The exemplified methods and systems provide hardware-circuit-level encryption for inter-core communication of photonic communication devices such as photonic network-on-chip devices. In some embodiments, the hardware-circuit level encryption uses authentication signatures that are based on process variation that inherently occur during the fabrication of the photonic communication device. The hardware level encryption can facilitate high bandwidth on-chip data transfers while preventing hardware-based trojans embedded in components of the photonic communication device such as PNoC devices or preventing external snooping devices from snooping data from the neighboring photonic signal transmission medium in a shared photonic signal transmission medium. In some embodiments, the hardware-circuit-level encryption is used for unicast/multicast traffic.