An Image Encryption Algorithm Based On Discrete Wavelet Transform And Chaotic Sequences

With the development of the broad band,image data is more and more popular on the internet recently. But some image datas of internet request secrecy communications. For protecting them from eavesdropper, we need to encrypt important image data.In this paper, the significance ,present state and perspectives of image encryption is represented simply, and we discuss the essential theory of digital image encryption and cryptography. Based on chaotic systems with good properties such as pseudorandom,determinacy and sensitive dependence on their initial condition and system parameter, chaotic theory and digital image encryption are combined, which can design the better system of image encryption. In this paper, the character of two-dimensin logistic map is studied, present a kind of the generating method of two-dimension logistic chaotic sequences. And then the problem of adjusting and scrambling the discrete wavelet transform coefficient matrix of an image using this chaotic sequence is presented. We organize the attack experiments anti-disturb experiments, cryptography experiments after clustering compression experiments. Concluding from experiments prove that the method expanded the cryptograph space, the property of cryptograph is uniform distribution. The algorithm overcomes low dimensional chaotic prone to be defected. The encryption method has advantages in high secrecy, simple secret key and good identity between the original image and the restored image. Moreover, during the transmission ,the algorithm can go through the effects of noise. Combined with clustering compression algorithm, encrypt the compression image ,the result is better,and this has greatly reduce the transmission of image data.