There are laws, and social mores - but those certainly don't stop people from hacking road signs or removing traffic signals.(1,2) Moreover, unlike spikes on th

There are laws, and social mores - but those certainly don't stop people from hacking road signs or removing traffic signals.(1,2) Moreover, unlike spikes on the road, a tampered-with indicator might not be immediately obvious, even in its effects. Anyway, I finally had a chance to read through the patent; it's enough of a concern that they specifically address it: "In some embodiments, the data provided by the reference indicator 250 may be encoded or cryptographically signed for security purposes. By providing encoded or cryptographically signed data, the ability for a third party to disrupt the autonomous vehicles may be mitigated." (1) http://www.google.com/search?q=sign+hacking http://www.google.com/search?q=sign+hacking (2) http://en.wikipedia.org/wiki/Street_sign_theft http://en.wikipedia.org/wiki/Street_sign_theft