对ICBGCM混沌图像加密算法的安全性分析

Security Analysis on ICBGCM Chaotic Image Encryption Algorithm

针对一个用于图像加密的密码算法(ICBGCM)在已知图像条件下的安全性问题,给出了求解加密算法等效密钥的攻击算法.该算法基于ICBGCM算法所使用的广义混沌Cat映射的短周期性和仿射特性,在已知图像的条件下,通过求解两个线性无关的加密前后的图像像素灰度值点,获得广义混沌Cat映射的全部等效密钥参数.利用穷尽方法求出加密算法的其余等效密钥,给出了应用该算法的具体步骤,并分析了攻击算法的计算复杂性.所得结果证明了ICBGCM算法在已知图像攻击下是不安全的.

To study the security with the known image of a chaotic symmetric image encryption scheme（ICBGCM）,the attack algorithm for equivalent key is given.The attack algorithm is based on the short periodicity and affinity of general chaotic cat map used by ICBGCM symmetric image encryption scheme.With the known image,the equivalent keys of general chaotic cat map can be found by two linearly independent plain-cipher text image grey values.The other equivalent keys can be found by brute attack algorithm.The concrete steps and complexity of the attack algorithm are given.The investigation proves that the ICBGCM encryption algorithm is insecure in the known image attack.