The advent of Internet of Things have paved the way for providing smart services for mobile users in the smart city. Due to the rapid movement of users and their fast information exchange, the global mobility network (GLOMONET) is a proper candidate to be used as the communication platform to provide roaming services. However, privacy and security preservation of mobile users becomes an important issue due to the open and public nature of communication channels. To address this issue, many roaming authentication schemes have been recently proposed. In this article, we first review the work presented by Ghahramani et al., and demonstrate its weaknesses. We then propose a provably secure and efficient authentication and key agreement scheme for roaming users in GLOMONETs in the smart city. To evaluate the performance of the proposed scheme, we first perform a comprehensive descriptive discussion on security preservation and utilise the widely accepted Scyther tool. We then consider the computational complexity and communication overhead of the proposed scheme, and compare it with the recent related work. The results demonstrate the outperformance of the proposed scheme in terms of very low computation and communication overhead as well as resistance against well-known ecurity attacks.

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