基于一种四维忆阻超混沌系统的图像加密算法

Image Encryption Algorithm Based on a Four-dimensional Memristor Hyperchaotic System

鉴于低维混沌的图像加密算法存在密钥空间小、安全性不高等问题,通过引入光滑三次型忆阻器,构建一个改进的四维忆阻超混沌系统。对改进系统的相图、耗散性、平衡点稳定性、Lyapunov指数谱和分岔等进行数值仿真与分析,表明该系统具有丰富的动力学行为与混沌特性。并提出一种通过哈希算法进行混沌序列选择的加密算法。经过直方图、密钥空间分析、鲁棒性分析等实验仿真,表明该图像加密算法密钥空间较大,可以有效抵御暴力穷举等恶意攻击,具有较高的安全性。

The image encryption algorithm based on low dimensional chaotic system has the problems of the key space small and the security not high.In this paper,an improved four-dimensional Lorenz dissipative hyperchaotic system is constructed by introducing a cubic smooth memristor model.The dynamic characteristics of the improved system such as phase portraits,dissipation,equilibrium stability,Lyapunov exponent,and bifurcation are investigated,it is proved that the system has good dynamic characteristics and chaotic attractor.Therefore,a chaotic sequence encryption algorithm based on Hash algorithm is proposed.By histogram,key space analysis,robust analysis and other verifications show that the image encryption algorithm has higher key space and can resist brute-force attack.