BSc CSIT (TU) Science Cryptography (BSc CSIT, CSC316) Question Paper 2081
This is the official BSc CSIT (TU) (Science stream) Cryptography (BSc CSIT, CSC316) question paper for 2081, as set in the regular annual examination. It carries 60 full marks and a time allowance of 180 minutes, across 12 questions. On Kekkei you can attempt this Cryptography (BSc CSIT, CSC316) past paper online with a timer, get instant AI feedback and step-by-step solutions, and track the topics where you lose marks — completely free. Whether you are revising for your BSc CSIT (TU) Cryptography (BSc CSIT, CSC316) exam or solving previous years' question papers, this 2081 paper is a great way to practise under real exam conditions.
Section A: Long Answer Questions
Attempt any TWO questions.
What is a digital signature? Explain the digital signature scheme using RSA and the role of digital signatures in authentication and non-repudiation.
Explain the RSA algorithm. Show how encryption and decryption are performed. Choose two primes p=7 and q=11, compute the public and private key pairs and encrypt the message M=8.
Explain the structure of the Data Encryption Standard (DES) algorithm with a block diagram. Describe a single round of DES including the function F.
Section B: Short Answer Questions
Attempt any EIGHT questions.
Explain the basic logic of malicious code: viruses, worms and trojan horses.
State the Chinese Remainder Theorem and use it to solve a system of congruences.
Explain the goals of security: confidentiality, integrity and availability. List the different types of security attacks.
Differentiate between symmetric and asymmetric key cryptography with examples.
Explain the Caesar cipher and the mono-alphabetic substitution cipher with examples of their cryptanalysis.
Explain modular arithmetic and Euler's totient function. Compute phi(35) and phi(24).
Explain the ElGamal cryptographic system for encryption and decryption.
Differentiate between block ciphers and stream ciphers. Explain the different modes of operation of block ciphers.
What is a Message Authentication Code (MAC)? Explain how HMAC works.