Candidate Number
G6077
THE UNIVERSITY OF SUSSEX
BSc FINAL YEAR EXAMINATION
MComp THIRD YEAR EXAMINATION
August 2019 (A3)
Introduction to Computer Security
Assessment Period: August 2019 (A3)
DO NOT TURN OVER UNTIL INSTRUCTED TO BY THE LEAD INVIGILATOR
Candidates should answer TWO questions out of THREE.
If all three questions are attempted only the first two answers will be marked.
The time allowed is TWO hours.
Each question is worth 50 marks.
At the end of the examination the question paper and any answer books/answer sheets, used or unused, will be collected from you before you leave the examination room.
G6077 Introduction to Computer Security
1.
a) Explain the key characteristics of a secure hash function. [10 marks]
b) Show the working of the RSA algorithm for the following values
p=3, q=11.
[25 marks]
c) Explain what is indicated by the curve shown below in the area of computer
security. Explain how it can be used for public and private key pairs.
[15 marks]
/Turn over
G6077 Introduction to Computer Security
2.
• Identify and explain the principles of information security. [15 marks]
• Explain why a brute force attack will fail when using One Time Pad cipher.
[10 marks]
• Using the Vigenere cipher, show the encryption of the plaintext listed below:
Plaintext: we are discovered save yourself
Key: deceptive
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[10 marks]
d) Using the rail fence technique, show the encryption and decryption of the
following plaintext:
Plaintext: meet me after party
Depth: two
[15 marks]
/Turn over
G6077 Introduction to Computer Security
3.
a) Explain the key processes listed in the diagram below for the DES
algorithm.
[20 marks]
b) Explain steganography. Provide at least two examples of steganography
use.
[10 marks]
c) Using the Hill cipher, encrypt and decrypt the plaintext code. Show all
your working.
Plaintext: code
3
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12
Key:
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[10 marks]
d) Using the rectangular/route cipher, encrypt the following plaintext:
Plaintext: attack postponed
Key: 431256
[10 marks]
End of paper