基于8方向折叠与自更新置乱的图像加密算法
An Image Encryption Algorithm Based on the Eight-Direction Folding and Self-Update Scrambling Technique

当前的图像加密算法主要是在一个方向上对像素进行扩散，且在整个加密过程中，都是利用相同的扩散、混淆函数来改变像素位置与灰度值，导致算法的随机度与安全性不佳，因此本文提出了一种基于8方向折叠机制与自更新的图像加密算法.首先，联合Lucas、Fibonacci序列，通过二维Arnold变换设计一种像素自更新置乱算法，对输入明文进行混淆操作，充分提高像素位置的置乱度；引入Logistic映射，利用明文像素来生成其初始值，根据其随机序列的量化密钥流来设计8方向折叠机制，从8个方向对置乱图像进行高度加密，对于每一个方向的像素扩散，利用不同的加密函数来改变其像素值，显著降低了置乱、扩散的周期性.测试数据显示：与当前的图像加密机制相比，本文所提算法具有更高的安全性与用户响应值，其密文像素分布更为均匀.
The current image encryption algorithm suffers from the defects of low randomness and security, for it diffuses the pixels in one direction and uses the same diffusion function to change the pixel value in the whole encryption process. In order to solve this problem, a new image encryption algorithm based on the eight-direction folding mechanism and the quantum complex chaotic system is proposed in this paper. Firstly, a pixel self-update scrambling technique is designed by jointing the Lucas and the Fibonacci sequences and using the 2D Arnold transformation to scramble the image. Then, an 8-direction folding mechanism is designed based on the stochastic sequence of the logistic map to encrypt the highly scrambled images from 8 directions, so that different encryption functions are used to change their pixel values for significantly reducing the periodicity of scrambling and diffusion. The test data show that compared with the current image encryption algorithm, this new algorithm has higher security and user response, and more uniform distribution of cipher pixels