FR2852715A1 - Object e.g. person, authentication method for controlling access into building, involves decomposing image of object into two parts of information, and storing respective parts in portable unit and data storage system - Google Patents

Abstract

The method involves taking an image (3) of an object and decomposing the image into two parts of information (3a, 3b). The two parts of information (3a, 3b) are stored in a portable unit (4) and a data storage system (6), respectively. The portable unit is read for recovering the two parts of information. The image is reconstructed from the two parts of information. An independent claim is also included for an installation for authenticating an object.

Description

The present invention relates to the technical field of authentication

a

  animate or inanimate object such as for example a person or a product in the general sense.

  In many applications, there is a need to authenticate or securely identify an object in the general sense. A known application concerns the control of persons wishing to access premises or buildings.

  Another known application relates to the identification of an object having for example a significant market value.

  To authenticate a person, the prior art has proposed various technical solutions. One of them is to use a portable data storage unit such as a smart card or a magnetic card to identify its carrier. However, it should be noted that such a portable unit can be falsified or stolen so that the identification function of the wearer of the portable unit is no longer assured.

  The present invention therefore aims to remedy the disadvantages of the state of the art by proposing a technique for authenticating in a safe and simple manner an object in the general sense.

  To achieve such an object, the present invention relates to a method of authenticating an object by the image using a portable data storage unit.

  According to the invention, it comprises the following steps: in a protection phase: to take at least one image of an object; to decompose the image into a first piece of information and a second part; information, - to store the first part of information on the portable unit and the second part of information on a data storage system, ò and in an identification phase: - to read the portable unit in order to recovering, on the one hand, the first piece of information contained in said unit and, on the other hand, the second part of information corresponding to said portable unit and stored on the storage system, and to proceed with the reconstitution of the image from the first and second pieces of information.

  According to a preferred embodiment, the method consists in taking an image of a person integrating biometric data.

  According to another preferred embodiment of the invention, the method according to the invention consists in storing the first piece of information on a portable unit such as a smart card.

  In general, the first part of information corresponds to characteristic values of the image while the second part of information corresponds to transformation matrices of the image.

  According to a first variant embodiment, the method consists in decomposing the image represented by a matrix A of dimensions M × N (with M 2 N) by a singular value decomposition type coding technique for which: A = UAVT with U and V matrices of dimension respectively M x N and N x N, with orthogonal columns and A, the diagonal matrix of dimension N x N containing the singular values of A on its diagonal.

  According to this first embodiment of decomposing the image by a singular value decomposition type encoding technique, the method consists of: ò calculating two matrices AA and A TA, ò to be taken for each calculated matrix, n eigenvectors corresponding to the n largest eigenvalues (n "M, n" N), θ to calculate the matrix of singular values according to the formula: Aopt = UTopt A Vopt, with Upt and V0pt the matrices of n n eigenvectors chosen for the matrices AAT and AT, and Apt the diagonal matrix of the first n singular values, 30 has to extract the diagonal elements of the diagonal matrix A0Vpt in order to obtain the n main singular values, e to be stored in the portable unit, the n values singulars, to and to store in the storage system, matrices Uopt and Vopt.

  According to this first variant embodiment, the reconstruction of the image is carried out according to the following formula: ## EQU1 ## According to a second variant embodiment, the method consists of ensuring the image decomposition using a technique image compression type analysis of the main component.

  According to this second variant embodiment of decomposition of the image by an analysis technique of analysis images of the main component, the method consists in: calculating the average A of N different images A of an object of dimensions mxn by:] NN mX ni =, j ò to compute two covariance matrices R (mxm) and C (nxn) such that:

NOT

  R (mxm) = Z (A (mxn) -A (nxn)) (A (mxn) -A (mxn)) T

NOT

  qn.xn, = Y, (AL (mxn '- to-nmxn')) (A (mxn) - A / - (inxn ') * to choose the q eigenvectors corresponding to the largest eigenvalues for each matrix in order to obtain two matrices of eigenvectors WR of dimension mxq and Woc of dimension nxq, 20. to calculate the transformed matrix such that: = WR T Awc Y (qxq) = op t iA opt TO to be stored in the unit portable, the qxq elements of the matrix transformed Y (qxq) * and to register in the storage system the matrices WoTP and Woc.

