雙語暢銷書《艾倫圖靈傳》第5章:解謎接力賽(8)

a laborious business, and the kind of thing I have always been bad at.

這是非常吃力的工作，這類工作是我最不擅長的。

First, one had to subtract from the groups of numbers in the telegram corresponding groups from a so-called one-time pad;

首先，要取一張一次性的密鑰紙，將電報中的很多組數字，減掉密鑰紙上對應的數字，

then to look up what the resultant groups signified in the code book.

首先，要取一張一次性的密鑰紙，將電報中的很多組數字，減掉密鑰紙上對應的數字，

Any mistake in the subtraction, or, even worse, in the groups subtracted, threw the whole thing out.

在相減的過程中，一旦出了任何差錯，就會全部前功盡棄。

I toiled away at it, getting into terrible muddles and having to begin again…

我廢寢忘食地做着這項工作，但卻不斷地陷入可怕的混亂，然後又要從頭開始……

Alternatively, a cipher system might be based upon the 'substitution' idea.

在相減的過程中，一旦出了任何差錯，就會全部前功盡棄。

In its simplest form, this was used for puzzle-page cryptograms, such as they had solved in Princeton treasure hunts.

在相減的過程中，一旦出了任何差錯，就會全部前功盡棄。

It meant that one letter of the alphabet would be substituted for another, according to some fixed rule like:

這種方法就是，將字母表中的字母，按照特定的規則進行替換，比如：

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

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

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

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

so that TURING would become VNQOPA.

根據這個規則，TURING加密後就變成了VNQOPA。

Such a simple, or 'mono-alphabetic' cipher could easily be solved by looking at letter frequencies, common words, and so forth, and in fact the only point of puzzle-page problems was that the setter would include peculiar words like XERXES to make this difficult.

但是，這樣一個簡單的、單字母的替換規則，只要通過觀察字母的頻率、相同字母的規律等等，就可以很容易地破解。在普林斯頓的尋寶遊戲中，艾倫他們通過設計一些XERXES之類的古怪詞語，來增加破解的難度，

Such a system would be too simple-minded for military application.

但這樣的系統對於軍事應用來說，實在是過於幼稚了。

But there were systems in use in 1939 which were not much more advanced.

不過，1939年使用的某些系統，並沒比這先進到哪裏去。

One sophistication lay in the use of several alphabetic substitutions, used in rotation or according to some other simple scheme.

某些字母替換系統，使用了一些技巧，比如說輪流使用多套規則。