FR3067845A1 - METHOD FOR AUTHENTICATING A DOCUMENT COMPRISING A TRANSPARENT WINDOW, METHOD FOR REALIZING TRANSACTIONS, AND DEVICE FOR IMPLEMENTING THE SAME - Google Patents

Abstract

Method for authenticating a document, the document being provided with a window at least partially closed by a transparent film bearing a mark, the method being implemented by means of an image sensor connected to a computer unit image processing, and comprising the steps of: - controlling the image sensor to capture at least one image of the document presenting a dynamic background; and - control the processing unit to check that the background visible in the window on the image corresponds to an expected background and check that the mark is visible in the window.

Description

The present invention relates to the authentication of documents such as gaming or betting receipts (lottery for example), identity documents ... and the carrying out of transactions after a tellé;

authentication.

STATE OF THE ART

There are documents which it is necessary to make falsification difficult. These documents include identity documents and betting receipts. These documents generally incorporate security means which may include a particular paper, watermarks, complex security patterns, holograms, parts made of shiny material or the appearance of which is modified according to the direction of light ...

Bar elsewhere., A current trend is aimed at the development of transactions, especially financial, carried out remotely and more particularly via the Internet and / or: mobile telephone networks 20 (of the CSM type for example). The accomplishment of these transactions often requires the transmission of an image of at least one official document such as an identity document. The image is captured using the optical sensor, for example from a telecommunications terminal 25 such as a “smartphone” type telephone, then coded to be transmitted via the network to a server programmed to at least initiate the service.

However, the advances · made in the field of document reproduction and the democratization of 30 printers · and good or very good quality scanning devices (scanners) facilitate the falsification of these documents and make it difficult to detect this falsification. from an image of the document.

OBJECT OF THE INVENTION

An object of the invention is to provide a means for improving the security of transactions using an image of a document.

BRIEF STATEMENT OF THE INVEHTION

To this end, provision is made, according to the invention, for a method of authenticating a document, the document being provided with a window at least partially closed by a transparent film bearing a mark, the method being implemented by means an image sensor connected to a computer-based image processing unit, and comprising the steps of:

- control the image sensor to capture at least 'an image of the document with a dynamic background'; and

- control the processing unit to verify that

The visible background; in the window on the image corresponds to an expected background and check that the mark is visible in the window.

Thus, with relatively simple document securing means (a window in which is' fixed · a transparent film on which is made 'a mark in the form of a pattern or a series of alphanumeric characters)', the method of the invention allows relatively reliable authentication; of the document. Indeed, in the case of a simple · photocopy of the document, the background does not appear- in the window or is fixed · (case of a background printed in the window) and, in in the case of a photocopy of the document in which a window has been cut, the mark does not appear ·.

The invention also relates to and a method of; validation of a transaction between a connected server and terminal; â a network, the terminal comprising an image sensor, the method comprising the steps of:

connect the terminal to the server via the network;

asking the terminal to initiate authentication of a document provided with a window at least partially closed by a transparent film bearing a mark, the authentication being carried out according to the authentication method of the invention;

- validate the transaction if the authentication is positive.

The invention finally relates to a device designed to implement these methods.

The device is for example a mobile telephone provided with a camera and a processor suitable for the image processing to be carried out or a fixed document reading device.

Other characteristics and advantages of the invention will emerge on reading the following description of particular non-limiting embodiments of the invention.

2/0 BRIEF DESCRIPTION OF THE FIGURES

Reference will be made to the appended drawings, among which:

- Figure 1 is a schematic view of a document for the implementation of the invention;

- Figure 2 is a schematic perspective view illustrating a capture operation according to a first embodiment of the invention;

- Figure 3 is a schematic perspective view illustrating a capture operation according to a second embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION With reference to FIG. 1, the document to be authenticated is referenced D and is provided with a window in which extends a transparent film F provided with a mark M here a series of alphanumeric characters. The transparent film is here a strip extending across ^ of window 0 but the transparent film F can occupy all or part of window 0. The mark M can also include a geometric pattern or consist of one or more geometric patterns associated or not with a sequence · of aump hanumic characters.

