Chaotic-based Encryption Algorithm Research

The rapid development of computer network and communication technology makes the world enter the information age.So,how to protect information transmit and store securely in an open network environment has become a hot issue.Encryption technology is an important means to guarantee the security of information.For the past few years,many kinds of attack means and the complexity of information make it particularly urgent to study out more secure and efficient encryption algorithm.The similarity between chaos and cryptology inspire us apply chaos to encryption technology to improve the security of cryptosystem.So the cryptology based on chaos comes into existence.Multi-scroll chaotic attractors of chaotic system have more complicated dynamical behaviors than double scroll chaotic attractors,so it has been widely used and studied in many fields.In this paper,the research on the generation of multi-scroll chaotic attractors and the image encryption algorithms based on chaos are conducted respectively.Firstly,based on the existing multi-scroll and multi-wing chaotic attractors the ways to generate multi-scroll and multi-wing chaotic attractors are analyzed.Propose a new piecewise exponential function and use it for generating multi-scroll chaotic attractors,including double scroll,multi-scroll and grid multiscroll chaotic attractors.Secondly,in the study of chaos-based image encryption,the defects in security and practicality of a new image alternate encryption algorithm based on chaotic map and its improved algorithm are analyzed.Then an improved algorithm is proposed and its experimental analyses of cryptographic performance are given.The main contents in this paper as follows:1)By designing a new piecewise exponential function as the nonlinear term of a 3-D autonomous system,double scroll chaotic attractors are generated and expanding the function to a multi-segment function series multi-scroll chaotic attractors are generated.Furthermore,through numerical simulation,the dynamical properties including equilibrium points,Lyapunov exponent,bifurcation diagram,Poincaré map are investigated to prove that the system is chaotic.2)The security and practicality of a new image alternate encryption algorithm based on chaotic map and its improved algorithm is analyzed.Then the merits and flaws of two algorithms are pointed out.While retaining the merits of original algorithm,improved its confusion and diffusion process efficiently.The simulation results such as practicability,statistical analysis,differential attack analysis,key sensitivity and key space,information entropy,speed analysis all indicate that the new improved algorithm can overcome the flaws of original one and has better cryptographic performances.Moreover,the encryption scheme has widely application prospects in image secure field.