The Research Of Fragile Watermarking For Tamper Detection Of Web Pages

With the development of the Internet, it is popular for people to get information through websites. However, due to the drawbacks and vulnerability of systems, many websites are usually attacked and web pages are often tampered maliciously. Therefore, the integrity protection of web pages has become an exigent problem. More and more people pay attention to fragile watermarking of web pages because it is an effective method to solving the integrity of web pages. Researching effective fragile watermarking methods of web pages have important significance.Digital multimedia contains a large amount of redundant information which is used to embed watermark information. For example, in the digital image watermarking, in order to ensure the watermarked image without distortion, some pixel values or band coefficients of image are changed. However, the source file of a web page is a plain text which has no much redundant information. At present, embedding watermarks into web pages can only rely on Hyper Text Markup Language(HTML)itself.This article focuses on utilizing limited redundant vacuum of HTML file to implement fragile watermarking scheme for tamper detection of web pages.The innovative works of this article are as follows:(1)An improved fragile web page watermarking scheme based on word watermark and line watermark is proposed. One characteristic of HTML is that it is insensitive to space character. Our scheme makes full use of it to generate digital watermark information which consists of Space-Tab keys. Then they are embedded into the source code of HTML. In contrast with the existing schemes, this scheme has abilities to locate the locations of modifications and identify the types of modifications besides having sensitivity for tamper.(2)A fragile watermarking scheme based on Singular Value Decomposition (SVD) for web pages is proposed. A web page is transformed into a frequency matrix. Then we take SVD transformation on the matrix. The digital watermark information can be obtained by using singular values and Secure Hash Algorithm 1(SHA-1). Another characteristic of HTML is that it is insensitive to the case of letters. We can also use it to design watermark embedding and detecting scheme. This scheme has better abilities to detect and locate the modifications, at the same time, it can also identify the types of modifications and has a little increment of web page size.