Research On Fragile Semi-Fragile Digital Watermark And Application Of Them

With the popularity of network and the development of mulitimedia technology, it is easy to create, replicate, tranmit. So it is important to ensure the integrity of digital mulitimedia content. Digital watermark especially fragil and semi-fragil watermark techonolgy as a new method to protect digital media's security, intellectual property and authtification of information. It protects security of digital vetors by embedding copyright or their own characteristics into the open mulitimedia data. And it has become a very active research hotpot in information security fields. In this pater, we concern on the text-based, image-based, audio-based fragil and semi-fragile watermarking algorithm and application of them.Firstly, introducting the background, significance, present situation of fragil and semi-fragil watermarking technology. And common block diagram and application areas of digital watermark are instroducted; then explain the general principles of authentication watermark, the basic requirements and common assault behavior.Secondly, for different features of carriers, this pater take out severals watermarking techniques on the text-based fragile, especially based on hypertext, with formatted text (Word) and two values of the text image algorithms. By HTML aren't sensentive with the tags and attrbutions, combiding with Hash function, to validate integrity of web pages. As two value-text reference section thinking and chaotic system utmost with initial value, design a fragile watermarking based block. The simulation results show that: The above algorithm should be a good tamper-resistant capability, and can navigate to the text lines, or block of characters. With the image carrier, focused on airspace (SVD) and transform domain (DCT) coefficients based on the relationship between the semi-fragile digital watermarking technologies. Studied the audio waveform file integrity verification method is by quantifying wavelet-domain coefficients to embedded implementation.Finally, this paper designed the electronic seal system by combinating of these vectors Watermarking Algorithm together. In this way, both sources of identification documents can be verified and the integrity of the document can be ensured. This has a strong practical in the document transmission system; for webpage, especially the homepage of government and institutions'website, often be attacked, this paper design a website tamper-resistant system, can find malicious tampering and can restore the original information so as to preserve its public image.