Research And Design Of Electrical Seal System Based On Digital Watermark

With the development of Internet and the application of OA (Office Automation) in the government and the business, the electronic information security becomes a hot spot and difficult point studying in e-administration. The electron document as an important electron carrier, how ensure that its authenticity, completeness have aroused broad attention.And the digital signature techniques are the foundation and guarantee of the information security and offer some services such as identity authentication service, information privacy service and undeniable service.On the basis that the technology studies to the digital signature technology and the digital watermark, a scheme—Electrical seal system based on digital watermark was brought forward. The system takes cryptology and PKI as rationale and bases on digital watermark technology to imply documents seal, documents verification and seal management.This thesis introduces digital watermark technology rationale and popular image processing technology—wavelet transform and fractal image coding. Secondly, introduces digital signature rationale, analyzes the general digital signature algorithms. Carries out an electrical seal system based on digital watermark.Design a proposal of multi-signatures with signers'intentions, which enhanced system flexibility.Finally, researches the watermark embedding and extraction scheme in wavelet domain. According to image texture, a wavelet watermarking algorithm based on human visual system is proposed. Experimental results demonstrate that the proposed method is robust against JPEG compression, image processing and attack such as filtering and noise. Fractal is robust against Geometry deformation through studies.As the inefficient of the traditional fractal image coding, a fractal image watermarking algorithm based on zerotree wavelet is proposed. Experimental results demonstrate that the method is safty.