Originally posted by @ponderable
The easy way would be to synchronize and update signals frequently. Like in a Hardware toekn for safety. No Need for Quantum encryption.
That was the gist of my second idea about this situation, changing codes. but they would have to change maybe once a second to be useful. I don't think the gang stealing that car could have done that in one second but that is a difficult engineering job for sure. One second off sync and you don't open your own frigging car door🙂
Maybe the code could be something like starting with digit 20 or Pi, then both car and fob programmed to update the next number which would be in a memory bank but that would mean you would have a one in ten chance of getting it right.
When I was working Apollo tracking and timing, it was kind of like that, there was a bank of digital codes, based on n^1 plus n^2 plus n^3 and so forth and that combination sent up to Apollo which had a transponder onboard that retransmitted the signal back to Earth from some ground station and it was a unique code so when the return pulses came back to Earth and put through an algorythm it would give the distance to Apollo within 50 feet.
So maybe there could be something like a huge memory bank of digits of Pi, say to the first 35 million digits, I think Pi is now known a LOT deeper than that.
So start at digit X, whatever, 20, 40 and start upping the number but keeping the first set of numbers in memory once per second would allow a year long advance of digits where each step would have one more number in it but referencing all the previous digits so there would be one long set of digits that would have to match besides the latest update of one digit at a time. There would be just about zero chance then for hackers to figure out exactly where you are in the sequence, at least in a reasonable amount of time.
If computer tech was able to actually figure it out but it takes 2 hours, they would just try something easier.
I don't know if there IS a program that could input a few digits of pi and figure out just which digit number a random selection of actual Pi digits a string represents, especially when you could have millions of digits in memory, not a huge feat in terms of present memory capability.