Natural language watermarking using semantic substitution for Chinese text

Numerous schemes have been designed for watermarking multimedia contents. Many of these schemes are vulnerable to watermark erasing attacks. Naturally, such methods are ineffective on text unless the text is represented as a bitmap image, but in that case, the watermark can be erased easily by using Optical Character Recognition (OCR) to change the representation of the text from a bitmap to ASCII or EBCDIC. This study attempts to develop a method for embedding watermark in the text that is as successful as the frequency-domain methods have been for image and audio. The novel method embeds the watermark in original text, creating ciphertext, which preserves the meaning of the original text via various semantic replacements.