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.

Matlab question: use switch and anythe lottery game matches three different integer numbers between 1 and 10. winning depends on how many matching numbers are provided by a player. the player provides three different integers between 1 and 10.if there is a match of all 3 numbers, the winning $ 1000.if there is a match with 2 numbers, the winning $ 10.if there is a match of all with 1 numbers, the winning $ 1.with no match, the winning is $0.write a function lottery3 that checks three numbers provided by a player and determine the winning amount. if the user mistakenly enters same number twice/thrice and if that number matches one of the winning numbers, the code should count that number only once and display correct result. the player doesn’t have to guess the order of numbers. the input to the function lottery3 can have up to two input arguments. the first input argument is a row array numbers with 3 numbers. if the second argument input testcode is present, and is a row vector of 3 values, the function lottery3 uses the code in testcode as the three winning numbers (the test must be three different integer numbers between 1 and 10), else three different numbers will be automatically generated by testcode. the ouput should return the variable winnings and the three winning numbers in the row array winnumbers. hint: make use of the internal function any. restriction: the function must use switch-case statements to determine the winning. example #1: winning = lottery3( [1,2,1],[1,2,3])produceswinning =10example #2: [winning, winnumbers] = lottery3( [1,2,3])produceswinning =3winnumbers =8 5 3

Write a program that takes in 3 inputs [players (int type), expected game time (double type), team (char type)] and calculates actual game time (double) based on the following conditions: if the number of players or the expected game time is less than or equal to zero, it should output wrong input if the number of players is greater than 0 and less than or equal to 6 and if they are on the â€r’ or â€r’ team, their game time will be 10% faster. and if they are on the â€b’ or â€b’ team, their game time will be 15% faster. and if they are on the â€y’ or â€y’ team, their game time will be 20% faster. and if they are on any other team, they will play 0% faster. if the number of players is greater than 6 but less than or equal to 12 and if they are on the â€r’ or â€r’ team, their game time will be 20% faster. and if they are on the â€b’ or â€b’ team, their game time will be 25% faster. and if they are on the â€y’ or â€y’ team their game time will be 30% faster. and if they are on any other team, they will play 0% faster. if the number of players is greater than 12 but less than or equal to 18 and if they are on the â€r’ or â€r’ team, their game time will be 30% faster. and if they are on the â€b’ or â€b’ team, their game time will be 35% faster. and if they are on the â€y’ or â€y’ team, their game time will

3. bob is arguing that if you use output feedback (ofb) mode twice in a row to encrypt a long message, m, using the same key each time, it will be more secure. explain why bob is wrong, no matter what encryption algorithm he is using for block encryption (15 points).