Title: Privacy-preserving Data Aggregation over Participatory Networks Abstract: The emerging participatory networked embedded systems, designed for aggregated information collection with fine-granularity, are viewed as new generation of pervasive computing systems. We expect both social and economic impact of participatory networks. Applications of participatory networks are likely to deal with highly sensitive or private information. Hence, one of the pressing concerns of users is the confidentiality of the data collected about them. Therefore, we need a way to collect aggregated information while at the same time preserve data privacy. In this talk, I will present two privacy-preserving data aggregation schemes for additive aggregation functions. The first scheme, Cluster-based Private Data Aggregation (CPDA), leverages clustering protocol and algebraic properties of polynomials. It has the advantage of incurring less communication overhead. The second scheme, Slice-Mix-AggRegaTe (SMART), builds on slicing techniques and the associative property of addition. It has the advantage of incurring less computation overhead. The goal of this work is to bridge the gap between collaborative data collection and privacy preservation of individual data. I assess the two schemes by privacy-preservation efficacy, communication overhead, and data aggregation accuracy. Since both schemes trade message overhead for privacy, I will propose efficiency enhancement method for privacy preserving data aggregation when message overhead is a big concern.