International Journal of Emerging Technology in Computer Science and Electronics ( IJETCSE)
Cloud computing refers to both the applications delivered as services over the Internet and the hardware and systems software in the data centers that provide those services. Software stacks have improved interoperability among platforms, but the storage API's for cloud computing are still essentially proprietary. Cloud computing provides an economical and efficient solution for sharing group resource among cloud users. Sharing data in a multi-owner manner while preserving data and identity privacy from an untrusted cloud is still a challenging issue, due to the frequent change of the membership.