雙語暢銷書《艾倫圖靈傳》第5章:解謎接力賽(25)

The strength was that every message, after the first six letters, was enciphered on a different setting.

這樣做的優點是，每個信息在開頭六個字母之後，都是以不同的盤位設定進行編碼的。

The weakness was that for one day, all the operators in the network would be using exactly the same state of the machine for the first six letters of their messages.

缺點是，在一天當中，整個通信網絡中的每一條信息，開頭的六個字母都是以完全相同的機器狀態進行編碼的。

Worse, those six letters always represented the encipherment of a repeated triplet.

更嚴重的是，這六個字母總是代表着兩個相同的三位字母串。

It was this element of repetition that the Polish cryptanalysts were able to exploit.

正是這種重複的特性，被波蘭的密碼分析人員抓住了。

Their method was to collect each day, from their radio intercepts, a list of these initial six-letter sequences.

他們的方法是，每天從攔截到的所有無線電信息中，收集其開頭六個字母，形成一份列表。

They knew that in this list, there would be a pattern.

他們知道，這個列表肯定有規律可循。

For if in one message the first letter were A, and the fourth letter was R, then in any other message where the first letter was A, the fourth letter would again be R.

如果在一條信息中，第一個字母是A，第四個字母是R，那麼在其他信息中，只要第一位是A，那麼第四位肯定也是R。

With enough messages, they could build up a complete table, say:

收集足夠多的信息，就可以建立一個完整的表，比如：

First letter: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

第一個字母：A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Fourth letter: R G Z L Y Q M J D X A O W V H N F B P C K I T S E U

第四個字母：R G Z L Y Q M J D X A O W V H N F B P C K I T S E U

There would be two further tables, connecting the second and fifth letters, and the third and sixth.

還有另外兩個表，分別表示第二和第五個字母的關係，以及第三和第六個字母的關係。