A Bandwidth-Efficient Middleware for Encrypted Deduplication

Data deduplication is a vital component of current cloud storage systems for optimized space utilization. However, users cannot fairly enjoy the storage savings of deduplication. Uploading two identical files consumes twice the storage quota from a user's account, but the server may store one file copy only. In this paper, we design and implement a middleware system, namely UWare. It brings storage and bandwidth savings back to users, while preserving user data privacy. UWare starts from the message-locked encryption for efficient deduplication over encrypted data, and initiates the endeavor in leveraging the similarity characteristics of block-level deduplication to balance the effectiveness of secure deduplication and system efficiency. Also, UWare patches a practically feasible side-channel threat when deploying the proof-of-ownership protocol, i.e., hiding the existence of a target file during the protocol execution. We implement a prototype and use a real-world dataset to demonstrate that UWare can save about 30% storage and bandwidth cost for users, and reduce over 80% memory space consumption compared to the secure block-level deduplication.