Poster: inference attacks against searchable encryption protocols

The advent of cloud computing has ushered in an era of mass data storage in remote servers. Remote data storage offers reduced data management overhead for data owners in a cost effective manner. Sensitive documents, however, need to be stored in encrypted format due to security concerns. But, encrypted storage makes it difficult to search on the stored documents. Therefore, this poses a major barrier towards selective retrieval of encrypted documents from the remote servers. Various protocols have been proposed for keyword search over encrypted data (commonly referred to as searchable encryption) to address this issue. Oblivious RAM type protocols offer secure search over encrypted data, but are too expensive to be used in practical applications. Unfortunately, all of the symmetric key based encryption protocols leak data access patterns due to efficiency reasons. In this poster, we are the first to analyze the effects of access pattern disclosure. To that end, we introduce a novel attack model that exploits access pattern leakage to disclose significant amount of sensitive information using a modicum of prior knowledge. We also present a preliminary set of empirical results on a real dataset to justify our claim.