IT-801 Information Security - Jun 2025 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aDefine the terms threat and attack. List and define categories of security attacks.
   How to answer

   • Define threat vs attack
   • List categories: interruption, interception, modification, fabrication
   • Define passive vs active attacks with examples
   • Brief impact on confidentiality, integrity, availability
2. 7 Marks
   bWhat are the differences between security and protection? Explain.
   How to answer

   • Define security vs protection
   • Compare objectives, scope and mechanisms
   • Give examples of each
   • Summarize differences in tabular form
3. 7 Marks
   aWhat is play fair cipher? Explain with suitable example.
   How to answer

   • Define Playfair cipher and 5x5 key matrix rules
   • Explain key preparation and digraph formation
   • Show encryption rules for same row, column, rectangle
   • Illustrate with suitable example
4. 7 Marks
   bCompare steganography with encryption techniques.
   How to answer

   • Define steganography and encryption
   • Compare on visibility, purpose, security principle
   • Give examples of each technique
   • Tabulate differences
5. 7 Marks
   aDefine block cipher. Explain design principle of block cipher.
   How to answer

   • Define block cipher and block size
   • Explain confusion and diffusion design principles
   • Describe Feistel and SPN structures
   • Mention padding and modes of operation
6. 7 Marks
   bWhat is the purpose of Sboxes in DES? Explain the avalanche effect.
   How to answer

   • Explain role of S-boxes for non-linearity and confusion
   • Describe DES S-box mapping 6-bit to 4-bit
   • Define avalanche effect
   • Explain with example of one-bit change
7. 7 Marks
   aExplain the terms diffusion and confusion. Explain steps of AES.
   How to answer

   • Define diffusion and confusion by Shannon
   • Relate to S-boxes and P-boxes
   • List AES steps: SubBytes, ShiftRows, MixColumns, AddRoundKey
   • Brief function of each AES step
8. 7 Marks
   bExplain working of ECB. Why ECB (Electronic Code Book) is rarely used to encrypt message?
   How to answer

   • Describe ECB encryption and decryption operation
   • Explain independent block processing
   • Discuss pattern leakage and lack of diffusion
   • Explain why rarely used for long messages
9. 7 Marks
   aCompare public and private key cryptography. Also list various algorithm for each.
   How to answer

   • Define public-key vs private-key cryptography
   • Compare keys, speed, key distribution, scalability
   • List symmetric algorithms: DES, AES, etc.
   • List asymmetric algorithms: RSA, Diffie-Hellman, ECC
10. 7 Marks
    bExplain Encryption and Decryption in RSA algorithm. Also discuss various attacks on it.
    How to answer

    • Explain RSA key generation, encryption $C=M^e \bmod n$
    • Explain decryption $M=C^d \bmod n$
    • Discuss mathematical, brute-force and timing attacks
    • Mention countermeasures like padding and large primes
11. 7 Marks
    aWhat is Primitive Root? Explain Diffie-Hellman Key exchange algorithm with example.
    How to answer

    • Define primitive root modulo prime
    • Explain Diffie-Hellman public parameters and private secrets
    • Show shared secret computation steps
    • Illustrate with small numerical example
12. 7 Marks
    bHashing does not ensure integrity of message in network communication. Justify answer with example.
    How to answer

    • Define hashing and its properties
    • Show attacker can modify message and recompute hash
    • Explain need for keyed hash / MAC and HMAC
    • Give example of integrity failure
13. 7 Marks
    aHow message authentication code can be used to achieve message authentication and confidentiality?
    How to answer

    • Define MAC and its generation
    • Explain MAC for authentication only
    • Explain MAC + encryption combinations for confidentiality
    • Mention HMAC and CBC-MAC usage
14. 7 Marks
    bWhy do these need to use double encryption when using Kerberos?
    How to answer

    • Outline Kerberos ticket and authenticator flow
    • Explain double encryption of session key and ticket
    • Show protection against eavesdropping and replay
    • Justify need for KDC secrecy
15. 7 Marks
    aWhat is Intrusion Detection? Explain Password Management.
    How to answer

    • Define intrusion detection and IDS types
    • Explain password management policies
    • Discuss password selection, aging and salting
    • Mention countermeasures against guessing attacks
16. Marks
    bWrite short notes on following: (any two)

    1. i)DOS
    2. ii)Firewalls
    3. iii)Trusted Systems
    How to answer

    • Define DOS attack and its types
    • Explain firewall types and functions
    • Define trusted systems and security levels
    • Write concise notes on any two with examples