双语畅销书《艾伦图灵传》第5章:解谜接力赛(42)
The Turing Bombe
Suppose now that the letters LAKNQKR are known to be the encipherment of GENERAL on the full Enigma with plugboard.
假设现在已知，有一台带有配线板的完整谜机将GENERAL编码成了LAKNQKR。This time there is no point in trying out LAKNQKR on the basic Enigmas, and looking at what emerges, for some unknown plugboard swapping must be applied to LAKNQKR before it enters the Enigma rotors.
因为GENERAL在进入转盘之前，已经执行了一些未知的配线对换，所以现在不能在原型谜机中进行检查。
Yet the quest is not hopeless. Consider just one letter, the A.
但是我们还有别的希望。先只考虑一个字母A。There are only 26 possibilities for the effect of the plugboard on A, and so we can think about trying them out.
配线板对A的改变只有26种可能，所以我们可以考虑把它试出来。We may start by taking the hypothesis (AA), i.e. the supposition that the plugboard leaves the letter A unaffected.
我们先假设（AA），也就是假设配线板不影响字母A。What follows is an exploitation of the fact that there is only one plugboard, performing the same swapping operation on the letters going into the rotors as on the letters coming out.
接下来，利用这样一个事实：字母在进入转盘之前，和从转盘出来之后，经过的是同一个配线板。(If the Enigma had been fitted with two different plugboards, one swapping the ingoing letters and one the outcoming, then it would have been a very different story.)
如果谜机用了两个不同的配线板，一个负责对换输入前的字母，另一个负责对换输出后的字母，那么这个故事就完全不一样了。It also exploits the fact that this particular illustrative 'crib' contains a special feature—a closed loop.
还要利用一个事实，在下面的像一组"床位"一样的图中，存在一种很特殊的特性——闭合回路。This is most easily seen by working out the deductions that can be made from (AA).
我们从（AA）出发，进行一些推导，就很容易看到这一点。
