Introducing Small Cell Networks (SCN) has significantly improved wireless link quality, spectrum efficiency and network capacity, which has been viewed as one of the key technologies in the fifth-generation (5G) mobile network. However, this technology increases the frequency of handover (HO) procedures caused by the dense deployment of cells in the network with reduced cell coverage, bringing new security and privacy issues. The current 5G-AKA and HO protocols are vulnerable to security weaknesses, such as the lack of forward secrecy and identity confusion attacks. The high HO frequency of HOs might magnify these security and privacy concerns in the 5G mobile network. This work addresses these issues by proposing a secure privacy-preserving universal HO scheme ($\UniHand$) for SCNs in 5G mobile communication. $\UniHand$ can achieve mutual authentication, strong anonymity, perfect forward secrecy, key-escrow-free and key compromise impersonation (KCI) resilience. To the best of our knowledge, this is the \textit{first} scheme to achieve secure, privacy-preserving universal HO with \textit{KCI} resilience for roaming users in 5G environment. We demonstrate that our proposed scheme is resilient against all the essential security threats by performing a comprehensive formal security analysis and conducting relevant experiments to show the cost-effectiveness of the proposed scheme.

翻译：摘要：引入小蜂窝网络（SCN）显著提升了无线链路质量、频谱效率及网络容量，该技术已被视为第五代（5G）移动网络的关键技术之一。然而，该技术因网络中小区密集部署且覆盖范围缩小，导致切换（HO）流程频率增加，从而引发新的安全与隐私问题。当前5G-AKA及HO协议存在安全缺陷，例如缺乏前向安全性和身份混淆攻击漏洞。5G移动网络中高频次的HO可能放大这些安全与隐私风险。本研究针对上述问题，提出一种面向5G移动通信SCN的安全隐私保护通用切换方案（$\UniHand$）。$\UniHand$可实现双向认证、强匿名性、完美前向安全性、无密钥托管及密钥泄露模拟（KCI）弹性。据我们所知，该方案是首个在5G环境下为漫游用户实现安全隐私保护通用HO且具备KCI弹性的方案。通过全面的形式化安全分析及成本效益相关实验，我们证明所提方案能够抵御所有关键安全威胁。