基于动态密钥选择与多方向扩散的图像加密算法

Image encryption algorithm based on dynamic key selection and multi-direction diffusion

设计了基于动态密钥选择与多方向扩散的图像加密算法。利用128位外部密钥来生成4个Logistic映射的初值,通过对其迭代,获取4个随机序列;利用明文自身像素特性,定义一个引擎计算函数,联合随机序列,在像素置乱过程中,根据引擎值来动态选择加密密钥,通过构建非线性像素交叉互换方法,不同的密钥来置乱不同的明文像素位置,消除了置乱周期性;设计4方向连续扩散方法,利用4个方向的扩散函数对置乱图像进行加密。测试数据表明：与当前图像加密技术相比,所提技术具备更高的安全性与抗明文攻击能力,能够较好地对图像完成解密。

An image encryption algorithm based on dynamic key selection and multi-directional diffusion is designed. Four initial value of Logistic map was generated based on 128 bits external key to get 4 random sequences by iterating it. Then an index calculation function was defined by using the pixel characteristics of the plain and joint random sequences and the index to scramble the plaint pixels positions with different keys according to the index for dynamically selecting the encryption key during the permutation. Then 4 direction continuous diffusion methods were designed to diffuse the scrambled image with diffusion function of4 directions for completing the image encryption. The test data show that compared with the current image encryption technology,the proposed technology has higher security and anti plaintext attack ability,and can decipher the image better.