Abstract:
Means and a method for authenticating a photographic image ( 3 ) on an identification device ( 1 ), the identification device ( 1 ) being provided with: a photographic image of a person ( 3 ) and a microprocessor ( 8 ), the microprocessor ( 8 ) having: a) a processor ( 7 ), b) a memory ( 9 ) connected to the processor ( 7 ) and having stored authentication data, and c) interface means ( 5 ) connected to the processor ( 7 ) for communicating with an external device, wherein said photographic image ( 3 ) comprises stegano-graphically hidden information, the content of which together with said authentication data allows authentication of said photographic image ( 3 ), the method having the following steps: a′) scanning the photographic image ( 3 ) and generating image data. b′) analyzing these image data in accordance with a predetermined image analysis procedure to derive said hidden information, and c′) carrying out the authentication of the photographic image ( 3 ) based on the hidden information and the authentication data.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a photo carrying identification device, like pass-ports, and (credit) cards used to identify persons, and thereafter authorize them to do a predetermined action, like entering a building, passing a boarder, carrying out an automatic debit transaction from an account, etc.  
       BACKGROUND OF THE INVENTION  
       [0002]     The invention relates to the use of identification (ID) documents equipped with a picture of a document&#39;s holder, e.g., a driver&#39;s licence, or a plastic card having the size of a credit card, or a passport. In a common use of such an ID document, a human operator compares the picture on the document with the face of the document holder to assess entitlements sought by the document&#39;s holder based on credentials as defined by additional data in the document. A passport, for instance, gives access to a country based on nationality of the document&#39;s holder.  
         [0003]     A problem encountered with such documents is that they are frequently copied with false credentials or a false picture.  
         [0004]     A common solution to this problem is the application of physical tamper detection methods such a sealing foil covering both the picture and the document, often combined with special inspection tools, like polarized light, to probe the tamper detection method. However, the use of such inspection tools often requires a skilled operator.  
         [0005]     Another possible solution, referred to in paragraph [0002] of EP-B1-0.539,439, to tampering with the picture attached to the ID document is in using smart cards provided with a microprocessor having a processor and a memory. The memory in the card chip stores a digital copy of the picture on the card. A terminal is provided to read the content of the memory of the chip card and to display the stored image on a monitor to an operator. Then, the operator compares the displayed image on the monitor with the face of the actual card holder. This solution may even obviate the need to attach the picture on the card itself. However, this solution requires costly display equipment which, amongst other reasons, has made this solution unsuitable in particular areas of industry which offers great potential to the use of smart cards, such as public transit systems where ID smart cards are sought as efficient improvement of traditional discount passes.  
         [0006]     A further problem encountered in ID systems is in protecting the privacy of the individual using the ID document. Especially in case such an ID document is realized as an electronically readable smart card protection may be required from uncontrolled and/or unapproved collection of data identifying the individual and his or her use of the smart card.  
         [0007]     To protect the privacy of the card holder, cryptographic techniques, e.g., blind signatures, may be applied to the process of reading ID and credential data from the smart card. However, the use of pictures stored in a card memory and read by a terminal for display on a monitor to an operator in principle defeats such cryptograpnic privacy protection. In such a case, the terminal is not only able to collect uniquely and strongly identifying data about individuals, i.e. their pictures, but also the nature of this data poses an additional threat in which, for instance, the individual may be compromised through digital image manipulation techniques.  
         [0008]     U.S. Pat. No. 5,748,763, column 58, line 24, to column 62, line 45, describes a method and an arrangement for enhancing the security of credit and debit cards. The arrangement disclosed has a computer arranged for receiving a digital image of the card holder. After having analyzed the digital image the computer generates a snowy image which is generally orthogonal to the digital image and adds this to the digital image to render an amended, unique image. The intended effect is to “texturize” the original digital image. It is not necessary that the snowy image itself is invisible to a person looking at the image. However, the image of the card holder may not be obscured by the snowy image. The amended, unique image is printed on the card. Moreover, tile unique information is also stored in a central accounting network.  
         [0009]     In a steganographic embodiment the snowy image is such that it is hidden in the photographic image of the person on the card. More detailed information as to steganography can be found in U.S. Pat. No. 5,613,004 and the references cited in this document. For the sake of the present invention steganography will be understood to relate to any method of obscuring information that is otherwise in plain sight. The information is hidden in another medium. It is used as an alternative to encryption. E.g., spreadsheets or graphics files could contain a text message invisible to an unaware person. People unaware of the hidden information will not recognize the presence of steganographically hidden information even if the information is in plain view.  
         [0010]     In U.S. Pat. No. 5,748,763, referred to above, a scanner is provided to scan the card when the card holder wishes to use his card for a predetermined transaction, e.g., automatic payment from his account to pay for a product. The scanner is connected to the central accounting network. By means of a secure communication protocol the image of the card scanned by the scanner is transmitted to the central network. The central network is arranged to receive the transmitted information and to authenticate the validity of the image on the card.  
         [0011]     Additional security to the known system may be provided by requesting the card holder to input a PIN during the scanning process. Moreover, additional security is provided by letting a third party, during the scanning process, check whether or not the person trying to carry out a transaction with the card is the person who&#39;s photo is on the card.  
         [0012]     A disadvantage of the system and method disclosed by U.S. Pat. No. 5,748,763 is that it is only to operate when a central network is provided having stored all unique images of all participating cards.  
       SUMMARY OF THE INVENTION  
       [0013]     A first object of the invention is to provide a photo carrying identification device that obviates the need for such a central network.  
         [0014]     Therefore the invention provides an identification device provided with: 
        a photographic image of a person and     a microprocessor, 
            the microprocessor comprising: 
                a processor,     a memory connected to the processor and comprising authentication data and     interface means connected to the processor for communicating with an external device;    
               
