RSA develops selective RFID blocker
RFID readers can’t talk to more than one tag at a time, so when multiple tags reply to a query, the readers detect a collision and revert to what’s known as a singulation protocol to communicate with each tag individually. To accomplish this, the reader queries each tag for its next bit, which identifies which portion of a binary tree the tag resides on. When queried, a blocker tag responds with a ‘0’ and a ‘1’ bit. This causes the reader to start over and explore the entire tree.
Such a tag could be programmed to block only a certain range of RFID serial numbers. This would still allow for benign uses of RFID tags while enabling users or corporations to control which tags are readable.
