# A Dynamic Multi-Layer Steganography Approach Based on Arabic Letters' Diacritics and Image Layers
## 3 The Proposed Approach
### Experimental and Investigations on the Proposed Method Based on the Steganography Metrics
#### 4.3.3 Security and Imperceptibility Features  
Regarding the first text, in the Hamza scenario, only 6 Hamzas were altered by adding a diacritic, whereas 14 characters were modified in the scenario, equivalent to the length of the secret message. As a result, the secret was easily detected by experts in the case of diacritics, whereas only part of the message was discovered in the Hamza scenario, specifically the number of changes, which was four. However, it is possible to reveal the complete message in both cases with certain software tests. In terms of the imperceptibility criterion, both scenarios are weak, and thus, we recommend employing the third and fourth layers of protection, which involve encrypting the small piece of text and encapsulating it within an image to enhance the level of security and imperceptibility (Figure 17). The second text in the diacritic scenario already contains random diacritics. However, after being hidden in specific locations according to the predefined MAP, 5 out of the 10 diacritics (the length of the secret message) were modified. This number represents only a portion of the message that experts were able to discover, rather than the entire message. Some experts believed that all movements comprised the message, resulting in the discovery of 21 diacritics, which is longer than the message itself. In both scenarios, experts were unable to decrypt the message due to incomplete message bits. Nevertheless, the encrypted secret message can be accessed by using a brute-force algorithm. Similarly, in the Hamza scenario, only modified Hamzas were detected, totaling five. As the number of Hamzas is less than the number of diacritics in the text, using the brute-force algorithm would be less costly for attackers. Regarding the imperceptibility criterion, it is inadequate in both scenarios. Therefore, we recommend using the third and fourth layer of protection by encrypting and encapsulating the entire small piece of text within an image. This approach increases the level of security and imperceptibility simultaneously. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{\#} & \multirow{2}{*}{**Description**} & \multirow{2}{*}{\begin{tabular}{c} **Size** \\ **(Characters)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Number of** \\ **Hamzas** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Secret msg** \\ **Diacritics** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Scenario 1** \\ **Size (Bits)** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Scenario 2** \\ **No. Changes** \\ \end{tabular} } \\ \hline
**T1** &
\begin{tabular}{c} Small Text \\ without Diacritics \\ Small Text with \\ some Random \\ Diacritics \\ \end{tabular} & 120 & 20 & 0 & 10 & 4 & 10 \\
**T2** &
\begin{tabular}{c} Small Text with \\ some Random \\ Diacritics \\ \end{tabular} & 719 & 17 & 21 & 10 & 5 & 11 \\
**T3** &
\begin{tabular}{c} Medium Size text \\ relatively long \\ \end{tabular} & 2500 & 59 & 1200 & 50 & 19 & 30 \\
**T4** &
\begin{tabular}{c} relatively long \\ \end{tabular} & 15,000 & 310 & 7000 & 200 & 56 & 123 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Description of tests used in the experiments. The third text was fully constructed, and subsequently, a longer message was concealed within it. The changes made involved altering 30 diacritics within the diacritic scenario and 19 in the Hamza scenario. Despite the secret being 50 characters long, the number of changes made was lower. The experts required greater focus and time to identify the specific locations of the changes and had to review the text multiple times. This process was particularly challenging due to the problematic nature of the entire text, making it difficult to precisely identify the necessary changes. The average time spent by the experts reviewing the text further corroborates this observation (Figure 17--Main).