Cryptography
The course introduces the underlying the principles and design of cryptosystems. The course covers the basics concepts of cryptography including: traditional ciphers, block ciphers, stream ciphers, public and private key cryptosystems. The course also includes the theory of hash functions, authentication systems, network security protocols and malicious logic.
Tribhuvan University
Institute of Science and Technology
2078
Bachelor Level / fifth-semester / Science
Computer Science and Information Technology( CSC316 )
Cryptography
Full Marks: 60 + 20 + 20
Pass Marks: 24 + 8 + 8
Time: 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.
Section A
Attempt Any Two Questions
Define CIA triad. State the encryption process of double and triple DES. What is the task of S-Box in DES ? Discuss with an example.
Explain the generic model of digital signature process. Consider the two prime numbers 7 and 19. Select 29 as public key and 41 as private key. Encrypt the plaintext 4 and decrypt the cipher text 3 using RSA.
Define Galois field with an example. Explain any two modes of block cipher encryption. Deterimine the quadratic residues of 7.
Section B
Attempt Eight Questions
What does intrusion mean? How the system detect intrusion? List any four types of firewall.
Decrypt the message “GVPJ” using Hill cipher taking the key as {Row1 = 3 7, Row2 = 5 12}.
Describe the PKI trust model.
Define authentication system. Illustrate the need of mutual authentication over one way authentication with an example.
Find the value of 7^2019 MOD 13 using Fermat’s Little theorem. Define Euler totient function with
an example.
List the properties of hash function. Discuss the first pass of MD4.
Differentiate between Symmetric and Asymmetric cipher. Encrypt the message “HELL” using
the key “FAIL” using Vernanm cipher.
Divide 3x2 + 4x +3 by 5x +6 over GF(7).
Define SSL protocol. Mention the services provided by PGP.