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MIT researchers have developed a cryptographic ID tag that offers enhanced security features and is significantly smaller and cheaper than traditional radio frequency tags (RFIDs) often used for product authentication. This innovative tag utilises smaller terahertz waves, which have much higher frequencies than radio waves, providing improved security measures over RFIDs. However, a major security vulnerability shared with traditional RFIDs was the potential for counterfeiting, where the tag could be removed from a genuine item. It reattached to a fake one, deceiving the authentication system.
To address this vulnerability, the researchers have devised an antitampering ID tag using terahertz waves that retains the benefits of being small, cost-effective, and secure. They achieved this by incorporating microscopic metal particles into the glue that adheres the tag to an object.
Using terahertz waves to detect the unique pattern formed by these particles on the item’s surface, similar to a fingerprint, the researchers can authenticate the item. Eunseok Lee, an electrical engineering and computer science (EECS) graduate student and lead author of the paper on the antitampering tag, explained that these metal particles act as mirrors for terahertz waves, reflecting them in a unique pattern that is disrupted if the tag is peeled off and reattached, thus thwarting counterfeit attempts.
The resulting light-powered antitampering tag is approximately 4 square millimetres and includes a machine-learning model that can detect tampering by identifying similar glue pattern fingerprints with over 99% accuracy. This innovative approach enhances security and offers cost-effectiveness, making it suitable for large-scale implementation throughout the supply chain. Additionally, its small size allows it to be used on items that are too small for traditional RFIDs, such as certain medical devices, expanding its potential applications.
The research team’s approach to security was inspired by the personal experience of Ruonan Han, an associate professor in EECS, who encountered an RFID tag at a car wash. The tag, made from fragile paper, was designed to be destroyed if tampered with, but Han recognised the limitations of such a method. Instead of authenticating the tag, the researchers aimed to authenticate the item by focusing on the glue interface between the tag and its surface.
The antitampering tag contains minuscule slots that allow terahertz waves to pass through the tag and strike the microscopic metal particles mixed into the glue. Unlike radio waves, terahertz waves are small enough to detect these particles, and their wavelength allows for creating a chip that does not require a larger, off-chip antenna. The unique distribution of metal particles on the object’s surface reflects the terahertz waves in a pattern similar to a fingerprint that is impossible to duplicate if a counterfeiter destroys the glue interface.
A key challenge in implementing this technology was the precise measurement required to determine whether two glue patterns match. To address this, Lee collaborated with a colleague in the MIT Computer Science and Artificial Intelligence Laboratory (CSAIL) to develop a machine-learning model to compare glue patterns and calculate their similarity with more than 99% accuracy. While the demonstration had a limited data sample, deploying many of these tags in a supply chain could significantly improve the neural network’s performance.
Despite its promising potential, the authentication system using terahertz waves has limitations. Terahertz waves suffer from high loss levels during transmission, limiting the sensor’s distance from the tag to about 4 centimetres for accurate readings. The angle between the sensor and tag must also be less than 10 degrees to avoid signal degradation. Future work will address these limitations to expand the technology’s applications.
Creating the anti-tampering ID tag with terahertz waves marks notable progress in secure identification technology. This cost-effective, secure, and scalable solution can be widely deployed, offering new opportunities for terahertz wave applications in various fields.
