为增强图像加密算法的安全性和高效性，基于量子 Logistic 混沌映射和二维离散小波变换，提出了一种结合置乱与扩散的自适应图像加密算法．首先，对图像进行离散小波分解，利用量子 Logistic 映射产生的随机序列对分解得到的低频子带系数进行排序，对改变后的小波系数分布结构做小波反变换，得到置乱图像; 然后，提取新的混沌序列，逐一替换置乱图像的像素，与此同时扰动量子混沌系统完成像素的自适应替换，从而达到更好的扩散效果．实验结果与性能分析表明，该图像加密算法具有密钥空间大、安全性高和运算速度快等特点，并且加密图像灰度值的分布具有类随机的行为．

In order to improve the safety and efficiency of image encryption algorithms,a new adaptive algorithm based on quantum Logistic map and 2D discrete wavelet transform (DWT),which combines confusion and diffu-sion,is proposed.In this algorithm,first,the original image is decomposed into low- pass subband and high- pass subband coefficients via the DWT,and the low- pass ones are sorted out by using the quantum Logistic map with random sequences,followed by an inverse DWT to obtain a shuffled image. Then,each pixel of the shuffled image is mixed with the chaotic sequence generated by the quantum Logistic system,and the quantum Logistic system is perturbed to substitute for pixel values adaptively.Thus,better diffusion effect is achieved.Experimental results and performance analysis demonstrate that the proposed algorithm is of large key space,high security and high operation speed,etc.,and that it helps to obtain cipher images with random gray distribution.