Yes, it's easy to find these decryption keys.
The only way you have to do this kind of stuff is to have some "replay" file that the server can re-run to validate scores. Yes, it's difficult, and yes it requires some resources. No, there is no other way to make a secure high scores thingy. And even then that doesn't stop bots and cheaters to make perfect, TAS-like replays.
The only way you have to do this kind of stuff is to have some "replay" file that the server can re-run to validate scores. Yes, it's difficult, and yes it requires some resources. No, there is no other way to make a secure high scores thingy. And even then that doesn't stop bots and cheaters to make perfect, TAS-like replays.