الفهرس 
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Abstract
The quick growth of computer networks and advances in information technology allow large files to be transmitted over the internet
A massive amount of data is being exchanged over unused channels. However, such channels can be exposed to many security threats causing illegal information access. Steganography is the art and science of embedding secret messages in a cover message so that no one, apart from the sender and intended recipient, suspects the message’s existence. The secret message capacity of any steganography method forms a performance bottleneck. The capacity refers to the amount of data that the cover carrier can hide. Maximizing the capacity is often at the expense of security. That is, it increases the opportunity to be easily discovered.
Many carriers, including image, audio, video, or text, are used to hide the message’s existence. Text steganography is the most challenging kind of steganography due to the relative lack of redundant information in a text file compared to an image or sound. Moreover, every language’s grammatical and orthographic characteristics are different; text steganographic schemes must be specified. However, the text is preferred over other media because it occupies lesser space, communicates more information, and is faster than other methods.
Abstract
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The richness of Arabic language writing characteristics makes it a strong candidate for hiding information. In this thesis, two Arabic text steganography algorithms are proposed. The main objective of the proposed algorithms is to overcome limited embedding size and to reduce suspiciousness.
The first proposed algorithm utilizes both the Arabic extension character (Kashida) and small space characters. The algorithm improves the secret message’s length embedded in an Arabic text document without affecting its quality as much as possible. Each existing Kashida can hide one bit, and each existing space can hide three bits. The proposed algorithm was tested for different lengths of stego-text messages. It provides superiority in achieving a high capacity hiding ratio compared to the most related Kashida-based techniques and spaces-based techniques.
The second algorithm improves hidden capacity by utilizing three features Arabic language and one other feature of any different language. It utilizes the Arabic extension character (Kashida), dotted and dotless letters, sun and moon letters, and three small spaces. Furthermore, security is enhanced by employing four different embedding scenarios instead of using one in the whole text. The cover text is partitioned into many other size blocks. Each block applies a different scenario. The proposed method is tested and compared to the current techniques.