I never understood why keyfobs work in a UDP style, when communication between the remote and car would be infinitely better. For instance, instead of just sen

I never understood why keyfobs work in a UDP style, when communication between the remote and car would be infinitely better. For instance, instead of just sending "12345" and having the doors open since the code was expected, What about if the remote said "hey car, whats your random number" - the car then transmits back "54321" at which point the transmitter sends a hashed reply sha512(54321 + unique-random-id-set-per-car) which the car receives then verifies matches expected output. The takeaway being that both the car and the remote know what "unique-random-id-set-per-car" is, but nobody else does. It should be randomly set at the factory so each car and the remotes have a unique id. My only thoughts as to why its not like this is that the logic required to do that type of operation might not be possible without a higher wattage 'processor' in the keyfob which would eat through batteries. Im totally out of the know in that area though. Also, unrelated- but the passenger door thing is likely just coincidence because they want to get in the glove box. But, there is another thing that could explain it. On my last car (mercedes) when I wanted to reprogram a new keyfob to work with the car, I had to do a long process of certain actions to make it work. It was like "press on brake, release brake, press on brake for 3 seconds then release, open drivers window, open passenger door, close drivers window, press open button on keyfob" So the car CPU is definitely aware and can take actions specific to which door is being opened, so its possible its related.