On document D, information I is printed such as- c

- a title 'of the document,

- name and date of birth of the document holder,

- an address of the document holder,

- a name of an organization which issued the document,

- a date of issue of the document ...

Although the document shown here is an identity document, it is understood that the document D can be any document and for example a lottery ticket.

the invention is here described in application to a method for validating a transaction between a server

1 and a terminal connected to a network 50 here the network

Internet. The server 1 is a conventional type computer computer.

With reference to FIG. 2, and according to the first embodiment, the terminal is a portable telephone 100 comprising an image sensor 110 connected to a processing unit 120. The portable telephone 100 is a telephone of _: type Classic “smartphone”, only the programming of which is specific, and which can connect via a cellular network of GSM type to the network

50.

The process includes the steps of:

- connect the mobile phone 100 to the server 1 via the network 50;

- Ask the mobile phone 100 to initiate an authentication of the document D;

- validate the transaction if the authentication is positive.

The server 1 is thus programmed to ask the mobile telephone to initiate the transaction. The server 1 can also impose the type of document D which will be used for authentication.

The processing unit 120 controls the image sensor 110 and executes a computer program whose instructions are arranged to implement the authentication method according to the invention. To perform authentication, the processing unit 120 is programmed to:

- control the image sensor 110 to capture at least one image of the document D with a dynamic back 20; and

- to check that the background visible in window 0 on the image corresponds to an expected background and to check that the mark M is visible in window 0.

2S ^: In this: mobile application, the dynamic background is random and obtained by moving the document D in front of its environment between a first position and a second position. A first image and a second image of the document D are successively captured by the image sensor 110 controlled by the processing unit 120. The first · image · is captured when the document D is in its first position and the second image is captured: when document D is in its second: position. It will be noted that the images can be captured while the document D is in motion if the acquisition speed of the sensor is sufficiently high, or the capture of the images can be carried out when the document is stationary.

The capture positions are defined randomly, for example by asking the user to move the document while holding the telephone facing it, to trigger a first capture at an instant t thus defining a first position and to trigger a second capture after a predetermined or random time thus defining the second position. The instant t is either predetermined or determined in a random manner after the start of the movement.

To be able to locate window 0 in the image of document D, it is necessary to know the type of document.

We can plan to:

- ask the user to present a document of known type for which the processing unit knows the position of the window O in the document;

- before authentication, display a menu in which the user can choose the type of document he wishes to identify;

- determine the type of document automatically. The type: document is determined by controlling the processing unit to:

- capture an image of document D;

- detect, in the image, characteristic points of document D and deduce therefrom a type of document) by comparison of the characteristic points detected with) characteristic points) stored in a database in relation to types of document and the position window correspondent for the type of document in question;

- depending on the type of document, locate a position in the document window in the image to detect the background.

The location of window 0 in the image of document D is carried out by locating the edges of document D and then deducing therefrom the position of window O in the image relative to the edges of document D.

Authentication is carried out by checking that the background visible in window G on the image corresponds to an expected background and by checking that the mark M is visible in window 0. The background expected in the second image is a different background from that visible in the first image: this expected background is therefore not · a predetermined background, we just expect that the background in the second image is different from that visible in the first image.

This double verification is either carried out by the processing unit 120, the processing unit 120 transferring one of the images to the server 1 after authentication, or by the server 1, the processing unit 120 'transferring to the server 1 the two captured images.

With reference to FIG. 3, and according to the second embodiment, the terminal is a dedicated device 200 comprising housing 250 in which are mounted:

- an image sensor 210 mounted on one side of a cavity 255 of the housing 250;

- A display 230 mounted on an opposite side of the cavity 255 of the housing 250 to face the image sensor 210 ';

a processing unit 220 connected to the image sensor 210 and to the display 230.

The cavity 255 is arranged to receive the document D and the display 230 is here horizontal to serve as a support for the document D during image capture.

25 (dynamic.

video or

The processing unit 220 of the device 200 is connected either directly to the network 50, or to a computer connected to the network 50. When the device '200' is connected to a computer, it constitutes a peripheral of this computer.

