I supposed location and information could be added to a sign along with a certification or checksum. As long as its done in a way that doesn't require exact pl

I supposed location and information could be added to a sign along with a certification or checksum. As long as its done in a way that doesn't require exact placement, signs found outside their location are ignored. ...something like, "Forest St. Northbound CLOSED (lat,lon) <encrypted checksum>"?