Generating watermark signals

A watermark signal generating method for generating watermark signals to be embedded as a digital watermark in real-time contents, the method comprising the steps of:

• inputting the real-time contents;
• storing the real-time contents;
• generating, from the real-time contents, watermark signals to be outputted corresponding to predicted intensities of the real-time contents;
• and
• storing the generated watermark signals to be outputted,
• wherein the generation step includes the steps of:
• predicting intensities of the watermark signals from prediction of perceptual stimulation values of the real-time contents after a predetermined lapse of time;
• controlling embedding by use of a message to be embedded as a digital watermark in the real-time contents;
• and
• generating the watermark signals to be outputted by use of outputs from the prediction step and outputs from the control step,
• wherein the perceptual stimulation values represent sound or luminance, and the prediction step includes a step of generating a predicted inaudible amount or a predicted invisible amount of watermark signals corresponding to intensities of the real-time contents after the predetermined lapse of time by use of data stored in the step of storing the real-time contents,
• wherein the control step includes a step of generating a value to be embedded, which is a binary based on a positive and a negative, by use of a secret key, the message and a pseudo-random number, and further comprising a step of controlling outputs from the step of storing the generated watermark signals to be outputted, by comparing the generated watermark signals with the real-time contents after a time needed to embed the generated watermark signals has passed,
• wherein the input step includes a step of dividing the real-time contents, and the generation step includes a step of generating the watermark signals by use of the divided real-time contents.