Strong and Secure Re-Encryption Technique to Protect Data Access by Revoked Users in Cloud

Data owner's stores encrypted data in the cloud to ensure security for his data in the cloud computing environment and issues decryption key to only authorized user to access the data from cloud. When user is revoked, data owner as to re-encrypt the data so that revoked user cannot access the data again .To perform this operation he will issue re-encryption command to cloud so that data in cloud gets re-encrypted. Once re-encryption is done there is a need for generation of new decryption keys to valid user, so that they can continue to access the data. In a cloud computing environment all such commands may not be received and executed by all of the cloud servers due to unreliable network communications. To solve this problem we are proposing time-based re-encryption scheme. In this scheme automatic re-encryption of data will takes place based on the internal clock value present at the cloud server. To perform this automatic re-encryption we will make use of encryption technique called Attribute Based Encryption (ABE). ABE provides fine -grain access control and easier user revoking system.