I'm implementing impossible differential cryptanalysis on 3.5 round IDEA using the methods in "Miss in the middle attack on IDEA and Khufu" paper.
In the first step, I need to provide $2^{32}$ pairs that are identical in $X_2$ and $X_4$ and have all the possiblitiespossibilities in $X_1$ and $X_3$ to start the cryptanalysis.
So I've tried to collect the text for various books to provide the first plaintext and the second plaintext of the pair is computed so that it matchsmatches the input difference of the pairs.
butBut all the text that I come up with is equivilantequivalent to only 2 million plaintexts so I'm repeating this for the rest of the pairs to reach $2^{32}$ pairs.
isIs this correct or should I have to get unique text for each pair and if that's what I should do where I could find these large texts?