Based On One-way Hash Function Fragile Digital Watermarking

With the rapid development of computer network and multimedia technology, it is more convenient to the dissemination of digital products. However this will lead to more issues of piracy and information tamper for some interests objectively. As one of the important applications of information hiding technology in computer field, digital watermarking provides a new method to protect the copyright of multimedia information. It embeds watermarks into digital multimedia, and carries out the functions such as infonnation hiding, secret storing, and copyright protection by detecting the watermarks that can track the use of digital multimedia.Digital watermarking system was introduced at first. It includes the digital watermarking model, evaluation standard, classification, attacks, applications, and so on. Then the chaos theory was introduced and analyzed. The main contents include the origin and development, definition, the essential feature of chaos.A hash function construction method based on cell neural network with hyper-chaos characteristics is proposed. The detailed analysis is performed, which presents the one-way hash function based on proposed algorithm possesses good performances of anti-attack and diffusion. Meanwhile, alterable length one-way hash function could be generated by proposed algorithm and simulation for the process shows its effectiveness and validity of our algorithm in various conditions.The fragile image watermarking algorithm based on one-way hash function is represented in this paper. The fragile image watermarking algorithm is spatial domain based. The LSB panel is set to 0 first. The remaining value of pixels in every row and column are regard as plaintexts of one-way hash function, and then get series of 128 bits hash code. Get the weight of every 128 bits hash code, and the every weight value can be present by 8 bits. The series bits can be embedded in the LSB panel. The tamper part could be decided by intersections of every changed row and column, which are determined by the comparison of weight values embedded and weight values extracted.The semi-fragile watermark algorithm based on DCT domain is represented in this paper. The edge of original image is cut, and the remaining is divided into 8*8block. Every8*8block was treated by Discrete Cosine Transform (DCT). The low coefficients and the coefficients location inner every block are chosen as plaintext to fulfill hash operation. The hash result and scrambled watermark sequence are embedded in the middle DCT coefficients by embedding algorithm. The watermark algorithm was robust to JPEG compression and maintains the ability oftampered positioning at block precision.