How can I make files inaccessible to the user, but accessible to my program?

I am making a small game at the moment, and want it to be possible for users to save their characters, which will likely be stored in a text file. Is there any way to make this text file inaccessible to the user in the windows explorer or whathaveyou, so that save tampering is impossible (or at least harder), but also accessible to my program?

via Chebli Mohamed