  According to this second variant embodiment, the method consists in reconstructing the image according to the following formula: ALe o = Wpt (qxq) opt Another object of the invention is to propose an installation for authenticating an object using a portable data storage unit. This installation includes: * means for transforming an image of an object into a first piece of information and a second piece of information, * a portable units reader adapted to record and read on at least one unit portable, the first part of information, * a data storage system adapted to store the second part of information, * and inverse transformation means that from the first part of information of the portable unit and of the second piece of information corresponding to the storage system makes it possible to reconstitute the image of said object.

  Various other features appear from the description given below with reference to the accompanying drawings which show, by way of non-limiting examples, embodiments of the object of the invention.

  Figure 1 is a schematic view illustrating the principle of the subject of the invention.

  Figure 2 is a diagram illustrating a first embodiment of the subject of the invention.

  Figure 3 is a schematic view illustrating a second embodiment of the subject of the invention.

  Figure 4 is a diagram explaining the second embodiment of the subject of the invention.

  The object of the invention relates to a method for authenticating an object by an image, using a portable data storage unit. In the following description, the object to be authenticated is a person even if it is clear that the present invention also applies to any type of objects.

  FIG. 1 illustrates the implementation of the method according to the invention with the aid of an installation 1 structured around a system for processing and storing data, known per se, such as a computer system in the sense general. The installation 1 comprises means 2 for transforming a so-called original image 3 representing at least a characteristic part of the object to be identified or authenticated. In the example considered, the object is a person and the image taken relates to the person's face. Of course, it can be expected to take an image 3 which incorporates different biometric data relating for example to fingerprints or the iris of the eye.

  The means 2 make it possible to transform the image 3 into a first piece of information 3a and a second piece of information 3b. Of course, these first and second pieces of information are of a digital nature to be processed by a computer system.

  The installation 1 also implements at least one portable data storage unit 4 associated with a reader 5, that is to say a system providing a data transfer between the portable unit 4 and the computer system.

  According to a preferred embodiment, the portable unit 4 is made by a smart card. However, it should be noted that the portable unit 4 can be made by a different medium such as a magnetic card for example.

  According to the invention, the portable unit 4 is adapted to store the first information part 3a.

  The installation 1 also comprises a data storage system 6 adapted to store in particular the second information part 3b. For example, such a data storage system 6 constitutes a database.

  The installation 1 also comprises means 7 making it possible to provide an inverse transformation to the transformation carried out by the transformation means 2 in order to obtain a so-called reconstituted image 8. These inverse transformation means 7 are adapted to reconstruct the original image from the first information portion 3a of the portable unit 4 and the second information portion 3b from the storage system 6 and corresponding to said portable unit 4.

  The reconstructed image 8 corresponds to the original image 3 if the inverse transformation operation uses the first information portion 3a and the second information portion 3b from the original image 3. In this case, the carrier of the portable unit 4 can be securely authenticated by the reconstruction of an image representing the face of the carrier of the portable unit 4. In the case where the reconstruction of an image is not performed from the first information part 3a and / or the second information 3b corresponding to said image, the reconstructed image such as the 81 is disturbed. In the case illustrated, the so-called original image 31, of which part of information obtained by the transformation means 21, identical or similar to the transformation means 2, is integrated in a portable unit 41 can not be reconstructed by the inverse transformation means 7 if the second piece of information 3b used does not come from the same original image. The reconstructed image 81 is disturbed and does not recognize the person or object of the original image. In other words, the object of the invention is a means of protection against fraudsters since changes made on only one of the pieces of information recorded on the portable unit 4 or on the storage system 6 do not allow not to reconstruct the original image.

  The method of authenticating an object and in the present case of a person follows directly from the foregoing description.

  It must be considered that the authentication method according to the invention comprises a first so-called protection phase followed by a second so-called identification or authentication phase.

  During the protection phase, at least one original image 3 is taken representing at least part of the object to be identified. Such a digitized image is decomposed into a first piece of information 3a and a second piece of information 3b. The first piece of information 3a is stored on a portable unit 4 while the second piece of information 3b is recorded on the storage system 6. Of course, each second piece of information 3b is identified so that it can be attached to the corresponding first information part 3a, that is to say the corresponding portable unit 4.

