Boosting efficiency and security in proof of ownership for deduplication

Deduplication is a technique used to reduce the amount of storage needed by service providers. It is based on the intuition that several users may want (for different reasons) to store the same content. Hence, storing a single copy of these files is sufficient. Albeit simple in theory, the implementation of this concept introduces many security risks. In this paper we address the most severe one: an adversary (who possesses only a fraction of the original file, or even just partially colluding with a rightful owner) claiming to possess such a file. The paper's contributions are manifold: first, we introduce a novel Proof of Ownership (POW) scheme that has all features of the state-of-the-art solution while incurring only a fraction of the overhead experienced by the competitor; second, the security of the proposed mechanisms relies on information theoretical (combinatoric) rather than computational assumptions; we also propose viable optimization techniques that further improve the scheme's performance. Finally, the quality of our proposal is supported by extensive benchmarking.