TRIBHUVAN UNIVERSITY
INSTITUTE OF SCIENCE AND TECHNOLOGY
2081 B.S.
Candidates are required to give their answers in their own words as far as practicable.
Group A
Long Answer QuestionsAttempt any Two questions.
- 1Let us consider the 4 bits key set as {1100, 1010, 0000, 1111, 0101, 1001} and input text as {1011, 1110, 1011, 1000}. Now trace the first full round operation of IDEA algorithm. [10]
- 2What is message authentification code? List the operations of computing digest value in different passes of MD4. Describe about Needhom-Schroeder protocol. [1+5+4]
- 3Why do we need discrete logarithms? Illustrate with an example. Consider a Diffie-Hellman scheme with $p=13$. User A public key = 10, User B public key = 8. Determine private keys and shared secret key using a valid primitive root. [3+7]
Group B
Short Answer QuestionsAttempt any Eight questions.
- 4Show encryption of plaintext "ALGORITHM" using the key "PSEUDOCODE" using playfair cipher. [5]
- 5Discuss the working mechanism of the Kerberos protocol. [5]
- 6What is the use of firewall? How circuit level gateway differs from stateful inspection. [2+3]
- 7What is intrusion? Explain any two types of intrusion detection system. [1+4]
- 8Find the multiplicative inverse of polynomial {95} using Extended Euclidean Algorithm. [5]
- 9What is DoS attack? Discuss about PKI trust model. [2+3]
- 10Using Vigenere cipher with key="worlds", encrypt the plain text "hello everyone". [5]
- 11Describe the different modes of block cipher encryption. [5]
- 12Write short notes on (any two): a) Totient value b) Hash properties c) Virus Vs Worms [2.5+2.5]