PUF Technology Catches Clones

When a retailer sells a tagged product, it can transmit a request to the item's manufacturer and obtain a list of challenges. An interrogator can then issue several different challenges (strings of numbers), each eliciting a digital signature that differs from those elicited by the other challenges. The reader will instruct the PUF circuit to send a challenge when prompted, and the chip will respond with the expected string of corresponding numbers and letters, indicating its authenticity, or with a separate set of numbers and letters signifying that it is counterfeit.

The response from an authentic chip will typically have a few variations of digits—up to 25 percent, Khandelwal says. If there are more than that figure, the chip is determined to be fraudulent—in other words, a cloned copy of an authentic chip. If there is any doubt, the reader operator can attempt another challenge and compare the results.

The PUF system, Khandelwal says, could be adapted for use with any RFID chip or tag, passive or active, and regardless of radio frequency and air-interface protocol. Because the PUF circuit is so small, and since no extra information needs to be stored on the chip (such as encryption data), the tag's power consumption remains unaffected. The addition of the PUF circuit adds only a slight increase to the tag's cost.

Verayo is presently working with RSIID Technologies to create the labels and tags in which the Verayo chips will be incorporated. Those labels and tags are commercially available now.

The RFID industry currently uses encryption algorithms to verify the authenticity of certain RFID ICs, such as NXP's Mifare passive 13.56 MHz chips. But this requires that the chip store encryption data, and that the reader and tag transmit via an encrypted signal. The EPC Gen 2 standard, however, does not support encryption, which means most passive UHF EPC Gen 2 tags presently on the market are vulnerable to cloning.

At the current time, Khandelwal says, Verayo is focusing on marketing the Vera X512H chip to the luxury products and ID cards market, where there is a high risk of tag counterfeiting. However, he notes, PUF-enabled tags could also be employed for other high-crime-risk industries, such as pharmaceutical products, sports memorabilia or airline cargo. Although Verayo is selling its own PUF-enabled RFID chips, any chip vendor could incorporate the PUF circuit into the chips it fabricates as well. Verayo is open to licensing agreements with RFID label makers, Khandelwal says.

On Sept. 17, RFID Journal will host a webinar during which Verayo will explain how its technology works, and how it can be employed to fight counterfeiting. For more information, or to register, click here.