  The omnipresent digitalization trend has enabled a number of related
malicious activities, ranging from data theft to disruption of businesses,
counterfeiting of devices, and identity fraud, among others. Hence, it is
essential to implement security schemes and to ensure the reliability and
trustworthiness of electronic circuits. Toward this end, the concept of
physically unclonable functions (PUFs) has been established at the beginning of
the 21st century. However, most PUFs have eventually, at least partially,
fallen short of their promises, which are unpredictability, unclonability,
uniqueness, reproducibility, and tamper resilience. That is because most PUFs
directly utilize the underlying microelectronics, but that intrinsic randomness
can be limited and may thus be predicted, especially by machine learning.
Optical PUFs, in contrast, are still considered as promising---they can derive
strong, hard-to-predict randomness independently from microelectronics, by
using some kind of "optical token." Here we propose a novel concept for
plasmonics-enhanced optical PUFs, or peo-PUFs in short. For the first time, we
leverage two highly nonlinear phenomena in conjunction by construction: (i)
light propagation in a silicon disk resonator, and (ii) surface plasmons
arising from nanoparticles arranged randomly on top of the resonator. We
elaborate on the physical phenomena, provide simulation results, and conduct a
security analysis of peo- PUFs for secure key generation and authentication.
This study highlights the good potential of peo-PUFs, and our future work is to
focus on fabrication and characterization of such PUFs.
