A novel color image encryption algorithm based on dynamic deoxyribonucleic acid (DNA) encoding and chaos is presented. A three-neuron fractional-order discrete Hopfield neural network (FODHNN) is employed as a pseudo-random chaotic sequence generator. Its initial value is obtained with the secret key generated by a five-parameter external key and a hash code of the plain image. The external key includes both the FODHNN discrete step size and order. The hash is computed with the SHA-2 function. This ensures a large secret key space and improves the algorithm sensitivity to the plain image. Furthermore, a new three-dimensional projection confusion method is proposed to scramble the pixels among red, green, and blue color components. DNA encoding and diffusion are used to diffuse the image information. Pseudo-random sequences generated by FODHNN are employed to determine the encoding rules for each pixel and to ensure the diversity of the encoding methods. Finally, confusion II and XOR are used to ensure the security of the encryption. Experimental results and the security analysis show that the proposed algorithm has better performance than those reported in the literature and can resist typical attacks.

提出了一种基于动态脱氧核糖核酸（DNA）编码和混沌的彩色图像加密算法。三神经元分数阶离散Hopfield神经网络（FODHNN）被用作伪随机混沌序列生成器。其初始值是通过由五参数外部密钥生成的秘密密钥和纯图像的哈希码获得的。外部密钥包括FODHNN离散步长和顺序。哈希是使用SHA-2函数计算的。这样可以确保较大的密钥空间，并提高了算法对纯图像的敏感度。此外，提出了一种新的三维投影混淆方法来扰乱红色，绿色和蓝色分量之间的像素。DNA编码和扩散用于扩散图像信息。FODHNN生成的伪随机序列用于确定每个像素的编码规则，并确保编码方法的多样性。最后，使用混淆II和XOR来确保加密的安全性。实验结果和安全性分析表明，该算法比文献报道的算法具有更好的性能，可以抵抗典型攻击。