A method for authenticating a document in which a document key for the document
is generated by examining one or more attributes of a physical media that underlies
the document. An original image is then imparted onto the physical media so that
the original image is associated with the document key in a way that enables a
subsequent recovery of the document key from the original image. This tying together
of the underlying physical media, through the document key, with an original image
enables detection of a forgery which was performed either through an alteration
of the original image, or ink stripping and re-printing, or a printing of the original
image on another physical media.