一个周期3的多表代替密码，第1个表由密钥字法产生（密钥字自拟），第2个表由洗牌法产生（注意，字母a~z与数字0~25一一对应），第三个表由公式法产生（数学公式自拟，注意它须是Z26上的一个一一变换）-a cycle of three multi-table instead of passwords, a table by key word method, (key word from the intended), Table No. 2 produced by shuffling method (note, a letter with a number of z ~ 0 ~ 25 he gathers), 3rd tables generated by the formula (from the proposed mathematical formula, it should pay attention to the Z26 is a transformation on January 1)