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Posted Date: 30 Nov 2009      Posted By:: arjunpandey007    Member Level: Silver    Points: 5 (Rs. 1)

2007 SRM University B.Tech Computer Science and Engineering QUESTION BANK FOR CS-356 NETWORK SECURITY Question paper

Course: B.Tech Computer Science and Engineering   University/board: SRM University




1. List and briefly define three classes of intruders.
2. What are the two common techniques used to protect a password file?
3. What are the three benefits that can be provided by an intrusion detection system?
4. What is the difference between statistical anomaly detection and rule based
intrusion detection?
5. What metrics are useful for profile based intrusion detection?
6. What is the difference between rule based anomaly detection and rule based penetration identification?
7. What is a honey pot?
8. What is a salt in the context of UNIX password management?
9. List and briefly define the four techniques used to avoid guessable passwords.
10. What is the role of compression in the operation of a virus?
11. What are typical phases of operation of a virus or worm?
12. How does a worm propagate?
13. What is a digital immune system?
14. What is meant by trap door?
15. Explain logic bombs.
16. Discuss Trojan horses.
17. Define virus.
18. What is a worm?
19. What does zombie mean?
20. List the different types of viruses.
21. Differentiate virus and worms in cryptographic system.
22. What is macro virus?
23. What are the design goals of firewall?
24. List the four general techniques that firewalls use to control access and enforce the site's security policy.
25. What are the limitations of firewalls?
26. What are the types of a firewall?
27. What do you mean by IP address spoofing?
28. What is a source routing attack?
29. Discuss about Tiny fragment attacks.
30. What is Bastion host? Write its characteristics also.
31. What are the important firewall configurations?
32. Write the basic elements of a general model of access control.
33. What are the advantages of screened subnet firewall configuration?
34. List the properties of the reference monitor.
35. What information does a typical packet - filtering router use?


1. Explain the intrusion detection approaches.
2. Explain the various intrusion techniques in detail.
3. With necessary sketch explain different types of firewalls.
4. Explain in detail about the following:
i) firewall characteristics
ii) firewall configuration
iii) firewall capabilities
iv) firewall implementations
5. Explain various ways to protect passwords
6. Describe the password selection strategies.
7. Explain the taxonomy of malicious programs in detail.
8. Explain the nature of viruses and give a general depiction of its structure.
9. Give a detailed note on Antivirus techniques.
10. Briefly explain the digital immune system
11. Discuss the concepts of trusted systems.


1. What is meant by security attack?
2. What is meant by security mechanism?
3. What is meant by security service?
4. Give 2 examples of security attacks.
5. Define passive and active attack
6. What are the 2 types of passive attacks?
7. What is traffic analysis?
8. What are the 4 categories of active attacks?
9. Give the general model for network security.
10.Give the general model for conventional cryptosystem.
11. What is cryptography?
12. Define cryptanalysis
13. Define brute force attack.
14. What is meant by computationally secure encryption scheme?
15. What is meant by unconditionally secure encryption scheme?
16. What are the essential ingredients of a symmetric cipher model.
17. List any two substitution encryption techniques.
18. List the drawbacks in caeser cipher.
19. Decrypt the term "piggybacking" using caeser cipher.
20. Why monoalphabetic ciphers are easy to break?
21. What is the difference between monoalphabetic cipher and polyalphabetic
22. List the 2 problems with one-time pad substitution technique.
23. List the differences between block cipher and stream cipher
24. What is steganography? Write about its merits and demerits.
25. What is a transposition cipher?
26. What are the differences between transposition and substitution encryption
27. Encrypt "the scheme really works well" using transposition cipher. Use the key
5 4 2 1 3 for encryption.
28. Encrypt the message "attack postponed until two am" using one stage of
transposition. Use the key 6 2 5 3 7 1
29. Briefly explain avalanche effect in DES.
30. What is the purpose of S-boxes in DES?
31. What are the different block cipher modes of operation?
32. What are the advantages of counter block cipher mode of operation?
33. Write the advantage and disadvantage of output feedback mode of operation.
34. How many sub keys are used in IDEA? How are they generated?


1. Explain the different security attacks in detail.
2. Explain symmetric cipher model with neat diagram.
3. Explain any 2 substitution encryption techniques in detail.
4. State the rules for play fair encryption technique. Encrypt and decrypt the
message POSTPONED. Assume the key to be HORLICKS.
5. Explain encryption and decryption in DES.
6. a) Discuss the strength of DES in brief.
b) Explain single round details of DES with a neat diagram.
7. Using hill cipher encrypt the plain text "friend" using the key
1 2 3
2 2 1
3 2 1
8. Using hill cipher encrypt the plain text "paymoremoney" using the key
17 17 5
21 18 21
2 2 19
9. Using hill cipher encrypt the plain text "indian" using the key
1 2 3
2 2 1
3 2 1
10. Explain the different block cipher modes of operation.
11. a) Explain subkeys and S-box generation in blowfish.
b) Explain single round details of blowfish.
12. a) Explain subkey generation in IDEA
b) Explain how encryption is done in IDEA.
13 a) Give the overall structure of IDEA.
b) Explain how decryption is done in IDEA.
14. Demonstrate RC5 decryption is the inverse of RC5 encryption
15. Demonstrate CAST128 decryption is the inverse of CAST 128
16. Explain RC5 sub key generation and encryption in detail with
necessary diagram.
17. a) Explain RC5 key expansion with neat diagrams
b) Explain RC5 modes of operation.
18. Explain Blowfish encryption and decryption.
19. Discuss traffic confidentiality in detail.

