1. A method for encoding a message and scale information into digital information corresponding to an audio signal, comprising: (1) storing in digital memory of an encoder, digital information defining the message; (2) receiving in said encoder, a digital audio signal block; wherein said digital audio signal block is a digital representation of one of a set of temporally sequential segments of the audio signal; (3) transforming, using said encoder and a transform, said digital audio signal block into the frequency domain, thereby defining a first set of amplitudes, wherein each one of said first set of amplitudes is associated with a corresponding one of a set of sequential frequencies ranges; (4) identifying, using said encoder and said first set of amplitudes, an amplitude based frequency range subset of said corresponding set of sequential frequency ranges; and (5) encoding, using said encoder and a primary mask of a key, at least some of said amplitude based frequency range subset, by altering the amplitude associated with the corresponding frequency range; (6) receiving, in said encoder, a digital audio signal block, and wherein the digital audio signal block received in the encoder in step (6) corresponds to a next temporally sequential segment of the audio signal; (7) repeating steps (3)-(5) on the digital audio signal bloc received in the encoder in step (6), followed by repeating step (6); (8) repeating step (7) for the remainder of the digital audio signal blocks corresponding to the temporally sequential segments of the audio signal; and (9) said encoder storing, in the key, said at least some of said amplitude based frequency range subset, and corresponding amplitudes, in association with one another; and (10) said encoder storing, in the key, a digital representation of a sequence of the original audio signal.