A team of MIT researchers has created a cryptographic ID tag that boasts several advantages over existing technologies – spurring hope it will revolutionize supply chain verification. The tag is several times smaller, much cheaper, and offers better security than the radio frequency identification (RFID) tags currently used for product verification. The new tag uses terahertz waves, superior to radio waves in both size and frequency, to increase security. In the past, terahertz tags, while offering significant improvements, shared a major flaw with RFID tags; counterfeiters could detach a tag from a genuine product and attach it to a counterfeit one without detection.
To overcome this problem, the researchers used terahertz waves to create an antitampering ID tag that remains small, inexpensive, and secure. The tag attaches to an item with a special glue that has microscopic metal particles mixed in. The terahertz waves identify the unique pattern these particles form, providing an authenticating “fingerprint” for each item. The researchers compared this process to how light reflects differently based on the arrangement of mirror shards scattered on a surface. If the tag is detached and reattached, the pattern is destroyed, preventing counterfeiting.
Making the tag even more secure, the researchers used a machine-learning model to detect a tampered tag by identifying similar glue pattern fingerprints with more than 99% accuracy. The model works by comparing the patterns and calculating their similarity. The tiny, inexpensive terahertz tag has potential for widespread implementation in supply chains, including applications for smaller items unsuitable for traditional RFIDs. Its size is similar to 4 square millimeters.
While their research showed significant potential for the terahertz tag, the team did also identify limitations. Precise measurements necessary to identify whether two glue patterns match were difficult and time-consuming to achieve, although this could be addressed by getting more data samples. Another limitation is that terahertz waves can suffer from significant loss during transmission, requiring the tag and sensor to be close (about 4 centimeters). This makes the tag unsuitable for applications where greater distance is needed, such as automated highway toll booths. Finally, the angle between the sensor and tag must be less than 10 degrees or the signal will degrade. The team aims to address these limitations in future research.
