Secure deduplication for multimedia data with user revocation in cloud storage

Increment of multimedia data motivates users to utilize cloud storage (CS) to exploit its massive size. For this extensible storage system, there are two desirable requirements: (1) the users should be able to ensure that their outsourced data is securely protected and (2) the cloud service provider should be able to eliminate redundant copies of data for improvement of storage utilization. Conventional encryption scheme does not satisfy the deduplication on ciphertext as it destroys message equality. Recent study, DupLESS, has enhanced Convergent Encryption (CE) and provided strong privacy. However, CE-based scheme allows the users to possibly decrypt cloud data even if the user loses his ownership to the data. In order to solve this problem, we propose a secure deduplication scheme with user revocation. Our scheme leverages oblivious pseudo-random function to generate encryption key. The CS enforces data access policy using privilege-based encryption to provide user revocation. The security analysis proves that the proposed scheme is secure against unauthorized decryption by revoked users or the cloud server, and brute-force attack on predictable set of data.