In order to provide secure remote access control, a robust and efficient authentication protocol should realize mutual authentication and session key agreement between clients and the remote server over public channels. Recently, Chun-Ta Li proposed a password authentication and user anonymity protocol by using smart cards, and they claimed that their protocol has satisfied all criteria required by remote authentication. However, we have found that his protocol cannot provide mutual authentication between clients and the remote server. To realize ‘real’ mutual authentication, we propose a two-factor remote authentication protocol based on elliptic curve cryptography in this paper, which not only satisfies the criteria but also bears low computational cost. Detailed analysis shows our proposed protocol is secure and more suitable for practical application
