Abstract: This invention safeguards the integrity of a machine-printed paper document by entangling a characteristic signature derived from the document's paper grain structure with the identities of the printing device and the person or organization which issued the document. This protection is achieved using a certification phase performed by an augmented document printer and an authentication phase performed by an augmented document scanner. In the certification phase, the grain structure of a specific area of the original paper is imaged and processed to generate a unique signature for the paper. This signature is doubly encrypted using the private keys of the augmented printer and the certifier. These encryption steps entangle the signature of the paper with its source information in a way that thwarts counterfeiting attacks which either copy the document or falsely attribute its source to a specific printer and/or certifier.

Abstract: This invention safeguards the integrity of a machine-printed paper document by entangling a characteristic signature derived from the document's paper grain structure with the identities of the printing device and the person or organization which issued the document. This protection is achieved using a certification phase performed by an augmented document printer and an authentication phase performed by an augmented document scanner. In the certification phase, the grain structure of a specific area of the original paper is imaged and processed to generate a unique signature for the paper. This signature is doubly encrypted using the private keys of the augmented printer and the certifier. These encryption steps entangle the signature of the paper with its source information in a way that thwarts counterfeiting attacks which either copy the document or falsely attribute its source to a specific printer and/or certifier.