Hey there
Can anyone inform me of a math problem that is easy going in one direction but difficult in the other?
In the sense of the encryption example using colours.(bob send yellow to alice and eve steals yellow, bob sends yellow mixed with green to alice and eve steals the mixture, alice sends red mixed with yellow to bob and eve steals the second mixture, bob and alice mix the colour they mixed with yellow with the mixture they got and they have a key that eve doesn't know about.)

Thanks!