A secure document processing system for receiving an original document and for printing a secure hardcopy version of the original document, wherein the secure hardcopy version includes a machine-readable encoded image signature which represents an image segment of the original document. Such hardcopy secure documents can be validated by inputting them to an secure document validation system operable to identify and process the machine readable encoded representation and in response to determine whether the recovered image signature indicates that the document is counterfeit or has been altered.