Distance-Based Data Mining Over Encrypted Data

When mining data, organizations rely on service providers to carry out the analyses. However, data owners often are only willing to transfer their data when it is encrypted. So encryption must preserve the mining results. Since many mining algorithms are distance-based, we propose the notion of distance-preserving encryption (DPE). Designing a DPE-scheme is challenging, as it depends both on the data and the distance measure in use. We propose a procedure to engineer DPE-schemes, dubbed KIT-DPE. In a case study, we instantiate KIT-DPE for SQL query logs. We design DPE-schemes for all SQL query-distance measures from the literature. For all these measures, we prove that one can use a combination of existing property-preserving encryption schemes with known security characteristics to guarantee the same mining result.