“Aliens WOULD NOT , encrypt their messages if they were trying to contact “EARTH” from light - years away.”
BUT they MIGHT encrypt their messages if they only wanted responses from a civilization capable of decrypting their messages. All lower life forms need not reply. Just sayin’
But that would be contradictory to the point of finding intelligent life. Unless you already know whats out there. Then why send anything?
That’s why SETI sends signals and looks for signals across the spectrum.
You wouldn’t encrypt a signal if you were looking for intelligent life. So you send it out, something comes back and wipes out your entire civilization. Next time.....what would you do, you encrypt it, no one hears it and it’s pointless. You don’t and you get bombed back into the stone age again.