Flexible Smart Labels for Mobile Authentication Using Photonic Physical Unclonable Functions

The Internet of Things (IoT) is a network of connected objects, interacting in real-time, without human supervision. However, the large-scale dissemination and the development of digital ecosystems requires mobile applications with fast and reliable methods to generate secure cryptographic keys, such as Physical Unclonable Functions (PUFs). In this work, functional operating photonic PUFs based on flexible tokens were produced at low-cost, energy-efficient, and scalable methods, using an organic-inorganic hybrid doped with lanthanide ions (Ln³⁺=Eu³⁺), displaying unique challenge-response pairs for two-factor authentication. Under laser irradiation, a speckle pattern is attained, and under UV light-emitting diodes, it displays a random luminescent intensity-based pattern, ensuring the two-factor authentication precision and recall values around 100%. Moreover, the two-factor authentication possibility enables this system to be used as a conventional PUF encryption proving a new paradigm of cryptographic key generation by featuring perceptual hash key extraction with images taken from a smartphone which can provide easy and fast remote authentication.<br/><br/>Acknowledgements: CICECO-Aveiro Institute of Materials (UIDB/50011/2020, UIDP/50011/2020, LA/P/0006/2020), Instituto de Telecomunicações (UIDB/50008/2020, UIDP/50008/2020); FCT/MEC, FEDER, PT2020. LMS Dias was supported by 2020.05802.BD.