Abstract: To solve the problems that the existing cloud storage access control models have low efficiency of users’ privilege revocation and are unable to adapt to a large number of users,this paper proposed a new model on the basis of analysis of cipher-text policy attribute-based encryption.Virtual group revocation policy was given,all users were mapped to multiple virtual groups,and the access structure was rebuilt.The range of users’ privilege revocation was limited within a virtual group.By redistributing the users’ private key in the certain virtual group where revocation takes place,users’ privilege revocation can be achieved without any changes in the other virtual groups.Obviously,this approach greatly improves the efficiency of users’ privilege revocation.A simulation experiment was conducted in Apache Hadoop platform,and the experiment results demonstrate that this model has higher efficiency on users’ privilege revocation.

Key words: Cloud storage,Access control,Virtual group,Users’ privilege revocation