Security Improvement of Two Dynamic ID-based Authentication Schemes by Sood-Sarje-Singh

Abstract

In 2010, Sood-Sarje-Singh proposed two dynamic ID-based remote user authentication schemes. The first schemeis a security improvement of Liao et al.’s scheme and the second scheme is a security improvement of Wang etal.’s scheme. In both cases, the authors claimed that their schemes can resist many attacks. However, we find thatboth schemes have security flaws. In addition, their schemes require a verification table and time-synchronization,making the schemes unfeasible and unsecured for electronic services. In order to remedy the security flaws ofSood et al.’s schemes, we propose a robust scheme which resists the well-known attacks and achieves all thedesirable security goals.