Abstract: Systems for, and methods of, detecting an attack on an optical communication channel are presented. The techniques can include sending, from a sender to a receiver, and over the optical communication channel, an optical signal, where the optical signal includes a classical optical signal representing first information and a quantum optical signal representing second information. The techniques can include detecting, by the receiver, third information from at least a portion of the quantum optical signal and sending, by the receiver to the sender, the third information. The techniques can include determining, by the sender, an indication of an attack on the optical communication channel based on at least a portion of the second information and the third information. The techniques can include triggering an alarm based on the determining.