Wireless applications have become pervasive in numerous fields, and relays play an essential role in extending wireless network coverage. They also, however, can introduce significant security risks, particularly regarding data integrity. Adversaries can potentially compromise relays, leading to unauthorized data modifications or injections that disrupt system operations. Current cryptographic methods, which rely on computational hardness, are at risk of being compromised by adversaries equipped with high-performance computing resources such as quantum computers. As these technologies advance, the threat to traditional cryptographic methods becomes increasingly pressing. This project aims to develop a secure method for verifying message integrity in wireless relay networks, addressing the urgent need for enhanced data security against emerging quantum threats. The project team will disseminate findings through conference presentations and journal publications, develop course modules, and implement outreach programs to attract students from diverse backgrounds to wireless security research.<br/><br/>The project will develop a novel approach to message authentication using non-orthogonal multiple access techniques. This method involves transmitting the message through a relay while sending the authentication tag directly to the destination, enabling detection of message modifications even if adversaries gain access to the key. This approach leverages the inherent properties of wireless channels to enhance security, providing a layer of protection beyond traditional cryptographic methods. Additionally, the project will develop a physical-layer authentication mechanism to verify message integrity when wireless channel impairments prevent tag decoding. The research will explore synergies between cryptographic and physical-layer authentication, leveraging the strengths of both approaches to create a comprehensive security solution. Furthermore, the project will investigate leveraging multiple network nodes to enhance authentication precision. The project also aims to extend physical-layer authentication to federated learning frameworks, addressing the unique security challenges in this emerging field of distributed machine learning.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.