Private Stream Aggregation Revisited

In this work, we investigate the problem of private statistical analysis in the distributed and semi-honest setting. In particular, we study properties of Private Stream Aggregation schemes, first introduced by Shi et al. [27]. These are computationally secure protocols for the aggregation of data in a network and have a very small communication cost. We show that such schemes can be built upon any key-homomorphic weak pseudo-random function. Thus, in contrast to the aforementioned work, our security definition can be achieved in the standard model. In addition, we give a computationally efficient instantiation of this protocol based on the Decisional Diffie-Hellman problem. Moreover, we show that every mechanism which preserves pǫ, δq-differential privacy provides computational pǫ, δq-differential privacy when it is executed through a Private Stream Aggregation scheme. Finally, we introduce a novel perturbation mechanism based on the Skellam distribution that is suited for the distributed setting, and compare its performances with those of previous solutions.