Webpage Link Tamper Localization Algorithm Based On Control Character Encoding

With the rapid development of Internet, more and more people use online shopping, online payment and online access to information. Once the user clicks the webpage link information been tampered with, will cause the user access to illegal webpage, even be invaded by virus, brings to the enterprises and institutions a huge losses. Therefore, how to protect the webpage link information authenticity and integrity has important research significance and broad application prospects. This paper mainly research focus on webpage watermark embedding and tampering localization. This analysis could be considered as the basis of the proposed algorithms in this thesis.To improve the contradiction between webpage information hiding capacity and concealment, this paper designs an watermark embedding algorithm with high capacity for webpage based on control character encoding and link block. Firstly, we get 99 control characters on the basis of the existing 33 control characters,64 control characters are randomly selected as a set by the user key, establish a control character encoding and 6 bit watermark information concealment corresponding relationship. Secondly, analysis control character encoding in the link to the influence of different location for webpage display, points out that behind the link all attribute information can add more control character encoding in order to improve the watermark embedding capacity. This algorithm has a high capacity of watermark embedding and good concealment.To realize webpage link information accurate positioning and protection, on the basis of the third chapter, this paper designs a fragile watermarking algorithm which could locate tampering on link. Firstly, divide a webpage into webpage-blocks according to whether the browser displays is a webpage link or not. Then, use the Hash function based on block information to generate watermark information. Finally, use the third chapter information hiding method to embed the watermarking information into webpage. The validity of a webpage-block can be detected if there exists inconsistency between extracted and reconstruction of different bits between the relationship and threshold. If a webpage-block is tampered, locate it on the browser with red background color attributes, remove all attribute information, including Uniform Resource Locator, so as to prevent damaged webpage link from spreading.The experimental results show that the algorithm not only has a good visibility, high watermark capacity, small webpage file increment, but also has a high positioning accuracy.Finally, we use GUI design a algorithm simulation system, which is used to verify the feasibility and effectiveness of the algorithm.