simulation results. To the best of our knowledge, this paper is among the first protocols to preserve privacy and integrity in data aggregation.