Coin Flipping Game
Scenario: A coin flipping game between two parties, Alice and Bob, works as follows. One party (e.g., Alice) holds a coin and asks the other party to guess one of the two possible cases, head or tail. Then Alice tosses the coin. Bob wins the game if his guess is the side of the coin landed on top; otherwise Alice wins the game (assuming that the coin will never land on its edge).
An alternative could be that Bob will reveal his guess while the coin is in mid-air. We can also imagine that the coin has been tossed, and reached the ground, but Bob has not yet revealed his guess. In this case, the coin would be covered with a material such as aluminium foil, and after Bob has revealed his guess, the coin is unwrapped, and the side facing up would be revealed.
Coin Flipping Game Over Telephone
Design a protocol such that Alice and Bob will be able to play a coin flipping game over the telephone, in a way that Alice cannot cheat Bob. (Hint: use one-way functions).
[1/2 mark]
You are also required to compare your protocol with the ordinary coin flipping game, and identify if your designed protocol is fair with respect to the ordinary coin flipping game.