Abstract: Since the demand for data storage is increasing day by day and by the industry analysis we can say that digital data is increasing gradually, but the storage of redundant data is excess which results in most of the storage used unnecessary to keep identical copies. So the technology de-duplication is introduced to efficiently utilize the cloud storage system. It is one of the important techniques used for eliminating duplicate data copies of repeating data, and has been widely used in cloud storage to reduce the amount of storage space and save bandwidth. To maintain confidentiality for the sensitive data while associating deduplication, the encryption technique has been used to encrypt the data before outsourcing to the users. To enhance data security this paper makes the first attempt to formally address the problem of authorized data deduplication for which the differential privileges of users are further deliberated in duplicate check besides the data itself. Security will be analysed in terms of four aspects that is making the data securely available, authorization of duplicate check, maintaining integrity and also to make the data confidential. The usage of hybrid cloud architecture is used which supports large cloud user by efficiently storing their data in the cloud environment by using the combination of both public cloud and private application server, So that it provides the facility to store sensitive data in private application server and less critical data on to the public cloud where huge savings can be made.

Keywords: cloud computing, de-duplication, data availability,data compression, cloud service provider, private application server, public storage server.