RSA Security has developed a countermeasure to block scanning of radio-frequency ID tags, responding to privacy concerns about the tiny devices that would allow retailers and manufacturers to track the whereabouts of their goods within a store and beyond.

The blocker tag, which can be placed over a regular RFID tag, prevents a receiver from scanning information transmitted by a tag by sending the receiver more data than it can read — the equivalent of a denial-of-service attack. RSA doesn’t have immediate plans to market the blocker and is waiting to see whether industry widely adopts RFID technology.

An RFID tag consists of a microchip the size of a grain of sand attached to an antenna that wirelessly transmits information by radio whenever it passes an RFID reader. Product manufacturers and stores want to place the tags on consumer items such as hygiene products, packaged foods and clothing to manage inventory, track consumer interest in products and thwart thieves. The devices could also benefit consumers by transmiting messages to smart appliances in their home. For instance, a tag in a milk carton could tell a computer-enabled refrigerator when its contents are running low.

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