Updatable Block-Level Deduplication with Dynamic Ownership Management on Encrypted Data

Deduplication is becoming increasingly important in that it can effectively reduce the storage space in the cloud server. Unfortunately the static file- level deduplication only supports limited data updatability and low deduplication ratio. In this paper, we show that by using updatable block-level deduplication (UBLDe) on encrypted data, all these issues can be addressed. In addition, this approach can also protect the user data privacy. However, updatable block-level dedeplication also faces several challenges. First, block-level deduplication should be achieved across different encrypted files. Second, an updatable authenticated data structure has to be designed for proof of file ownership. Finally, file ownership revocation has to be dealt with for forward secrecy. While the first challenge can be addressed by message-locked encryption, the last two challenges have not been solved yet. To address these two issues, we present a new UBLDe protocol on encrypted data with dynamic ownership management. Specifically, we design a new authenticated data structure for Proof of Ownership, named DBSL, to support update operations with low computation cost. We also propose a dynamic file ownership management scheme based on a novel lightweight MIX algorithm to protect forward secrecy. The security analysis and experimental results show that the proposed UBLDe protocol is secure and efficient.