Tribhuvan University
Bachelor of Science in Computer Science and Information Technology
Semester 5 · TU Board 2080
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
Define discrete logarithms. How key generation, encryption and decryption is done in RSA. In a RSA cryptosystem, given p=13 and q=7, determine private key, public key and perform encryption and decryption for the text M="hi" using 0 to 25 for letters from a to z.
- 2.10
Write down the encryption and decryption process at 2-DES and 3-DES. Explain the Fiestal cipher structure. Divide 5x^2 + 4x + 6 by 2x + 1 over GF(7).
- 3.10
What are the applications of hash functions? Discuss how SHA-1 algorithm generates hash value from a given message.
Answer comingAlso asked in 2082, 2079
Group B
Attempt any eight questions.(8 × 5 = 40)
- 4.5
Show encryption and decryption of "csit" using hill cipher having key, k=
3
2
5
7 - 5.5
Give the formal definition of authentication system. Describe about one way and mutual authentication system.
- 6.5
List the stage of certificate life cycle. What are the types of firewalls?
Answer comingAlso asked in 2082
- 7.5
What is malicious logic? How zombies are different from trojan horses?
- 8.5
How Miller Rabin test is used for primality testing? Show whether the number 561 passes the test.
- 9.5
Show that the set of integers is Ring under addition and multiplication.
- 10.5
How substitution ciphers are different from transposition ciphers? Given a message M="CSIT PROGRAM IS A HOT CAKE", encrypt M using Rail Fence cipher with rail size 3.
- 11.5
Describe about IPSec. List the five services of PGP.
- 12.5
How does meet in middle attack work in Diffie Helman key exchange protocol? Explain.
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