DWTC: A Dual Watermarking Scheme Based on Threshold Cryptography for Web Document

Text watermarking is one of the most effective methods for digital copyright protection. However, directly applying text watermarking to web documents will degrade the invisibleness and robustness of embedded watermarks. In this paper, we proposed a Dual Watermarking Scheme Based on Threshold Cryptography (DWTC) for Web Document to resolve the two problems. DWTC consists of watermark generation, embedding and detection process. Based on threshold cryptography, watermark generation process can enhance the robustness. To recover the embedded watermark only parts of watermark slices are needed. Watermarks are embedded in a given layer-based web document through vertically move the occupied layers, which guarantees watermark embedding cause no degradation on web display. Detection process can recover the lost watermark slice property by its next layer, which can further enhance the robustness of embedded watermark. Experimental results show that the DWTC effectively achieve both the invisibleness and robustness.