Institute of Science and Technology
Bachelor Level/second semester/Science
Computer science and information Technology
Candidates are required to give their answers in their own words as far as practicable. The figures in the margin indicate full marks.
ATTEMPT ALL QUESTIONS
1. Answer following questions in short (any Five)
a How MAC differs from Hash? Is authentication and authorization refers to same term or different? Justify.
b. Differentiate between virus and worms.
c . What is the importance of Trap Door function in cryptography?
d. How many rounds are used in AES and what does the number or rounds depend on?
e . what does Zn rerer to in cryptograpny ? illustrate with example
f . List the five services that PGP operation is based on.
g John obtains Peter’s credit card number and performs shopping. Does it violate confidentiality or integrity or both 7 Justity.
2. a. What is Fermat’s Little theorem? What is the totient of a prime number? Give an example.
Define primitive root of a prime number with a suitable example,
b. Find the multiplicative inverse of 11 in 2s using extended Euclidean algorithm.
3. a. Find the result of the following operations.
27 mod 5 36 mod 12 -18 mod 14 -7 mod 10 -13 mod 7
b. How can RSA can be used tor generating public and private key? Explain.
4. a. Encrypt the message “computing for human life” to playfair cipher using key ” BSCCSIT”
b. Explain about the working mechanism of Kerberos.
5. a. Does it possible to design collision free hash function? What does birthday attack refers to? Explain.
What is the role of SSL Record Protocol in SSL/UTLS? Explain
b Describe the mix column transformation that constitutes the third steep in each round of AES.