Mark Wahl has written to clarify the difference between the ScanPak RFIDs mentioned in my earlier piece and typical passive tags. He says the ScanPak press release mentions they have a read range of up to 200 meters and that the RF tag is “powered by two parallel lithium coin cells.”
These are active tags: they contain their own power source. In contrast, a passive tag does not contain batteries, it obtains power from from the reader, and generally could not be reliably accessed over such a distance. A tag that is intended to be read only from a few, well-defined locations such as a passing through a doorway, or a tag that is intended to be attached to a low-value consumer item, would likely be a passive tag.
Thanks for the heads up, Mark. It looks like hackers will have to get up out of the Food Court and head right on in to the stores.
Still, experts are routinely quoted as saying the range of passive RFID devices is being significantly extended by new reader and antenna technology. For example:
But what about a more powerful RFID reader, created by criminals or police who don't mind violating FCC regulations? Eric Blossom, a veteran radio engineer, said it would not be difficult to build a beefier transmitter and a more sensitive receiver that would make the range far greater. “I don't see any problem building a sensitive receiver,” Blossom said. “It's well-known technology, particularly if it's a specialty item where you're willing to spend five times as much.”
You can build quite a transciever for the price of a Comme des Garcons outfit.
And strangely, the RFID components used by the Britton School District were the size of a “roll of dimes” – meaning they could easily be Active tags.