Cryptanalysis of two dynamic ID-based remote user authentication schemes for multi-server architecture

Abstract

In NSS'10, Shao and Chin pointed out that Hsiang and Shih's dynamic ID-based remote user authentication scheme for multi-server environment has several security flaws and further proposed an improved version which is claimed to be efficient and secure. In this study, however, we will demonstrate that Shao-Chin's scheme still cannot achieve the claimed security goals, and we report its following flaws: (1) It cannot withstand offline password guessing attack under their non-tamper resistance assumption of the smart card; (2) It fails to provide user anonymity; (3) It is prone to user impersonation attack. More recently, Li et al. found that Sood et al.'s dynamic ID-based authentication protocol for multi-server architecture is still vulnerable to several kinds of attacks and presented a new scheme that attempts to overcome the identified weaknesses. Notwithstanding their ambitions, Li et al.'s scheme is still found vulnerable to various known attacks by researchers. In this study, we perform a further cryptanalysis and uncover its two other vulnerabilities: (1) It cannot achieve user anonymity, which is the essential goal of a dynamic ID-based scheme; (2) It is susceptible to offline password guessing attack. The proposed cryptanalysis discourages any use of the two schemes under investigation in practice and reveals some subtleties and challenges in designing this type of schemes. © 2012 Springer-Verlag.