  When the identification of an object and in the specific case of a person is performed, the portable unit 4 is read to recover the first part of information 3a contained in said unit. Similarly, the second piece of information 3b recorded on the data system 6 and corresponding to said portable unit 4 is recovered. Preferably, the reading of the portable unit 4 automatically provides the information necessary to retrieve the second piece of information 3b corresponding to said portable unit 4. From the first 3a and second 3b pieces of information retrieved, an image is reconstructed . If the two pieces of information 3a, 3b corresponding to an image are not associated, the original image can not be found, as explained above.

  According to a preferred embodiment, the first piece of information 3a stored on the portable unit 4 is defined by essential characteristics of the image so that the absence of such information leads to a significant alteration of the reconstructed image . Given the storage capacity of the portable unit 4, the method according to the invention provides a compression 10 or a coding of the first part of information 3a intended to be stored in the portable unit 4. Thus, advantageously, the first information part 3a corresponds to characteristic values of the image 3 while the second information part 3b corresponds to transformation matrices of the image.

  The following description describes a first embodiment of decomposing the original image 3 represented by a matrix A of dimensions M × N with M 2 N, by a singular value decomposition type coding technique for which: = UAVT with U and V matrices of dimension respectively M x N and N x N, with orthogonal columns and A, the diagonal matrix of dimension N x N containing the singular values of A on its diagonal.

  As is more precisely apparent from FIG. 2, according to this singular value decomposition type encoding technique, the method consists in: calculating two AAT and ATA matrices, to be taken for each calculated matrix, n corresponding eigenvectors to the n largest eigenvalues (n "M, n" N), * to compute the matrix of singular values according to the formula: Aopt = U UpA Vo with Uopt and Vopt the matrices of the n eigenvectors chosen for matrices AAT and At TA, and Aopt the diagonal matrix of the n first singular values, to extract the diagonal elements of the diagonal matrix Apt in order to obtain the n main singular values, ò to be stored in the portable unit, the n main singular values, * and to store in the storage system the matrices U0, t and V0p.

  When a portable unit 4 is introduced into its reader 5 in order to obtain the authentication of its carrier, the system retrieves the two clean vector matrices U0pt and V0, pt corresponding to the portable unit 4 identified. From these two matrices of vectors and the diagonal matrix of singular values, formed from the values extracted from the portable unit 4, an Are image is reconstructed according to the following formula: Are = Uopt Aopt VoptT If the matrices provided by the data storage system and the singular values coming from the portable unit come from the same image, so that the latter will be correctly reconstructed. However, if a change has occurred in the information contained on the portable unit 4 or in the sotckage system 6, a disturbed image 81 will be reconstructed.

  FIGS. 3 and 4 illustrate a second variant embodiment for compressing the image stored in the portable unit 4. This second variant consists in ensuring a decomposition of an image using a technique of type of analysis of the main component. According to the invention, this method of analysis of the main component is adapted to the compact and secure coding of images to capture the main characteristics of a series of images A of the same object in order to be able to reconstruct each of these images. by a single transformation.

  The method consists for this image coding technique: calculating the average A of N different images A of an object of dimensions mxn by: 2 N jmxn =, E = '* to calculate two matrices of covariance R (mx) and C (nxn) such that:

NOT

  R (mxni) = X <(A (mxn) - A (xn)) (A (fxn) - A (lxn)) 1V

NOT

  C (flxn) = (A (mxfl) - A ("Xf)) T (A (" Ixn) - A (mxn)) ò choose the q eigenvectors corresponding to the largest eigenvalues for each matrix in order to obtain two matrices of eigenvectors WR of dimension mxq and Wc of dimension nxq, ò to compute the transformed matrix such that: yqxq = WR; T Wt = to be stored in the portable unit, the qxq elements of the transformed matrix Y (qxq) ò and to save the matrices Wopt and WIPt in the storage system.

  When a portable unit 4 is introduced into the reader 5 for an authentication procedure, the two eigenvector matrices WopT and WOPt are provided by the storage system corresponding to the portable unit 4 read.

