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 OA 03 10 35 47 20 4B 04 63 [25 80 CO 00 show the value of state after SubstituteBytes. The S-box is as below. (6 points) 2B FO 304 C7 409 83 2 01 00 ED 600 EF AA FB 43 40 51 A3 40 75 206 x 8 CO EC 9 60 81 4F DC 22 46 33 85 45 9 2 2 38 75 BC D6 DA 21 10 44 17 C4 30 64 14 D 50 58 CF 3C 9 AB 02 EE 50 19 73] SE A EO 32 B E7 CB 7A 24 79 08 BA 70 BC AL 10 98 54 M16 (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 -I testfile", here is the result. (5 points) $15 -1 testfile -C-F-XCX 1 Acred users 1824 Nov 2 00:10 testfile Please explain what the above file permissions mean and write the octal number for the file permissions.