MIT researchers have advanced their previously developed cryptographic ID tag that uses terahertz waves instead of radio frequency (RFID) technology, to bolster its security and undermine counterfeiting efforts. The initial model of their tag had a major flaw in that it could be peeled off a genuine item and reattached to a counterfeit, thereby tricking the authentication system. The researchers overcame this security vulnerability by integrating metallic particles into the adhesive that connects the tag to the product. When terahertz waves are beamed onto these particles, they create a distinct pattern or “fingerprint” on the surface of the item, which aids in verifying its authenticity.
Eunseok Lee, an EECS graduate student and lead author of the paper on the antitampering tag, explains that the metallic particles behave like mirrors to terahertz waves. These waves reflect off the particles in a way that depends on their arrangement, size, and orientation, creating distinctive patterns. However, if the tag is detached and reattached, this pattern is destroyed, a key feature thwarting counterfeiters.
The research team produced an antitampering tag of about 4 square millimeters, powered by light. They also created a machine-learning model that can identify similar glue pattern fingerprints with over 99% accuracy, helping to detect tampering.
The terahertz tag, thanks to its small size and cheap production cost, has the potential to be widely employed across large supply chains. Its small size also allows it to be applied to items too small for traditional RFIDs like specific medical devices.
The research used a methodology where the tag consisted of tiny slots that allowed terahertz waves to hit the metal particles in the adhesive. The waves are reflected back to a receiver, forming a unique pattern for authentication. Different slots on the chip ensured that waves could strike various points on the product’s surface, capturing more information about the particle distribution.
The initial reading of the tag once attached to an item would be recorded and stored in the cloud for future verification. However, the terahertz waves face high levels of loss during transmission, limiting the read-range to about 4 cm and required an angle less than 10 degrees between the sensor and tag for accurate readings. Future research will focus on addressing these limitations.
