Patent ID: 8144558

Claim:
An apparatus comprising a data storage medium having an embedded recording layer to which is stored a first set of data characterized as a sequence of encoded data symbols arranged along concentric tracks on the medium each data symbol of nominally nT length where T is a channel clock rate and n is an integer, wherein a second set of data is selectively applied to at least selected ones of the data symbols of said sequence prior to being written to the recording layer to alter at least a selected one of said length, a width or a depth of each of the selected ones of the data symbols, wherein the second set of data is configured to adjust an access parameter of the medium, the second set of data characterized as hidden data such that the presence of the hidden data is undetectable to a human observer upon unaided visual inspection of the medium, wherein the second set of data is configured such that a surface plot of at least a portion of the medium renders visible the hidden data to authenticate the medium as an authorized copy, the surface plot generated by sequentially reading the data symbols in relation to the channel clock rate using a data transducer, extracting the second set of data therefrom and displaying the surface plot as an image of the medium on a graphical display device, and wherein the second set of data is further configured such that a playback device recovers the first set of data and forwards the recovered first set of data to an output device by reading the selected ones of the data symbols to which the second set of data have been applied.