International Association
for Cryptologic Research

A three-factor authentication combines biometrics information with user password and smart card to provide security-enhanced user authentication. An proposed user authentication scheme improved Das\'s scheme. But An\'s scheme is not secure against denial of service attack in login phase, forgery attack. Li et al. pointed out them and proposed three-factor remote user authentication scheme with key agreement. However, Li et al\'s scheme still has some security problem. In this paper, we present a cryptanalysis and improvement of Li et al.\'s remote user authentication scheme.