为了有效改进细胞自动机加密系统的实现复杂度和加解密效率,提出了一种二阶可逆耦合触发细胞自动机的图像加密方法.通过对简单的可逆细胞自动机进行扩展,构造二阶可逆细胞自动机,并以耦合触发规则对明文图像实行分块加密.二阶可逆细胞自动机的转移状态由其当前状态以及前一状态决定,有效增大了邻域范围,并且因为采用耦合触发规则,因此能明显增大加密系统的密钥空间,保证了系统的计算安全性.与一般触发自动机反向迭代的串行加密方式相比,该方法对于每个细胞的加密具有本质并行性,因此具有极高的加解密效率.通过实验验证其性能,结果表明与其它算法相比,该算法具有较大的密钥空间,能够有效抵抗蛮力攻击和差分分析攻击,且较小的邻域半径即可得到良好的加密效果,因此非常便于硬件实现.%To effectively improve the implement complexity and execution efficiency, an algorithm for image encryption is proposed which is based on two-order reversible couple toggle cellular automata (CA). By ways that extending the structure of simple reversible CA (RCA) and adopting couple toggle rules, the algorithm ciphers image which is divided into blocks previously. The CA's state is determined by previous state and next state, so it has larger key space and this can make system safe enough. Compared with general toggle CA (TCA) methods, the algorithm has much better efficiency because each cell is updated parallel Experiments and analysis indicate that this method has an enough large key space, high cipher and decipher speed and good scrambling effect. And the cryptosystem can resist brute attack and differential attack effectively.
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