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The first Physical Access Control that uses uncopiable keys based on butterfly scales

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Unique nanostructures provide uncopiable keys and real security

All lock systems can be cracked, except this one.


Modern lock systems are not as secure as they seem. Any mechanical key can be copied, plus manufacturers may have made duplicates without the client’s knowledge. Biometric key systems, relying on unique body features such as fingerprints or iris patterns, can be tricked. Electronic key cards can be cloned. Even today’s most sophisticated locks are vulnerable. Cryptographic locks match encrypted private and public sequences of numbers. Computers can crack these encryptions, given enough time. Likely computers of the future, such as quantum computers, should be able to break any encryption almost instantaneously. Critical high-security installations need a locking system that is truly unbreakable and this is what the EU-funded B-Lock project has developed. The team prepared a full demonstration system and readied the development for commercialisation.

Unique nanostructure

Like many modern lock systems, the B-Lock system consists of a locking mechanism containing an optical reader and a plastic key card. The difference is that each B-Lock card represents a unique nanostructure that is scanned and validated by the reader. “The structure is of biological origin,” explains project leader Aleksej Makarov. “The structures are called butterfly scales because they are literally the chitin scales from the wings of butterflies or moths.” The scales have a complex nanostructure, accounting for the wings’ iridescent colour patterns, unique to each individual butterfly. Miniscule chitin particles are applied on the key cards. The optical reader does not contain the chitin nanostructure itself, since reading it would require an extremely bulky and expensive electron microscope. “Fortunately,” adds Makarov, “chitin changes colour as the angle of illumination changes. This is called iridescence. Using this principle, a set of unique, unrepeatable sequences of photographs can be obtained for each key card under an arbitrary sequence of illumination angles.” This image sequence is called an iridescent signature, and it is unequivocally linked to one original nanostructure. The patterns cannot be replicated by human technology because they were not created using technology. A unique iridescent signature is encoded on each card.

Uncopiable keys

The lock scans the iridescent signature on the key card. The signature is checked against the lock’s database to verify whether that card is authorised. If so, it opens. According to Makarov, the signature cannot be copied either, because it must be generated by photographing an uncopiable 3D nanostructure under a set of arbitrary lighting angles. This makes each key card uncopiable. B-Lock researchers demonstrated the real-world effectiveness of both the concept and the technology. Certain technical issues remain to be addressed, such as lock miniaturisation, cost reduction via manufacturing automation and the application of nanostructures onto various other materials. The team also gained input from potential customers about their needs and the improvements they would like. The consortium plans to continue development using its own funds, and to apply for next-phase EU funding. The project’s completed business justification establishes that the B-Lock system would be price-competitive with existing systems, although far more secure. The technology also lends itself to other applications, such as identification features on bank notes, passports, credit cards and works of art. The market should be considerable.


B-Lock, nanostructure, chitin, uncopiable, iridescent signature, locks, security, keys, butterfly scales

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