The Research Of Image Encryption Algorithm Based On Chaotic Theory

With the development of network information technology, the multimedia information security has been paid more and more attention. Especially the image information security has become a subject of many researchers. The various limitations of the traditional encryption algorithms aren’t good for digital image encryption. People have proposed some new encryption algorithms based on the characteristics of the image. The image encryption algorithms are basically designed in a Spatial Domain or a Frequency Domain at present. Based on these excellent features, chaotic sequences and wavelet transform are used to design the image encryption algorithms. Security is greatly improved through combining the spatial domain with the frequency domain. On the basis of good qualities of chaotic sequence, it is combined with wavelet transform to encrypt the digital image in a Spatial Domain or a Frequency Domain. The efficiency of image encryption and security performance have been greatly improved by this means.Based on Arnold transform, logistic chaotic sequence, and wavelet transform, the gray image encryption algorithm has carried out in-depth research in this paper. Specific content is as follows:A gray image encryption algorithm based on logistic chaotic sequences has been designed. This algorithm is raised based on the scrambled and diffused grayscale. Firstly Arnold transformation are used to scramble the pixel position of original image, and the chaotic sequences—lpgistic map generates two groups of chaotic sequences. New pixel values will be got after xor computation, and then the diffused encryption of image pixel has been completed. Through the simulation and comparison, the result shows that this algorithm has a big key space and good effect on encryption. At last anti-interference decryption algorithm has been designed.The gray image encryption algorithm based on logistic mapping and wavelet transformation has been designed. This algorithm is basically designed in Spatial Domain and Frequency Domain. Firstly the chaotic sequences—logistic map generates two groups of chaotic sequences. The image is initially encrypted by these sequences. Then the encrypted image is decomposed by wavelet, and its wavelet approximation is extracted. At last this approximation is encrypted by logistic map. Through the simulation and comparison, the various statistical features of plaintext are greatly improved.