Cryptography & Network Security (CNS)

Question Bank- MSc IT-Part I

Unit 1
1. Specify the four categories of security threats.

2. Explain active and passive attack with example. /Compare active and passive attack.

3. Define i.integrity ii. non-repudiation iii. Confidentiality iv. authentication.

4. Differentiate symmetric and asymmetric encryption.

5. Discuss examples from real life, where the following security objectives are needed : i)
Confidentiality. ii) Integrity. iii) Non-repudiation. Suggest suitable security
mechanisms to achieve them.

6. Explain 1.ceaser cipher 2. Mono alphabetic cipher 3.one time pad cipher

7. Define cryptography. Define cryptanalysis?

8. Describe the various security mechanisms

9. Define computer security? Why network need security?

10. Compare Substitution and Transposition techniques.

11. What are hill cipher merits and demerits?

12. Explain the followings: (a) Playfair cipher. (b) Vernam cipher in detail.

13. Write short notes on i) Steganography

14. Explain classical Encryption techniques in detail.

15. Write short notes on (a) Security services (b) Feistel cipher structure

16. Explain OSI Security Architecture model with neat diagram

17. Explain various transposition ciphers in detail.

18. Convert “MEET ME” using Hill cipher with the key matrix Convert the cipher text
back to plaintext.

19. Let message = “Anna”, and k = 3, find the ciphertext using Caesar.

20. Encrypt the plaintext tobeornottobe using the vigenere cipher for the key value Now.

21. What is meant by padding? And, why padding is required?

22. What is meant by Denial of Service attack? Is it Active Attack or Passive Attack?
23. Discuss any four Substitution Technique and list their merits and demerits.

24. Explain in detail about various types of attacks.

25. Write short notes on (i)Fermat and Eluer’s theorem (ii)Chinese Remainder theorem

26. Discuss with neat sketch a network security model.

27. Let message = “graduate”, Key = “word”, find ciphertext using playfair cipher.

28. Using play fair cipher algorithm encrypts the message using the key "MONARCHY"
and Explains the poly alphabetic key.

29. List out any two di-gram, two tri-gram. Shortly describe the application of di-gram
and tri-gram in cryptography.

30. Encrypt the message “this is an exercise” using additive cipher with key = 20. Ignore
the space between words. Decrypt the message to get the original plaintext.

31. What is Monoalphabetic cipher ? Examine how it differs from Caesar cipher.

32. Demonstrate encryption and decryption process in hill cipher. Consider m = “sh” and
key = hill”.

Unit 2
1. State and explain the principles of public key cryptography?

2. Explain the key management of public key encryption in detail?

3. Compare stream cipher with block cipher with example.

4. What are the design parameters of Feistel cipher network?

5. Draw functional diagram of RSA based Digital Signature.

6. Explain simplified DES with example. / Explain the Key Generation, Encryption and
Decryption of DES algorithm in detail. / Explain single round DES with neat sketch. /
Explain Double &Triple DES with keys./ Mention the strengths and weakness of DES
algorithm.

7. Explain RSA algorithm in detail with an example?

8. Identify the possible threats for RSA algorithm and list their counter measures

9. What are the requirements and applications of public key? Compare conventional
with public key encryption.

10. Write short notes on block cipher modes of operation./ Give the five modes of
operation of block cipher.

11. State advantages of counter mode.

12. Explain in detail about Feistel cipher with diagram

13. Explain Diffusion & Confusion

14. Define Multiple Encryption.

15. List & Explain the attacks to RSA

16. List & Explain the schemes for the distribution of public keys.

17. Drawback of 3-DES.

18. What is Triple Encryption? How many keys are used in triple encryption?

19. Explain Avalanche effect.

20. Explain the generation sub key and S Box from the given 32-bit key by Blowfish.

21. For each of the following elements of DES, indicate the comparable element in AES if
available : a) XOR of subkey material with the input to the function. b) f function

22. Specify the design criteria of block cipher.

23. Draw the functionality diagram (functionality in one round) of DES with number of
bits in each flow of data.

24. Explain the bitwise XOR operation which involved in RC4.

25. Describe about RC4 algorithm.

26. What do you mean by AES ? Diagrammatically illustrate the structure of AES and
describe the steps in AES encryption process with example. / Explain in detail the key
generation in AES algorithm and its expansion format.

27. Explain with sample data: Four transformations in AES.

28. In AES, how the encryption key is expanded to produce keys for the 10 rounds

29. With a neat sketch, explain the Elliptic curve cryptography with an example.

30. Explain Diffie Hellman key Exchange in detail with an example?

31. Demonstrate the DH key exchange methodology using following key values : p  11 ,
g  2, XA  9 , XB = 4

32. Diffie–Hellman key agreement is not limited to negotiating a key shared by only two
participants. Any number of users can take part in an agreement by performing
iterations of the agreement protocol and exchanging intermediate, Write the steps and
formulas to be followed for DH key exchange between Alice, Bob, and Carol.

