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Comment by barryvan | Hacker News Reader

How would that work where streets signs _do_ change suddenly? A couple of examples I see every day are roadworks (new fixed signage for the duration of the works, or even a person flipping a sign between "stop" and "slow") and "smart" freeways/signage (screen-based speed limit signs that change, and have additional signs for speed-limits if all screens are off). Here in AU, we also have "school zones" with speed limit signs that turn on only during certain times and dates.

I'm not sure that governments would be quick enough to keep this "central roadmap" correct up-to-the-minute (to be honest, I suspect that "up-to-the-month" would be a stretch!).

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I would assume that "smart" signs would transmit their state via Vehicle-to-Infrastructure (V2I) network, same for roadworks (i.e. workers would mark affected zone and this state will be transmitted via a mobile battery-powered beacon). Such transmitted states will be signed, with road authority key in the root of the certificate tree, so it will be hard to spoof them (at the very least, it will be easy to identify responsible for key leaking). Of course, it assumes a proper digitalization of infrastructure and appropriate regulation changes, which is not given... But in my opinion massive adoption of full self-driving cars will be difficult without them.

>Here in AU, we also have "school zones" with speed limit signs that turn on only during certain times and dates.

Such conditions are usually fixed and do not suddenly change. Even OSM handles them today more or less fine.

Hmm, that would certainly be a solution. However, I'm a little dubious as to how this would work in practice. The current signage can be thrown on the back of a truck, bashed about, subjected to dirt and weather, and is really easy to use.

Smart signage would (likely) be more fragile, (likely) require charging or similar infrastructure, and would require configuration -- so that the sign can communicate in which direction of travel it applies and so on. Certainly not impossible hurdles to overcome, but the costs associated seem very high -- in terms of manufacture, maintenance, and training.

For what it's worth, I suspect that we will see FSD cars operating with infrastructure likely along the lines you outline in the not-terribly-distant future -- but I suspect that they will operate within very clearly prescribed zones, like freeways and highways.

> Such transmitted states will be signed

And pranksters, vandals and petty thieves won’t make off with these cryptographically signed signage? Because this already happens for our existing dumb infrastructure.

I don't quite follow you. Yes, we can't prevent keys from leaking here and there, which could allow malicious actors to cause some damage, but we can reduce its impact by making keys short-term (as we do today with TLS certificates) and capability-restricted, i.e. you would not be able to change highway speed limit with a road worker key and you will not be able to use a key generated for city A in a neighboring city B. And you probably will be able to use a leaked key only once, since after an illegal usage is detected it will be quickly revoked. Plus it will be clear whose negligence has caused the leak, thus responsible people/organizations can be held accountable, which eventually should improve cybersecurity level (at least a bit).

This doesn't work with banks. How is it going to work with governments?

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