1. Answer the following questions (a) What is the difference between diffusion and confusion? (4 points) (b) Suppose the AES state after initial AddRoundKey is 05 09 3D 0A 03 10 35 47 20 4B 04 63 5 80 CO 00 show the value of state after SubstituteBytes. The S-box is as below. (6 points) (c) What is the difference between a backdoor, a bot, a keylogger, spyware, and a rootkit? Can they all be present in the same malware? (6 points) (d) List at least three measures to prevent DoS attacks. (3 points) (e) In Unix system, when Bob enter "Is - testfile", here is the result. (5 points) S1s -1 testfile -qd-r-XCR-1 anca8d users 1024 Nov 200 : 10 testa,e Please explain what the above file permissions mean and write the octal number for the file permissions