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I am creating a program in C language with DES (Data Encryption Standard) functionality, but don't know how to apply the initial permutation.

Is it achieved by swapping the values? If "yes", then how is the index of the original message created?

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You should check out this:… Thanks. – Yang Xia Sep 24 '13 at 11:55
It's a bitwise permutation. What values are you thinking might be swapped? – B-Con Sep 25 '13 at 23:35
You haven't describe the interface type for your DES function (e.g. array of bits, arrays of bytes, array of .., 64 bit value). – user1155120 Nov 20 '13 at 16:57

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