Abstract:In this paper, a secure protocol to protect user privacy is improved. In this protocol the users does not directly communicate with the service provider, instead, the user connects through the service discoverers to complete their needs. Through analysis of the security system in the protocol, it becomes clear that this protocol protects users’ privacy, and prevents users from being tracked at the same time. The protocol reduces the computational complexity of the original protocol, and it is more suitable for ubiquitous computing. The protocol may very well protect users’ privacy, and can also prevent replayed attack.