This strikes me as ripe for abuse.
The QR codes would contain very little information I would imagine but rather a key that is used by the car as an argument for further operations. Leaving all the directional data on the road would be way too easy to abuse.
"it might link to a parking garage database of which parking slots are open"
Imagine creating a QR code, (or copying one that already exists) which tells the car to fetch information from http://your.competitor.example.com/. Then imagine going out late at night and sticking it on a busy motorway.
DOS by traffic.
Also. You better hope that your car doesn't have any vulnerabilities that can be abused by a specially crafted QR code, or by fetching specially crafted data that a QR code prompts it to fetch.
Also you're going out on a highway, at night, to lay down a big sticker. That's dangerous, suspicious, and illegal (before we even considering what the sticker does). If you want to DOS a competitor there are much more effective and safe ways to do so.
While we're there we better do something about all those people using radio jammers to down auto-landing aircraft.
Also, you better hope their are no vulnerabilities in the automatically driven mono-rail / train system you are riding in.
These type of issues are going to be discussed to the end of the earth but I can't wait to see driverless cars make their way from the lab to the car dealer.
As far as introduction, I would bet these features will be added to high-end luxury models and quite possibly initially limited to main roads (motorways / interstates) where the chances of encountering something unusual are lower. With the addition of a fair splattering of warning labels.
You're thinking way too tin hat.
I very, very rarely resort to ad hominem, least of all on HN, but your nickname says it all (if indeed VB refers to Visual Basic). Far too many computer problems of yore were created by VB programmers not being nearly "tin hat" enough. When engineering systems which can damage other systems or cause bodily harm, one's responsibility is to anticipate, mitigate, and prevent the worst case scenario to the maximum extent possible.
Given that you resorted to ad hominem I assume you have no other reasonable arguments against what I said.
Could you not have the QR codes generated against a private key and the vehicle verify it against the public key to determine whether the instruction came from a trusted source?
Just because it's plain text data in a QR code doesn't mean that it's inherently ripe for abuse.
How could people resist creating a loop of instructions...
Lots of assumptions here from everyone about how the signs are implemented and what the QR codes contain, but the general gist is that they could be secured. Assuming otherwise is also an assumption.
b) The idea is not to have electronic QR signs, it is to have QR signs that contain something like a URL that contains up-to-date info about a place. Replace that URL by your own, and have fun :-)
Yeah. The obvious first idea is to sign the codes, but then when the private key gets stolen (100% certain to happen sooner or later,) you have to repaint every road.