I would like to implement fast DES decryption using Bitslice technique. Without bitslice DES technique, I have already done decrpytion in this source code by changing the for loop from 15 to 0.
In this source code there is no decryption function for DES. How to implement decryption function using the encyption routine? What modifications can be done?
Another source code that is written with the same approach.
s1 (r31 ^ k, r0 ^ k, r1 ^ k, r2 ^ k, r3 ^ k, r4 ^ k, &l8, &l16, &l22, &l30);
I think the k indexes should be changed. At the encryption function, in first s1 box, I didn't get why the first k is selected 47, 11, 26 3, 13 ,41 and so on. If anyone tell me why, i may do it.