5. a) Define P-box and S-box. Mention the necessary condition for an S-box to be invertible. b) Show the permutation table for the following P-box. Figure 1: Question 5(b) Show the P-box defined by the following table. How to invert this permutation table? 7 5 2 3 4 8 61 c) The input/output relationship in a 4X4 S-box is shown by the following table. Show the corresponding table for the inverse S-box. MSBs of Input LSBs of Input 00 01 10 11 00 1000 0101 1010 0000 01 1011 000111000010 10 0100 1111 0110 1101 11 1100 0111 1001 0011 Figure 2: Question 5(c) If the input to the above S-box is 1001, then what is the output?