Solving the Secure Storage Dilemma: An Efficient Scheme for Secure Deduplication with Privacy-Preserving Public Auditing

Existing cloud storage systems receive the data in its plain form and perform conventional (server-side) deduplication mechanisms. However, disclosing the data to the cloud can potentially threaten the security and privacy of users, which is of utmost importance for a real-world cloud storage. This can be solved by secure deduplication mechanisms which enables the user to encrypt the data on the client-side (or via an encryption-as-a-service module) before uploading it to the cloud storage. Conventional client-side encryption solutions unfortunately make the deduplication more challenging because of the offline dictionary attacks by which the key is derived from the data. Additionally, encryptions become computationally indistinguishable when each owner possess different encryption keys. Hence, trivial encryption solutions may either lead to high storage or bandwidth costs on both the client and the server sides. Privacy-preserving public auditing schemes, on the other hand, is also crucial because the clients outsource their data to the cloud providers and then permanently deletes the data from their local storages. In this paper, we consider the problem of secure deduplication over encrypted data stored in the cloud while supporting a privacy-preserving public auditing mechanism. We show that existing solutions cannot support both goals simultaneously due to the conflict of their security and efficiency requirements. In this respect, we present an efficient and secure deduplication scheme that supports client-side encryption and privacypreserving public auditing. We finally show that our scheme provides better security and efficiency with respect to the very recently proposed existing schemes.