TRIBHUVAN UNIVERSITY
INSTITUTE OF SCIENCE AND TECHNOLOGY
2082 B.S.
Candidates are required to give their answers in their own words as far as practicable.
Group A
Long Answer QuestionsAttempt any Two questions.
- 1Describe 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. [3+7]
- 2Illustrate 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+7]
- 3List the properties of hash function. Describe the algorithm for SHA-1. [4+6]
Group B
Short Answer QuestionsAttempt any Eight questions.
- 4Describe any three types of malicious logic. [5]
- 5Given the key "HELLOWORLD", encrypt the plaintext "TURINGTEST" using Playfair cipher. [5]
- 6Explain any two modes of block cipher encryption. [5]
- 7State Fermat's theorem with example. What is the implication of discrete logarithm? [3+2]
- 8Describe the working mechanism of digital signature algorithm. [5]
- 9List and explain the types of firewall. [5]
- 10Decrypt the ciphertext "HI" using Hill Cipher where the key is $\begin{bmatrix}5&3\\ 4&3\end{bmatrix}$ [5]
- 11What is digital certificate? Discuss the certificate life cycle. [2+3]
- 12Define authentication system. Discuss about challenge response system. [2.5+2.5]