Abstract: Data de-duplication is used in cloud storage to save bandwidth and reduce the storage space by keeping only one copy of same data. But it raises problems involving data ownership and security when multiple users upload the same data to cloud storage. Since encryption preserves privacy, yet its randomization property hampers de-duplication. Hence, there is a need of secure data deduplication scheme to prevent unauthorized access and data leakage. In recent times, a number of de-duplication schemes have been proposed to solve this problem. However, many systems suffer from security flaws because they do not reflect the dynamic changes in the ownership of outsourced data. In this paper, we review several deduplication techniques over encrypted data to achieve secure and efficient cloud storage service. Furthermore, proposed scheme uses RCE and group key management mechanism to ensure that only authorized access to the shared data is possible, which is considered to be the most important challenge for secure and efficient cloud storage service in the environment where ownership changes dynamically.
Keywords: De-duplication, cloud storage, encryption, proof-of-ownership.