Cryptography & System Security - May 2015

Computer Engineering (Semester 7)

TOTAL MARKS: 80
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks.

1 (a) Distinguish between substitution cipher and transposition cipher. (5 marks)

1 (b) What are different types of malicious codes. (5 marks)

1 (c) What are the different types of IP-Spoofing. (5 marks)

2 (a) A and B decide to use Diffie-Hellman key exchange where P=13, g=2. Each choose his own secret no. and exchange nos. 6 and 11.
i) What is common secret key?
ii) What are their secret nos?
iii) Can intruder M, gain any knowledge from protocol run if he sees p, g and the 2 public keys 6 & 11. If yes, show how? (10 marks)

2 (b) Explain structure of DES. (10 marks)

3 (a) Describe block ciphers? Explain any one with example. (10 marks)

3 (b) Explain difference between MAC and message digest? What is role of compression function in general structure of message digest? (10 marks)

4 (a) What is Reverse Engineering? Explain need of Digital Rights Management. (10 marks)

4 (b) What is Buffer overflow and incomplete mediation in Software Security? (10 marks)

5 (a) How does ESP header guarantee confidentiality & integrity for packet payload? (10 marks)

5 (b) What makes a network vulnerable? (10 marks)

6 (a) What are different types of firewalls? Explain design, configuration and limitations. (10 marks)

6 (b) IPSec offers security at network layer. What is the need of SSL? Explain the services of SSL protocol? (10 marks)

Write short notes on (any two):

7 (a) MDS. (10 marks)

7 (b) Covert Chanel. (10 marks)

7 (c) CAPCHA. (10 marks)

7 (d) Trojan. (10 marks) 1 (d) Differentiate between - vulnerability, threats and controls.(5 marks)