CSIT 5th Semester
Cryptography Board Question Paper 2082

CSC 327-2082 ✡
Tribhuvan University
Institute of Science and Technology
2082
✡
Bachelor Level/Third Year/Fifth Semester/Science
Computer Science Information Technology (CSC 327)
(Cryptography)
(New Course)
Full Marks:60 Pass Marks:24 Time:3 hours

Candidates are required to give their answers in their own words as for as practicable.
The figures in the margin indicate full marks

Section A
Long Answer Questions
Attempt any Two question.
[2x10=20]
1.

Describe the Fiestel Cipher structure. Given the key {28,7F,,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.

0123456789ABCDEF
0637C777BF26B6FC53001672BFED7AB76

2.

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.

List the properties of hash function. Describe the algorithm for SHA -1 .

Section B

Attempt any Eight questions

[8x5=40]
4.

Describe any three types of malicious logic.

5.

Given the key "HELLOWORLD", encrypt the plaintext "TURINGTEST" using Play fair cipher.

6.

Explain any two modes of block cipher encryption.

7.

State Fermat's theorem with example. What is the implication of discrete logarithm?

8.

Describe the working mechanism of digital signature algorithm.

9.

List and explain the types of firewall.

10.

Decrypt the ciphetext "HI" using Hill Cipher where the key is

53
41
.

11.

What is digital certificate? Discuss the certificate life cycle.

12.

Define authentication system. Discuss about challenge response system.