            wherein the photographic image comprises steganographically hidden information, the content of which together with the authentication data allows authentication of the photographic image.        
 
         [0022]     Thus, the invention provides an identification device which are provided with a microprocessor, comprising the authentication data necessary to authenticate the photographic image on the identification device. In other words, the key to authenticate the photographic image is in the identification device itself instead of in a central network.  
         [0023]     Such an identification device may be, for instance, a passport or a plastic identification card, like a smart card.  
         [0024]     In one embodiment of the invention the processor is arranged to carry out at least part of the authentication. To that effect the processor will carry out a program preferably stored in the memory of the microprocessor.  
         [0025]     The authentication data stored in the memory of the microprocessor may be a part of the photographic image on the identification device. However, it may also be data related to the photographic image. For instance, it may be related to grey level, intensity distribution, or image entropy of the photographic image.  
         [0026]     A second object of the invention is to provide a terminal, which is arranged to communicate with the identification device of the invention to allow carrying out the authentication process required.  
         [0027]     In a first embodiment the invention therefore provides a terminal arranged to communicate with an identification device, the identification device being provided with: 
        a photographic image of a person and     a microprocessor, 
            the microprocessor comprising: 
                a processor,     a memory connected to the processor and comprising authentication data, and     interface means connected to the processor for communicating with a external,    
               
            wherein the photographic image comprises steganographically hidden information, the content of which together with the authentication data allows authentication of the photographic image,     the terminal being provided with: 
            a picture scanner to scan the photographic image and to generate image data,     a terminal interface allowing communication with the processor of the identification device, and 
                an image processor arranged     to receive the image data,     to analyze these image data in accordance with a predetermined image analysis procedure to derive the hidden information,     to receive the authentication data from the memory, and     to carry out at least part of the authentication of the photographic image based on the authentication data and the hidden information.    
               
               
 
         [0043]     In this first embodiment, the authentication of the photographic image is either partly or entirely carried out by the image processor in the terminal.  
         [0044]     The steps necessary to carry out said authentication will, in practice, be stored in a terminal memory. In an embodiment of the invention, the way in which these steps are carried out depends on the authentication data received from the memory of the identification device. In such an embodiment, the authentication carried out by the terminal will depend on data received from the identification device itself. This makes it impossible to predict the actual authentication steps carried out by the terminal, which enhances the security.  
         [0045]     However, the security can also be enhanced in an alternative embodiment in which the processor of the identification device itself carries out at least part of the authentication of the photographic image. Therefore, the invention also provides a second embodiment of the terminal. This second embodiment terminal is arranged to communicate with an identification device, the identification device being provided with: 
        a photographic image of a person and     a microprocessor, 
            the microprocessor comprising: 
                a processor,     a memory connected to the processor and comprising authentication data, and     interface means connected to the processor for communicating with a terminal, wherein the photographic image comprises steganographically hidden information, the content of which together with the authentication data allows authentication of the photographic image,    
               
            the processor being arranged to carry out at least part of the authentication of the photographic image,     the terminal being provided with: 
            a picture scanner to scan the photographic image and to generate image data,     a terminal interface allowing communication with the processor of the identification device, and     an image processor arranged 
                to receive the image data,     to analyze these image data in accordance with a predetermined image analysis procedure to derive the hidden information, and     to transmit at least the hidden information to the processor to allow the processor to carry out the at least part of the authentication of the photographic image.    
               
