UniHaCh: Unicode and Hash Function Supported with Counting and Frequency Recurrence of Arabic Characters for Quranic Text Watermarking

The increasing usage of the Internet for sharing the digital Holy Quran reinforces the requirement for its protection from security breaches. Watermarking is the most widely used tool to preserve integrity and authenticity during data transmission. Previously proposed Quranic text watermarking techniques have limitations in terms of providing high capacity, imperceptibility and security simultaneously. This paper proposed an invisible watermarking technique, i.e., UniHaCh that employs Unicode UTF-8 values of the top six most frequently occurring characters in the Quranic verses integrated with the character counting mechanism, resulting in a high-capacity watermark key. The SHA3 hash function is used to obtain a fixed 256-bit watermark key that is embedded in the text at random locations using a secret key of 256 bits. The insertion of the watermark key is made imperceptible by utilizing zero-width spaces, preserving the original appearance of the text. Experimental results proved that the proposed approach is robust against modification, insertion and deletion attacks. UniHaCh was found efficient in providing authenticity and integrity simultaneously.