Tribhuvan University
Bachelor of Science in Computer Science and Information Technology
Semester 5 · TU Board 2081
Course Title: Cryptography (CSC316)
Full Marks: 60Pass Marks: 24Time: 3 hours
Candidates are required to give their answers in their own words as far as practicable. The figures in the margin indicate full marks.
Group A
Attempt any TWO question.(2 × 10 = 20)
- 1.10
Let 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.
- 2.10
What is Message Authentication Code? List the operation of computing digest value in different passes of MD4. Describe about Needhom-Schroeder protocol.
- 3.10
Why do we need discrete logarithm? Illustrate with an example. Consider a Diffie-Hellman scheme with a common prime p = 13 between user A and user B. Suppose public key of A is 10 and public key of B is 8. Now determine their private keys and shared secret key. Select any valid primitive root of 13.
Group B
Attempt any EIGHT question.(8 × 5 = 40)
- 4.5
Show the encryption of plain text "ALGORITHM" using the key "PSEUDOCODE" using playfair cipher.
- 5.5
Discuss the working mechanism of kerberos protocol.
- 6.5
What is the use of firewall? How circuit level gateway differs from stateful inspection firewall?
- 7.5
What is intrusion ? Explain any two types of intrusion detection system.
- 8.5
Find the multiplicative inverse of polynomial {95} using extended euclidean Algorithm.
- 9.5
What is DoS attack ? Discuss about PKI trust model.
Answer comingAlso asked in 2078
- 10.5
Using Vignere cipher with key = "worlds", encrypt the plain text "hello everyone".
- 11.5
Describe the different modes of block cipher.
Answer comingAlso asked in 2082, 2078
- 12.5
Write short notes on (any two)
- Totient value of any positive integer.
- Properties of hash function.
- Virus or Worms.
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