提出了一种改进的双重加密算法,利用新构造的位置置乱方法将二维矩阵中行和列映射到一维向量中,然后采用Logistic映射产生一组伪随机序列,将伪随机序列由小到大进行排序,对排序后的位置以集合序列的形式记录下来,形成密钥流;最后对一维向量按照密钥流形成的索引值进行重新排列,重排后的一维向量转换为与原始图像矩阵大小相同即得到加密图像.实验结果表明,该算法具有密钥空间大,加密后直方图分布具有白噪声的特性,提高了图像传输的安全性.

A new improved image encryption algorithm is proposed.The rows and columns of 2D matrix is mapped into 1D vector by making use of new proposed scrambling method based on pixel position.Then using the logistic mapping to generate a set of pseudo sequence,the pseudo sequence is ranked from small to large.The position that corresponds to each element is recorded by group sequence,which called key stream.Finally the corresponding pixel position of 1D vector is scrambled by index value which is formed by key stream.The encrypted image is obtained by 1D vector rearranged into a new 2D matrix.In addition,the new proposed method based on pixel position is extended to color image R,G,B components and dual scrambling based on color image pixel position and intensity value.The experimental results show that the proposed method has a large key space,and the scrambled image has a histogram distribution of white noise.It is greatly increasing the safety of encrypted image.