Dynamic Cryptography through Plasmon‐Enhanced Fluorescence Blinking

Abstract

Merging cryptographic primitive technologies and physical unclonable functions (PUFs) have become a new paradigm of one-way encryption. Herein, the authors report a dynamic PUF cryptographic primitive based on plasmonic fluorescence blinking from single or a few dye molecules embedded within the nanogaps of plasmonic patch nanoantennas. This cryptographic primitive carries two sets of high-capacity optical codes: the fluorescence blinking of the embedded dye molecules and multi-color light scattering enabled by the plasmonic nanoantennas. The former allows the generation of temporal binary codes from a large number of individual plasmonic patch nanoantennas by holding either "1" (bright state) or "0" (dark state), while the latter provides a permanent color-based novenary code that acts as a decryption channel for authentication. Benefiting from the high electromagnetic field localized within the nanogaps and the large Purcell enhancement of the plasmonic nanoantennas, the fluorescence blinking is readily detectable by a common fluorescence microscope with a mercury arc lamp as a lowpower excitation source. The developed dynamic PUF codes are robustly and accurately authenticated by a self-programmed computer vision algorithm. This study revolutionizes the conventional static PUF encryption to nanophotonics-based dynamic encryption, opening a new avenue for next-generation advanced anti-counterfeiting.

Plasmonic Physical Unclonable Function Labels Based on Tricolored Silver Nanoparticles: Implications for Anticounterfeiting Applications

“…In addition, the colorful plasmonic PUF labels have been tested for exposure to air over 3 months, and no obvious change in optical property is observed, revealing that the labels have excellent air- and photo-stabilities under the air condition and natural light (see Figure S8). To further increase the lifetime of plasmonic labels, it is expected that the silica shell would be able to protect it from oxidization and external mechanical or chemical damages . The unique size-, shape-, and assembly configuration-dependent colorful plasmon-response is free from photobleaching and cannot be mimicked by chemical dyes.…”

“…To further increase the lifetime of plasmonic labels, it is expected that the silica shell would be able to protect it from oxidization and external mechanical or chemical damages. 5 The unique size-, shape-, and assembly configuration-dependent colorful plasmonresponse is free from photobleaching and cannot be mimicked by chemical dyes. 3.5.…”

“…The global community has been devoted to comprehensively combating counterfeit and shoddy products due to their catastrophic destruction to property safety, social financial order, and resultant immeasurable losses. − Developing anticounterfeiting labels is one of the most effective solutions. − For example, a wide range of traditional anticounterfeiting labels are available, including polymer QR codes, barcodes, stimulus-response color-changing papers, holograms, , silica-polymer fingerprints, perovskite nanocrystal labels, structural color patterns, , metasurface anticounterfeiting devices, ,, and so forth. However, these traditional security labels featuring single-pattern recognition can be easily forged by unscrupulous counterfeiters.…”

“…The unique optical LSPR properties can be obtained by simply tuning its structure (e.g., the size, shape, composition, and dielectric properties of the surrounding medium of metal NPs). ,,,,− Large NPs have strong scattering and weak absorption of visible light while small NPs have strong light absorption and weak scattering. − , Herein, we have created a colorful plasmonic anticounterfeiting label by drop casting AgNPs of three sizes to generate randomly distributed colorful patterns, which endows huge encoding capacity (≥8 7396 ) and fast readout (∼0.06 s per label), can be achieved using self-optimized Python language. The correct readout/feedback of the colorful plasmonic PUF labels can be readily unaffectedly achieved without interference by applying different brightness, contrast, and even accidental cracks/scrapes on the labels.…”

Designed Growth of AgNP Arrays for Anti-counterfeiting Based on Surface-Enhanced Raman Spectroscopy Signals

“…The anti-counterfeiting label of the three-dimensional (3D) structural code integrates various anti-counterfeiting technologies to form a new comprehensive anti-counterfeiting technology, such as label anti-counterfeiting, digital information anti-counterfeiting, and processing technology anti-counterfeiting, which overcome the shortcomings of the traditional anti-counterfeiting technologies, simple identification labels, digital labels, and self-adhesive labels . However, the labeling technologies reported recently cannot meet the abovementioned conditions at the same time due to the complexity of the manufacturing process or its random structure, such as luminescent magnetic nanoparticles, , dendritic silver nanoparticles, two-photon direct laser writing lithography, and dynamic cryptography through plasmon-enhanced fluorescence blinking . Therefore, it is still a challenge to manufacture anti-counterfeiting signs with mass-produced, highly reliable, nonreproducible, and markable patterns.…”