A Meliorated Kashida Based Approach for Arabic Text Steganography

A new method to hide secret message within Arabic texts has been proposed. This method depends primarily on the nature of letters; whether they are pointed or un-pointed letters. We have exploited this feature of Arabic text to add a kashida (-). Since there are two cases of each letter; pointed or un-pointed, a table of four cases is used to add a kashida between two letters every time to hide two bits in each kashida. The most common kashida-based methods hided just one bit in each kashida or used a kashida as well as a zero-width character to hide two bits, while the proposed method hided two bits using kashida without the need to add the zero-width character. Adding zero-width character increases the file size dramatically, which affects the security measures. By hiding two bits in each kashida, the capacity is remarkably increased as compared with some of the well-known kashida-based approaches. The dependency on the nature of both of the surrounding letters of the kashida as well as dividing the cover text into two blocks, each one is being dealt with in a different way, increases the security of the proposed method. Since, intruders are not able to expect the method of extraction. Furthermore, the original kashida case is considered. Ignoring the original kashida in the cover text affects the accuracy of extraction phase. A system of embedding the secret message within a cover text and extracting the secret message from a stego text has been built. This system has a hashing phase in order to distinguish between the authorized user and the un-authorized user, which may increase the robustness of the system. In some cases, the capacity ratio of the proposed method may affected by the sequences of the secret bits, and suitable appearances of the targeted kashida(-). This might be considered as limitation that may yield to undesirable results in such cases. As a future work, we should overcome this drawback by proposing a suitable method to make use of all kashidas irrespective to the sequences of the secret bits.