  The compact size and high wavelength-selectivity of microring resonators
(MRs) enable photonic networks-on-chip (PNoCs) to utilize
dense-wavelength-division-multiplexing (DWDM) in their photonic waveguides, and
as a result, attain high bandwidth on-chip data transfers. Unfortunately, a
Hardware Trojan in a PNoC can manipulate the electrical driving circuit of its
MRs to cause the MRs to snoop data from the neighboring wavelength channels in
a shared photonic waveguide, which introduces a serious security threat. This
paper presents a framework that utilizes process variation-based authentication
signatures along with architecture-level enhancements to protect against
data-snooping Hardware Trojans during unicast as well as multicast transfers in
PNoCs. Evaluation results indicate that our framework can improve hardware
security across various PNoC architectures with minimal overheads of up to
14.2% in average latency and of up to 14.6% in energy-delay-product (EDP).
