Space-air-ground integrated networks (SAGINs), which have emerged as an expansion of terrestrial networks, provide flexible access, ubiquitous coverage, high-capacity backhaul, and emergency/disaster recovery for mobile users (MUs). While the massive benefits brought by SAGIN may improve the quality of service, unauthorized access to SAGIN entities is potentially dangerous. At present, conventional crypto-based authentication is facing challenges, such as the inability to provide continuous and transparent protection for MUs. In this article, we propose an AI-oriented two-phase multi-factor authentication scheme (ATMAS) by introducing intelligence to authentication. The satellite and network control center collaborate on continuous authentication, while unique spatial-temporal features, including service features and geographic features, are utilized to enhance the system security. Our further security analysis and performance evaluations show that ATMAS has proper security characteristics which can meet various security requirements. Moreover, we shed light on lightweight and efficient authentication mechanism design through a proper combination of spatial-temporal factors.

翻译：星空天地一体化网络（SAGINs）作为地面网络的扩展，为移动用户（MUs）提供灵活接入、全域覆盖、大容量回传以及应急/灾难恢复服务。尽管SAGIN带来的巨大优势可提升服务质量，但对SAGIN实体的未授权访问存在潜在风险。目前，基于传统密码的认证面临挑战，例如无法为MUs提供持续且透明的保护。本文通过引入智能化认证，提出了一种面向人工智能的两阶段多因子认证方案（ATMAS）。卫星与网络控制中心协同实现持续认证，同时利用独特时空特征（包括服务特征与地理特征）增强系统安全性。进一步的安全分析与性能评估表明，ATMAS具备恰当的安全特性，可满足多样化安全需求。此外，我们通过合理组合时空因子，阐明了轻量级高效认证机制的设计方法。