| Nowadays,with the deepening revolution of Internet technology and big data technology,the derived technologies of cloud computing,cloud storage,Internet of things and other technologies are developing rapidly.The demands of storage and transmission of information in a variety of fields increase.Information with poor security is easy to be stolen,resulting in immeasurable losses.Image information contains more information than text information and presents certain rule in the perspective of space.Therefore,the traditional encryption scheme cannot meet the security needs of image encryption.Chaotic systems show superior performance in image encryption.Its combination with encryption algorithms has been widely discussed.Based on the background,a new high-dimensional discrete hyperchaotic system is proposed.A pseudo random sequence generator is constructed and applied in the design of image encryption algorithm.First,a novel closed-loop coupling modulation model is proposed.By considering the influence of the values of different dimension and different time series simultaneously,the coupling degree is increased.Through this coupling model,one-dimensional discrete chaos can be extended to any dimension.At the same time,it is combined with cascade operation to improve the performance of chaos and form a new high-dimensional discrete hyperchaotic system architecture.Second,in order to verify the validity of the architecture,the CLS system is constructed by using logical map and sine map as seed mapping,the CTS system is constructed based on Tent map and sine map.The chaotic effects of 2D-CLS and 2D-CTS are analyzed based on Lyapunov exponent,bifurcation diagram and permutation entropy,showing the universal applicability of the architecture to general one-dimensional discrete chaotic systems.And the parameter range of the original one-dimensional chaos can be increased.The spectrum entropy of the two systems is analyzed globally,and the range of the parameters is given,which provides a strong basis for the design of pseudo-random sequence generator.Finally,based on the high-dimensional discrete hyperchaotic system,a pseudo-random sequence generator adaptive to image is designed and applied to the proposed image encryption scheme.In the design of encryption scheme,a scrambling method based on chaotic sequence is proposed,which can randomly divide pixels into two parts.An improved Feistel network diffusion method is proposed,which can reduce the dependence of the encryption algorithm on the original image information.The simulation results show that the key space of the proposed algorithm is large enough,and the key is sensitive,and it can resist brute force attack.The statistical characteristics of the image encrypted by the algorithm are eliminated and can resist statistical attacks.The algorithm has strong ability of resisting differential attack,for a small change in the original image can make the value of the encrypted pixels change greatly.The information of the encrypted image can be restored even if the encrypted image contains noise or losses information,which shows that the encryption algorithm has strong robustness. |
