Earlier quoted context omitted.
My solution wasn't to protect against that - if you're up for desoldering stuff you may as well just replace the ECU with your own one which is happy to start the car. This was just an idea to thwart installation of compromised firmware by thieves via the diagnostics port. It's just a little layer of security, not designed to be bulletproof, merely to slow down thieves by forcing them to actually swap the hardware.
if you're up for desoldering stuff you may as well just replace the ECU with your own one which is happy to start the car. I demand a source that teaches me how to do this. :) Orrr if you're in Chicago let's go figure it out ourselves!
https://www.cesvi.com.ar/index2.html
I remember reading about the people that dismantled cars to find where manufacturers source the parts:
https://jalopnik.com/the-fascinating-company-that-tears-cars...
Those guys can probably switch you the ECU :)