(Answered): Suppose the following matrix is mistakenly used foranencryption matrix in a Hill cipher (with n = 26 ...

Problem 4 [Hill Cipher, 25 pts.]: Suppose the following matrix is mistakenly used for an encryption matrix in a Hill cipher (with n=26). A = ( 3) Find two plaintexts that encrypt to the same ciphertext. Problem 5 [Vigenère Cipher, 25 pts.]: Suppose you have a language with only 3 letters, namely a, b, and c, which occur with frequencies 0.7, 0.2, and 0.1, respectively. The following ciphertext message was encrypted by the Vigenère method (shifts are mod 3 instead of mod 26): ABCBABBBAC 1. Compute the length of the key used in this Vigenère cipher. Show your work step by step. Otherwise, your answer is wrong. 2. Compute the key of this Vigenère cipher based on the above-mentioned frequencies of the letters a, b, and c. Show your work step by step. Otherwise, your answer is wrong. 3. Using the above key, decrypt the ciphertext ABCBABBBAC. Show your work step by step. Otherwise, your answer is wrong. Good Luck!