I am designing a mobile (iOS/Android) game and I try to save data (such as levels, coins, status) in local files.
In this way, I am concerning a case that someone can just copy these files and give them to a friend, so the friend can have achieve certain levels and all the coins held in the data files right away.
Instead of saving the data in a server, is there any way to prevent this happen?
I am thinking to encrypt the data with a key that is unique for a device. Is this a good idea or it might cause some other problem?