Data security and authentication in hybrid cloud computing model

With the progress and mature of cloud computing technology, the social demand for cloud computing is growing. Meanwhile the demand of data security is increasing sharply, especially in hybrid cloud computing model. This paper describes several methods to protect user data, which includes single encryption, multi-level virtualization, and authentication interface. Authentication intercloud is the other main theme of this paper. This paper also discussed a model of authentication intercloud which based on CA and PKI model which be extended to the scenario without CA system or it crashed.