取代式密码的存在，已经超过2500年 以上，最早利 用的范例 是在西元600年 左右，内容是以颠倒的希伯來 文构成的。凯萨大帝（Julius Caesar）也曾经使用称为Caesar密码法。方法为将每个字母用其后的第三个字母來 取代。-Replace passwords existence, has more than 2,500 years or more, the first example is using a range of about the year 600 AD, the contents of the text is upside-down Heber future composition. Great Caesar (Julius Caesar) has also been known as the Caesar cipher using the method. Method is used then each letter is replaced by the third letter.