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If you just want to feed computers just put a database with every sign location and data. That way even faking or destroying sign would be ineffective. Would

• mbreese 4y ago
  > That way even faking or destroying sign would be ineffective In theory you could add an HMAC (or similar) signature to the QR code. It would be bigger, but if cars maintained a DB of state DOT public keys, you could mitigate this somewhat. Then you’d also have to worry about duplicate codes, but at least they wouldn’t be “fake”. Maybe even add lat/long coordinates to the code… again, more data, more pixels required, but it would make sure the signs are roughly in the right place. Which doesn’t seem all that feasible to require construction crews to put the right sign in the right place. Logistically this doesn’t seem all that promising.
  • labcomputer 4y ago
    Just give the road crew a phone app that can read the sign. Given the phone's camera, compass and GPS, validating that the sign has been installed as specified (location, facing direction) is almost trivial.