Privacy Naiveté

The State Department has placed RFID chips in the identity card usable for surface travel between the US and Canada or Mexico. On the page Where they describe this card they state have the following question and answer: Won’t this chip violate Americans’ privacy?

There will be no personal information written on the electronic chip itself. The chip will have only a unique number pointing to a stored record contained in secure government databases.

However the card will have a unique identifier--the number State is using as a database key--and this number can be used to track specific individuals and to detect the proximity of a US citizen. Carrying one of these outside a Faraday cage will threaten the bearer's privacy.