## 1 Introduction  
As next-generation wireless communication technologies continue to evolve, satellite communication networks are playing an increasingly important role. These networks support a range of critical wireless services, including voice communication, global positioning, and message transmission. In Low-Earth-Orbit (LEO) satellite networks, inter-satellite links (ISLs) are essential for connecting multiple satellites, facilitating data exchange and command coordination, and enabling real-time monitoring of the network. ISLs are especially vital for large-scale satellite constellations like SpaceX's Starlink, as they enhance global coverage and support diverse applications. To ensure secure and reliable communication, ISLs must be protected by strong security protocols that defend against threats such as eavesdropping and spoofing. Recently, the emerging zero-trust authentication model has attracted enormous interest and has been implemented in NextGen LEO satellite networks to secure communications from illegitimate access using Hyperelliptic Curve Cryptography (HECC) [1]. However, continuous authentication performance could increase operation costs, especially while covering a greater number of satellite users. Additionally, provably secure optimal homomorphic sign encryption was employed in [2] to achieve privacy-preserved data transmission from multiple IoT devices to LEO satellites. However, wireless communication latency has been increased. A secure authentication was performed in [3] by utilizing key agreement systems and Elliptic Curve Cryptography (ECC) for satellite communication systems. However, the operation time taken for the reliable authentication process was increased significantly. A one-class classification support vector machine (OCC-SVM) was applied in [4] to enhance the performance of physical layer authentication. However, the authentication rate was unsatisfactory. A Lightweight Authentication and Key Sharing Protocol was applied in [5] for secure satellite communication with better computational complexity, speed, and bandwidth. However, the scalability of this protocol has remained an open issue. The Encryption-based Mutual Authentication and Key Update (EMAKU) protocol was implemented in [6] to find the replay attack and man-in-the-middle attack. However, the latency during the secured satellite communication process was not minimal. An orbital zero-trust architecture (oZTA) was implemented in [7] for securing the LEO satellite networks. However, the types of anomaly detection remained an open issue. In [8], the handover authentication protocol was investigated to rapidly and strongly authenticate the user's identity during the handover process. However, communication and computational efficiency cannot be balanced effectively. Elliptic curve cryptography and a three-factor authentication procedure have been used in [9] for satellite communications. However, the data loss rate was determined using elliptic curve cryptography, which was still higher than in other studies. A robust three-factor authentication protocol was implemented in [10] for satellite communication. However, the successful authentication rate was poor while assuming a larger satellite network as input. To address the outlined challenges, the MRFCO-ZTS approach has been introduced to provide enhanced security for next-generation Low-Earth-Orbit (LEO) satellite networks. It ensures secure and reliable communication between satellites operating in dynamic and complex non-terrestrial environments. This model introduces several key improvements over conventional Zero-Trust Security (ZTS) frameworks:  
1. Continuous Authentication for ISLs: The MRFCO-ZTS model implements continuous authentication mechanisms specifically tailored for Inter-Satellite Links (ISLs) in LEO networks. This strengthens security by improving data confidentiality, authentication reliability, integrity, and privacy protection, while effectively resisting a wide range of cyber threats. 2.