Tribhuvan University
Bachelor of Science in Computer Science and Information Technology
Semester 5 · TU Board 2082
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 questions.(2 × 10 = 20)
- 1.10
Describe the Fiestel Cipher structure. Given the key {2B, 7E, 15, 16, 28, AE, D2, A6, AB, F7, 97, 66, 01, 02, 03, 04}, compute the first 4 byte of next key after first iteration, using the following S-Box in AES.
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
0
63
7C
77
7B
F2
6B
6F
C5
30
01
67
2B
FE
D7
AB
76 - 2.10
Illustrate the man in middle attack in Diffie – Hellman key exchange protocol. Assume the prime number be 19 and 10 as its primitive root. Select 5 as private key and 4 as random integer. Find the cipher text of M = 2 using Elgamal crypto system.
- 3.10
List the properties of hash function. Describe the algorithm for SHA-1.
Answer comingAlso asked in 2080, 2079
Group B
Attempt any EIGHT questions.(8 × 5 = 40)
- 4.5
Describe any three types of malicious logic.
- 5.5
Given the key "HELLOWORLD", encrypt the plaintext "TURINGTEST" using Play fair cipher.
- 6.5
Explain any two modes of block cipher encryption.
Answer comingAlso asked in 2081, 2078
- 7.5
State Fermat's theorem with example. What is the implication of discrete logarithm?
- 8.5
Describe the working mechanism of digital signature algorithm.
- 9.5
List and explain the types of firewall.
- 10.5
Decrypt the ciphertext "HI" using Hill Cipher where the key is [5/4 3/3].
- 11.5
What is digital certificate? Discuss the certificate life cycle.
Answer comingAlso asked in 2080
- 12.5
Define authentication system. Discuss about challenge response system.
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