Unit III

1. Find GCD of (60,24) using Euclid's Algorithm.
2. State Fermat's theorem
3. State Euler's theorem
4. Define Euler's Totient function.
5. Determine the following
(a) F(41) b) F(27)
6. What is the primitive root of a number?
7. What is discrete logarithm?
8. Using Fermat's theorem find 3201 mod 11.
9. What are the principal elements of a public key encryption scheme?
10. Differentiate conventional and public key encryption techniques.
11. Diagrammatically represent public key cryptography for Authentication.
12. Diagrammatically represent public key cryptography for Confidentiality.
13. What are the roles of public and private key in a public key encryption
14. What are the three broad categories of applications of public key
15. What is an elliptic curve?
16. Define zero point of an elliptic curve.
17. What is the advantage of elliptic curve cryptography over RSA?
18. What does blinding in RSA mean?
19. List the different counter measures to avoid timing attacks in RSA.


1.State and prove Fermat's and Euler's theorem.
2. a) Summarize extended Euclid's algorithm.
b) Find GCD and multiplicative inverse of 550 mod 1759
3. a) Summarize RSA algorithm.
b) Perform encryption and decryption for the following: p = 11, q = 13, e = 11,
M = 7.
4. a) In a public key system using RSA, cipher text C = 10 is sent to a user whose
public key is e = 5, n = 35. What is the plain text M?
b) Briefly discuss the security of RSA algorithm.
5. Consider Diffie-Hellman scheme with a common prime q = 11 and a primitive
root a = 2.
a) Show that 2 is a primitive root of 11.
b) If user A has public key YA = 9, What is A's private key XA?
c) If user B has public key YB = 3. What is the shared secret key K?
6. Consider Diffie-Hellman scheme with a common prime q = 71 and a primitive
root a = 7.
a) If user A has private key XA= 5, What is A's public key YA?
b) If user B has private key X B = 12. What is B's public key Y B?
c) What is the shared secret key K?
7. a) Summarize elliptic curve cryptography key exchange algorithm.
b) Briefly discuss encryption and decryption using elliptic curve


1. What types of attacks are addressed by message authentication?
2. Write the three types of functions that may be used to produce an
3. Write any three properties of a hash function used in message authentication
4. What is meant by message authentication?
5. What is a message authentication code (MAC)?
6. What is the difference between a message authentication code and a one-way hash
7. What is the difference between weak and strong collision resistance?
8. What basic arithmetical and logical functions are used in SHA-1?
9. What basic arithmetical and logical functions are used in MD-5?
10. What basic arithmetical and logical functions are used in RIPEMD-160?
11. What is the difference between little-endian and big-endian format?
12. What are the properties a digital signature should have?
13. How is the public key calculated from the private key in DSA?
14. How many additive constants are there in MD-5, SHA-1 and RIPEMD-160?
15. Draw the DSS approach for generating digital signature.
16. Write about brute-force attack on hash function.
17. For SHA - 1 algorithm show the values of w16 and w17.


1. (a) Discuss the basic uses of message encryption with neat block diagrams.
(b) Discuss the basic uses of message authentication code (MAC) in
authentication and confidentiality with neat block diagrams.
2. Explain the requirements for MAC and hash function.
3. (a) Explain the basic uses of hash function in message authentication.
(b) Write short notes on birthday attack.
4. Compare SHA-1, MD-5 and RIPEMD-160 algorithm.
5. Explain the DSS algorithm and give the proof of it.
6. Discuss in detail the operation of MD5 message digest algorithm and its
compression function with neat diagrams.
7. Explain in detail the processing of message using RIPEMD-160 message digest
algorithm and explain the details of its single step.
8. Explain the message processing and compression function of SHA-1 in detail.
9. Explain the major groups of attack on MAC and hash functions with conventional
and public key encryption.


1. What problem was kerberos designed to address ?
2. What are the three threats associated with user authentication over a network or
3. List three approaches to secure user authentiucation in a distributed environment.
4. What four requirements were defined for kerberos?
5. What are the five principal services provided by PGP?
6. Why does PGP generate a signature before applying compression?
7. What is R64 conversion?
8. Why is the segmentation and reassembly function in PGP needed?
9. What is S/MIME?
10. Give the general format of PGP message.
11. What is PGP?
12. Give the uses of IPSecurity?
13. What are the benefits of IPSecurity?
14. Give the overview of IPSec documents.
15. What are the major IPSec services?
16. What is the security association?
17. What is anti- reply mechanism in authentication header?
18. Give the format of Ipv4 packets after applying AH in transport mode.
19. Give the format of Ipv6 packets after applying AH in transport mode.
20. What are web security threats?
21. Give the uses of web security.
22. Give the SSL protocol stack
23. What is SSL session and SSL connection?
24. Give the SSL record format.
25. What are the three SSL specific protocols?
26. What is SET?
27. What are the three main services of SET?
28. Who are the participants in SET system?
29. What are the roles of the Oakley key determination protocol in IPSec?
30. What are the roles of the ISAKMP in IPSec?


1. Explain the Kerberos version 4 architecture dialogue and summarize its message exchanges.
2. Explain PGP and write about cryptographic keys and key rings.
3. Explain the following PGP services
i. Authentication
ii. Confidentiality
iii. Compression
iv. E-mail compatibility
v. Segmentation
4. With suitable diagram explain the transmission and reception of PGP messages.
5. Explain the following
i. Benefits of IP-security
ii IPSec services
iii. ESP formats.
iv. Transport mode ESP
6. Explain the transport and tunnel modes of operation in both AH and ESP with
diagrams describing the packet form.
7. Explain the IP Security architecture in detail.
8. Discuss about SSL architecture and SSL record protocol.
9. Explain security in transport layer.
10. Explain secure electronic transaction.
11. Explain the S/MIME functionality in detail with sample messages.
12. Explain the default automated key management protocol for IPSec
13. Give the formats, explain the various payloads and exchanges of ISAKMP.

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