Given the rapid expansion of the Internet of Things and because of the concerns around counterfeited goods, secure and resilient cryptographic systems are in high demand. Due to the development of digital ecosystems, mobile applications for transactions require fast and
reliable methods to generate secure cryptographic keys, such as Physical Unclonable Functions (PUFs). We demonstrate a compact and
reliable photonic PUF device able to be applied in mobile-based authentication. A miniaturized, energy-efficient, and low-cost token was
forged of flexible luminescent organic–inorganic hybrid materials doped with lanthanides, displaying unique challenge–response pairs (CRPs)
for two-factor authentication. Under laser irradiation in the red spectral region, a speckle pattern is attained and accessed through conventional charge-coupled cameras, and under ultraviolet light-emitting diodes, it displays a luminescent pattern accessed through hyperspectral
imaging and converted to a random intensity-based pattern, ensuring the two-factor authentication. This methodology features the use of
a discrete cosine transform to enable a low-cost and semi-compact encryption system suited for speckle and luminescence-based CRPs.
The PUF evaluation and the authentication protocol required the analysis of multiple CRPs from different tokens, establishing an optimal
cryptographic key size (128 bits) and an optimal decision threshold level that minimizes the error probability.publishe
