# Performance Analysis of Quantum Key Distribution Technology for Power Business
## 3 Performance Characteristics of Power QKD System
### Simulation Environment Test
As shown in Figure 4, compared with 2#, 3# and 6# fiber optic trays, the use of 1*, 2* and 3* spliced fibers increased the losses by 1.243 dB, 1.566 dB and 1.897 dB, respectively. Meanwhile, when the 2# and 3# fiber optic trays are connected, the macro-bend radius of less than 4 cm will cause the line to fail to communicate properly. From Table 5, it can be concluded that the average secret key rate fluctuates greatly with little change in attenuation. It is demonstrated on the side that the instability of wind force has a greater impact on the key rate of quantum overhead lines. At the same time, the average secret key rate of occasions with less spliced optical fibers was reduced by 11.285 Kbps, 13.103 Kbps and 1.489 Kbps, respectively. Figure 5 describes the experimental results of QVPN unidirectional transmission throughput under different encryption methods. In addition to the byte size of 1280 B, the \"AES + quantum key\" obtains the best performance among three algorithms. By analyzing the test results, the QVPN has insufficient support for AES algorithm when the packet byte size is 1280 B. When the byte size is 64 B, the \"SM4 + quantum key\" achieves the same throughput performance as the IKE algorithm. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Distance (km)**} & \multirow{2}{*}{**Loss (dB)**} & \multicolumn{6}{c}{**Average Secret Key Rate (Kbps)**} \\ \cline{3-7}  & & **Calm** & **Light Air** & **Light Brezeze** & **Gentle Brezeze** & **Moderate Brezeze** \\ \hline
10 & 1.86 & 40.75 & 39.55 & 37.50 & 38.77 & 38.68 \\
20 & 3.88 & 32.64 & 31.81 & 30.48 & 29.09 & 29.66 \\
30 & 5.98 & 26.03 & 20.65 & 20.12 & 21.28 & 21.90 \\
40 & 7.65 & 5.56 & 0.80 & 0 & 0 & 0 \\
16.58 & 8.71 & 6.24 & - & - & - & - \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Quantum key rates of distance loss test and gallop loss test. Figure 4: Test of connection loss (2# + 3# and 6#). \begin{table}
\begin{tabular}{c c c} \hline \hline
**Test Case** & **Loss (dB)** & **Average Secret Key Rate (Kbps)** \\ \hline
6\# + 1* & 3.736 & 20.194 \\
6\# + 2* & 3.738 & 18.374 \\
6\# + 3* & 3.737 & 29.990 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Connection loss based on light breeze. In the case of other byte sizes, the throughput performance of the SM4 algorithm is lower than the IKE algorithm. Since the QVPN uses software technology to implement the SM4 algorithm, as an algorithm of the same order of magnitude as AES algorithm fails to achieve better performance, we should find solutions from the software and hardware collaborative architecture to improve the performance of QVPN for SM4 algorithm. QVPN provides quantum keys for SM4 algorithm and AES algorithm to encrypt and decrypt data. SM4 algorithm has a greater impact on data transmission performance than AES algorithm, and the performance degradation range is about 40%-50%. Meanwhile, the network performance tester was used to test business data traffic of different scales. The results show that when the IKE algorithm is used, the maximum throughput of QVPN unidirectional transmission is 538 Mbps. Under the condition of the SM4 algorithm, the maximum unidirectional throughput supported by the QVPN is 201 Mbps. For AES algorithm, the maximum unidirectional throughput supported by QVPN is 575 Mbps. QVPN can stably transmit without exceeding the maximum throughput of each encryption algorithm. Table 6 shows the stability test results of the secure transmission system for QKD. In the actual environment, the quantum equipment can be stable and coded for a long time, the control system runs smoothly, and it can be confirmed that the QKD system can run stably for a long time. According to the analysis of the above test results, it can be seen that gallop loss and connection loss are the key factors that affect the performance of the key layer QKD. At the business layer, the choice of encryption algorithm can affect the interactive performance of power services.