33. In a public-key system using RSA, you intercept the ciphertext C = 20 sent to a user
whose public key is e = 13, n = 77. What is the plaintext M?
34. Alice and Bob use the Diffie – Hellman key exchange technique with a common prime
number 11 and a primitive root of 2. If Alice and Bob choose distinct secret integers as
9 and 3, respectively, then compute the shared secret key

35. In an RSA system, the public key of a given user is e = 65, n = 2881, What is the private
key of this user?

36. Write the steps involved in the Generation of Message Digest.

37. Alice chooses 173 and 149 as two prime numbers and 3 as public key in RSA. Check
whether the chosen prime numbers are valid or not?

38. (ii) Prove that Euler’s Totient value of any prime number (p) is p  1 and the Euler’s
Totient value of the non-prime number (n) is (p 10 ( q 1 )where p  q are prime
factor of n.

39. Mr. Ram chooses RSA for encryption, and he chooses 3 and 7 are two prime numbers.
He encrypt the given message (message given in English alphabets) by mapping A =
1, B = 2, C = 3.., Z = 26. Find atleast two problems in his implementation.

40. For p = 11 and q = 19 and choose d = 17. Apply RSA algorithm where Cipher message
= 80 and thus find the plain text.

41. What is MAC ? Mention the requirement of MAC.

42. Explain the classification of authentication function in detail.

43. Describe MD5 algorithm in detail. Compare its performance with SHA-1.

44. Describe SHA-1 algorithm in detail. Compare its performance with MD5.

45. Describe HMAC algorithm in detail.

46. Write and explain the Digital Signature Algorithm.

47. Explain in detail Hash Functions.

48. What is the meet in the middle attack?

49. Compare the Features of SHA-1 and MD5 algorithm.

50. What are the requirements of the hash function?

51. Discuss about the objectives of HMAC and it security features.

52. How man in middle attack can be performed in Diffie Hellman algorithm.

53. Explain in detail EIGamal Public key cryptosystem.

54. Differentiate MAC and Hash function?

55. Discuss clearly Secure Hash Algorithm(SHA).

56. What are the properties a digital signature should have? What requirements should a
digital signature scheme should satisfy?

UNIT 3
1. Find gcd (2740, 1760) using Euclidean Algorithm.
2. Find GCD (1970, 1066) using Euclid's algorithm.
3. Using Fermat’s theorem, check whether 19 is prime or not? Consider a is 7.
4. Write short notes on i) Euler’s theorem (ii)Chinese Remainder theorem.

5. Discuss the role of digital certificates in establishing secure communication.

6. How does a Certificate Authority (CA) function in PKI?
7. Explain the different ways of public key distribution in detail.
8. Explain the format of the X.509 certificate.
9. Explain the operational description of PGP.
10. Write a short note on SSL Record Protocol.
11. Why is the SSL layer positioned between the application layer and the transport
layer?
12. Write a short note on SSL Handshake Protocol
13. Write Short notes on S/MIME.
14. How is 3-D Secure different from SET?
15. Discuss the seven types of MIME content type.
16. Explain in detail the operation of Secure Socket Layer in detail.
17. Explain Secure Electronic transaction with neat diagram.
18. Write brief note on E-mail Security.
19. How doe GSM security work?
20. Define PGP. What are the services provided by PGP services?
21. Explain about PKI in detail.
22. Describe about SSL/TLS Protocol.
23. Explain in detail the operation of Internet Key Exchange with an example.
24. List & Explain password selection strategies.

UNIT 4
25. Explain the architecture of IP Security.
26. Write short notes on authentication header and ESP.
27. Draw IPSec Authentication Header and write short notes on each element of the
Header.
28. Write brief note on IP Security.
29. What is Kerberos? Explain how it provides authenticated service.
30. Discuss the four requirements of Kerberos.
31. Write brief note on Web Security.
32. How does ‘something derived from a password’ work? What is the main drawback
here?
33. Explain any one mutual authentication mechanism with its advantages and
drawbacks.
34. Explain in detail about KDC.
35. Explain the technical details of firewall and describe any three types of firewall with
neat diagram. / Explain firewalls and how they prevent intrusions.
36. Explain the firewall design principles.
37. What are the positive and negative effects of firewall? 16. Describe the familiar types
of firewall configurations.
38. Write short notes on Intrusion Detection.
39. Explain any two approaches for intrusion detection.
40. Define intrusion detection and the different types of detection mechanisms, in detail.
41. Explain the types of Host based intrusion detection. List any two IDS software
available
42. Describe trusted system in detail.
43. What is virtual private network?
44. What is SSO?
45. Explain how NAT works with an example.
46. What is the significance of tunnel mode?
47. What is DDoS?
48. What are the two security services provided by IPsec?
49. Write a short note on applications of IPsec.
50. Explain Architecture of IPSec in detail.