               
 
         [0060]     Moreover, the invention relates to a method for authenticating a photographic image on an identification device, the identification device being provided with: 
        a photographic image of a person and     a microprocessor, 
            the microprocessor comprising: 
                a processor,     a memory connected to the processor and comprising authentication data, and     interface means connected to the processor for communicating with an external device,    
               
            wherein the photographic image comprises steganographically hidden information, the content of which together with the authentication data allows authentication of the photographic image,     the method comprising the following steps: 
            scanning the photographic image and generating image data,     analyzing these image data in accordance with a predetermined image analysis procedure to derive the hidden information, and     carrying out the authentication of the photographic image based on the hidden information and the authentication data.    
               
 
         [0072]     Finally, the invention relates to data carriers provided with a computer program and to computer programs as such for such a method.  
         [0073]     Hereinafter, the present invention will be illustrated with reference to some drawings which are intended to illustrate the invention and not to limit its scope. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0074]      FIG. 1  is a schematic drawing of the system according to the invention showing a smart card and a terminal;  
         [0075]      FIG. 2  shows the functional units of the microprocessor of the smart card in a schematic way;  
         [0076]      FIG. 3  schematically shows how information can be hidden in a photographic image;  
         [0077]      FIG. 4  shows a flow diagram of the method according to the invention. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0078]      FIG. 1  shows a smart card  1  provided with a photographic image  3  of the card holder. The smart card  1  is provided with an interface  5  shown to be made of metallic pads. However, the interface  5  may have any other form, e.g., an antenna hidden within the smart card  1  allowing for contactless communication with an external device.  
         [0079]     As shown in  FIG. 2 , the interface  5  is connected to a card processor  7  which is also connected to a card memory  9 .  
         [0080]     Returning now to  FIG. 1 , the smart card  1  is, preferably, provided with one or more orientation signs  2  assisting a scanner during scanning the photographic image  3 , as will be explained hereinafter.  
         [0081]     It is observed that  FIG. 1  shows a smart card  1  but that the invention is equally applicable for other types of documents having a photographic image of the document holder and a processor arranged to communicate with an external device.  
         [0082]     The smart card  1  may be inserted into and removed from an opening  14  in a terminal  11 . The terminal  11  is provided with a picture scanner  13  and a connector  15 .  
         [0083]     The picture scanner  13  is arranged such that it may scan the photographic image  3  either during insertion of the smart card  1  into the opening  14  or after the smart card  1  has been inserted entirely in opening  14 .  
         [0084]     The connector  15  will contact the interface  5  of the smart card  1  when the smart card  1  has been inserted entirely in the opening  14 . Of course, when interface  5  is designed in another form, e.g. an antenna, the connector  15  is to be replaced by another type of interface arranged to communicate with interface  5 .  
         [0085]     The picture scanner  13  is connected to a processor  17  which is also connected to the connector  15  and to a memory  19 .  
         [0086]      FIG. 1  also shows some input means, like a mouse  21 , and a keyboard  23 , allowing an operator to input data to the processor  17 . A monitor  25  connected to the processor  17  is provided to allow the processor to display necessary information to the operator. Of course, any other kind of display means may be provided instead of or in addition to monitor  25 .  
         [0087]     In an alternative embodiment of the terminal shown in  FIG. 1 , the processor  17  is provided as a processing unit within the picture scanner  13 . Then, the picture scanner  13  is directly connected to connector  15  (or any other interface) by a direct link indicated with reference sign  16 .  
         [0088]      FIG. 3  schematically shows that the photographic image  3  is provided with additional information  4 . The additional information  4  is added to the photographic image  3  such that it is invisible to the human eye. Moreover, the additional information  4  may have such small dimensions that it is virtually impossible to be detected by automatic scanners if they do not know where to look for the additional information. The additional information  4  is added to the photographic image  3  by using steganographic techniques which are known to persons skilled in the art.  
         [0089]     It is observed that, in  FIG. 3 , the additional information  4  is shown on such an enlarged scale that it is visible but in practice it will not be visible to the human eye. Moreover, in a preferred embodiment, the individual dots of information  4  are distributed over the entire image  3  to make it more difficult to find them.  
         [0090]     The additional information  4  may have no relation at all to the content of the photographic image  3 . However, the photographic image  3  before being printed on the smart card  1  may be preprocessed in such a way that the additional information  4  is calculated in dependence on the content of the photographic image  3  such that the degree to which it is hidden in the photographic image  3  is as best as possible.  
