基于混沌理论并引入时变参数的图像加密技术

针对单一离散混沌映射在计算机有限精度下存在的退化问题以及密钥空间小、安全性低等缺点,提出了一种基于时变参数的混沌图像加密算法。该算法由Chebyshev映射和Log istic映射级联而成,利用一级Chebyshev混沌模型生成的混沌序列作为二级Log istic映射的控制参数,进而生成混沌二维变换矩阵并完成图像的置乱和像素替换。方案中利用系统时钟信息作为时变密钥来锁定两个混沌映射的初始参数,达到了"一次一密"。由于采用一级混沌序列扰动二级混沌参数,使二级混沌序列在不同的状态空间来回迁移,以此解决了数字化混沌序列有限精度效应问题。仿真实验表明该算法具有良好的加密效果,密钥空间大,速度快,安全性高。

Image Encryption Technique Based on Chaos Theory with the Introduction of Time Varying Parameter

For the shortcomings of single discrete chaotic map degradation under limited computer accuracy,little cipher key space and low security,a cryptographic algorithm based on time varying parameters has been proposed.The algorithm is composed of Chebyshev mapping and Logistic mapping,using a Chebyshev chaotic model to generate a chaotic sequence as a two stage Logistic mapping control parameter,and generating a chaotic two-dimensional transform matrix and image scrambling and pixel replacement.The scheme adopts system clock information as a time-varying keys to lock the two chaos mapping of initial parameters,which could realize ＂one time once encryption＂.Due to the adoption of level 1 chaotic sequence to disturbance level 2 chaotic parameter,the two stage of chaotic sequences in different state space return migration,so as to solve the problem of digital chaotic sequences of finite precision effect.The simulation experiments show that the algorithm has good encryption effect with large key space,high speed,and safety.