Abstract: Aiming at the high requirements for security of cloud computing services, it  proposes an anonymous authentication protocol in cloud computing, and designs a model that suits identity authentication. The temporary identity of the user was constructed by using bilinear pairings. Besides, the nonce was used to replace time stamps to avoid the problem of clock synchronization. The protocol implements mutual authentication, based on the calculation difficulty of  the Discrete Logarithm Problem and the irreversibility of hash function. The protocol is efficient and has the characteristic of high security. It can be applied in distributed cloud environments, which need to protect the users privacy.

Key words: cloud computing, identity authentication, nonce, bilinear pairing, anonymity