CY-503-B Network Security - Dec 2024 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
   aExplain the principle behind symmetric and asymmetric encryption. Describe the process of secure message authentication using hash functions with a relevant example.
   How to answer

   • Define symmetric encryption (single shared key) vs asymmetric (public/private key pair)
   • Explain principles: key distribution, confidentiality, speed vs scalability
   • Describe hash-based message authentication (e.g., HMAC / hash + signing) steps
   • Give relevant example of sender hashing message and receiver verification
2. 7 Marks
   bGive the ciphertext 'ZICVTWQNGRZGVTWAVZHCQYGLMGJ,' decrypt it using the Caesar cipher with a shift of 17. Show each step clearly.
   How to answer

   • State Caesar cipher decryption rule with shift 17 (shift back by 17)
   • Show alphabet mapping / formula for each character
   • Decrypt given ciphertext letter-by-letter showing steps
   • Write final plaintext result
3. 7 Marks
   aExplain how public-key cryptography can be used for digital signatures. Why are digital signatures considered a crucial aspect of secure communication?
   How to answer

   • Explain public-key signing: hash, encrypt with private key, verify with public key
   • Describe authentication, integrity and non-repudiation provided
   • Explain why signatures are crucial for secure communication
4. 7 Marks
   bDiscuss RC4 encryption algorithm. Considering a 5-bit RC4 key, generate the first 3 bytes of any pseudo-random key stream.
   How to answer

   • Describe RC4 KSA and PRGA steps
   • Explain 5-bit / small-state key scheduling concept
   • Show generation of first 3 pseudo-random keystream bytes
   • Note XOR with plaintext for encryption
5. 7 Marks
   aCompare Virtual Private Networks (VPN) with Trusted Operating Systems in terms of their security architecture and applications.
   How to answer

   • Define VPN and Trusted Operating System
   • Compare security architecture: network tunnel vs OS-level access control
   • Compare applications and trust models
   • Summarize differences in tabular form
6. 7 Marks
   bExplain the working of the Pretty Good Privacy (PGP) protocol and its use in securing email communication.
   How to answer

   • Outline PGP services: confidentiality, authentication, compression
   • Explain session key, public/private key and hash use
   • Describe PGP message format for email
   • State use in securing email communication
7. 7 Marks
   aDescribe the difference between Host-based IDS and Network-based IDS.
   How to answer

   • Define IDS and HIDS vs NIDS placement
   • Compare data source, visibility, deployment and scope
   • Compare advantages/limitations with examples
8. 7 Marks
   bList the types of firewalls and explain their operational differences with examples.
   How to answer

   • List firewall types: packet filter, stateful, proxy, NGFW etc.
   • Explain operation of each type
   • Highlight operational differences
   • Give examples for each
9. 7 Marks
   aMalicious software (malware) can infiltrate a network in various ways. Describe different types of malicious software and explain how IDS and firewalls can help safeguard against them.
   How to answer

   • List malware types: virus, worm, trojan, ransomware, spyware etc.
   • Describe infiltration vectors into network
   • Explain IDS detection and firewall prevention roles
   • Give safeguard strategy
10. 7 Marks
    bDescribe the main security concerns associated with online financial transactions and how the Secure Electronic Transaction (SET) protocol addresses them.
    How to answer

    • List online financial transaction threats: fraud, MITM, replay, data theft
    • Explain SET participants and dual signature concept
    • Show how SET provides confidentiality and authentication
    • Conclude how concerns are addressed
11. 7 Marks
    aDiscuss the security challenges associated with Wireless LANs.
    How to answer

    • List WLAN vulnerabilities: eavesdropping, rogue AP, MITM
    • Explain weak authentication and encryption issues
    • Discuss interference, mobility and access control challenges
12. 7 Marks
    bExplain WAP security mechanisms, specifically focusing on WTLS. How does it help to secure wireless communications?
    How to answer

    • Describe WAP security stack and WTLS layer
    • Explain WTLS services: encryption, integrity, authentication
    • Show WTLS handshake and datagram security
    • Explain role in securing wireless communication
13. 7 Marks
    aOutline the SSL Handshake Protocol and explain each step in establishing a secure connection between client and server.
    How to answer

    • List SSL handshake phases: hello, authentication, key exchange
    • Explain client-hello, server-hello, certificate exchange steps
    • Describe session key generation and finished messages
    • Show establishment of secure client-server connection
14. 7 Marks
    bDifferentiate between SSL Connection and SSL session. How do these concepts contribute to securing web traffic?
    How to answer

    • Define SSL connection vs SSL session
    • Differentiate on lifetime, state, parameters
    • Explain session resumption and caching
    • Show contribution to securing web traffic efficiently
15. 14 Marks
    Write short notes on (any four):

    1. a)Message Authentication Codes
    2. b)Parameter Pattern Matching
    3. c)IPSec
    4. d)Access point security in a public network environment
    5. e)Types of VPN
    How to answer

    • Define each chosen topic with principle and purpose
    • Explain working / components / steps
    • Give application or example in network security
    • Maintain concise short-note format for any four