At South Korea’s Gwangju Institute of Science and Technology (GIST), researchers have used natural silk fibres, silk fibres that are made from domesticated silkworms to create a digital security system. The system is environmentally friendly, and the researchers assert that the system is “practically unbreachable.”

The first natural physical unclonable function (PUF) […] takes advantage of the diffraction of light through natural microholes in native silk to create a secure and unique digital key for future security solutions,” the researchers said.

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Physical unclonable or PUFs are devices that use randomness—an inherent feature—and minute differences in electronics that happen during manufacturing to generate a separate unique identifier (e.g., cryptographic keys) for a given set of inputs and conditions.

PUFs don’t use algorithms, and PUFs is unidirectional, obtained from unique elements to produce unbreakable identifiers for a robust authentication system. In the last few years, PUFs have been a common feature in smartcards that are used for “silicon fingerprints” to uniquely recognise cardholders. A challenge-response authentication scheme underlies the card recognising system. 

The new method, created by GIST, uses native silk fibres made from silkworms to make PUF-based tags. These tags are then used to create a PUF module. This mechanism banks on the underlying principle that a light beam experiences diffraction when it hits an obstacle, in this case, the silk fibre.

“In addition, the nanofibrillar structures in each microfiber significantly improves the light intensity contrast between the background and focal spots owing to the strong scattering,” the researchers noted in a paper published in Nature Communications. “These novel optical features could easily implement the module of a lens-free optical PUF by placing a silk ID card on the image sensor.”

“To our knowledge, this is the first PUF module designed using silk, a naturally abundant biomaterial,” Prof. Yong said in a statement. “It means that we don’t need to invest time in developing complicated security keys, nature has already done this for us.”