An enhanced Kashida-based watermarking approach for Arabic text-documents

Rapid advancements in communication technologies have enabled the digital community to benefit from the advantages of fast and simple digital information exchange over the internet. Such benefits, however, come in-hand with the problems and threats associated with ensuring digital copyright protection preventing digital counterfeiting, proof-of-authentication, tamper-detection, and content-originality verification for multimedia digital content. These issues have been largely addressed in the literature for the case of image, audio, and video, with notably less emphasis on addressing the challenge of text media. With text being the predominant communication medium on the internet, it is clear that more attention is required to secure and protect text document. In this work, invisible watermarking technique based on Kashida-marks is proposed. The watermarking key is predefined whereby a Kashida (redundant Arabic character extension) is placed for a bit 1 and omitted for a bit O. By going through the document, Kashidas are inserted before a specific list of characters (***) until the end of the key is reached. If the end of the document is not reached then we repeat the key-embedding for the remainder of the document in a round robin fashion until the end. In comparison to other Kashida methods in the literature, our proposed technique proved to achieve our goal of document protection and authenticity with enhanced robustness and improved perceptual similarity with the original cover-text.