In recent years, the development of mobile networks is thriving or flourishing from 2G GSM, 2.5G GPRS, 3G UMTS to All-IP 4G, which integrates all heterogeneous networks and becomes mature and popular nowadays. Using mobile devices for voice transferring and multimedia sharing is also a part of our life. Mobile networks provide us an efficient way to exchange messages easily. However, these messages often contain critical personal data or private information. Transferring these messages freely in mobile network is dangerous since they can be eavesdropped easily by malicious mobile users for some illegal purposes, such as committing a crime. Hence, to avoid the exposure of the transmitted messages, robust security mechanisms are required. In this thesis, we will propose a one-round mutual authentication protocol which is computation and communication efficient and secure such that the privacy of mobile users¡¦ identities and the confidentiality of their transmitted data are guaranteed. In computation complexity, the protocol only employs symmetric encryption and hash-mac functions. Due to the possession of forward secrecy, the past encrypted messages are secure, even under the exposure of long-term keys. Furthermore, our scheme achieves the goal of user privacy and location privacy by changing TMSI in every session. Therefore, the third party cannot link two different sessions by eavesdropping the communication. Finally, our scheme also can prevent false base attacks which make use of a powerful base station to redirect mobile users¡¦ messages to a fake base station to obtain certain advantages.