1. A method of encoding content with message information, comprising: receiving, in an encoder, data defining content; said encoder, using a processor and applying a transform function, that transforms from a time or space domain to a temporal or a spatial frequency domain, to a first contiguous subset of said content in the time or space domain, which results in a first transform having first transform values in the frequency domain, and first transform amplitudes associated with said first transform values; said encoder selecting, based upon said first transform amplitudes, a first transform values first subset of said first transform values; said encoder using a primary mask and said first transform values first subset to select a first transform values second subset of said first transform values, wherein said first transform values second subset is a subset of said first transform values first subset; and said encoder manipulating, depending upon the value of a first bit of said message information, the first transform amplitude associated with said first transform values second subset; wherein said encoder comprises a processor and memory for storing data in non transient form, said memory storing said primary mask and said message information, and at least one transform function, and said encoder using said processor in said applying and said manipulating; wherein said content is one of audio, still image, video, and multimedia; wherein said first bit of said message information has either a first logical value or a second logical value; and wherein said manipulating changes the first transform amplitudes associated with said first transform values second subset if said first bit of said message information has said first logical value, and does not change the first transform amplitudes associated with said first transform values second subset if said first bit of said message information has said second logical value.