Cryptography and Network Security Question Bank–All Units

Anna University

Department of Information Technology.

Cryptography and Network Security


Subject: IT2352/ Cryptography and Network Security

Question Bank


Unit-I

Part-A (2 Marks)


1. What are the types of attacks on encrypted message?

2. What is cryptanalysis and cryptography?

3. What are the key principles of security?

4. How does simple columnar transposition work?

5. What is avalanche effect?

6. Define threat and attack.

7. Give any four names of substitution techniques.

8. Specify the four categories of security threads.

9. Distinguish active and passive attack with example .

10. Compare stream cipher and block cipher with example.

11. How many keys are required for two people to communicate via a cipher?

12. What are the two approaches to attacking a cipher?

13. Compare Substitution and Transposition techniques.

14. Define Fermat Theorem.

15. Define Euler’s totient function or phi function and their applications.

16. Define Euler’s theorem and it’s application.

17. List the properties of Euler’s phi.

18. What is the difference between diffusion and confusion?

19. What is the advantage and disadvantage of one time pad encryption algorithm?

20. List the properties of Congruences.

21. Find gcd (56, 86) using Euclid’s algorithm.

Part-B (16 Marks)

1. (i) Discuss any four Substitution Technique and list their merits and demerits. (10)

(ii) Explain in detail Transposition Technique? (6)

2. Write short notes on

(i). Security attacks (8)

(ii). Security services. (8)

3. (i) Convert “MEET ME” using Hill cipher with the key matrix

Convert the cipher text back to plaintext (8)

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(ii) Explain in detail the Legendre and Jacobi symbols.

4. (i) Briefly explain the design principles of block cipher. (8) (ii) Discuss in detail block cipher modes of operation. (8)

5. Write short notes on

(i)Fermat and Eluer’s theorem (8)

(ii)Chinese Remainder theorem (8)


Unit-II

Part-A (2 Marks)


1 Perform encryption and decryption using RSA Algorithm. for the following.

P=7; q=11; e=17; M=8.

2. Where is the miller-rabin algorithm is used?

3. What is the purpose of the Sub Bytes?

4. What is the difference between Sub Bytes and Sub Word?

5. Mention any one technique of attacking RSA.

6. List four general characteristics of schema for the distribution of the public key.

7. What is the purpose of the S-boxes in DES?

8. What primitive operation is used in RC4?

9. What is the role of session key in public key schemes?

10. What is the purpose of the State array?

11. How is the S-box constructed?

12. If a bit error occurs in plain text block b1, how far does the error propagate in CBC mode of DES.?

Part-B (16 Marks)

1. (i) Identify the possible threats for RSA algorithm and list their counter measures. (8)

(ii) Perform decryption and encryption using RSA algorithm with p=3, q=11, e=7 and N=5. (8)

2. (i) Draw the general structure of DES and explain the encryption decryption process. (10)

(ii) Mention the strengths and weakness of DES algorithm. (6)

3. (i) Explain the generation sub key and S Box from the given 32-bit key by

Blowfish. (8) (ii) In AES, hoe the encryption key is expanded to produce keys for the 10 rounds(8)

4. (i) Describe about RC4 algorithm. (8) (ii) Explain the Miller-Rabin Algorithm . (8)


Unit-III

Part-A (2 Marks)


1. User A and B exchange the key using Diffie-Hellman algorithm. Assume α=5 q=11 XA=2 XB=3. Find the value of YA, YB and k.

