PrivApprox: Privacy-Preserving Stream Analytics

How to preserve users’ privacy while supporting high-utility analytics for low-latency stream processing? To answer this question: we describe the design, implementation and evaluation of PRIVAPPROX, a data analytics system for privacy-preserving stream processing. PRIVAPPROX provides three important properties: (i) Privacy: zero-knowledge privacy guarantee for users, a privacy bound tighter than the state-of-the-art differential privacy; (ii) Utility: an interface for data analysts to systematically explore the trade-offs between the output accuracy (with error estimation) and the query execution budget; (iii) Latency: near real-time stream processing based on a scalable “synchronization-free” distributed architecture. The key idea behind our approach is to marry two techniques together, namely, sampling (used for approximate computation) and randomized response (used for privacypreserving analytics). The resulting marriage is complementary — it achieves stronger privacy guarantees, and also improves the performance for stream analytics.