Do you know that it is possible to play crush or face remotely? I choose crush or face and the other player launches the coin… but how to check that the other does not lie? Just use mathematics In fact just use a function F difficult to reverse (hash function) : i.e.
- if I choose x and that I calculate y=f (x) and that I give you y, it is impossible for you to find x.
- if you choose x and x' different, it is quasi impossible that f (x) =f (x').