Webpage Fragile Watermarking Algorithm for Tamper Localization on the Browser

To timely prevent the diffusion of tampered information and make full use of authentic information, a fragile watermarking scheme is proposed to detect the validity of webpage and mark the tampered parts of it on the browser. To locate the tampered locations, a webpage is firstly divided into webpage-blocks according to the labels which include the displayed characters on the browser. For each webpage-block, the watermark data is generated based on the content of it and randomly hidden into the color attributions of other webpage-blocks according to the secret key, which will further improve the secrecy of watermark data. The validity of a webpage-block is determined by comparing the number of the inconsistent bits with the given threshold. If a webpage-block is judged as tampered, the displayed characters of the webpage-block are replaced with the given symbol to shield the tampered information, and the last-label attributions of it are changed to highlight the tampered webpage-block. These strategies not only prevent the spread of tampered information in webpage, but also make efficient use of the unmodified ones in it. Experimental results show that the file delta of watermarked webpage is smaller. The proposed method achieves good imperceptibility and the tampered webpage-blocks are reasonably and accurately localized on the browser when the threshold value is two. Whats more, time efficiency is also improved.