A novel authentication protocol for multi-server architecture without smart cards

For most of the resources provided by remote sites, users are charged a fee in order to access data and must pass an authentication procedure to receive authorization. Because most conventional password authentication schemes are designed for single-server environments, they no longer suffice for users' needs. In 2003, Lin et al. proposed a secure password authentication scheme for multi-server environments; Juang presented an improved version to increase the authentication efficiency with smart cards, but it is confined to place with card readers. This article proposes an efficient and secure password authentication protocol without smart cards for multi-server environments that can be applied in the real world.