# Development of Cybersecurity Technology and Algorithm Based on Quantum Computing
## 6 Encryption Evaluation
### Unified Average Changing Intensity  
The UACI [10] measures the average intensity of the differences between two images and is defined as  
\[UACI=\frac{1}{M\times N}\sum_{i,j}\frac{\mid C_{1}(i,j)-C_{2}(i,j)\mid}{255} \times 100\ (\%) \tag{7}\]  
where \(C_{1}(i,j)\), \(C_{2}(i,j)\), M, and N are the same as those in the NPCR described above. Figure 20: Result of the encryption/decryption using the proposed methods. We performed plain image sensitivity analysis through changing 1 px of random location for each experiment for plain images Lena, Baboon, and Pepper, and then calculating NPCR and UACI for all pixels. In addition, 10 experiments were conducted each in plain images of Lena, Baboon, and Pepper, and the results of NPCR and UACI for the plain images are shown in Tables 7 and 8. The average NPCR was higher 99% and the average UACI was higher 33%. This means that, even with a slight difference between the two plain images, the two encrypted images are completely different, and the results show that the proposed algorithm is highly sensitive to small changes in the plain image. Thus, the proposed algorithm indicates that it is robust against differential attacks. Differential attack refers to slightly changing the encrypted image (ex: modifying only 1 px) to observe the change in the result, thereby finding a meaningful relationship between the plain image and the encrypted image. However, differential attacks become useless if minor changes in plain images can cause significant changes in encrypted images. Therefore, it can be seen that the algorithm proposed in this paper has improved security compared to the existing algorithm. Table 9 shows the performance time of the original AES algorithm and the proposed AES algorithm and the time uni. Compared to the existing AES method, the part that increased time complexity is the part that generated random numbers through quantum simulators. Encrypting an image with Original AES took 0.05 min, and 0.05 to 0.07 min to encrypt an image by generating random numbers with the Linear Consequential Generator and Mersenne Twitter. However, the time spent using quantum random walk using the quantum simulator may seem to have increased significantly to about 53-55 min, but this is time-consuming because random numbers were generated in the quantum simulator. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & & \multicolumn{3}{c}{**NPCR (\%)**} \\ \hline
**Image** & **Color** & **Original** & **Method by** & **Method by** & **Method by** \\
**(256 \(\times\) 256)** & **Channel** & **AES** & **the LCG** & **the MT** & **the QRW** \\ \hline  & R & 0.0079 & 99.5883 & 99.601 & 99.6214 \\ [PERSON] & G & 0.0082 & 99.5972 & 99.588 & 99.6001 \\  & B & 0.0081 & 99.5903 & 99.6222 & 99.6053 \\ \hline  & R & 0.0081 & 99.6012 & 99.6201 & 99.6144 \\ Baboon & G & 0.0081 & 99.6097 & 99.6114 & 99.6196 \\  & B & 0.0082 & 99.6105 & 99.6063 & 99.6077 \\ \hline  & R & 0.0081 & 99.5899 & 99.5972 & 99.5929 \\ Pepper & G & 0.0079 & 99.5933 & 99.6104 & 99.5944 \\  & B & 0.0081 & 99.6016 & 99.6018 & 99.6022 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: NPCR result of the original AES and the proposed methods. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & & \multicolumn{3}{c}{**NPCR (\%)**} \\ \hline
**Image** & **Color** & **Original** & **Method by** & **Method by** & **Method by** \\
**(256 \(\times\) 256)** & **Channel** & **AES** & **the LCG** & **the MT** & **the QRW** \\ \hline  & R & 0.0029 & 33.4453 & 33.451 & 33.4648 \\ [PERSON] & G & 0.0026 & 33.4366 & 33.4935 & 33.4796 \\  & B & 0.0028 & 33.3944 & 33.456 & 33.4287 \\ \hline  & R & 0.0027 & 33.4097 & 33.4058 & 33.4803 \\ [PERSON] & G & 0.003 & 33.4201 & 33.4408 & 33.4448 \\  & B & 0.0024 & 33.4096 & 33.4115 & 33.4726 \\ \hline  & R & 0.0029 & 33.4744 & 33.4787 & 33.4774 \\ [PERSON] & G & 0.0029 & 33.4134 & 33.4216 & 33.4609 \\  & B & 0.0028 & 33.4386 & 33.4553 & 33.4736 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: UACI result of the original AES and the proposed methods.