| Summary: | 碩士 === 國立交通大學 === 資訊科學系 === 91 === The advance of computer network brings convenience to people. Through the Internet, people can transmit messages to each other, search desired data, or announce public information easily. But in the public network environment, illegal users can detect and intercept secret messages, misuse Webpage images or contents, or tamper with publications on Web pages, resulting in misrepresentation of them. Therefore, effective methods for three applications, including covert communication, copyright protection, and tamper proofing, on Webpage images, Chinese text-type documents, and HTML files are proposed in this study. For covert communication, secret messages are embedded into Webpage images, text-type documents, and HTML files by data hiding techniques, respectively. With imperceptible modifications of these media, the hidden secret can be transmitted securely. For copyright protection, copyright data are embedded into HTML documents to protect the intellectual property of their contents by text steganographic techniques. Instead of embedding copyright data directly, it is proposed in this study to embed an active data stream into a Webpage image to create actively a visible copyright logo onto a protected image when the image is downloaded. For tamper proofing of Web page content, an authentication signal generation and embedding method is proposed for verifying whether or not the content has been tampered with. Good experimental results show the feasibility of the proposed methods.
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