# A Practical Implementation of Post-Quantum Cryptography for Secure Wireless Communication +
## 1 Introduction
In the PQC standalone mode, a secure communication channel is established between the sender and receiver through a PQC key encapsulation algorithm. The exchanged public key is used for encryption, while each party uses its secret key for decryption (asymmetric-key cryptography). On the other hand, in the hybrid mode, a two-way shared secret key between the client and server is used to generate a symmetric key (symmetric-keycryptography) as the encryption and decryption keys using a key derivation function (KDF). The encryption and decryption keys are then used by the client and server to encrypt and decrypt their files. As stated in our prior work [12], the client generates a pair of PQC public and private keys, and the server generates its own keys in a similar manner. Using the PQC KEM, the public key is exchanged, establishing secure communication. Subsequently, the client encrypts its file using the encryption key, based on the protocol being used (PQC standalone or PQC-AES hybrid). Upon receiving the encrypted file, the server decrypts it using the decryption key to access the content. This process ensures end-to-end secure communication between the two parties (i.e., the client and the server). Furthermore, we devise various use-case scenarios for implementing the proposed PQC-based protocols in real-world applications. To integrate these protocols with pre-existing applications, they are designed to mitigate replay and MITM attacks, enhancing connection security. This ensures secure and seamless end-to-end communication between the two parties using the process defined by the proposed protocols. This improvement demonstrates the feasibility of these protocols for real-world secure communications over wireless networks while minimizing their impact on application use cases and network performance. The goal of our proposed protocols is to enable the practical adoption of the PQC algorithm in real-world applications, balancing its impact on use cases and network performance. Our approach could also benefit 5G and 6G development by guiding the transition to PQC, particularly as there is growing consideration for shifting 5G security to a PKI-based trust model. The proposed protocols adopt the standardized algorithms by NIST, as in [8; 9; 10], and are designed to facilitate a smooth transition of applications from classical cryptography to quantum resistance utilizing both standalone PQC and PQC-AES hybrid protocols, thereby aligning with NIST's PQC migration guidelines as stated in SP 800-208 [13]. This paper significantly extends our prior work [12], in which we proposed the first PQC-based and PQC-AES hybrid PKE protocols for wireless file transfer and conducted initial performance benchmarking. In this paper, we expand on that work by introducing a new framework that includes a sequence-number-based mechanism to defend against replay and MITM attacks, along with an expanded security evaluation against common cybersecurity threats. Moreover, we extend the protocols to support a wider range of applications, including chat-based communication, video streaming, and live streaming. We also evaluate system performance under more diverse and realistic conditions and analyze the impact of these protocols on QoS and operational efficiency. This detailed analysis, along with the additional protocol advancements, provides critical insights beyond what was reported in [12] and offers practical guidance for deploying PQC in next-generation communication systems. The rest of this paper is organized as follows. Section 2 reviews related works on PKE and PQC. Section 3 describes the proposed PQC-based protocols, while Section 4 details the use cases and the implementation of the protocol in applications. In Section 5, we discuss the security analysis of the proposed PQC standalone and PQC-AES hybrid PKE protocols. Section 6 presents a performance evaluation of the proposed method, and Section 7 concludes this paper.