Spectral Differential Privacy: Application to Smart Meter Data

We present spectral differential privacy (SpDP), a novel form of differential privacy (DP) designed to protect the frequency content of time-series data that come from wide sense stationary (WSS) stochastic processes. This notion is motivated by privacy needs in applications with time-series data over unbounded time, such as smart meters. First, a notion of DP on the space of (discretized) spectral densities is introduced. A Gaussian-like mechanism for SpDP is then presented that provides DP to the spectral density. Next, a novel streaming implementation is developed to enable real-time use of the proposed mechanism. The privacy guarantee provided by SpDP is independent of the time duration over which data are collected or shared. In contrast, time-domain trajectory-level DP (TrDP) will require noise with large variance to provide privacy over an extended time duration. The technique is numerically evaluated using smart meter data from a single home to compare the utility of SpDP to that of time-domain TrDP. The noise added by SpDP is substantially smaller than that added by time-domain TrDP, particularly when privacy over long time horizons is sought by TrDP.

Automated summary

Spectral differential privacy (SpDP) is a form of differential privacy designed to protect the frequency content of time-series data from wide sense stationary stochastic processes. It provides privacy guarantees that are independent of the time duration over which data are collected or shared, and offers higher utility compared to time-domain trajectory-level DP through smaller noise added.