Cryptanalysis of lightweight authentication scheme with user untraceability

Abstract

In 2015, Yeh proposed a lightweight authentication scheme with user untraceability. Yeh claimed that their proposed scheme is secure to an off-line password guessing attack. However, this paper points out that Yeh's scheme has the following security and efficiency problems unlike their claims: (1) The scheme is still vulnerable to off-line password guessing attack with stolen smart card. (2) The scheme has computational efficiency problem when the service provider authenticates the user sending message. For this reason, Yeh's scheme is insecure for practical application.