Property preserving encryption in NoSQL wide column stores

Abstract

Property preserving encryption (PPE) can enable database systems to process queries over encrypted data. While a lot of research in this area focusses on doing so with SQL databases, NoSQL (Not only SQL) cloud databases are good candidates either. On the one hand, they usually provide enough space to store the typically larger ciphertexts and special indexes of PPE-schemes. On the other hand in contrast to approaches for SQL systems, despite PPE the query expressiveness remains almost unaffected. Thus, in this paper we investigate (i) how PPE can be used in the popular NoSQL sub-category of so-called wide column stores in order to protect sensitive data in the threat model of a persistent honest-but-curious database provider, (ii) what PPE schemes are suited for this task and (iii) what performance levels can be expected.