Methods and systems for cyber secure data communications are provided. In some embodiments, a method for transmitting data comprises: performing a marker-based data encoding process to embed a digital watermark into each of a plurality of original data flows to be transmitted to a plurality of receivers; performing a non-orthogonal multiple access process to allocate transmission powers to the plurality of original data flows, such that the plurality of original data flows are simultaneously superposed on a carrier frequency to generate a superposed signal; performing a noise modulation process to modulate the superposed signal to generate a noise-like signal and a reference noise signal; transmitting the noise-like signal and the reference noise signal through orthogonally polarized antennas; and performing a portal-based data integrity analysis process to check whether a receiver in the plurality of receivers is compromised or manipulated.