Method and system for authenticating cloud service provider through terminal and method and system for authenticating terminal through cloud service provider

The invention discloses a method and a system for authenticating a cloud service provider through a terminal, a method and a system for authenticating a terminal through a cloud service provider, and a bidirectional cloud authenticating method and system. The method for authenticating the cloud service provider through the terminal includes that generating a predicate evaluation token STKf related to the terminal according to predicate evaluation functions; generating a data packet which comprises the predicate evaluation token STKf and a public key SKpu, wherein the data packet further comprises identity data which indicates the identity of the cloud service provider; sending the data packet to a device related to the cloud service provider; analyzing the received data packet at the device related to the cloud service provider according to predicate evaluation anonymous judgment functions, and authenticating the cloud service provider according to the analyzed result.