A secure email system is expected to provide confidentiality, sender's non-repudiation, and message integrity. Alice uses three keys to achieve this goal. The three keys are Alice's private key (KA), Bob's public key (KB+), and a randomly generated symmetric key (Ks). The encryption procedure is shown below: How can Bob 1) decrypt the data, 2) verify the message's integrity, and 3) verify the sender's non- repudiation? Describe the detailed steps (including the formulas) and show your work. KA m➡ HO KA m I am using SHA-256 KA(H(M)) + Ks Ks() + KB(*) Ks Ks(m, KA(H(m)) + + KB(KS) Internet

Computer Science Assume we use transposition cipher to encrypt the data, and the original message is stored in a 8 by 5 matrix (8 rows and 5 columns). If the ciphertext is shown below, what is the original plaintext?WMHPSCATEEEUCELELTCTIASLOTMRNCA

Part 2: Perform encryption and decryption using the RSA algorithm for the following. Show all your steps. 1. p = 3;q=11, e = 7; M = 5 2. p=5;q=11, e = 3; M = 9

In an RSA system, the public key (n,e) of a given user is (323, 11). 1. What is the value of the exponent in the private key (n, d), of this user? 2. Suppose you want to send this user the message m = 45, write down the expression to generate the ciphertext for this message. 3. Suppose that your ciphertext, c, is 5, write down the expression to generate the plaintext matching this ciphertext. 4. Can you encrypt the message m=322 with this public key? O a. Yes O b. No

Alice and Bod have decided to use a symmetric encryption algorithm. They have some assumptions about their messages:- Messages only contain capital letters (i.e. A to Z)- The length of their shared key must be greater than or equal to the length of the plaintext- They assign each letter a number as follows: (A,0), (B,1), (C,2), (D,3),…, (Z,25)Their algorithm combines the key and the message using modular addition. The numerical values of corresponding message and key letters are added together, modulo 26. For example, if the plain text is “HELLO” and the key is “SECRET” then the encrypted message is calculated as following:Since the length of the plaintext is 5, we just need the first 5 letters of the key (i.e. “SECRE”), then for each letter, we should add corresponding letters in both the plaintext and the key modulo 26.Plaintext: H (7) E (4) L (11) L (11) O (14)Key: S (18) E (4) C (2) R (17) E(4)Cipher: Z (25) I (8) N(13) C(2) S (18) Write a program in Python, C/C++ or JavaScript to…

Perform Encryption and decryption using the RSA algorithm for the following: a. p=5; q = 11; e = 3; M = 12 b. p= 3; q = 17; e = 7; M = 2 c. p=7; q = 19; e = 11; M = 5 d. p= 7; q = 13; e = 11; M = 8 e. p= 13; q = 23; e = 5; M = 10