TCP guarantees message authenticity rather reliably using packet sequence number. Other option would be going with UDP and using digital signatures to make the message authentic. What could be my other options (basically are there any I missed)? Maybe there is some sort of framework which I could use which would allow me to plug into a game engine without writing all authentication logic(each time using tcp i would need that clients login into my system, with udp i would rely on client public signatures inside my db).

TY