一种基于混沌映射的图像加密算法

Image encryption based on discrete chaotic maps

应用离散混沌序列易于生成,对初值敏感以及具有白噪声的统计特性,设计了一种"仿Feistel网络结构"的数字图像加密/解密算法。该算法的所有密钥都由不同的混沌动力系统产生,增加了破译难度。算法中的置换和替代操作,组成了具有良好密码特性的SP网络结构,置换也受密钥控制,增加了算法的复杂性。加密操作的输出结果依赖于密钥的强非线性耦合,增强了安全性。在"仿Feistel网络结构"的每次迭代操作中,都能够对所有的明文进行加密,提高了加密效率。最后,以Matlab中的图像Pout为例进行了仿真试验,结果表明,该算法具有良好的安全性和效率。

Discrete chaos is used to generate cipher systems because it is easy to create, sensitive to initial value and similar to white noise of statistical nature. A 'quasi-Feistel network' algorithm is designed using discrete chaotic maps for image encryption/decryption. All secret keys of the algorithm are generated by different chaotic maps, and this improves difficulty of decryption. Permutation and substitution consist of SP networks with good cipher performance. Permutation is also controlled by cipher to improve algorithm complexity. Safety is enhanced by the output of encryption which strongly depends on nonlinear coupled secret keys. All of white text is encrypted during each iteration of 'quasi-Feistel network', and this improves the encryption efficiency. Finally, a simulation test is conducted by taking the image Pout in Matlab as an example, and the simulation results show that the algorithm proposed possesses perfect safety and efficiency.