[a] A part of ciphertext was received as follows by a wireless station in Playfair code with the key "Royal new Zealand navy". Decrypt this received message and show all your steps in details (3 Points]? Received Ciphertext: KXJEY UREBE" [b] Consider the message "Hello World that we would like to hide in a image using Least Significant Bit (LBS) insertion where each pixel is represented by 4 bits. What is the minimum image size (in bits) required for storing this message? [2 Points] le Consider a block cipher that takes n-bit block as input with k-bit key. 1. Assuming the cipher to be ideal, what is the key size in bits? [1 Point] 2. Assuming the cipher to be following the Feistel cipher, what is the key size in bits? [1 Point [d] Consider the shown state matrix in one round of AES which is the input for Mix columns stage. CS 30 F294 BO CS 37 74 DD 50 D120 B7 55 F866 What was the input of the shift rows stage in this round? [2 Points] [e] The final round of both encryption and decryption in AES consists of only three stages. Explain why? (1 Point