# A Practical Implementation of Post-Quantum Cryptography for Secure Wireless Communication +
## 1 Introduction  
The development of quantum computing is advancing rapidly, transforming theoretical concepts into reality and raising concerns about the security of classical cryptographic systems. Among recent breakthroughs, Equal1 has launched Bell-1: The First Quantum System Purpose-Built for the HPC Era [1], complementing advancements by companiessuch as IBM and Microsoft. Recent studies, such as [PERSON] et al. 's work on CMOS position-based charge qubits [2] and [PERSON] et al. 's development of cryogenic controllers for quantum dots [3], provide critical insights into the foundational technologies driving this revolution. It is anticipated that fully developed quantum computers will render classical cryptography insecure, potentially compromising all data encrypted using classical methods, including currently encrypted data. Therefore, addressing the imminent risks posed by traditional cryptographic algorithms has become increasingly urgent. To address this issue and provide quantum-resistant cryptographic algorithms, the National Institute of Standards and Technology (NIST) introduced PQC algorithms [4; 5; 6], which will ensure that applications and network communications are secure against quantum attacks. However, it is not clear what impact or overhead will be introduced by migrating applications to be PQC-compliant, as PQC algorithms come with large ciphertext and key sizes. It is important to evaluate the practical implementation of PQC algorithms in real-world applications. Therefore, there is a need to investigate the performance trade-offs associated with the practical use of PQC algorithms and to address the unique requirements of emerging technologies such as 5G/6G and IoT. Furthermore, it remains uncertain how to ensure and meet their stringent quality-of-service (QoS) requirements. NIST has selected four PQC algorithms [7] and released the standards for the selected PQC algorithms, which include one key encapsulation mechanism (KEM), CRYSTALS-Kyber (renamed to Module-Lattice-Based Key-Encapsulation Mechanism (ML-KEM) in the standards) [8], and three digital signature algorithms: CRYSTALS-Dilithium (Module-Lattice-Based Digital Signature Algorithm (ML-DSA)) [9]; FALCON (Fast-Fourier Transform over NTRU-Lattice-Based Digital Signature Algorithm (FN-DSA)), whose draft will be released in FIP206; and SPHINCS+ (Stateless Hash-Based Digital Signature Algorithm (SLH-DSA)) [10]. In addition, as a backup to the ML-KEM algorithm, NIST has selected HQC [11] for the next PQC KEM algorithm to be standardized among the four PQC algorithms in Round 4: BIKE, Classic McEliece, HQC, and SIKE. The draft standard for HQC is expected to be released later. Additionally, while the NIST standard [8] provides detailed specifications for implementing the ML-KEM algorithm, including key generation, key encapsulation, and decapsulation, it does not finalize specific methods for securing application data. Instead, it recommends the application of established symmetric-key cryptographic techniques, as outlined in other NIST standards, for encrypting and decrypting data to protect against unauthorized access. Therefore, to fully understand the implications of integrating PQC algorithms into various applications, particularly those in IoT, 5G, and 6G systems with stringent QoS requirements, a dedicated PQC-based protocol for securing data transmission is essential. This paper introduces new and improved PQC-based protocols that extend the PQC standalone and PQC-AES hybrid PKE protocols to secure the communication of application data transmitted between two parties and mitigate common cybersecurity attack vectors. Specifically, we introduce a sequence-number-based mechanism to the PQC-based protocols to prevent replay attacks and man-in-the-middle (MITM) attacks, providing a practical application of PQC algorithms in real-world scenarios. This offers a tangible example of how these quantum-resistant cryptographic methods can be applied to secure communication and their impact on applications.