Blind and bidirectional ownership verification for deduplicated cloud computing systems

Cloud storage systems provide several benefits, such as scalable storage capacity, cost efficiency with pay-as-you-go pricing models, easy access from any location with an internet connection, and robust data backup options. These advantages drive the growing popularity of cloud storage, resulting in a rapid increase in the volume of data stored on the cloud. Deduplication is an effective data management technique used in these systems to reduce storage costs and enhance efficiency through the elimination of redundant data. However, in a deduplication system, a hash digest, i.e., a small piece of information, is used as ownership proof of the entire file. Therefore, a malicious user can gain access to a sensitive file already stored on the cloud by obtaining and presenting the hash digest of that file. On the other hand, data stored in the cloud may be susceptible to loss or damage due to various accidental or intentional reasons. Hence, there is a need for an ownership verification protocol where both the user and server can verify each other’s file ownership without revealing details about the file. Some existing state-of-the-art schemes consider the server as a trusted entity and focus solely on verifying the ownership of the user, while others emphasize bidirectional ownership verification but do not incorporate obliviousness in their solutions. In this paper, we propose a novel bidirectional and oblivious ownership verification scheme for deduplication systems. We cryptographically prove that adversaries lacking complete ownership of the file, cannot successfully pass ownership verification with non-negligible probability. Additionally, we show that adversaries cannot gain any knowledge about the file through the ownership verification process. We implement our scheme in two real cloud scenarios and analyze performance compared to the recent state-of-the-art schemes. The experimental results demonstrate that our approach incurs moderate computational, communication, storage, and energy overheads while achieving ownership authentication and maintaining obliviousness in deduplicated cloud storage systems.