## 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 Studen

Q1. 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.

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. Use any online decimal to binary conversion calculator to convert your RMIT Student Number to binary string.

20240621092756AM-22281560-2044367371.png

Figure-1.a: Conversion RMIT Student Number into of binary plaintext segments from the original plain text

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

20240621092756AM-2129049979-1456101353.png

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.

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-in- the-Middle (MiM) . Answer the following questions in the context of the Diffie-Hellman Key Exchange protocol.

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.

Q3. Implementing Firewall Rules using Iptables

In this task, you will demonstrate your knowledge of firewall using Iptables , a Linux command line utility to manage firewall . 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
You are required to execute Iptables commands in Kali Linux 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 Otherwise, marks will be deducted.

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