Talk:Two-square cipher

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A couple notes on conventions[edit]

From what I have seen, it is far more common to merge i and j in making the squares, rather than remove q from the alphabet. At least, the references I have seen all do this. I wonder if the examples here (and in related ciphers) should be changed accordingly.

Also, so far as I have seen, the different convention for same-row digraphs in horizontal two-square (reversing the digraph rather than preserving it) is universal, so I've updated the page to reflect this. I figure this had to be done, as otherwise the text in the cryptanalysis section made no sense. Mahousu (talk) 02:22, 29 May 2008 (UTC)

You should change it -- but for maximum historical accuracy it would be best if we could find Delastelle's original paper and see what he did. Of course which letter to drop is largely arbitrary, but it should be one which minimises the risk of confusion in the plaintext language in use. Whereas Playfair was largely used by the British and Commonwealth, Two-square is French, and in French the letter Q is not a particularly rare letter, being more common than 10 other letters including "H", "F", "W" and "B." But the difference between "I" and "J" is probably more important in French too, because the sounds of these two letters are much more different than in English. In French the most logical letter to drop is "K" but I don't know if that is what Delastelle actually chose. -- (talk) 08:07, 13 July 2009 (UTC)