基于仿射和复合混沌的图像自适应加密算法

基于有限整数域上的三维仿射变换和复合混沌,提出了一种新的数字图像加密算法,先置乱图像中像素的位置并根据像素坐标混合像素值,然后依次进行非线性的扩散、代换、再扩散,代换时用图像数据扰动耦合的多个混沌系统以进行自适应加密.算法如此迭代3轮,可有效地抵御选择明文攻击;密钥空间巨大,可抵御穷举攻击.其中的置乱操作可以直接作用于任意宽高比的图像,不需要进行预处理.构造的混沌系统形式简单,符合模块化设计思想,易于并行实现.

Self-adaptive encryption algorithm for image based on affine and composed chaos

On the basis of three-dimensional affine transformation in limited integer domain and composed chaos,a novel digital image encryption algorithm was proposed.Firstly,it scrambled pixels’ position and confused pixels’ value according to corresponding coordination.Secondly,it took a series of nonlinear diffusion,substitution and re-diffusion.In the process of substitution,it introduced pixels’ value to perturb multiple chaos systems that were coupled together for self-adaptive encryption.The algorithm proceeded the above two steps for 3 times to defend chosen plaintext attack,and had huge key space to defend violent attack.The scrambling function in it was compatible with images at any ratio of length to width without any preprocessing; the constructed whole chaos system which had a simple form was designed modularly,and could be realized parallel conveniently.