The present disclosure relates to authenticating identification and security documents, and methods and systems for authenticating such. One claim recites a method of authenticating a security or identification document with a cell phone. The cell phone comprising an optical sensor and a graphical display, the document comprising micro-printing, in which the micro-printing is imperceptible by an unassisted human observer. The method comprises: receiving from the optical sensor optical scan data corresponding to the document; analyzing the optical scan data to recognize the micro-printing; scaling or magnifying the micro-printing; and rendering at least some of the scaled or magnified micro-printing via the graphical display, in which rendered, scaled or magnified micro-printing is perceptible by a human observer of the graphical display. Other claims, implementations and embodiments are provided as well.