# A Practical Implementation of Post-Quantum Cryptography for Secure Wireless Communication +
## 6 Evaluation
### Results and Discussion
#### 6.2.3 Impact of PQC Algorithms on Performance in the File Transfer Use Case  
To demonstrate the impact of PQC algorithms on various applications, we evaluated the proposed protocols using a file transfer application. We measured the overall processing time, throughput, and RTT as metrics. Since PQC algorithms can be more computationally intensive than traditional algorithms, the requirements to secure the data may adversely affect the performance of the applications and the network's data-handling capabilities. Therefore, file transfer was selected as the use case to test the application of the proposed protocols. In our evaluation, we paired F512 and F1024 with each PQC KEM algorithm (the KEM algorithm paired with the F512 and F1024 signature algorithms is denoted as BIKE-L1-F512, BIKE-L3-F512, BIKE-L5-F512, BIKE-L1-F1024, BIKE-L3-F1024, BIKE-L5-F1024, HQC-128-F512, HQC-192-F512, HQC-256-F512, HQC-128-F1024, HQC-192-F1024, HQC-256-F1024, K512-F512, K768-F512, K1024-F512, K512-F1024, K768-F1024, and K1024-F1024) to perform the key exchange process for each algorithm in our proposed protocols. We measured the processing time, throughput, and RTT efficiency of the proposed protocols using various paired KEM and signature PQC algorithms during data transfer across a wireless LAN environment and compared the metrics achieved by different PQC algorithms for data sizes of 1 KB, 10 KB, and 100 KB. The results of the data transfer between the client system and the server, including a key agreement (i.e., the PQC public keys of both parties are exchanged securely) and the actual file transfer, are shown in Figures 6-8. Figure 5: Average decryption times: (**a**) BIKE, (**b**) HQC, (**c**) CRYSTALS-Kyber. Figure 6: File transfer total processing times: (**a**) PQC–AES-256 for 1 KB. (**b**) PQC standalone for 1 KB. (**c**) PQC–AES-256 for 10 KB. (**d**) PQC standalone for 10 KB. (**e**) PQC–AES-256 for 100 KB. (**f**) PQC standalone for 100 KB. The overall processing times on the server system, segmented into 1 KB, 10 KB, and 100 KB file sizes, highlight the performance disparities between PQC-AES hybrid implementations, PQC standalone methods, and conventional AES-256. For 1 KB files, as shown in Figure 6a, the hybrid BIKE-L1-F512 protocol recorded an average processing time of 1.56 s, marginally faster than its PQC standalone counterpart (1.64 s), while AES-256 achieved 2.06 s, demonstrating comparable efficiency to hybrid approaches. Conversely, according to the results in Figure 6b, HQC-256-F512 in PQC standalone mode required 2.79 s, exceeding AES-256 by 35%, whereas its hybrid variant reduced this to 1.56 s. For CRYSTALS-Kyber, K512-F512 exhibited inverse behavior, with hybrid processing at 1.73 s outperformed by its PQC standalone counterpart (1.48 s), suggesting algorithm-specific optimization variances. Figure 6c shows the processing times for 10 KB files. Hybrid methods generally retained advantages: BIKE-L5-F512 hybrid processing required 1.48 s, significantly lower than the time of its PQC standalone counterpart of 6.08 s, while AES-256 required 1.82 s. HQC-256-F512's PQC standalone time, as shown in Figure 6d, surged to 16.78 s, 9.2 times slower than that of AES-256, whereas its hybrid implementation reduced this to 2.11 s. In comparison, K1024-F512 hybrid processing (2.73 s) was slightly higher than the PQC standalone variant (1.55 s), although both remained within 1.5-2.7 s, aligning closer with the efficiency of AES-256. Similarly, the 100 KB file processing times showed the scalability challenges of PQC standalone methods. As shown in Figure 6f, BIKE-L5-F512 PQC standalone processing reached 32.02 s, 13.5 times slower than AES-256's 2.37 s, while its hybrid variant, as shown in Figure 6e, achieved 1.62 s, outperforming AES-256 by 34%. HQC-256-F512's PQC standalone time escalated to 119.18 s, 50.3 times higher than AES-256, whereas hybrid modes like HQC-128-F512 (1.77 s) and K768-F512 (2.20 s) demonstrated competitive or superior performance relative to AES-256.