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INSTITUTE EXAMINATIONS – ACADEMIC YEAR 2012-2013

SEMESTER II MAINEXAMINATION

FACULTY OF ENGINEERING

COMPUTER AND INFORMATION TECHNOLOGY

FOUR YEAR CEIT SEMESTER I FULL TIME

CIT3324: NETWORK SECURITY

DATE:

TIME: 2 HOURS

MAXIMUM MARKS = 60

INSTRUCTIONS

1.

This paper contains ONE (1) question in SECTION A and THREE (3) questions in

SECTION B

2.

Answer ALL questions in SECTION Aandany TWO (2) questions from SECTIONB

3.

4.

No written materials allowed.

Write all your answers in the answer booklet provided.

5.

Do not forget to write your Registration Number.

6.

Do not write any answers on this question paper.

SECTION A

Question One

a) i. ii.

iii.

iv.

v.

Mention any two network security basic components

Mention any two independent malicious softwares

Mention any two stages in worm’s development

Mention any two cryptic key systems

[1 × 2]

[1 × 2]

[1 × 2]

[1 × 2]

[1 × 2]

Mention anytwo elements of the security life cycle b) i. Explain the reasons why security is a crucial factor in the Internet

Environment [5] ii.

iii.

iv.

With the help of a sketch, describe a network security model

Explain the operation of the trapdoormalware

Describe the operation of a topological worm

[10]

[2]

[3]

SECTION B

Question One

a) b) c)

Describe the characteristics of the Denial of Service according to the CERT

Threat model [5]

Briefly, describe the transposition and substitution ciphers [5]

Givenans-boxresults as in the table below, find the output for the input of

27. [10]

Middle 4 bits of input

S

5

0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111

00 0010 1100 0100 0001 0111 1010 1011 0110 1000 0101 0011 1111 1101 0000 1110 1001

Outer

01 1110 1011 0010 1100 0100 0111 1101 0001 0101 0000 1111

bits

10 0100 0010 0001 1011 1010 1101 0111 1000 1111 1001 1100

1010

0101

0011

0110

1001

0011

1000

0000

0110

1110

11 1011 1000 1100 0111 0001 1110 0010 1101 0110 1111 0000 1001 1010 0100 0101 0011

Question Two

a) Discuss the major benefits of an asymmetric cryptosystem [5] b) Discuss how the public key system addresses the non-repudiation issues [5] c) Given an RSA system with two prime numbers of 47 and 71, and the public key of 79, calculate the private key [10]

Question Three

a) Briefly give the meaning of firewall security system [5] b) Alice and Bob are business partners. They always correspond their business deals using the Internet, and they are looking for a network security specialist to help them with the knowledge of solutions that would best secure their online communications, because they have been alerted that Internet is a very insecure environment for communicating sensitive matters.Assuming you won this contract, propose them to use the IPSec security system and discuss its operation. [15]

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