Based On Chaotic Encryption Digital Watermarking Algorithm Study

With the rapid development of computer, network and communication technology, especially the popularization of Internet, the problems of the security protection of information become more and more pressing. Based on the technology of computer and network, the multimedia information exchange provides a convenient way for using and spreading digital produces. Therefore, the characteristic that digital produces are easily copied and tampered, which makes digital produces security protection become an urgently resolved problem. The digital watermarking technology as a new information hiding technology, it utilizes the redundant date and random in the digital produces, embeds imperceptible but distinguishable secret messages----watermarks into the media to protect the copyright or the integrity of the working. Digital watermarking technology is widely studied and used as an effective means of knowledge copyright protection. In the paper, after describing in detail the basic concepts, the basic principle, typical algorithms, attack types, application fields and development aspects of digital watermarking, digital watermarking technology based on the chaotic theory is mainly researched. The main work has two parts as shown: (1)In this dissertation, a watermarking algorithm in the DCT domain based on the Baker's transformation is proposed. Firstly, chaotic kinetic characteristic of the baker's transformation is analyzed, using it to encrypt watermark image; Secondly, a quantization matrix related to image's gray value is corrected utilizing the visual masking in DCT domain, making the watermark adaptively embed into the least sensitive part; Chaotic array is used as location matrix, making watermark extraction without original image. Lastly experiment result for this watermarking algorithm is given. (2)In this dissertation, a DC component watermark algorithm based on Kent mapping is proposed. Firstly, chaotic kinetic characteristic of Kent mapping is analyzed, using it to encrypt watermark image; Secondly, an algorithm of only modifying the decimal part of DC components is given, bringing the least error, effectively solving the problem which embedding watermark in DC components is easy to the image's block effect; Watermark is extracted without original image utilizing two-bits algorithm. Lastly experiment result for this watermarking algorithm is given.