基于无序分割投影策略与重力模型的图像加密算法

Image Encryption Algorithm Based on Chaotic Segmentation Projection Strategy and Gravity Model

目的解决当前图像算法因其像素置乱和扩散操作与明文无关,导致其抗明文攻击能力较弱,且其置乱过程存在周期性,使其安全性不佳等问题。方法提出基于无序分割投影策略与重力模型的图像加密算法。首先对输入明文进行无序分割,获取重叠子块,并构建每个子块的位置坐标计算模型,输出图像子块的位置;根据明文像素量计算Kent映射的初值,通过迭代Kent映射获取随机序列组;定义位置置乱机制,对重叠子块进行混淆;再引入分割投影策略,互换每个置乱子块中的像素位置,再对其重组,输出置乱密文;通过设计像素质量变化函数替换重力模型的固定质量,改进重力模型,对置乱密文完成像素加密。结果实验结果显示与当前图像加密技术相比,文中算法具有更高的安全性,输出密文中的相邻两像素间的关联度最低,具有更强的抗明文攻击与剪切攻击性能。结论所提加密算法能够较好地用于图像信息安全传输,具有较好的应用价值。

The work aims to solve these defects, such as low anti-plaintext attack ability induced because the pixel scrambling and diffusion of the current image algorithm are not related to the plaintext, and the poor security caused by periodicity in the scrambling process. The image encryption algorithm based on chaotic segmentation projection strategy and gravity model was proposed. Firstly, the overlapping sub-blocks were obtained by chaotic segmentation of the input plaintext, and the calculation model for the position coordinates of each sub-block was built to output the positions of image sub-blocks. Then, the initial value of Kent mapping was calculated according to the quantity of plaintext pixels, and the random sequence set was obtained by iterative Kent mapping. Overlapping sub-blocks were confused by defining the position scrambling mechanism. The pixel positions in each scrambled sub-block were interchanged by introducing the segmentation project strategy and the scrambled cipher was outputted by reorganizing theses sub-blocks. Finally, the gravity model was improved by designing the quality change function of the pixel to substitute the fixed quality for pixel encryption of the scrambled cipher. The experimental results showed that, compared to the current image encryption technique, the proposed algorithm had greater security, and the correlation of two adjacent pixels in the outputted cipher was the minimum, with stronger anti-plaintext and anti-shear attack performances. The proposed encryption algorithm can be better used for the safe transmission of image information and has better application value.