An Encrypted In-Memory Column-Store: The Onion Selection Problem

Abstract

Processing encrypted queries in the cloud has been extended by CryptDB's approach of adjustable onion encryption. This adjustment of the encryption entails a translation of an SQL query to an equivalent query on encrypted data. We investigate in more detail this translation and in particular the problem of selecting the right onion layer. Our algorithm extends CryptDB's approach by three new functions: configurable onions, local execution and searchable encryption. We have evaluated our new algorithm in a prototypical implementation in an in-memory column store database system.

Frequency-Hiding Order-Preserving Encryption

“…In this case, it can be solved by executing the sub-select first, applying the maxC operator on the client and then executing the query. An automated rewriting algorithm for such queries is presented in [22]. For a few, rare queries this download to the client can imply a significant overhead.…”