Network Security — Summer 2023

Answers the following: 1. Give one use case of passive and an active attack. 2. What is a clear signed message in SMIME? 3. What do you mean by Asymmetric encryption? 4. Differentiate Transport and Tunnel Mode in Ipsec. 5. What is a honey pot? 6. Write name of any two block Cipher algorithms. 7. Explain the term “Salt”.

Mention and very briefly explain design features/parameters considered while designing the symmetric block cipher.

1. Compare DES, 3DES and AES. (3) 2. List different fields of Authentication Header.(4)

Why is the mode of operation defined? Explain any two cipher block modes of operations.

1. Write two important advantages of public key cryptography over shared secret key based cryptography. (3) 2. How MAC is calculated using a one-way hash function? (4)

Briefly explain the structure/format indicating the different fields of Public Key Ring in PGP.

What is the need of a Hash function? Explain SHA512 algorithm with a suitable diagram.

Explain RSA public key encryption algorithm using suitable examples.

Explain pseudo random function and cryptographic computation of TLS with suitable diagrams.

Explain the public key ring and its structure with a suitable diagram.

What is IPSec? What are the applications of IPSec? Explain the modes of IPSec operations.

Explain ESP packet format in detail with suitable examples.

Why is web security a more important issue today? List at least four reasons for the same. Page 1 of

Explain types of firewalls in detail using suitable diagrams.

1. Explain how one can use Markov model for proactive password checking. (3) 2. What do you mean by false positive and false negative in an Intrusion Detection System? (4)

Explain how attacks like IP address spoofing, source routing and tiny fragments can be carried out on packet filtering routers? What are the countermeasures?

Explain the three parts and four phases of computer viruses. Page 2 of