Security analysis of 'an improved low computation cost user authentication scheme for mobile communication'

Recently, Lee et al. proposed 'an improved low computation cost user authentication scheme for mobile communication'. We demonstrate that their scheme is vulnerable and susceptible to the attacks and can be easily cryptanalyzed. We point out that their scheme performs unilateral'authentication (only client authentication) and there is no mutual authentication between user and remote system, so their scheme suscepts from the server spoofing attack. Furthermore, an adversary can impersonate legitimate users by copying data of their stolen or lost smart card. Moreover, Lee et al.'s scheme is poorly reparable, which makes their method infeasible to implement.