(2) If the input to the S1 box is 101000 (the lookup table of S1 box is shown below), what is the output and why? (5 points) (3) Please discuss why C0=C16,D0=D16 in key schedule. (5 points) (4) Consider a simple block cipher using 8-bit block that is based on the Feistel Structure. It has only two rounds and has no initial or final permutation. The F-function for round i(i=1,2) is defined as fi(Ri1,ki)=5iRi1kimod20 , where Ri1 is a plaintext (right half), ki is a key that k1=10,k2=3 and plaintext is 10100101 (i.e. L0=1010,R0=0101 ). i. What is the ciphertext after the first round? (10 points) ii. What is the ciphertext after the second round? (10 points)