As the key problem in cloud storage, security is always drawing the users' attention. A safe and efficient cloud storage scheme is designed for users' identity and data privacy protection in cloud storage security. In the scheme, a storage structure based on time series is constructed and designs a key-deriving algorithm based on the structure. It can not only be good for the generation and management of the key but also can save the storage space. By analyzing the security of scheme, it indicates the scheme can insure the security of data and can protect the privacy of users' identity.