一种新的基于混沌序列的双随机置乱算法

New Double Random Confusion Algorithm Based on Chaotic Sequence

为克服目前基于混沌序列的置乱算法安全性不够高,密钥空间小的缺点,本文提出了一种新的双随机置乱算法。该算法利用2个logistic混沌系统分别产生分离索引序列和置乱索引序列。分离索引序列是对logistic映射迭代产生的实值序列进行二值量化得到的,该序列用于对图像矩阵的行(列)进行随机的分离;置乱索引序列是利用混沌映射产生的轨迹点的遍历性以及良好的相关特性,对分离后的矩阵的列(行)进行排序置乱。排序置乱完毕后再按分离索引序列合并得到加密一次的图像。新提出的置乱算法采用双重随机置乱,掩盖了混沌序列的轨迹,增加了破译的难度,扩大了密钥空间。

Traditional digital image scrambling algorithms based on chaotic sequences have low level security and small key space. In order to overcome these disadvantages, this paper proposes a novel double random scrambling algorithm. The new method makes use of two logistic chaotic systems to produce a separate index sequence and a scrambling index sequence. The separate index sequence is obtained from the binary quantization of the sequence produced by logistic map, and this sequence is used to separate the image matrix randomly into two parts. The scrambling index sequence makes use of the wonderful performance of chaotic sequence to sort each of the image matrixes. At last, we get the encrypted image by combining the two parts according to separate index sequence. The proposed method can not only blanket the track of chaotic sequence well but also improve the security and expand the key space.