  From these matrices and from the matrix of the compressed image extracted from the portable unit 4, the image Are is reconstructed by the following formula Are = opt (qxq) oWt If the two matrices provided by the storage system and the characteristic values coming from the portable unit 4 come from images of the same object, each image will be correctly reconstructed. If, on the other hand, the portable unit 4 contains modified information, a disturbed image will be reconstructed.

  The invention is not limited to the examples described and shown since various modifications can be made without departing from its scope.

Claims (7)

  1 - Method for authenticating an object by the image with the aid of a portable data storage unit, characterized in that it comprises the following steps: in a protection phase: to be taken at least one image of an object, - to decompose the image into a first piece of information and a second piece of information, - to store the first part of information on the portable unit and the second part of information on a data storage system, and in an identification phase: to read the portable unit in order to retrieve, on the one hand, the first portion of information contained in said unit and, on the other hand, the second part corresponding information to said portable unit and stored on the storage system, and to reconstruct the image from the first and second pieces of information.   2 - Authentication method according to claim 1, characterized in that it consists in taking an image of a person integrating biometric data.   3 - Authentication method according to claim 1, characterized in that it consists in storing the first part of information on a portable unit such as a smart card.   4 - Authentication method according to claim 1 or 3, characterized in that the first part of information corresponds to characteristic values of the image while the second part of information corresponds to transformation matrices of the image .   - Authentication method according to claim 1 or 4, characterized in that it consists in decomposing the image represented by a matrix A of dimensions M x N (with M> N) by a decomposition type coding technique of singular values for which: A = UAVT with U and V matrices respectively of dimension M x N and N x N, with orthogonal columns and A, the diagonal matrix of dimension N x N containing the singular values of A on its diagonal.   6 - Authentication method according to claim 5, characterized in that it consists, to decompose the image by a singular value decomposition type coding technique: ò to calculate two matrices AAT and ATA, * to be taken as each calculated matrix, n eigenvectors corresponding to the n largest eigenvalues (n "M, n <N), * to calculate the matrix of singular values according to the formula: At = UTAV pt Opt A opt with U0pt and V0pt the matrices n eigenvectors chosen for the matrices AAT and ATA, and A0tpt the diagonal matrix of the n first singular values, 15 has to extract the diagonal elements of the diagonal matrix Aopt in order to obtain the n main singular values, * to be stored in the portable unit, the n singular main values, * and to store in the storage system, matrices U0, pt and V.Pt.   7 - Authentication method according to claim 5, characterized in that it consists in reconstructing the image according to the following formula: Are = Uopt Aopt VoptT 8 - Authentication method according to claim 1 or 4 , characterized in that it consists in providing an image decomposition using a technique of analysis type of the main component.   9 - Authentication method according to claim 8, characterized in that it consists, to decompose the image by a type of analysis of the main component technique: calculating the average A of N different images A of an object of dimensions mxn by: N 1 zn, AN mn j) N1, m Xn =, = a to compute two matrices of covariance R (mxm) and C (nxn) such that: NOT   R (nxm) = (A (mxn) -A (4mxn)) (A (nxn) -A (nxn)) T NOT   C (nxn) = (A (.xn) -A (mxn)) (A (mxn) - A (xn)) To choose the q eigenvectors corresponding to the largest eigenvalues for each matrix in order to obtain two matrices of eigenvectors WoRt of dimension mxq and WoCt of dimension nxq, to compute the transformed matrix such that: wRT AWC y (qxq) oRpT t to be stored in the portable unit, qxq elements of transformed matrix Y (qxq) 10. and to register in the storage system, the matrices Wot and WoCt.   - Authentication method according to claim 9, characterized in that it consists in reconstructing the image according to the following formula Are = R t (CTxq) and opi Y (qxq) o "pt 11- Installation for to authenticate an object using a portable data storage unit, characterized in that it comprises: means for transforming an image of an object into a first information part and a second one part of information, * a portable unit reader adapted to record and read on at least one portable unit, the first part of information, * a data storage system adapted to store the second part of information, * and reverse transformation means which from the first information part of the portable unit and the corresponding second information part of the storage system, allows to reconstruct the image of said object.