5 Sep
2000
5 Sep
'00
8:18 p.m.
Hi all, I was just wondering... In DES, there's an Initial Permutation (IP) on the plaintext, then 16 rounds, and then the inverse permutation (IP^-1) of the result to produce the ciphertext. How effective are these permutations? Do they really add diffusion to the algorithm, considering that they don't depend on the key? Someone told me that they are necessary to provide reversibility to DES. Is this correct? Thanks in advance, Best Regards, Devegili