基于像素-位水平联合扩散的图像加密算法

Image encryption algorithm based on pixel-bit level combined diffusion

针对当前图像加密算法因其混沌系统的动力学特性易退化,导致其抗统计攻击性能不佳等不足,提出基于像素交叉扩散的图像加密算法。通过迭代Logistic函数,获取随机特征增强的序列,引入像素位置集合扰乱技术,形成像素置乱源,打乱图像像素位置;基于神经网络,结合混沌映射,设计混沌密钥生成器,获取神经混沌数组,通过神经网络响应误差与混沌生成器的精确响应来偏离混沌轨迹;基于交叉方法,在位水平上构造扩散函数,完成像素掩码,形成像素水平置乱-位水平双重扩散的加密结构,有效增加密钥序列的循环长度。仿真结果表明,与当前图像加密算法相比,该算法具有更好的鲁棒性与加密性能。

To solve the problem of poor anti-statistical attack performances induced by using chaotic system to realize the pixel diffusion with 2N dimensional finite space resulting in chaotic dynamics degrading in current image encryption algorithm,the image encryption algorithm based on cross diffusion of pixels was proposed.The uniform Logistic map was iterated to obtain the chaotic sequence of random performance enhancement,and the pixel position of image was permutated by introducing the pixel location set permutation technology to act as pixel scrambling source.Chaotic key generator was designed by introducing neural network and combining chaotic system,and it was taken as image pixel scrambling source to disturb pixel position using the error between the neural network response and the exact response of the chaotic generator for deviation from chaotic trajectory.The image pixels were diffused by introducing cross method.The encryption structure of pixel level scrambling and bit level double diffusion was produced for effectively increasing the cycle length of the key sequence.Simulation results show that this algorithm has better robustness and encryption performance compared with the current image encryption algorithm.