Secure file sharing using cryptographic techniques in cloud

Cloud computing is a type of computing that relies on sharing resources rather than having local servers or personal devices. But sharing resources among many users in the cloud is a challenging issue. The proposed scheme provides the facility of secure storing and sharing the data for dynamic groups in the cloud. By using group signature and encryption techniques any cloud users can efficiently share their data in untrusted cloud. Data Owner can store the file without revealing their identity to others in the cloud. Revocation of the user takes place without updating the private keys of the remaining users. Data Owner or Group Manager can be able to delete the file which is stored in the cloud. The scheme allows that the new registered users can directly decrypt the other group members file which is stored in the cloud using their own private key without contacting the owner of the data file. Specially, it reduces the computation overhead to encrypt the data files and the cipher text size is constant and independent of the revocation users.