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Privacy-Preserving Stream Aggregation. Elaine Shi (PARC/UC Berkeley), T-H. Hubert Chan (HKU), Eleanor Rieffel ( FXPal ), Richard Chow (PARC), Dawn Song (UC Berkeley). Privacy in Smart Grids. Smart grid operator. Time-series data. Privacy in Population Surveys.
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Privacy-Preserving Stream Aggregation Elaine Shi (PARC/UC Berkeley), T-H. Hubert Chan (HKU), Eleanor Rieffel (FXPal), Richard Chow (PARC), Dawn Song (UC Berkeley)
Privacy in Smart Grids Smart grid operator Time-series data
How can we allow a data aggregator to perform data analytics, while preserving individual privacy?
Homomorphic Encryption? (PK, SK)
New Paradigm SK5 SK4 SK1 SK3 SK2
New Paradigm Evaluate SK4 SK5 SK3 SK2 SK1
Expressiveness: Summation Evaluate
Expressiveness: Distributions Evaluate
Aggregate Once: Simple Construction SK4 SK5 SK3 SK2 SK1
Aggregate Once: Simple Construction … … SK4 SK5 SK3 SK2 SK1
Aggregate Once: Simple Construction … … SK4 SK5 SK3 SK2 SK1
Multiple Time Steps … … SK4 SK5 SK3 SK2 SK1
Differential Privacy [Dwork06] ? 0 0 1 1 1 1 0 1 1 1 8 neighboring vectors x and x’, 8 sets of transcripts S: Pr [π (x) є S] ≤ exp(ε) ∙ Pr [π (x’) є S]
Naïve Scheme Error: v1+ r1 v2+ r2 v3+ r3 v4+ r4 v5+ r5
Crypto + Differential Privacy Error: … … Enc(v1+ ρ1) Enc(v5+ ρ5)
Open Problems and Future Work • More expressive queries • Larger plaintext space • Fault tolerance [CSS10] • Reduce privacy loss over multiple time steps [CSS10]
Take-Home Messages • Differential Privacy against an Untrusted Aggregator • The Power of Combining Cryptography and Differential Privacy
Our Results – Property • Periodic aggregation • Non-interactive • No interactions among users • Users upload ciphertext to aggregator, and no more communication needed
Privacy in Sensor Networks • Building monitoring • Employee sensing • Body sensor nets • …