Security has been regarded as one of the hardest problems in the development of cloud computing.This paper proposes an Alliance-Authentication protocol among Hybrid Clouds that include multiple private clouds and/or public clouds.Mutual authentication protocol among entities in the Intra-Cloud and Inter-Cloud is proposed.Blind signature and bilinear mapping of automorphism groups are adopted to achieve the Inter-Cloud Alliance-Authentication,which overcome the complexity of certificate transmission and the problem of communication bottlenecks that happen in traditional certificate-based scheme.Blind key,instead of private key,is adopted for register,which avoids the unauthorized Key Management Center (KMC)faking the members to access the resources in traditional identity-based scheme.Compared with the traditional scheme,our scheme can also achieve anonymity,traceability and privacy protection.Extensive security and performance analysis show that the proposed schemes have an advantage in security,computation consumption and communication consumption.