The Construction Of Chaotic System And Its Application In Image Encryption

Chaos is a unique form of motion in nonlinear dynamical systems.In recent years,Chaos theory has been from simple cognitive and analytical development to the theoretical research and practical engineering applications,such as chaotic image encryption,speech chaotic secure communications,etc.Especially chaotic characteristics of more complex and changeable hyperchaotic system,with greater sensitivity and unpredictability,and thus more widely used.In the construction of a new hyperchaotic system,although there are some theoretical guidance,but because of the characteristics of the hyperchaotic system,the initial parameters of the sensitivity,mainly through the computer numerical simulation,computational Lyapunov exponent dynamics analysis,to determine whether the system is hyperchaotic system.The high sensitivity and unpredictability of chaos to the initial conditions,such as diffusion and substitution in cryptography.With the development of chaotic cryptography,image encryption algorithm based on chaotic cryptography has become a hotspot.From the 90 s of last century based on chaotic image encryption algorithm to get a lot of applications.However,with the development of science and technology,the original encryption algorithm has been threatened to design a higher security encryption algorithm is a challenge.This paper introduces the development of chaos theory,summarizes the basic contents and characteristics of chaotic dynamical system,and expatiates the common methods of computer numerical simulation and analysis of chaotic system in detail.Secondly,some basic concepts of cryptography and the theoretical knowledge of encryption system are introduced,and the image encryption algorithm based on chaos theory is summarized.Finally,the current image encryption algorithm is analyzed,and the shortcomings are pointed out and corrected.In this paper,the main work is as follows:(1)This paper constructs a new hyperchaos system of 4 wings.In three-dimensional autonomous chaotic systems introduced in a simple nonlinear controller,constructed a new hyperchaos autonomous systems.Analysis of the new system phase diagram,balance,Lyapunov exponential spectrum and bifurcation diagram the basic dynamic characteristics,such as changes of system parameters of Lyapunov exponential spectrum and bifurcation diagram analysis,detailed and analog circuit design of the system.Circuit experiment results are consistent with the theoretical analysis results,verify the hyperchaos of system behavior,and the system of the cycle,conversion between chaos and hyperchaos is also analyzed.(2)This paper proposes a new image encryption algorithm based on hyperchaos.Put forward a kind of image encryption based on hyperchaos of chaotic sequence of new project,completed the clear image scrambling and pixel gray value of the replacement and diffusion,each iteration adopts different encryption keys,through the simulation analysis,the algorithm has large key space,have the ability to resist brute force attack.The scheme has good encryption effect,the key space is large,strong ability against the attack,the sensitivity to the initial key is strong,for the pretreatment of the chaotic sequence time is short,encryption algorithm has good effectiveness,speed is quick and easy to realize image encryption algorithm.