Abstract: cloud computing is an economical and effective solution for sharing group resource among cloud users. Unfortunately, sharing data in a multi-owner manner while protect data and identity privacy from an un trusted cloud is still a challenging issue, due to the recurrent change of the membership. The major aims of this method a secure multi-owner data sharing scheme. That is any user in the group can securely share data with others by un trusted cloud. Moreover, the real identities of data owners can be exposed by the group manager when disputes occur. User revocation can be achieved by a novel revocation list and no need to update the secret Keys of the remaining users. The drawback of IBE is computation over head. To overcome the drawback introduces outsourcing computation.

Keywords: Cloud Computing; Revocation; Multi owner data sharing; Identity based encryption.