cryptography and network security

B.E/B.Tech DEGREE EXAMINATION, May/june 2009
(Regulation 2004) Computer Science and Engineering
1. What are the key principles of security?
2. How does simple columnar transposition work?
3. Show that 3 is a primitive root of 7
4. Find the GCD of 2740 and 1760 using Euclidian algorithm.
5. Why is SHA more secure than MD5?
6. Mention the fundamental idea of HMAC.
7. What are the security options PGP allows when sending an email message?
8. How IPSec does offers the authentication and confidentiality services?
9. What is IP address spoofing?
10. What are the common technique used to protect a password file?
Part –B
11. (a) (i) Draw the general structure of DES and explain the encryption decryption
(ii) Mention the strengths and weakness of DES algorithm. (6)
(b) Describe the block cipher modes of operation in detail. (16)
12. (a)(i) Explain how encryption and decryption are done using RSA crypto system (8)
(ii) How do elliptic curves take part in Encryption and Decryption process (8)
(b) Users A and B use the Diffie Hellman key exchange technique a common prime q=11 and
a primitive root alpha=7.
(i) If user A has private key XA =3 what is A’s public key YA?
(ii) If user B has private key XB =6 what is B’s public key YB?
(ii) What is the shared secret key? Also write the algorithm.(4)
(iv) How man in middle attack can be performed in Diffie Hellman algorithm
13. (a) (i) how does SHA-1 logic produce message digest? (10)
(ii) Explain the challenges/ response approach in mutual authentication.(6)
(b) (i) Explain Digest signature algorithm(DSA) in detail. (10)
(ii) What is Message Authentication? Explain. (6)
14. (a) How does PGP provide confidentiality and authentication service for e-mail and file
storage applications? Draw the block diagram and explain its components. (16)
(b) (i) Bring out the importance of security associations in IP. (6)
(ii) Describe the SSL Specific protocol – Handshake action in detail. (10)
15. (a) Explain the types of Host based intrusion detection. List any 2 IDS software available.
(b)(i) What are the positive and negative effects of firewall? (8)
(ii) Describe packet filtering router in detail. (8)