1. A communication method, comprising:selecting a decoy data signal vector for transmission;
generating a MIMO precoding matrix from a message to be sent; and
multiplying the decoy data signal vector by the MIMO precoding matrix for constructing a precoded signal to be transmitted, the precoded signal comprising information-bearing synthesized channel distortions;
multiplexing a reference signal and the precoded signal for transmission to a receiver; wherein the receiver decrypts the message in the precoded signal based on channel estimation performed on the reference signal.