Comments on yet another log-in authentication using n-dimensional construction

Smart cards mechanisms are explored to mitigate the burden of the server systems in remote login authentication. Different methods such as geometric approaches are invented and researched. Recently, Wang proposed yet another new scheme utilizing a circle property on an n-dimensional space instead of the simple Euclidean space in past schemes. The author claimed that this new scheme would be more secure than previously proposed scheme. However, in this paper, we show that the scheme of Wang is vulnerable to replaying and off-line password guessing attacks. Countermeasures are also presented.