Abstract
The development in mobile devices and wireless technologies (e.g Cellular, Wi-Fi) has facilitated a growth in mobile services. As mobile users are usually moving, roaming services are deployed to allow users to access foreign network services without being limited to the geographical coverage of their home networks. Several solutions have been proposed to allow ubiquitous mobile access authentication; however, limitations still exist in these approaches, such as performance issues and security vulnerabilities. In this paper a novel hybrid mobile authentication model is proposed, with its realisation through suitable protocols that combine the advantages of both distributed and centralised models. The proposed Passport and Visa tokens assist a foreign network in authenticating and authorising visiting mobile users. These tokens also offer a unique solution to achieving secure and efficient key management. Most importantly, the proposed solution provides an efficient technique, using recency evidence (a Passport Stamp), to tackle the problem of a user revocation status check. The security and performance analysis demonstrates that the proposed protocols efficiently ensure secure roaming, greatly enhance computation speed, and reduce communication costs.