Described are a method and system for secure transmission of data through a network. A subcarrier sequence for data transmission is generated. The subcarrier sequence designates at least one subcarrier from a number of orthogonal subcarriers for each of a plurality of intervals in a time sequence. The subcarrier sequence is provided to a receiver. A data signal that includes the subcarriers identified in the subcarrier sequence modulated according to the data is transmitted from a transmitter to the receiver. For additional security, the subcarrier sequence can be transmitted to the receiver using a communications channel that is separate from the communications channel for the data signal. The data signal is detected at the receiver and demodulated according to the subcarrier sequence.