         [0091]     In accordance with the present invention, the card memory  9  is provided with authentication data. The content of this authentication data, together with the hidden information  4  allows authentication of the photographic image  3 .  
         [0092]     In its simplest form, the authentication data has a one to one relation to the hidden information  4 . However, the hidden information  4  may be present within the photographic image  3  in cryptographically processed form, e.g., it may be provided with a cryptographic signature such that the validity of the hidden information  4  can only be checked by an apparatus knowing the key to the cryptographic signature. Such a key is, then, stored in the card memory  9 .  
         [0093]     The hidden information  4  is such that it can be recognized by digitization of the photographic image  3  even if it is incomplete or otherwise impaired. The hidden information may have the form of a digital watermark.  
         [0094]     Checking the validity of the hidden information may be based on any kind of calculation using both the hidden information  4  and the authentication data in the card memory  9 .  
         [0095]     As shown in  FIG. 4 , in order to allow for authentication, the card holder has to insert his or her smart card  1  into the opening  14  of the terminal  11 . During insertion or after completing the insertion, the picture scanner  13  scans the photographic image  3 , while interfaces  5  and  15  may communicate with one another. The orientation signs  2  may assist the picture scanner  13  in detecting where to search for the hidden information  4 . The picture scanner  13  processes the photographic image  3  and generates image data which is sent to the processor  17 , step  30 .  
         [0096]     The processor  17  digitally processes the received image data, as well as the authentication data stored in the card memory  9  in accordance with a predetermined program. In accordance with the predetermined program, which is preferably stored in memory  19 , the processor  17  separates the hidden information  4  from the photographic image  3 , step  32 , and uses the hidden information  4  to establish the authenticity of the photographic image  3 , step  34 .  
         [0097]     The authentication data received from the smart card  1  may be protected with any cryptographic means known to persons skilled in the art. Additionally, the data may be provided with a digital signature.  
         [0098]     The authentication process carried out by the processor  17  may depend on the authentication data received from the smart card  1  in such a way that for different authentication data a different authentication process is carried out. This further enhances security.  
         [0099]     In an alternative embodiment, instead of the processor  17  in the terminal  11 , the card processor  7  is arranged to carry out the authentication process. To that end, it receives the hidden information  4  by means of the terminal  11 .  
         [0100]     However, since the card processor  7  and its memory  9  will only have a limited capacity, in practice, it will be preferred that both the processor  17  of the terminal  11  and the card processor  7  carry out part of the authentication process. The card processor  7  may, for instance, perform a final authentication step of the authentication process.  
         [0101]     In a further embodiment the card memory  9  may be provided with credential data, i.e., data indicating predetermined actions the card holder is allowed to do, e.g., entering a building or an area, debitting an account, etc. In that case, the card processor  7  is, preferably, arranged to transmit these credential data to the processor  17  only when its own part of the authentication process has been carried out successfully. Thus, by receiving the credential data the processor  17  is informed that the authentication steps carried out by card processor  7  did not find any problems. When it does not receive the credential data the processor  17  knows that the authentication process has been unsuccessful.  
         [0102]     To further enhance the security, the authentication data stored in card memory  9  may be related to one or more specific or general characteristics of the image  3  itself, like grey level, intensity distribution or image entropy. These parameters will be derived by the picture scanner  13  and transmitted to the processor  17 . These parameters may be used by the processor  17  during the authentication process. However, in order to further enhance security, these parameters may be passed through the processor  17  to the card processor  7  which uses one or more of these parameters during carrying out its authentication steps.  
         [0103]     Instead of the picture scanner  13  establishing the value of one or more of these parameters, these parameters may be digitally stored in the photographic image  3 . The digitized value of these parameters may have been printed after being encoded. Before these digitized values of these parameters are added to the photographic image  3  they may be encoded.  
         [0104]     In the embodiment described above, the terminal  11  is shown to include a memory  19 . As is evident to persons skilled in the art memory  19  may comprise any kind of memory type like RAM, ROM, EPROM, EEPROM, etc. or any combination thereof. For the purpose of the present invention the memory  19  need not necessarily be physically located within the terminal  11 .  
         [0105]     Moreover, the processor  17  is shown to be one block. However, if preferred, the processor  17  may be implemented as several subprocessors communicating with one another each dedicated to perform a predetermined task. Preferably, the processor  17  is (or the subprocessors are) implemented as a computer with suitable software. However, if desired, they may be implemented as dedicated digital circuits.  
         [0106]     The method in accordance with the present invention is preferably implemented by suitable software. This software may be distributed by data carriers like CDROM&#39;s or through the Internet or any other data communication medium.