M.Sc. (Semester IV) (CBCS) Examination Mar/Apr-2018
Computer Science
NETWORK SECURITY
Time: 2½ Hours
Max. Marks: 70
Instructions: Q.1 and Q.2 is compulsory. Attempt any three questions from Q. 3 to 7. Figures to the right indicate full marks.
Q.1

Choose correct alternatives:
10
Which of the following is passive attack?
Masquerade
Replay
Denial of Service
Traffic Analysis
Which of the following attack is not a threat to the integrity of data?
Masquerade
Modification
Repudiation
Snooping
The conversion of ciphertext into plaintext is known as
Encryption
Decryption
Cryptography
Cryptanalyst
Which of the following is a component of cryptography?
Ciphertext
Ciphers
Key
All of these
The cipher can be categorized as a stream cipher.
Additive
Hill
Playfair
None of these
Which of the following service is based on the IDEA algorithm?
PGP
S/MIME
SET
SSL
RSA be used for digital signatures.
Can
Can not
Must
Must not
In which year was X.509 first issued?
1988
1978
1982
1977
Which of the following are IPSec protocols?
PGP and S/MIME
Kerberos Kerberos 5
AH and ESP
SSL and SET
10) The firewall should be situated
Outside the network
Inside the network
Between the network and the outside the world
None of these
Page 2 of 2
SLR-UG-289

State whether true or false:
04
The loss of integrity is the unauthorized disclosure of information.
VPN stands for Virtual Personal Number.
SHA-1 length is 128 bit.
The block cipher processes the input elements continuously.
Q.2

Write short notes on the following:
08
Audit Record
Cryptanalysis

Answer the following:
06
What is the purpose of the S-boxes in DES?
Define threat and attack
Q.3
Answer the following:
14

What is the need of network security? Explain its goals.

Explain passive attacks and active attacks.
Q.4
Answer the following:
14

What is key management? Also explain the functions of key management.

What do you mean by modern block cipher? What are its components?
Q.5
Answer the following:
14

Explain the working principle of the Kerberos protocol.

Explain the X.509 authentication service and its certificates.
Q.6
Answer the following:
14

What do you mean by firewall? Describe its characteristics.

Explain any two approaches for intrusion detection.
Q.7
Answer the following:
14

Explain DES with its structure. Also Explain its function.

What is ElGamal encryption system? Explain its encryption and decryption processes.