双语畅销书《艾伦图灵传》第5章:解谜接力赛(33)
These were simply tables of all the core-positions, in which instead of printing 'has a female' or 'has no female', there would either be a hole punched, or not.
这是一套所有核位的卡片,上面并不是写着"有母鸡"或"无母鸡",而是靠是否打孔来区分。In principle they could first have constructed one such huge table, and then each day could have made a template with the pattern of females observed in the traffic of that day.
理论上讲,他们可以事先构造一张巨大的表,然后再把当天的母鸡模式制成一张卡片。Passing the template over the table, they would eventually have found a position where the holes matched.
拿着这张卡片,叠在核位大表上慢慢移动,与每个核位进行对比,最后就会找到一个核位,使它们所有的孔都匹配。
But that would have been far too inefficient a method.
但是,这个做法效率太低了。Instead, they had a method of piling pieces of the table of core positions on top of each other, staggered in a manner corresponding to the observed relative positions of the females.
他们换了一种做法,把核位分成多张表格,全部重叠在一起,然后把它们按照某种方式错开(错开的方式取决于当天的母鸡模式),A 'matching' of the pattern would then show up as a place where light passed through all the sheets.
这时能够透光的位置就是匹配的核位。The advantage of this staggering system was that 676 possibilities could be examined simultaneously.
这种错开法的好处是,每次操作可以同时检查676个核位。It was still a long job, requiring 6 × 26 operations for a complete search.
但这仍然是一项很耗时的工作,一次完整的查找,需要进行6×26次操作,It also required the construction of perforated sheets listing the 6 × 17576 core-positions.
另外还需要代表6×17576个核位的打孔卡片。Yet they achieved this within a few months.
不过,勤劳的波兰人只用了几个月,就成功地实现了这一切。This was not the only method they devised. The perforated sheet system required the location of about ten females in the traffic.
这并不是他们设计的唯一方法。打孔卡片系统需要掌握大约10个母鸡的位置才能有效工作。A second system required only three, but it used not only the mere existence of a female, but the particular letter that appeared as female in the cipher-text.
他们设计的另一种方法,只需要知道3个母鸡就可以了。但这种方法不仅利用母鸡的位置,还同时利用了作为母鸡的字母。It was essential to the principle of the method that these particular letters had to be among those left unaffected by the plugboard.
这个方法还有一个限制:这些特定字母必须是不受配线板影响的。