The display 230 is arranged · to present or broadcast an animated sequence behind the window O of the document D. The animated sequence constitutes a background The animated sequence can be a sequence more simply a combination of effects:

basic lights depending on the complexity of the display 230.

The animated sequence is predetermined here, that is to say that at all times of the projection we know what is displayed, and the projection of the animated sequence and the image capture are synchronized in such a way that the background expected plan is determinable according to the moment of capture; Thus, the projection of the animated sequence is started and after a predetermined duration of random bu se: has elapsed since · the start of the projection, the capture is carried out. From the time thus elapsed, it is possible to determine the expected background.

As a variant, the device 200 comprises a lighting device 240 for lighting the document D during the; capture images.

The processing unit 220 controls the lighting device 2: 4 0 to modify a wavelength ·: of lighting between two captures: of image. The wavelength selection is random.

The background, which can be static or dynamic, is arranged to have a different response to the lighting wavelengths used for image capture.

Thus, the expected background depends both on the time of capture but also on the choice of wavelength making fraud even more difficult.

If document D also has a different appearance depending on the wavelength used for lighting, it is interesting to capture several images at different wavelengths and to compare the images obtained with expected aspects of the document D at these wavelengths. This further complicates fraud.

Of course, the invention is not limited to the embodiments described but encompasses any variant coming within the scope of the invention as defined by the claims.

In particular, the invention can combine the different modes of implementation - or repeat only part of the steps mentioned.

The processing unit can control a background display behind the document. The dynamic background is the result of a piloting · of the presentation device by means of a very · soul; command · selected in a background library. The selection is for example random.

The display can be replaced by a non-opaque background comprising a light source of changing wavelength in different spectral bands.

The device can include several image sensors in · spectral bands; different.

Claims (14)

1. Method for authenticating a document, the document being provided with at least one window 5 partially closed by a transparent film bearing a mark, the method being implemented by means of an image sensor connected to a computer image processing unit, and comprising the steps of: - control the image sensor to capture at least one image of the document while presenting a dynamic background; and - control the processing unit to check that the background visible in the window on the image corresponds to an expected background and check that the 15 mark is visible in the window. 2. Method according to claim 1, in which the dynamic background is random and a first image and a second image of the document are successively captured, the background expected in the 20 second image being a different background from that visible in the first image. 3. Method according to claim 2, the random dynamic background is obtained by moving the document in front of its environment between a first 25 position and a second position, the first image being captured when _the: document is in its first position and the second image being captured when the document is in its second position. 4. Method according to claim 3, at least 30 one of the images is captured on the fly. 5. Method according to claim 1, in which the dynamic background is obtained by projection of an animated sequence behind the document window. 6. Method according to claim 5, in which the animated sequence is predetermined, the projection and the image capture being synchronized in such a way that the expected background can be determined as a function of the capture instant. 7. Method according to claim 1, comprising the step of controlling the processing unit for: detect, in the image, characteristic points of the document and deduce therefrom a type of document; depending on the type of document, locate in the image a position of the document window to detect the background there. 8. Method: according to claim 1, in which the processing unit controls a background presentation device behind the document and 15 the dynamic background is the result of piloting the presentation device by means of control parameters selected from a background library. 9. The method of claim 8, wherein 20 the selection is random. 10. Process according to any one of the claims? previous, comprising a step of controlling a lighting device to illuminate the document when capturing the images. 25 11. The method of claim 10, comprising the step of controlling the lighting device to modify a lighting wavelength between two image captures. 12, The method of claim 11, in The background of which has a different response to the light wavelengths used for the two image captures, 13. Method for validating a transaction between a server and a terminal connected to a network, the 35 terminal comprising an image sensor, the method comprising the steps of: connect the terminal to the server via the network; asking the terminal to initiate authentication of a document provided with a window at least partially closed by a transparent film bearing a mark, the authentication being carried out according to the method according to any one of the preceding claims; - validate the transaction if the authentication is positive. 14. Device comprising an image sensor (110) connected to a processing unit (120) programmed for the implementation of a method according to any one of the preceding claims.