Researchers from MIT have developed a cryptographic ID tag that’s considerably smaller, more secure, and cost-effective than traditional radio frequency tags (RFIDs) regularly used in product authenticity verification. These ID tags use terahertz waves, which are smaller and have higher frequencies than radio waves, thus being more compact and secure.
An issue with traditional RFIDs is that counterfeiters can move the tag from a genuine item to a counterfeit one, misleading the authentication system. To overcome this, MIT researchers have mixed microscopic metal particles into the glue holding the tag to an object. They then use the terahertz waves to examine the pattern these particles form on the object’s surface, essentially creating a unique fingerprint for each item.
The researchers compared these metal particles to mirrors for terahertz waves, reflecting different patterns based on their orientation, size, and location. If the tag is moved, the pattern gets destroyed, ensuring that counterfeiters cannot tamper with the ID tags. Importantly, the system can pinpoint tampering with an exceptional accuracy of over 99%, thanks to a machine-learning model developed to identify similar glue pattern fingerprints.
The small size and affordable production cost of the terahertz tag make it highly suitable for large supply chains. It can even be attached to smaller items usually too tiny for traditional RFIDs, such as certain medical devices.
The antitampering tag consists of minuscule slots that allow terahertz waves to strike the microscopic metal particles mixed into the glue. The waves are then backscattered to a receiver for authentication, depending on the distribution of metal particles.
To verify an object’s authenticity, a vendor would take an initial reading of the tag once it gets stuck onto the item. The data are stored in the cloud for future reference, creating a digitally secure check-in and check-out system.
Though promising, the system does have limitations. Terahertz waves suffer from high levels of loss during transmission, limiting the sensor-tag distance to about 4 centimeters for accurate reading. Moreover, the angle between the sensor and tag must be given considerations since it needs to be less than 10 degrees to ensure signal quality. The team hopes to address these issues in their future work.
Ultimately, the application of the terahertz spectrum can go beyond simply broad wireless, benefitting ID, security, and authentication measures. Despite the challenges, this development exemplifies the wide range of possibilities that terahertz waves can offer. This project is partly supported by the U.S. National Science Foundation and the Korea Foundation for Advanced Studies.
