Recently, information hiding has become the main focus of the researchers in the last two decades because of its benefits in document security and image protection versus copyright. In fact, this research paper proposed a modified authentication method based on the curve fitting technique with curves hiding in the images in the way that is sturdy for printing and scanning. Apparently, the introduced method proceeds by inserting a secure imprint designed by curves interpolated using cubic spline interpolation technique within the printed imagpe. Mainly, by using the proposed modified methods, several secures imprints can be embedded into images with a perfect recovery against the print-scan operation. In conclusion, the proposed models have been tested by producing samples with some image samples; the samples were printed on the traditional papers using traditional inks and printers.