# A Novel Image Encryption Algorithm Based on Voice Key and Chaotic Map
## 2 Principles of the Proposed Method
### Proposed Image Encryption and Decryption Algorithm
#### 2.2.1 Encryption Process
80 groups of face images and voice data, all of which passed the encryption and decryption tests. Figure 6 shows the effects of image recognition, encryption and decryption. Table 1 shows the accuracy rate of the method proposed in this paper compared with other schemes reported in the literature. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Scheme** & **Year** & **Accuracy Rate (\%)** \\ \hline Ref. [2] & Iris Recognition & 2001 & 98.4 \\ Ref. [3] & Retina Identification & 2011 & 99.75 \\ Ref. [4] & Face Authentication & 2019 & 96 \\ Ref. [6] & Signature Recognition & 2020 & 97.5 \\ Ref. [7] & Finger vein Recognition & 2020 & 99.56 \\ Ref. [17] & Face Verification + ID Image Recognition & 2019 & 97.5 \\ Ref. [18] & Facial Authentication + Speaker & 2021 & 82.71 \\ Proposed (Tolerance 100 Hz) & Facial Authentication + Voice Recognition & 2022 & 100 \\ Proposed (Tolerance 30 Hz) & Facial Authentication + Voice Recognition & 2022 & 91.3 \\ Proposed (Tolerance 10 Hz) & Facial Authentication + Voice Recognition & 2022 & 61.3 \\ Proposed (Tolerance 10 Hz) & Facial Authentication + Voice Recognition & 2022 & 23.8 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Comparison of recognition results. Figure 6: Image recognition, encryption and decryption. (**a**,**e**,**i**) Target image; (**b**,**f**,**j**) Face recognition image; (**c**,**g**,**k**) Logistic chaotic encryption; (**d**,**h**,**l**) Decrypted image. ### Security Analysis

The identity recognition method used in this article utilizes encryption and decryption methods and compares and authenticates both voice and image. No identity authentication scheme similar to the one proposed in this article is found in the various existing references. Other identity authentication schemes only collect a single biometric feature of the user for identity authentication, such as fingerprint authentication, face recognition, etc. Therefore, this article only analyzes the key sensitivity, the correlation between adjacent pixels, the resistance to differential attack and the size of the key space from the perspective of encryption. #### 4.2.1 Key Sensitivity Analysis

The applied system is a completely closed system and the key image is not visible from the outside. Therefore, the key sensitivity is the most important item for verifying the scheme [23; 24; 25]. Lena image and various voice data samples are used in the scheme verification. When comparing images, the normalized cross-correlation parameter \(C_{ncc}\) shown in Equation (7) is used in addition to the visual observation to measure the changes in the image. \[C_{ncc}=\frac{\sum_{x_{c}=0}^{N-1}\sum_{y_{c}=0}^{N-1}\delta_{c}(x_{c},y_{c})f_ {c}(x_{c},y_{c})}{\sum_{x_{c}=0}^{N-1}\sum_{y_{c}=0}^{N-1}\ell^{2}(x_{c},y_{c})} \tag{7}\]

In Equation (7), \(f_{c}\) and \(g_{c}\) are the two images to be compared, and \(x_{c}\) and \(y_{c}\) are the index values of the image matrix. The experimental data shown in Tables 2-7 were obtained after various experimental comparisons. In the tables, \(F_{p}\) is the peak frequency of the speech spectrum; \(n_{w}1\) to \(n_{w}6\) are the number of single-waveform peaks of six single syllables; and \(C_{nccr}\), \(C_{nccg}\) and \(C_{nccr}\) are the normalized cross-correlation parameters of the red, green and blue channels of the image. Table 2 shows the experimental results of the normalized cross-correlation calculated by adding one to the number of single-syllable waveforms of the voice key without changing the peak frequency. Table 3 shows the experimental results of the normalized

\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{\(F_{p}\) (Hz)} & \multirow{2}{*}{\(n_{w}1\)-\(n_{w}6\)} & \multicolumn{3}{c}{**Horizontal**} & \multicolumn{3}{c}{**Vertical**} & \multicolumn{3}{c}{**Diagonal**} \\ \cline{2-9}  & **R** & **G** & **B** & **R** & **G** & **B** & **R** & **G** & **B** \\ \hline
55 & \( \begin{array}{c}5,4,2,3,\\ 2,4\\ \end{array}