Assume that A and B share a long-term 256-bit AES key K. Our key exchange protocol has two goals: (1) let A and B agree on a new fresh session key Ks to be used for a current session, and (2) perform mutual authentication. Nb is a nonce and Ks is a new session key generated by B. Assume that Ks and Nb are of the same bit-length and both are always chosen at random. EK(.) denotes AES encryption of everything inside () with key K. HMACK(.) denotes SHA2-based HMAC of everything inside () using key K. Protocol:
1.A −→ B: EK(A, B, "Hello")
2.B −→ A: EK(Ks, Nb, HMACK(A, B, "Hello"))
3.A −→ B: HMACK(Ks, Nb, 1)
What (if any) are the vulnerabilities of this protocol? If there are any, how can you fix them? For fix, you need to show modification of the protocol. Limit each answer (vulnerabilities and their fixes separately) to 10 lines

Write a program that uses a random number generator to generate a two digit positive integer and allows the user to perform one or more of the following operations: a. double the number. b. reverse the digits of the number. c. raise the number to the power of 2, 3, or 4. d. sum the digits of the number. e. if the number is a two-digit number, then raise the first digit to the power of the second digit. f. if the number is a three-digit number and the last digit is less than or equal to 4, then raise the first two digits to the power of the last digit. after performing an operation if the number is less than 10, add 10 to the number. also, after each operation determine if the number is prime. each successive operation should be performed on the number generated by the last operation. your program should not contain any global variables and each of these operations must be implemented by a separate function. also, your program should be menu driven. 7. (fraction calculator) write a program that