Recently I decided to learn "Playfair Cipher", and I have hit a road block. what do i substitute the letters for if they are on the same column? Here is an example:


With the Key being CIAD (Random Text)

I want to spell the word "trust" but I do not know what rule to follow for the T & R. I would really appreciate help on this. TIA


1 Answer 1


TR would be replaced using rule 2 of the Wikipedia description:

If the letters appear on the same row of your table, replace them with the letters to their immediate right respectively (wrapping around to the left side of the row if a letter in the original pair was on the right side of the row).

So TR would become PS. See also step 10 of the example there.

Note that T and R are on the same row, not the same column.

You may want to use a larger key (i.e. one that includes more characters of the alphabet).

  • $\begingroup$ Thanks @MaartenBodewes! that solved my problem perfectly. $\endgroup$
    – John S.
    Mar 16, 2016 at 2:05

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