Privacy preserving revocation update protocol for Group Signature in cloud

Cloud computing provides the secured data sharing among the groups. In which, dynamic group data sharing in a multi-owner environment in the untrusted clouds is the vital problem. While, the group manager updates the revocation list every day, even when no user currently moving away from the group it creates the storage overhead and high data encryption. To overcome this, the proposed technique is based on Revocation Time protocol for each user in the group. Here Revocation Time protocol defines when the user revoked from the group the access of the information should be restricted. Then, this particular user´s identification will become invalid. Due to this, the revocation list cannot be updated each day. So the storage overhead can be reduced. Until the data owner provides the new identity for the novel user, the group data cannot be accessed by any member. Elliptic curve algorithm is used to maintain the integrity of information and makes the secure access to the requested user. Based on this, security is maintained to restrict the unauthorized access and data integrity is achieved.