One way of doing this was by means of the one-time principle.
其中一个重要的原则，叫作一次性原则。
This was one of the few sound ideas of 1930s cryptography, as well as the simplest.
对于30年代的密码技术来说，这是一个简单又实用的方法。
It required the key to be written out explicitly, twice over, and one copy given to the sender, one to the receiver of the transmission.
把密钥复制两份，一份给信息的发送方，另一份给接收方。
The argument for the security of this system was that provided the key were constructed by some genuinely completely random process, such as shuffling cards or throwing dice, there could be nothing for the enemy cryptanalyst to go on.
该系统的安全性就在于，只要密码是完全随机生成的，那么敌人的密码分析员就束手无策。
Given cipher text '5673', for instance, the analyst might guess that the plain-text was in fact '6743' and the key therefore '9930', or might guess that the plaintext was '8442' and the key '7231', but there would be no way of verifying such a guess, nor reason to prefer one guess to another.
比如，给出一个密文"5673"，分析员可能会猜，明文是"6743"而密钥是"9930"，但是，也有可能明文是"8442"而密钥是"7231"，他无法判断哪种猜想是正确的，也看不出来哪一种更像是正确的。
The argument depended upon the key being absolutely patternless, and spread evenly over the possible digits, for otherwise the analyst would have reason to prefer one guess to another.
因为密钥是没有规律的，每个数字都有均等的概率。
Indeed, discerning a pattern in the apparently patternless was essentially the work of the cryptanalyst, as of the scientist.
实际上，在明显无规律的密码中找到内在的规律，这就是科学家和密码分析员的工作。
In the British system, one-time pads were produced, to be used up one at a time.
在英国通信系统中，有一次性的密钥本，每次使用一页，
Provided the key was random, no page was used twice, and the pads were never compromised, the system was fool-proof.
取出一组随机的密钥，用过了就作废。每一页的密钥都是不同的，因此这个系统十分安全。
But it would involve the manufacture of a colossal quantity of key, equal in volume to the maximum that the particular communication link might require.
但是，这需要人工编制大量的密钥，从工作量来说，甚至与通信本身不相上下。
Presumably this thankless task was undertaken by the ladies of the Construction Section of GC and CS, which on the outbreak of war was evacuated not to Bletchley but to Mansfield College, Oxford.
这项吃力又枯燥的工作，由政密学校编构部门的女士们来承担，该部门在战争爆发后，并没有撤入布莱切利庄园，而是迁到了牛津大学曼斯菲尔德学院。
As for the system in use, that was no joy either. Malcolm Muggeridge, who was employed in the secret service, found it2
至于使用的系统，也没什么乐趣.。情报部门的麦卡姆·马格瑞治说：