雙語暢銷書《艾倫圖靈傳》第5章:解謎接力賽(149)
From a logical point of view, the 'hole' in the tape might as well be a 1, and the 'no hole' a 0.
So the transmissions were in the form of five sequences of binary digits, 0s and 1s.
通訊就是基於5位的二進制數進行的。It had long since occurred to cryptographers that the Baudot-Murray code could be used as the basis for an 'adding on' type of cipher.
自從博多默裏碼進入密碼領域以來，經常作爲一種疊加型密碼的基礎。
The principle was dignified with the name of the American inventor G.S. Vernam.
這種密碼，因美國發明家G.S.維爾南而得名。In fact a Vernam cipher was based on the simplest possible kind of adding, since 'modular' addition with binary digits would use nothing but the rules shown in the figure.
實際上，維爾南密碼就是基於最簡單的疊加密碼，因爲二進制數的模加，無非就是下面表格中的規則：In other words, a plain-text teleprinter tape could be 'added' to a key teleprinter tape, according to the rule that a 'hole' in the key-tape would change the plain-text-tape (from 'hole' to 'no hole' or vice versa), while a 'no hole' would leave the plain-text unchanged, as below.
也就是說，一條明文紙帶，可以與一條密鑰紙帶進行疊加，規則就是，如果密鑰紙帶上面某個位置有孔，就會改變明文紙帶相應位置的孔（把有孔改成沒孔，或者反之），如果密鑰紙上沒有孔，就保持明文的相應位置不變。比如If the key were produced truly randomly, and used on the one-time principle, then such a system would be secure, the same for binary digits as for decimal digits.
如果密鑰是隨機生成的，並且遵守一次性原則，那麼這套系統將會很安全，在這方面二進制與十進制沒有什麼區別。If all keys were equally likely, then no weight of evidence could accrue to any particular possible plain-text.
因爲如果所有的密鑰都有同樣的概率，那就無法增加其中某一個的證據權重。But that was not the case with these German transmissions. The key was generated by the action of a machine.
但德國的密碼系統並不是這樣的，他們的密鑰是由機器生成的。There were several different kinds of teleprinter-enciphering machines in use, but they shared common features, the key being a pattern generated by the irregular motion of ten or so wheels.
目前正在使用的，有若干種不同的電傳打字機，但它們都有一個共同的特徵，密鑰是有10個左右的轉盤自動生成的。
