一种基于动态约瑟夫遍历和比特平面交叉置乱–扩散的彩色图像加密算法
A Color Image Encryption Algorithm Based on Dynamic Joseph Traversal and Crossing Bit-Plane Scrambling-Diffusion

本文提出一种基于动态约瑟夫遍历和比特平面交叉置乱–扩散的彩色图像加密算法。首先，对图像的各行像素值求和量化，作为约瑟夫遍历的起点，使得约瑟夫遍历依赖于明文图像；利用斜帐篷混沌系统生成混沌序列并进行量化，得到约瑟夫遍历的步长，然后实现彩色图像的像素位置的约瑟夫遍历，达到置乱的效果。其次，将置乱后的图像像素值进行高低四比特分裂，利用变型Chen混沌系统生成的改进混沌序列对高低四比特序列进行动态置换，初步改变像素值。最后，通过变型Chen混沌系统生成的伪随机灰度值序列对初步加密的密文图像进行扩散操作，进一步增强加密算法的安全性。实验仿真结果表明，该算法加密效果优良，具有密钥空间大、密钥和明文敏感性高、密文图像统计性能好等优点，能够很好地抵御穷举攻击、统计分析攻击、差分攻击和选择明文、已知明文攻击等。
A color image encryption algorithm based on dynamic Joseph traversal and crossing bit-plane scrambling-diffusion is proposed in this paper. Firstly, the values of each pixel of the image are summed and quantized as the starting numbers of Joseph traversal, which makes Joseph traversal depend on the plaintext image. The chaotic sequence generated by skew tent chaotic system is quantized to obtain the steps of Joseph traversal. Then, the Joseph traversal of the pixel position of a color image is realized to achieve the scrambling effect. Secondly, the scrambled image is divided into high and low 4-bit planes, and the chaotic sequences generated by the improved chaotic sequences derived by one modified Chen chaotic system are used to dynamically confuse the high and low 4-bit planes and preliminarily change the pixels values. Finally, the initially encrypted image is diffused by the pseudo-random gray value sequence yielded by the modified Chen chaotic system, further enhancing the security of the encryption algorithm. Experimental simulation results show that the proposed algorithm has a good encryption effect, has the advantages of large key space, high key sensitivity and plaintext sensitivity, good statistical performance for cipher images and so on, and can well resist exhaustive analysis attack, statistical analysis attack, differential attack, chosen-plaintext attack, known-plaintext, etc.