双语畅销书《艾伦图灵传》第5章:解谜接力赛(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.
通讯就是基于5位的二进制数进行的。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.
自从博多默里码进入密码领域以来，经常作为一种叠加型密码的基础。
The principle was dignified with the name of the American inventor G.S. Vernam.
这种密码，因美国发明家G.S.维尔南而得名。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.
实际上，维尔南密码就是基于最简单的叠加密码，因为二进制数的模加，无非就是下面表格中的规则：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.
也就是说，一条明文纸带，可以与一条密钥纸带进行叠加，规则就是，如果密钥纸带上面某个位置有孔，就会改变明文纸带相应位置的孔（把有孔改成没孔，或者反之），如果密钥纸上没有孔，就保持明文的相应位置不变。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.
如果密钥是随机生成的，并且遵守一次性原则，那么这套系统将会很安全，在这方面二进制与十进制没有什么区别。If all keys were equally likely, then no weight of evidence could accrue to any particular possible plain-text.
因为如果所有的密钥都有同样的概率，那就无法增加其中某一个的证据权重。But that was not the case with these German transmissions. The key was generated by the action of a machine.
但德国的密码系统并不是这样的，他们的密钥是由机器生成的。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，有若干种不同的电传打字机，但它们都有一个共同的特征，密钥是有10个左右的转盘自动生成的。
