Privacy Preserving Statistics in the Smart Grid

Smart meters are widely deployed to provide fine-grained information pertaining to tenant power consumption. These data are analyzed by suppliers for more accurate statistics, energy consumption predictions and personalized billing. Indirectly this aggregation of data can reveal personal information of tenants such as number of persons in a house, vacation periods and appliance preferences. To date, work in the area has focused mainly on privacy preserving aggregate statistical functions such as the computation of sum. In this paper we propose a novel solution for privacy preserving individual data collection per smart meter. We consider the operation of identifying the maximum consumption of a smart meter as an interesting property for energy suppliers, as it can be employed for energy forecasting to allocate electricity in advance. In our solution we employ an order preserving encryption scheme in which the order of numerical data is preserved in the cipher text space. We enhance the accuracy of maximum consumption by utilizing a delta encoding scheme.