The Application Of Wavelet Analysis And Chaos Theory On Image Encryption

With the development of information technology. The problems of information security get more attention. How to maintain the information security, especially the image of information security, which has become a hot topic for many researchers. The image digital watermarking, image encryption, etc, which are the effective protection measures of the information security. Because of the digital image have its own characteristics. Many researchers put forward to some image encryption schemes in order to improve the efficiency and safety of image encryption. In the schemes, the image encryption scheme based on chaotic that shows good characteristics of encryption.Current image encryption algorithm often simply on Spatial Domain or Frequency Domain. Based on chaotic sequences and the good characteristics of wavelet transform, and then introduce the chaos and wavelet transform into digital image encryption algorithm. And combination of encryption method of the Spatial Domain or Frequency Domain encrypts the image. Make the safety of encryption improve, and encryption effect will be better.On this basis, the application of wavelet analysis and chaos theory on image encryption of the study to obtain the following results:(1) The study of encryption scheme of binary image based on two-dimensional Logistic Chaotic Map. Based on the Transformation of partitioned Magic Square for original drawing, which use two-dimension Logistic chaos mapping of generated binary sequences with xor operation, and then have an Arnold after scrambling. This solution can be used for the pretreatment of digital image watermarking. The experiment result shows that it has a large key space and good effect on encryption with strong antidamages.(2) The study of image encryption scheme about two-dimensional Logistic mapping and wavelet. This scheme combine a two-dimensional Logistic mapping of coupling form, and then Mapping Generate chaotic sequences and encrypt the image in the Spatial Domain. Then make the encrypted image wavelet decomposition, and make the wavelet coefficients chaos mapping transformation. Thus scrambling encryption in wavelet domain. Conclusion from computer simulation results verifies that the encryption algorithm to improve the degradation problems of single chaotic sequence with better randomness. The statistical properties of plain-image have been great changes, and can effectively resist all kinds of attacks.(3) The study of image encryption scheme of multidimensional chaotic system that is spatial-frequency domain of combination. Firstly, by using two-dimensional Logistic mapping to produce encryption template so that adjust low-frequency coefficients of wavelet decomposition. Secondly, by using Chen system, it has a xor operation of wavelet image reconstruction. And it can further make encryption has been greatly improved. The experimental results demonstrate that the encryption algorithm not only has a large key space but also has a very sensitivity with respect to the secret key and the original image. The encryption algorithm proposed in this paper possesses perfect diffusion and confusion properties and it can resist the various attacks.