# A Comparative Analysis of Arabic Text Steganography
## 4 Arabic Text Steganography
### Diacritic Method  
The Arabic language uses varying marks or diacritics (Arabic redundant characters) known as harakats to represent vowel sounds. Using diacritics for security purposes is beneficial because diacritics exist naturally as a fundamental characteristic of Arabic language scripts [77, 78]. Diacritics are used to differentiate between words with the same alphabets so that each word is pronounced differently, as explained in Table 10. Fathah is used to hide the bit '1' while the rest of the diacritics embed a 0 bit. This is because Fathah accounts for almost half of the diacritics' usage in Arabic texts. This approach has the flaw of attracting the reader's attention. The early method presented by the authors of [79] exploits eight varying diacritical symbols to conceal mystery message. Fully diacritic Arabic texts are utilized as cover media. The first bit of a secret message is compared with the initial diacritic in the cover media. For instance, if the first secret bit is 1 and the initial diacritic is a Fathah, the diacritic remains on the cover media. Then, the index is incremented for both the cover media and the embedded text. If the first diacritic is not a Fathah, it is taken out of the cover media. A repetition of the approach is done until the next Fathah is realized. A secret 0 bit is used or embedded in a similar approach for the remaining seven diacritics (i.e., with the exemption of the Fathah). In the same line, the authors of [80] changed the diacritic's font style to cover the secret data. A new font style set was designed to embed \"1\" or unset to embed \"0.\" The idea involved two approaches: The textual approach and the image approach. The textual approach chooses a font that hides extra (or all) diacritic marks completely. It then uses any encoding scenario to conceal secret bits in an arbitrary number of repeated but invisible diacritics. On the other hand, the image approach selects one of the fonts that slightly darkens multiple occurrences of diacritics. This approach needs to convert the document into a picture form to facilitate printing. Two steganography algorithms for Arabic script were presented by the authors of [81]. The algorithms were designed based on the wasting/nonwasting property of the Arabic diacritics. In the first algorithm, a fixed-sized block parsing is used. A stream of binary bits is parsed into cover blocks. The second algorithm uses the variable size content-based approach. Here, binary data is parsed into an integer number of blocks irrespective of the number of bits they possess. These algorithms have different properties and are thereby suited for various application types as well as steganography requirements (i.e., robustness, file size, and capacity). In contrast to the content-based algorithm, the fixed size algorithm permits a straightforward computation of the required quantity of cover text. Still, it cannot instantly predict the output's file size. Concealing Chinese text inside Arabic text was introduced by the authors of [82]. Characters of messages are automatically converted to capital letters of the English alphabet. Letters, numbers, or special characters can be hidden using two diacritics. In this case, the Unicode used warrants that each letter or diacritic is 16 bits in length. Thus, two tables (diacritics and elements tables) are used. The diacritic table has 64 inputs and \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Authors** & **Methodology** & **Pros** & **Cons** \\ \hline \multirow{4}{*}{[75]} & A pointed character moves & Improves the robustness by & \\  & its point to conceal “1” and & changing the remaining & \\  & remains untouched to & characters randomly. & \\  & hide “0.” & Enhances the capacity by & \\  & A pointed character shifts its & & \\  & point and increases the & Converts stego file (text) to & 1 font type. \\
[76] & distance between its dots to & image file to overcome the & \\  & hide 2 secret bits in one & retyping challenge. & \\  & character. & & \\ \hline \hline \end{tabular}
\end{table}