Cryptology ePrint Archive: Report 2016/172

We thoroughly study file-injection attacks--in which the server sends files to the client that the client then encrypts and stores--on the query privacy of single-keyword and conjunctive SE schemes. We show such attacks can reveal the client's queries in their entirety using very few injected files, even for SE schemes having low leakage. We also demonstrate that natural countermeasures for preventing file-injection attacks can be easily circumvented. Our attacks outperform prior work significantly in terms of their effectiveness as well as in terms of their assumptions about the attacker's prior knowledge.