Suppose Bob and Alice want to flip a coin over a network and decide who is the winner. Alice proposes the following protocol.

(i) Alice randomly selects a value X in {0,1} (i. e., either 0 or 1).
(ii) Alice generates a 256-bit random symmetric key K.
(iii) Using the AES cipher, Alice computes Y = E(X, R,K), where R consists of 255 randomly selected bits.
(iv) Alice sends Y to Bob.
(v) Bob guesses a value Z £ {0,1} and tells Alice.
(vi) Alice gives the key K to Bob who computes (X, R) = D(Y, K).
(vii) If X = Z then Bob wins, otherwise Alice wins.

This protocol is insecure.

a. Explain how Alice can cheat.
b. Using a cryptographic hash function h, modify this protocol so that Alice cannot cheat.

Assume the existence of a bankaccount class. define a derived class, savingsaccount that contains two instance variables: the first a double, named interestrate, and the second an integer named interesttype. the value of the interesttype variable can be 1 for simple interest and 2 for compound interest. there is also a constructor that accepts two parameters: a double that is used to initialize the interestrate variable, and a string that you may assume will contain either "simple", or "compound", and which should be used to initialize the interesttype variable appropriately. there should also be a pair of functions getinterestrate and getinteresttype that return the values of the corresponding data members (as double and int respectively).

Write a grading program for a class with the following grading policies: a. there are two quizzes, each graded on the basis of 10 points. b. there is one midterm exam and one final exam, each graded on the basis of 100 points. c. the final exam counts for 50% of the grade, the midterm counts for 25%, and the two quizzes together count for a total of 25%. (do not forget to normalize the quiz scores. they should be converted to a percentage before they are averaged in.) any grade of 90 or more is an a, any grade of 80 or more (but less than 90) is a b, any grade of 70 or more (but less than 80) is a c, any grade of 60 or more (but less than 70) is a d, and any grade below 60 is an f. the program will read in the student’s scores and output the student’s record, which consists of two quiz and two exam scores as well as the student’s average numeric score for the entire course and final letter grade. define and use a structure for the student reco

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