A communication system (20) includes a transmitter (22) with (i) a transmitter photonic crystal (30) having a waveguide (40) and multiple cavities (42, 44, and 46) spaced along the waveguide (40); (ii) a light source (32); and (iii) a controller (34) that controls the cavities (42, 44, and 46) to translate multiple electronic data bits to optical data bits simultaneously in respective cavities (42, 44, and 46) illuminated by the light source (32). A corresponding receiver (24) includes a receiver photonic crystal (92) having a data/key waveguide (104) for receiving a data/key signal and a latch waveguide (106) for receiving a latch signal. The photonic crystal (92) also includes data readout cavities (110, 112, 114, and 116) and lock cavities (160, 162, and 164) adapted to compare the key bits to respective lock bits. The data readout cavities (110, 112, 114, and 116) are spaced to read out the data bits simultaneously if (a) the data/key signal and the latch signal are received simultaneously, (b) the data/key signal and the latch signal have the same length, and (c) the key bits in the key/data signal match the lock bits.