| The network carries a lot of information, especially multimedia information.The protection of sensitive image data will inevitably bring about the problem ofinformation security. Data encryption is an effective and reliable method forinformation security which uses computer systems to ensure the safety ofinformation.The greatest characteristic of a chaotic system is very sensitive to the initialvalue. In addition, chaos has the property of ergodicity, the overall stability ofregional instability, pseudo-randomness, fractal structure and so on. Thesecharacteristics of chaos are in accordance with the elementary requirements ofcryptography. However, many chaotic maps used for image encryption such as theLogistic map, Henon map and Tent map are all low dimensional maps. Lowdimensional chaotic system generates chaotic sequences only by simple iteration.Low dimensional chaotic system is influenced by a few system parameters andinitial values, which has been mastered by attackers. In recent years, variousmethods with good attack effect have been presented. Thus, the research onhigh-dimensional hyperchaotic system develops more and more widely in theselection of a chaotic map.In this paper, the existence of strange attractors of chaotic financial system andRabinovich system is proven based on the dynamics analysis and numericalsimulation. Two new four-dimensional hyperchaotic systems are presented byadding new nonlinear feedback and new dimension to three-dimensional chaoticsystems. New systems are proven to be hyperchaotic system through the dynamicsanalysis and numerical simulation. The pre-processed sequence of values generatedfrom hyperchaotic sequences is combined with plaintext to realize image encryption.In addition, a more optimized sequence can be achieved by combininghyper-Rabinovich system with the index chaos. In this paper, seperate chaoticsequences are selected for separate plaintext."Confusion-diffusion" encryption structure is utilized in the image encryptionalgorithm. Pseudo-random sequence generated by the ciphertext image has passedthe random and pseudo-random sequence of SP800-22test standard. The results ofseveral analysis about histogram, information entropy, resistance to differentialattacks and key sensitivity of the encrypted image show that the algorithm based onnew four-dimensional hyperchaotic maps has large key space and high security.Two new four-dimensional hyperchaotic systems presented in this paper havesuperior practical values and are helpful for image encryption based on chaos. Applying them to image encryption can improve security and increase complexity. |
