Naturally safe: Cellular noise for document security

• Published in: Journal of biophotonics 2019-12, Vol.12 (12), p.e201900218-n/a
• Main Authors: Pavlović, Danica, Rabasović, Mihailo D., Krmpot, Aleksandar J., Lazović, Vladimir, Čurčić, Srećko, Stojanović, Dejan V., Jelenković, Branislav, Zhang, Wang, Zhang, Di, Vukmirović, Nenad, Stepanenko, Dimitrije, Kolarić, Branko, Pantelić, Dejan V.
• Format: Article
• Language: English
• Subjects: biophotonics; Bleaching; Butterflies & moths; Coloration; complexity; Copying; Cryptography; Diffractive optical elements; Embossing; Insects; iridescence; Optical components; optical document security; Optical memory (data storage); Security; variability
• ISSN: 1864-063X; 1864-0648
• DOI: 10.1002/jbio.201900218

Modern document protection relies on the simultaneous combination of many optical features with micron and submicron structures, whose complexity is the main obstacle for unauthorized copying. In that sense, documents are best protected by the diffractive optical elements generated lithographically and mass‐produced by embossing. The problem is that the resulting security elements are identical, facilitating mass‐production of both original and counterfeited documents. Here, we prove that each butterfly wing‐scale is structurally and optically unique and can be used as an inimitable optical memory tag and applied for document security. Wing‐scales, exhibiting angular variability of their color, were laser‐cut and bleached to imprint cryptographic information of an authorized issuer. The resulting optical memory tag is extremely durable, as verified by several century‐old insect specimens still retaining their coloration. The described technique is simple, amenable to mass‐production, low cost and easy to integrate within the existing security infrastructure. Natural biophotonic structures are used to create the unbreakable cryptographic concept and devices.