This set of homework is for the contents covered in Chapter 3 Data Encryption Standard 1. Answer the following concept questions about DES 1 What are the block size and key length? 2) How many rounds does DES iterate? How many S-boxes does DES use? 3) How many round-keys (sub-keys) does DES have? What is the length of a round-key? What are the input and output sizes of a S-box? 5 What are the inputs and output of round function f, and their sizes? 2. One important property which makes DES secure is that the S-Boxes are nonlinear. Here we want you to verify this property by computing the output of S; for the following two pairs of inputs. The S-box S2 is given as follows: S-box S2 S20 1 2 3 4 5 67 8 9 10 11 12 13 14 15 0 15 01 08 14 06 11 03 04 09 07 02 13 12 00 05 10 103 13 04 07 15 02 08 14 12 00 01 10 06 09 11 05 2 00 14 07 11 10 04 13 01 05 08 12 06 09 03 02 15 3 13 08 10 01 03 15 04 02 11 06 07 12 00 05 14 09 Show that S2(x) Sdx) # Sdx1x2), where-g denotes bitwise XOR for: 1) x, 000000, x2=000001 2) x 01001, x-100111 3. Please verify that IP) and IP() are truly inverse operations. We consider a vector x (x x .. xs) of 64 bit. Show tIP(IPx)) x for the first 10 bits of, i.e. for , ,2,3,4, 5, 6,7,8 9, 10