A DEVICE designed to allay privacy fears over the introduction of radio frequency identification (RFID) tags could also wreak havoc with security systems.
RFID tags are small microchips containing a unique 96-bit code that can be used to identify any object they are attached to. While retailers hope the tags will replace barcodes and act as anti-theft devices, privacy advocates worry they could be used to track buyers. So RSA Laboratories in Bedford, Massachusetts, has created a modified tag that produces a barrage of noise, drowning out all other tags in range.
When a tag reader sends out a query, all the RFID tags in the vicinity reply. The query takes the form of checking each of the 96 bits in turn, progressively building up the sequences of the tags that are present. When a tag fits the sequence so far, it replies yes; otherwise it stays silent. In this way it homes in on the sequences of all the tags that are present. The RSA Laboratories鈥� blocker tag always replies 鈥測es鈥�, confusing the reader and effectively making all other tags within range unidentifiable 鈥� thus protecting a consumer鈥檚 privacy.
Advertisement
However, a blocker tag planted in a shop could render the shop鈥檚 whole tag system useless. To prevent this, RSA limits its system to drowning out the reader only when it queries specific bits. 鈥淲e stopped pursuing the universal blocker and made it selective,鈥� says Burt Kaliski, director of RSA Laboratories.
But a malicious user could easily create universal blockers that could be scattered around a supermarket or stockroom, or planted on the body of a thief. 鈥淏locker tags could be a new high-tech shoplifting tool,鈥� says Richard Smith, an independent security expert in Boston, US.
Smith points out that there are also low-tech ways to bring an RFID system to its knees. You could always wrap tagged items in aluminium foil, he says.
