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learn.mq.edu.au Question1. [5 marks] 2, A\' is Consider the Caesar Cipher that c

ID: 3859596 • Letter: L

Question

learn.mq.edu.au Question1. [5 marks] 2, A' is Consider the Caesar Cipher that cyclically shifts all letters by a key k. Say, for k encrypted as ‘C, 'B, is encrypted as 'D, , 'Z, is encrypted as 'B'. a. (3 marks) Given an encrypted message 'KDVKLQJ' encrypted with an unknown key k, explain how to use the chosen cipher tert attack. For example, assume that you know that LGHD is an encryption of 'IDEA', then decrypt the original message *b. 2 marks) What property of natural languages makes Caesar Cipher very weak? Write no more than 2-3 lines Question . [6 marks] Question 2. [6 marks]

Explanation / Answer

Answer:

a. Yes Alice has authenticated Bob by encryption and decryption techniques of the message.

b.No Bob has not authenticated Alice by encryption and decryption techniques of the message since there are no exchange messages between them

c.The weakest point in the system is near the decryption of the cipher text and it can be done by performing any security algorithms.