Résumé
Cloud storage enables users to access their data anywhere and at any time. It achieves the dream of getting computing, storage and communication resources as easy as to get water and electricity. All resources can be gotten in a plug-and-play way. It has the advantages of high scalability, ease-of-use, cost-effectiveness and simplifying infrastructure planning etc. However, the emerging use of cloud storage has led to the problem of verifying that storage server indeed store the data. When users store their data in cloud storage, they mostly concern about whether the data is intact. In this paper we propose an efficient approach for making cloud data management and sharing in a secure manner. For this we mainly concentrate on six different security majors which are Confidentiality, Availability, Integrity, Possession, Authenticity and Utility. We implement these phenomena in java.