Security analyses of a variant of a new block cipher system ( called cac ) based on cellular automata theory are given using two cryptanalytic approaches . the results show that this variant of cac is very insecure under chosen - plaintext attacks 利用两种方法对一个基于细胞自动机的分组密码系统cac的变形进行了分析，结果表明： cac的这种变形在选择明文攻击下是极不安全的。
