CS-703-A Cryptography and Information Security - Nov 2023 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
   aDescribe Fermat's little theorem with an example.
   How to answer

   • State Fermat's little theorem: a^(p-1) = 1 mod p for prime p, a not divisible by p
   • Give general form a^p = a mod p
   • Work out numeric example e.g. p=7, a=2
   • Mention use in primality testing / RSA
2. 7 Marks
   bDefine Cryptanalysis. Explain the concept of cryptanalysis on substitution cipher.
   How to answer

   • Define cryptanalysis and its goal
   • Define substitution cipher
   • Explain frequency analysis and attack steps on substitution cipher
   • Give small example of breaking substitution
3. 7 Marks
   aIllustrate DES algorithm with neat diagram. Explain S-box importance in DES.
   How to answer

   • Outline DES structure: IP, 16 Feistel rounds, swap, FP
   • Draw block diagram of DES with F-function
   • Explain S-box substitution 6-bit to 4-bit
   • Explain importance: non-linearity, confusion, security
4. 7 Marks
   bHow to establish a shared secret between two parties using Diffie-Hellmann key exchange algorithm? Explain.
   How to answer

   • State Diffie-Hellman global parameters p, g
   • Explain private and public key generation for A and B
   • Show shared secret computation K = Yb^Xa = Ya^Xb mod p
   • Explain discrete logarithm difficulty and man-in-middle limitation
5. 7 Marks
   aExplain RSA algorithm? Give an example of encryption and decryption using RSA?
   How to answer

   • Outline RSA key generation: p, q, n, phi, e, d
   • State encryption C = M^e mod n and decryption M = C^d mod n
   • Give small numeric example with p, q
   • Mention security based on factoring
6. 7 Marks
   bDescribe the Schnorr Identification Scheme in detail.
   How to answer

   • State Schnorr identification setup and parameters
   • Explain prover commitment, verifier challenge, response steps
   • Give verification equation
   • Mention zero-knowledge property and security
7. 7 Marks
   aWhat are the types of attacks addressed by message authentication? What are the two levels of functionality the comprise a message authentication or digital signature mechanism?
   How to answer

   • List attacks: disclosure, traffic analysis, masquerade, content modification, sequence modification, timing modification
   • Define lower level: authentication function producing authenticator
   • Define higher level: protocol using function for verification
   • Relate to MAC and digital signature
8. 7 Marks
   bDescribe the Digital Signature Standard (DSS) in detail.
   How to answer

   • Introduce DSS/NIST standard and DSA basis
   • Explain global parameters p, q, g and key generation
   • Explain signature generation r, s steps
   • Explain verification steps
9. 7 Marks
   aWhat is Firewall? Explain different types of firewalls in detail.
   How to answer

   • Define firewall and its purpose
   • Explain packet filter, stateful, application proxy, circuit gateway
   • Compare filtering capabilities
   • Mention limitations and placement
10. 7 Marks
    bWrite about the usage of Session keys, Public and Private keys in PGP.
    How to answer

    • Outline PGP services for confidentiality and authentication
    • Explain random session key generation and encryption
    • Explain use of recipient public key and sender private key
    • Explain decryption and key management flow
11. 7 Marks
    aAnalyze the Cryptographic algorithms used in S-MIME. Explain S-MIME certification processing.
    How to answer

    • List S-MIME crypto functions: hash, signature, encryption
    • Mention algorithms: RSA, DSS, AES, 3DES, SHA
    • Explain certificate processing and CA hierarchy
    • Explain enveloped and signed data
12. 7 Marks
    bDiscuss about Encapsulating Security Payload.
    How to answer

    • Define ESP in IPSec context
    • Explain header format and fields
    • Explain transport vs tunnel mode
    • Mention confidentiality, authentication services
13. 7 Marks
    aExplain different types of DoS attack understanding tools.
    How to answer

    • Define DoS and DDoS
    • Classify attacks: flooding, SYN, Smurf, etc.
    • Explain attack tools and their working
    • Mention countermeasures
14. 7 Marks
    bWhat is Steganography? Explain different types of Steganography.
    How to answer

    • Define steganography vs cryptography
    • Explain text, image, audio, video, network types
    • Explain embedding and extraction principle
    • Give examples of LSB technique
15. 14 Marks
    Write short notes on any Two:

    1. i)Block Cipher
    2. ii)Hash Function
    3. iii)Transport Layer Security
    4. iv)Foot Printing Tools
    How to answer

    • Select any two topics from list
    • Give definition, principle and diagram for each
    • Mention applications and security role
    • Conclude with advantages/limitations