雙語暢銷書《艾倫圖靈傳》第5章:解謎接力賽(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.
這是一套所有核位的卡片,上面並不是寫着"有母雞"或"無母雞",而是靠是否打孔來區分。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.
理論上講,他們可以事先構造一張巨大的表,然後再把當天的母雞模式製成一張卡片。Passing the template over the table, they would eventually have found a position where the holes matched.
拿着這張卡片,疊在覈位大表上慢慢移動,與每個核位進行對比,最後就會找到一個核位,使它們所有的孔都匹配。
But that would have been far too inefficient a method.
但是,這個做法效率太低了。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.
他們換了一種做法,把核位分成多張表格,全部重疊在一起,然後把它們按照某種方式錯開(錯開的方式取決於當天的母雞模式),A 'matching' of the pattern would then show up as a place where light passed through all the sheets.
這時能夠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.
這種錯開法的好處是,每次操作可以同時檢查676個核位。It was still a long job, requiring 6 × 26 operations for a complete search.
但這仍然是一項很耗時的工作,一次完整的查找,需要進行6×26次操作,It also required the construction of perforated sheets listing the 6 × 17576 core-positions.
另外還需要代表6×17576個核位的打孔卡片。Yet they achieved this within a few months.
不過,勤勞的波蘭人只用了幾個月,就成功地實現了這一切。This was not the only method they devised. The perforated sheet system required the location of about ten females in the traffic.
這並不是他們設計的唯一方法。打孔卡片系統需要掌握大約10個母雞的位置纔能有效工作。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.
他們設計的另一種方法,只需要知道3個母雞就可以了。但這種方法不僅利用母雞的位置,還同時利用了作爲母雞的字母。It was essential to the principle of the method that these particular letters had to be among those left unaffected by the plugboard.
這個方法還有一個限制:這些特定字母必須是不受配線板影響的。