Abstract: With an increase in the usage of cloud storage, effective methods need to be employed to reduce hardware costs, meet the bandwidth requirements and to increase storage efficiency. This can be achieved using Data Deduplication. Data Deduplication is a method to reduce the storage need by eliminating redundant data. Thus by storing less data you would need less hardware and would be able to better utilize the existing storage space. Based on this idea, we design an encryption scheme that guarantees semantic security for unpopular data and provides weaker security and better storage and bandwidth benefits for popular data. This way, data deduplication can be effective for popular data, whilst semantically secure encryption protects unpopular content. We show that our scheme is secure under the Symmetric External Decisional Diffie-Hellman Assumption in the random oracle model.

Keywords: Cloud, Deduplication, Security, Bandwidth.