Abstract: Regarding the security problem with cloud storage, it proposed a security cloud storage scheme, based on cipertext policy attributebased encryption. A trusted third party was introduced between the terminal and the cloud server in order to solve the problems of large load, heavy burden of key distribution and management. It ensured the data security of the cloud storage system in an incomplete security environment. The results show that it can keep the data security and reduce the load on the terminal, which is in accordance with the developing trend of cloud storage service.

Key words: storage security; authorization centre; access control; cipertext policy attribute-based encryption; collusion attack