Frequency-Hiding Order-Preserving Encryption

Order-preserving encryption allows encrypting data, while still enabling efficient range queries on the encrypted data. This makes its performance and functionality very suitable for data outsourcing in cloud computing scenarios, but the security of order-preserving is still debatable. We present a scheme that achieves a strictly stronger notion of security than any other scheme so far. The basic idea is to randomize the ciphertexts to hide the frequency of plaintexts. Still, the client storage size remains small, in our experiments up to 1/15 of the plaintext size. As a result, one can more securely outsource large data sets, since we can also show that our security increases with larger data sets.