Abstract: This paper puts forward an access control method with ciphertext-policy attribute-based encryption in cloud storage. It encrypts the data with asymmetric encryption. As the attribute of users is revoked, authority generates new version key of attribute group which is sent to the cloud to reencrypt the ciphertext so as to decrease the computing overload of data owner. Because this method doesnt need to update the private key of users, the complexity of algorithm is decreased. The theoretical analysis and experiment result show that this method performs well in the security of data as the attribute of users is revoked. In addition, the method also makes some contributions for reducing the computing overload of authority and transmission cost.

Key words: cloud storage, access control, revoke attributes, re-encryption