Server side package ID validation,Proper way to authenticate unity game

I am trying to make a API for my unity game and i hit a wall with security. Everything on Unity is client side and can be seen/decrypted.

I saw that Unity services use Package-ID. How do i go about validating that the client connecting is my game and not someone who decrypted my Package ID from the project? Is there an API that can validate package-ID at least so that i can check packages are actually created by Unity ( in witch case i can al least contact Unity for help blocking those accounts )

Or maybe upload checksum to server on build programmatically? manually its too risky since i can forget

Help appreciated!

, I am trying to make a API for my unity game and i hit a wall with security. Everything on Unity is client side and can be seen/decrypted.

I saw that Unity services use PackageID. How do i go about validating that the client connecting is my game and not someone who decrypted my Package ID from the project? Is the an API that can validate packageID atleast so that i can check packages are actually created by Unity ( in witch case i can alteast contact Unity for help blocking those accounts )

Or maybe upload checksum to server on build programmatically? manually its too risky since i can forget

Help appreciated!