So printed with the table there was another list of eight-letter sequences such as 'BMTVKZMD'.
除了替换表之外，还有一份单独的列表，上面全是8个字母的序列，比如BMTVKZMD。
The clerk would choose one of these sequences and add it to the beginning of the message proper.
操作员会选择其中一个序列，把它添加到密文的开头。
The receiver, equipped with the same list, could then see which table was being used.
接收者拥有同样的列表，于是就知道该查找哪一张替换表。
This simple rule illustrated a very general idea.
这个简单的方法，体现了一个非常重要的概念。
In practical cryptography, as opposed to the setting of isolated puzzles, there would usually be some part of the message transmitted which did not convey the text itself, but which conveyed instructions on how to decipher it.
在密码技术中，密码的某些部分并不传递消息，而且说明如何解码。
Such elements of the transmission, which would be disguised and buried within it, were called indicators.
这种伪装起来、隐藏在密文中的信号，称为指示信号。
Even a one-time pad system might employ indicators, to give a check on which page of the pad was being used.
一次性密钥系统，也是通过这种指示信号，来说明使用的是哪一页密钥。
In fact, unless everything were spelt out in advance and in complete, rigid, detail, without any chance of ambiguity or error, there would have to be some form of indicator.
除非双方事先把所有的一切都固定下来，进行详细的约定，而且不会发生任何变化，否则都必须要在密文中加入某种形式的指示信号。
It must surely have struck Alan, who had been thinking at least since 1936 about 'the most general kind of code or cipher', that this mixing of instructions and data within a transmission was reminiscent of his 'universal machine',
从1936年开始，艾伦就在思考一种通用的密码系统，现在他非常兴奋，因为这种数据与指令相结合的模式，使他立即联想到他的通用机。
which would first decipher the 'description number' into an instruction, and then apply that instruction to the contents of its tape.
他的机器首先把描述数解码成指令，然后根据指令来操作纸带上的数据。
Indeed any cipher system might be regarded as a complicated 'mechanical process' or Turing machine, involving not just the rules for adding or substituting, but rules for how to find, apply and communicate the method of encipherment itself.
实际上，任何密码系统，都可以看成是一个机械的过程，也就是图灵机，不光是加法或替换，还包括对本身的操作过程进行查找和执行。
Good cryptography lay in the creation of an entire body of rules, not in this or that message.
良好的密码学是建立在整个规则基础上的，而不是在这个或那个信息中。