Method for certifying and authentifying security documents based on a measure of the relative variations of the different processes involved in its manufacture

A computer-implemented method for certifying a security document, comprising:

• providing a security document which is the result of a plurality of independent manufacturing processes that provide each an image, said security document having thus a set of unique characteristics related to the use of different supplies for manufacturing the security document;
• obtaining, via the one or more processors, a digital image of the security document;
• selecting, via one or more processors, a determined set of locations in images of each of the plurality of different manufacturing processes in the document image;
• determining a reference location in an image of a manufacturing process of the plurality of different manufacturing processes;
• calculating relative positions (register data) of a location within the determined set of locations in images of each of the different manufacturing processes with respect to the reference location;
• constructing, via the one or more processors, a message from said register data measured from the determined set of locations of the document image;
• constructing, via the one or more processors, a hashed message, wherein the hashed message is obtained by encoding the message with a unidirectional cryptographic hash function;
• encrypting, via the one or more processors, the hashed message using a private key, by a public key cryptographic system, to obtain a digital certificate;
• visibly printing the digital certificate on the security document;
• and
• storing, via the one or more processors, the digital certificate in an external database.