# A Practical Implementation of Post-Quantum Cryptography for Secure Wireless Communication +
## 7 Conclusions  
As part of the advancement toward the post-quantum era, this paper proposed PQC standalone and PQC-AES hybrid protocols to evaluate their practical implementation within real-world secure communication systems. Specifically, the secure exchange of keys is achieved using PQC algorithms (KEM) in either PQC standalone or hybrid protocol modes. In PQC standalone mode, the KEM (public) keys exchanged between the client and server are used for encryption, while each party uses their secret keys for decryption, following the principles of asymmetric-key cryptography. Conversely, PQC-AES hybrid mode uses two-way shared secret keys derived from PQC KEM algorithms to generate encryption and decryption keys using a key derivation function (KDF), thereby reducing the computational overhead for larger data sizes. The proposed PQC-based protocols mitigate replay, MITM attacks, and other conventional cybersecurity attack vectors. A performance evaluation of the proposed protocols was conducted through experiments using various real-world use cases (file transfer, chat-based communication, video streaming, and live streaming) in a client-server setup. For file transfer, the results confirmed that the hybrid protocols, which leverage the strengths of PQC algorithms, achieved performance relatively closer to that of AES-256 for larger payloads. For 10 KB files, the K512-F1024 hybrid mode achieved 0.8 Mbps compared to AES-256's 0.0035 Mbps, without the significant latency bottlenecks observed in PQC standalone mode, such as 19.5 Mbps for K1024-F512 and K1024-F1024. Additionally, it was confirmed that the hybrid protocol achieved better performance in terms of processing time compared to the PQC standalone protocol and AES-256. The processing times for the hybrid protocol were consistently lower across all algorithms, except for HQC192-F512 and K1024-F512, which recorded 2.6 s and 5.4 s for 1 KB files, compared to AES-256's 2.06 s. For 100 KB files, HQC-192-F1024 and HQC-256-F1024 experienced higher processing times of 2.4 s and 3.1 s compared to AES-256's 2.37 s.  
Our findings confirm that PQC standalone algorithms remain effective for lightweight applications with smaller data sizes (e.g., file transfer with smaller size data and chat-based communication), while PQC-AES hybrid protocols provide a scalable and efficient solution for larger payloads (i.e., all use cases), ensuring quantum-resistant security with manageable latency and computational complexity. Using PQC algorithms directly in most applications will adversely impact performance, while the hybrid approach is more suitable for most applications. This reaffirms the necessity of designing and migrating applications to quantum-safe cryptographic protocols tailored to specific application requirements. In the advancement toward quantum-resistant security, a critical focus should be on addressing stringent QoS requirements in emerging technologies like 5G/6G and IoT. These sectors necessitate a balance between robust security and real-time performance, requiring a hybrid approach that leverages the strengths of both PQC and traditional cryptographic algorithms. Our evaluation results provide valuable insights into the practicality and performance of standalone PQC protocols and can be extended to facilitate secure data transmission in 5G and IoT environments, ensuring a balance between quantum-resistant security and operational efficiency that upholds the stringent QoS requirements inherent in modern wireless networks. In future work, we will evaluate the complexity and overhead of the proposed protocols. We will extend the implementation of the PQC standalone PKE to include other PQC algorithms such as McEliece, Dilithium, and \(SPHINCS^{+}\), among others. In addition, we will explore methods for utilizing the PQC standalone PKE in various applications like video streaming and messaging. Furthermore, we will perform an extensive evaluation using various network environments, including 5G/6G. Conceptualization, B.O. and K.Y. ; methodology, B.O. ; software, B.O.