SRM University 2007 B.Tech Computer Science and Engineering BANK FOR CS-356 NETWORK SECURITY - Question Paper

9. What are the principal elements of a public key encryption scheme?
10. Differentiate conventional and public key encryption techniques.
11. Diagrammatically represent public key cryptography for Authentication.
12. Diagrammatically represent public key cryptography for Confidentiality.
13. What are the roles of public and private key in a public key encryption
scheme?
14. What are the 3 broad categories of applications of public key
cryptosystems?
15. What is an elliptic curve?
16. Define zero point of an elliptic curve.
17. What is the advantage of elliptic curve cryptography over RSA?
18. What does blinding in RSA mean?
19. List the various counter measures to avoid timing attacks in RSA.

PART B

1.State and prove Fermat's and Euler's theorem.
2. a) Summarize extended Euclid's algorithm.
b) obtain GCD and multiplicative inverse of 550 mod 1759
3. a) Summarize RSA algorithm.
b) Perform encryption and decryption for the following: p = 11, q = 13, e = 11,
M = 7.
4. a) In a public key system using RSA, cipher text C = 10 is sent to a user whose
public key is e = 5, n = 35. What is the plain text M?
b) Briefly explain the security of RSA algorithm.
5. Consider Diffie-Hellman scheme with a common prime q = 11 and a primitive
root a = 2.
a) Show that two is a primitive root of 11.
b) If user A has public key YA = 9, What is A's private key XA?
c) If user B has public key YB = 3. What is the shared secret key K?
6. Consider Diffie-Hellman scheme with a common prime q = 71 and a primitive
root a = 7.
a) If user A has private key XA= 5, What is A's public key YA?
b) If user B has private key X B = 12. What is B's public key Y B?
c) What is the shared secret key K?
7. a) Summarize elliptic curve cryptography key exchange algorithm.
b) Briefly explain encryption and decryption using elliptic curve
Cryptography.


UNIT IV
PART A

1. What kinds of attacks are addressed by message authentication?
2. Write the 3 kinds of functions that may be used to produce an
authenticator.
3. Write any 3 properties of a hash function used in message authentication
4. What is meant by message authentication?
5. What is a message authentication code (MAC)?

Earning:   Approval pending.