2. What are the properties a digital signature should have?

3. What is masquerading?

4. Define weak collision property of a hash function.

5. Why is SHA more secure than MD5?

6. Mention the fundamental idea of HMAC.

7. Define the one way property to be possessed by any hash function.

8. What is the block size of MD5 and how many bits are produced as the message digest?

9. What are the functions used to produce an authenticator?

10. List the properties a digital signature should possess.

11. What do you meant by hash function?

12. Differentiate MAC and Hash function.

13. List any three hash algorithm.

14. What are the requirements of the hash function?

15. What is the role of compression function in hash function?

16. Distinguish between direct and arbitrated digital signature?

17. What is Birthday attack?

Part-B (16 Marks)

1. (i) Briefly explain Deffie Hellman key exchange with an example. (16)

2. (i) Write and explain the digital signature algorithm. (8) (ii) Explain in detail Hash Functions. (8)

3. (i) Compare the Features of SHA-1 and MD5 algorithm. (8)

(ii) Discuss about the objectives of HMAC and it security features. (8)

4. Users A and B use the Diffie Hellman key exchange technique, a common prime q=11 and a primitive root alpha=7.

(i) If user A has private key XA=3.What is A’s public key YA? (4)

(ii) If user B has private key XB=6 What is B’s public key YB? (4) (iii) What is the shared secret key? Also write the algorithm. (4)

(iv) How man in middle attack can be performed in Diffie Hellman algorithm.(4)

5. (i) Explain in detail EIGamal Public key cryptosystem. (8)

(ii) Discuss clearly Secure Hash Algorithm(SHA) (8)

6. Describe the MD5 message digest algorithm with necessary block diagrams. (16)


Unit-IV

Part-A (2 Marks)


1. What are the services provided by PGP services?

2. What is X.509 Standard?

3. Give IPSEC ESP Format.

4. What are the security options PGP allows when sending an email message?

5. How IPSec does offer the authentication and confidentiality services?

6. What is the role of Ticket Granting Server in inter realm operations of Kerberos?

7. Why the leading two octets of message digest are stored in PGP message along with encrypted message digest?

8. Mention the scenario where Kerberos scheme is preferred.

9. What are the technical deficiencies in the Kerberos version 4 protocols?

10. Define S/MIME.

11. What are the key algorithms used in S/MIME?

12. What are the headers fields define in MIME?

13. What are the function areas of IP security?

14. Give the application of IP security.

15. Specify the IP security services.

16. What is meant by SET? What are the features of SET?

17. What are the steps involved in SS L required protocol?

18. Draw the general format for PGP message.

19. Draw the header format for an ISAKMP message.

20. What is man in the middle attack?

21. What do you meant by Reply Attack?

Part-B (16 Marks)

1. How does PGP provide confidentiality and authentication service for e-mail and file storage applications? Draw the block diagram and explain its components. (16)

2. Write Short notes on S/MIME .

3. Explain the architecture of IP Security (16)

4. (i) Describe the SSL Specific protocol – Handshake action in detail. (8)

(ii) Explain Secure Electronic transaction with neat diagram. (8)

5. (i) What is Kerberos? Explain how it provides authenticated service. (8)

(ii)Explain the format of the X.509 certificate. (8)


Unit-V

Part-A (2 Marks)


1. What is meant by polymorphic viruses?

2. What are honey pots?

3. List down the four phases of virus.

4. What is IP address spoofing?

5. What are the common techniques used to protect a password file?

6. What services are provided by IP Sec?

7. What is the role of bastion host?

8. List the classes of intruders

9. Define virus. Specify the types of viruses.

10. List the design goals of firewalls.

11. What is application level gateway?

12. What does meant by a trusted system?

Part-B (16 Marks)

1. (i) Explain any two approaches for intrusion detection. (8) (i) Identify a few malicious programs that need a host program for their existence.(8)

2. (i) Explain firewalls and how they prevent intrusions. (8) (ii)List and Brief, the different generation of antivirus software (8)

3. (i) Define intrusion detection and the different types of detection mechanisms, in detail. (8)

4. (i)Explain the types of Host based intrusion detection. List any two IDS software available. (8)

(ii) What are the positive and negative effects of firewall? (8)

5. (i) Describe packet filtering router in detail. (16)

6. Describe the familiar types of firewall configurations. (16)