INTE2625 - Introduction to Cyber Security Assignment

Assignment Task

Overview

The objective of Assignment 2 Part 1 is to evaluate your knowledge of the topics covered in Lectures, Tutorials, and Workshops from 1 to 7. Topics include Cyber Security concepts, Design principles for the cyber security environment, symmetric and asymmetric key cryptography concepts, Security protocols, Firewalls, and Iptables. Assignment 2 Part 1 will focus on developing your abilities in designing and analyzing a security system by leveraging the concepts of cryptography, standard security protocols, and threat or attack prevention using advanced secure systems. Please note that You are expected to do your own research to find out appropriate solutions to the given problems in addition to the lesson learned in the lecture, tutorial, and practical classes. You are required to prepare the solutions with the description of the step-by-step processes as a single PDF or MS Word file.

Develop the solution of this assignment in an iterative fashion (as opposed to completing it in one sitting). At the end of Week-7, you should be able to acquire all necessary knowledge to solve the questions. However, you will still get two additional weeks to finalize your answers before submission.

Learning Outcomes

This assessment is relevant to the following Learning Outcomes:

• Explain cryptography and security protocols and their roles in securing data communication and authenticating users.
•  Identify and evaluate attack prevention and protection methods to safeguard networks, enterprise systems and cloud applications
•  Describe the design of secure systems for large enterprise applications.

Questions

1. Symmetric Key Cryptosystem

In this task, you will demonstrate your understanding of symmetric key encryption and decryption techniques. Assume that you want to send your RMIT Student Number to your friend. To ensure the security, both of you have decided to use symmetric key encryption and decryption techniques. Consider the numerical part of your RMIT Student Number as the plaintext (P). For example, if your RMIT Student Number is S4123456, then the value of P = 4123456. Please note that you must use your RMIT Student Number as plaintext. You and your friend have decided to use a shared secret key K which is a 6-bit binary string. Use K = 101011 as the shared secret key. Therefore, you need to use this value of K throughout this question.

a) Convert the plaintext P (the numerical part of your RMIT Student Number) into 24-bit binary strings by inserting additional ‘n’ zeros to the left of the binary string of the actual binary string of your RMIT Student Number if necessary (see Figure-1a). Show the 24-bit binary string of the RMIT Student Number as output.

b) Divide the obtained 24-bit binary string of the plaintext (i.e., the outcome of Q1(a)) into four segments and generate four binary plaintext segments (see Figure-1b). Show all four plaintext segments.

c) Consider a 6-bit binary Initial Vector, IV = 111010. Using the Block Cipher Mode shown in Figure-1c, encrypt the plaintext segments obtained in Q1(b) to find the four ciphertext segments. Show detailed steps for computing all ciphertext segments. 

d) Using the Symmetric Encryption and Decryption steps shown in Figure-1d:

I. Encrypt the plaintext segments obtained in Q1(b). Find the four ciphertext segments. Show detailed steps for computing all ciphertext segments (see Figure 1d for the encryption process). 

II. Based on the encryption process shown in Figure-1d, draw the diagram for the decryption process. 

III. Using the diagram that you have presented in Q1(d-II), show detailed computations for finding plaintext segments to prove that your diagram is correct.

2. Public Key Cryptosystem

In this task, you need to exhibit your understanding of the Public Key Cryptosystem based Key Exchange Protocol. Assume that Alice and Bob want to establish a shared key using the Diffie-Hellman Key Exchange protocol. Trudy is a Man-inthe-Middle (MiM). Answer the following questions in the context of the Diffie-Hellman Key Exchange protocol. [Note: You should use online calculators to perform necessary computations as shown in Week 5 Tutorial.

a) Alice and Bob agree on using a prime number p = 431 and a generator g = 11. Alice chooses her secret number a = 47 and Bob chooses his secret number b = 69. With necessary diagram, show detailed computations how Trudy can perform the MiM attack.

b) Using the concept of Public Key Cryptography, the MiM attack in the Diffie-Hellman Key Exchange protocol can be prevented. You need to do your own research to find out how to prevent this attack. Please note that you do not need to propose any new techniques. Instead, use an existing method. With necessary diagram, show detailed calculations to justify the correctness of your prevention technique

3. Implementing Firewall Rules using Iptables

In this task, you will demonstrate your knowledge of firewalls using iptables, a Linux command line utility to manage firewalls. You are expected to do the following:

• In addition to the lesson learned in practical class, you are required to do your own research to solve this question.
• You are required to execute iptables commands in the Kali Linux environment. You must provide all necessary screenshots of your work. Otherwise, marks will be deducted.
• You must show the status of the FILTER Table before or after executing commands. Otherwise, marks will be deducted.

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