基于复合混沌序列与小波变换的图像加密算法

针对单一混沌映射有可能退化为周期问题以及图像置乱加密计算量大的缺点，提出了一种基于复合Logistic和Chebychev映射与小波变换的图像加密算法。算法根据密钥控制复合混沌序列的初始参数，生成混沌序列，进而对图像进行置换加密，然后对加密后的图像进行小波分解，再对小波近似系数进行置乱加密。实验结果表明，该算法改进了单一混沌序列的退化问题，使混沌序列具有更好的随机性并改进了图像的直方图分布，算法具有良好的加密效果。

Image Encryption Algorithm Based on Compound Chaotic Sequence and Wavelet Transform

An image encryption algorithm based on compound chaotic sequence and wavelet transform is proposed for the possible degradation of single chaotic map sequence and the high computing work of scrambling encryption of image. The algorithm combines Logistic mapping with Chebychev mapping which are both controlled by a random initial parameter generated by m-sequence to substitute encryption the image, then decomposes the image with wavelet transform, and in the end scrambles the approximation wavelet coefficient. The experiment result shows that the algorithm improves the degradation problem of single chaotic sequence with better randomness and improves the histogram distribution of the image. The algorithm has good encryption result to digital image data.