Cryptanalysis of Sun and Cao's Remote Authentication Scheme with User Anonymity

Dynamic ID-based remote user authentication schemes ensure efficient and anonymous mutual authentication between entities. In 2013, Khan et al. proposed an improved dynamic ID-based authentication scheme to overcome the security flaws of Wang et al.'s authentication scheme. Recently, Sun and Cao showed that Khan et al. does not satisfies the claim of the user's privacy and proposed an efficient authentication scheme with user anonymity. The Sun and Cao's scheme achieve improvement over Khan et al.'s scheme in both privacy and performance point of view. Unfortunately, we identify that Sun and Cao's scheme does not resist password guessing attack. Additionally, Sun and Cao's scheme does not achieve forward secrecy

Cryptanalysis and improvement of chen-hsiang-shih's remote user authentication scheme using smart cards

Recently, Chen-Hsiang-Shih proposed a new dynamic ID-based remote user authentication scheme. The authors claimed that their scheme was more secure than previous works. However, this paper demonstrates that theirscheme is still unsecured against different kinds of attacks. In order to enhance the security of the scheme proposed by Chen-Hsiang-Shih, a new scheme is proposed. The scheme achieves the following security goals: without verification table, each user chooses and changes the password freely, each user keeps the password secret, mutual authentication, the scheme establishes a session key after successful authentication, and the scheme maintains the user's anonymity. Security analysis and comparison demonstrate that the proposed scheme is more secure than Das-Saxena-Gulati's scheme, Wang et al.'s scheme and Chen-Hsiang-Shih.Peer ReviewedPostprint (published version