CCML-based Color Image Encryption And Watermark

As the rapid progress of information technology and computer networking, copying, storage and communication of digitized multimedia become conveniently available through networks. There are occasions when neither of the transmission terminals is unwilling to see; that the video data package transmitted be sneaked or addressed by the unauthorized, which encrypted communication between terminals is demanded. Here comes the technology of graphics encryption. While encrypted, the original digital graphics became some information very much like random noise in channels, which is unrecognized to the unauthorized without the key, so as that the encrypted graphical data is under well protection. Meanwhile, digital watermark offers a very productive solution for urgent issues including copyright protection and content security for multimedia digital artworks.We propose a new way to encryption the image, which is called by chaos coupled-map lattices (OCML).The concept of chaos and introduction of digital watermark was stated in Chapter 1, which provided fundamentals for following graphic encryption and watermarks.In Chapter 2, the relative basic knowledge of graphic encryption technologies were reviewed, followed by the basic introduction of algorithms of graphic encryption; a systematic statement of classical graphic encryption methods was shown here, and we investigated its current development, finished a simulation and assessment based on a typical algorithm.An introduction to a OCML based algorithm applying to chromatic graphics was presented in Chapter 3; with the generation of keys and the realization of encryption/decryption algorithms being further elaborated.In Chapter 4 the previous algorithm is improved in aspects as generating keys and producing chaotic sequence, with detailed analysis on the key sensitivity, statistics of encrypted data body and sub encryption key, as well as the correlation among pixels.A new algorithm on digital watermark for graphics was provided in Chapter 5.We will introduce two types of image encryption and digital watermarking algorithm. The first category is encrypting the watermark image to ensure the security of the watermark image, the second category is encrypting image which has watermark image to ensure the transmission security. In the future, the combination of watermark and chaotic encryption will make prospects.