METHOD OF MODIFICATION AND IDENTIFICATION THE COPY OF THE DOCUMENT FOR THE INSTALLATION THE UNAUTHORIZED DISTRIBUTION CHANNEL Russian patent published in 2018 - IPC G06K9/52 H04N1/387 H04N21/8352 

FIELD: data processing; information security.

SUBSTANCE: invention relates to a method for modifying copies of documents and identifying them to protect documents against nonauthorized distribution. A method for modifying and identifying a copy of a document is disclosed by creating a document image, modifying and identifying a copy of the document in which, in the image creation step, a digital copy structure of the original document is formed, for this purpose the document is changed into a graphical representation in the form of a set of pixel images for each page in an ordered form and forms the structure of the protected document in the form of a set of rectangular blocks with the coordinates of the upper left corner and the width and height parameters of the block, at the modification stage of the document image, at least one personalized electronic copy of the document with a unique set of geometric characteristics of the graphic objects of the changed copy of the image is formed, parameters of a unique set of geometric characteristics of graphic objects of a personalized electronic copy of the document and information about the user who requested access to it are registered, at the stage of identification of a copy of the document to establish the fact of creation and unauthorized distribution of a copy of the document, recognize the structure of the studied copy of the document, from the database the image is uploaded as a digital copy of the original document and its structure, in addition from the database all copies of the original document with all the transformations generated for this document are downloaded, form and save a calibration copy of the document, compare the calibration copy of the document, the studied copy of the document and all copies of the original document with all the transformations generated for this document by overlaying the sample image on the calibration copy image, choice size of the studied sample to the size of the calibration copy by the difference of the distances between the rectangular blocks, further, the number of matching pixels of the calibration copy and the studied sample is determined by calculating the percent of match and based on the calculated value, the results are sorted, by the maximum value of the percentages of the pixel matching of the previously created personalized electronic copy of the document and the studied image of the document a judgment about the fact of creating and unauthorized distribution of a copy of the document is made.

EFFECT: technical result is to increase the protection of the document from unauthorized distribution by ensuring the possibility of identifying the user who authorized the distribution of the document.

6 cl, 4 dwg