The Research Of Digital Image Encryption Based On Composite Nonlinear Discrete Chaotic Dynamical Systems And Wavelet Transformation

Encryption with stream cipher is the main arithmetic in digital image encryption based on chaos. Currently, almost all the algorithms are from plaintext to ciphertext relevant to generated stream cipher that controlled by the key. Though some algorithms study newer and more complicated chaotic functions, they are only mapping between spaces and some have self-designed bug that you can not use them expediently. Stream cipher algorithms based on composite nonlinear discrete chaotic dynamical systems keep all the chaotic characteristic of single iterations that it keeps composite nonlinear discrete chaotic dynamical systems more complicated than any other single chaotic system. But it also can not keep safety of information in strategy when the only defence is broken, especially can not give the owner highly control with self-determination, let alone additional security guarantee. And when selecting sub-system of chaotic systems, they ignored the long periodicity of linear feedback shift register (LFSR)and there is theoretical error and bug in their testify. This causes to give some improvement.The work of the paper is to perfect and set up a system of encryption and decryption algorithms based on composite nonlinear discrete chaotic dynamical systems. They are wavelet transformation fusing and getting rid of digital seal, encryption and decryption algorithms based on composite nonlinear discrete chaotic dynamical systems, improvement on LFSR. So the algorithms we suggest have more big key space, more systemic security, more uniformity of ciphertext and pretty much sensitive to key, ciphertext bit is confined to the next plaintext bit and selection of sub-system of chaotic functions is more complicated.From the view of the two level defence strategy and perfect composite nonlinear discrete chaotic dynamical systems and wavelet transformation, our algorithm has higher secure intensity, the owner can freely control the encryption and decryption of digital image, tally with the mode of the distributed computer systems, we can say that our algorithm is utility and has perfect applications.