Preserving identity privacy is a significant challenge for the security in cloud services. Indeed, an important barrier to the adoption of cloud services is user fear of privacy loss in the cloud. One interesting issue from a privacy perspective is to hide user’s usage behavior or meta-information which includes access patterns and frequencies when accessing services. Users may not want the cloud provider to learn which resources they access and how often they use a service by making them anonymous. In this paper, we will propose an adaptive and flexible approach to protect the identity privacy through an anonymous authentication scheme.