Chaotic Digital Watermarking And Application Research

The digital media has become a main way for information communication along with the wide use of network. At the same time, multimedia information security problems emerged as side effects of the popularity of digital representation and distribution over network. So the protection and enforcement of intellectual property for digital media has become an important issue. Watermarking which is one of the important fields of information hiding and the effective means to protect copyrights piracy is receiving increasing attention.Research works focus on the excellent properties of chaotic sequence and its use in watermarking, which include: (1) Analysis of the properties of chaotic sequence;(2) Watermarking methods based on single chaotic system and multi-chaotic systems;(3) An authentic watermarking method to resist copyright deadlock. The main research fruits are as follows:1 Summarize and analyze the status of the use of chaotic theory in watermarking at present and give some examples of the use of watermarking, then point out some problems of exiting chaotic watermarking.2 A chaotic watermarking method based on private keys is proposed to resist finite word length effect and improve its security. Both Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT) are used in the process of embedding watermark according to Human Visual System (HVS). Performances after many attacks are analyzed, and the feasibility of this method is proved though theory and simulation. Furthermore, it is not only simple but also secure to use the initial value of the chaotic sequence as a key to embed and detect watermark. Besides, the proposed method can improve some non-blind watermarking to blind watermarking.3 Based on the analysis of some shortages of existing watermarking method, an authentic watermarking method is proposed to resolve copyright deadlock problem (unreliability) and improve its security and robustness. The watermark is encrypted by a key which is very sensitive to the change of original image. Simulation results show its feasibility.