Abstract
Multi-Server Authentication (MSA) provides the user an efficient way to avail multiple services of various multimedia service providers, once after getting registered from a registration centre. Previously, a user had to register all servers individually to use their respective service; which proves to be a redundant and inefficient procedure in comparison with MSA. Many MSA-based techniques have been put forward by researchers, so far, however with proven pitfalls. In the last few years, the focus has been shifted towards a more flexible and efficient Chebyshev cryptographic technique. In this regard, recently Tan's scheme presented a chaotic map based multi-server authentication scheme with a focus on login scalability. Nonetheless, Tan's scheme has been found vulnerable to insider (impersonation attack) and stolen smart card attacks. Besides, the Tan's scheme fails to differentiate the login requests between the two presented cases. The current study work is based on improving the Tan's technique in terms of security in almost an equivalent cost. The security for proposed work is evaluated in the performance evaluation section, while it shows that the security is provable under formal security model, as well as using BAN Logic.