Abstract:
A biometric authentication apparatus includes a single reading sensor configured to acquire first matching authentication characteristics data being unique to a first hand and used for matching, and second matching authentication characteristics data being unique to a second hand and used for matching; and a communications part configured to externally transmit the first and second matching authentication characteristics data for one person as authentication data and to receive an authentication result.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation application of International Application PCT/JP2013/050850 filed on Jan. 17, 2013 and designated the U.S., the entire contents of which are incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The disclosures discussed herein are related to a biometric authentication apparatus, a biometric authentication system, and a biometric authentication method. 
       BACKGROUND 
       [0003]    Biometric authentication indicates a technology to identify individuals by using biometric information such as fingerprint patterns or vein patterns. Fingerprint patterns on the surfaces of one&#39;s fingers or palms vary among individuals, and hence individuals may be identified by using these patterns. Veins of the palm or the like may be imaged by using near infrared radiation. The vein patterns vary among individuals so that individuals may be identified by the vein patterns. 
         [0004]    Biometric authentication includes different types of authentication, namely, 1:1 authentication and 1:N authentication. The 1:1 authentication includes inputting an ID of each individual, and matching new biometric information and the registered biometric information of the individual. The 1:N authentication includes matching new biometric information and all the data of registered biometric information without inputting IDs or the like of the individuals. The 1:N authentication is convenient because IDs of individuals need not be input. However, the 1:N authentication may increase a rate of erroneously identifying a wrong person as the matched individual (a false acceptance rate, hereinafter called “FAR”) along with an increase in the number of N because new biometric information is matched with all the data of the registered biometric information. It is preferable that the accuracy in large-scale 1:N authentication be high. 
         [0005]    In performing biometric authentication of individuals based on biometric information, matching a position of a living body at registration and its position at authentication relative to a sensor capturing biometric information may increase the matching accuracy as well as improving the accuracy of authentication. For example, there is a technology known in the art to guide a position of a living body at authentication by displaying an image of the living body captured at registration as a guide image. Further, there are technologies known in the art to guide a position of a hand of a person to be authenticated without delaying authentication operations regardless of the right hand and the left hand being held over a sensor (e.g., Patent Documents 1 and 2 described below). 
         [0006]    However, in such related art technologies, the position of one of the left hand and the right relative to the sensor is matched at registration and at authentication as biometric information. Further, one of the left hand and the right hand captured as an image of the hand at registration is displayed as a guide image to guide the position of the hand at authentication. 
         [0007]    Even though the positions of the living body at registration and at authentication are matched, it may be difficult to increase the matching accuracy to improve the accuracy of the authentication. Hence, there seems to be a limit to the reduction of FAR. To implement ten million accurate biometric authentications as well as introducing the biometric authentication into public services or the like of the government, FAR needs to be reduced even further. 
         [0008]    To reduce FAR, matching the biometric information of the left and right hands may be considered. In this case, when matching the left and right hands is conducted using the same sensor, angles of the left and right hands held over the sensor are different unless the person to be authenticated is moved. When the biometric information of the left and right hands is registered at the same angles relative to the body of the person to be authenticated, the authentication is conducted without interruption when the person places or holds one of the hands at an angle similar to the angle at registration. However, the authentication may be interrupted when the person places or holds the other one of the hands at the angle differing from the angle at registration. 
       RELATED ART DOCUMENTS 
     Patent Documents 
       [0000]    
       
         Patent Document 1: Japanese Laid-open Patent Publication No. 2008-71158 
         Patent Document 2: Japanese Laid-open Patent Publication No. 2010-146158 
       
     
       SUMMARY 
       [0011]    According to an aspect of the present invention, there is provided a biometric authentication apparatus that includes a single reading sensor configured to acquire first matching authentication characteristics data being unique to a first hand and used for matching, and second matching authentication characteristics data being unique to a second hand and used for matching; and a communications part configured to externally transmit the first and second matching authentication characteristics data for one person as authentication data and to receive an authentication result. 
         [0012]    The object and advantages of the embodiment will be realized and attained by means of the elements and combinations particularly pointed out in the claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0013]      FIG. 1  is a diagram illustrating a configuration example of a biometric authentication system in a first embodiment; 
           [0014]      FIG. 2  is a side view illustrating an example of a reading sensor in the first embodiment; 
           [0015]      FIG. 3  is a top view illustrating the example of the reading sensor in the first embodiment; 
           [0016]      FIG. 4  is a flowchart illustrating a registration process of the biometric information in the first embodiment; 
           [0017]      FIG. 5  is a diagram illustrating a model of the registration process of the biometric information in the first embodiment; 
           [0018]      FIG. 6  is a diagram illustrating a table having an example of shape characteristics data in the first embodiment; 
           [0019]      FIG. 7  is a flowchart illustrating a matching process of the biometric information in the first embodiment; 
           [0020]      FIG. 8  is a diagram illustrating a model of the matching process of the biometric information in the first embodiment; 
           [0021]      FIG. 9  is a diagram illustrating a rotation of a hand in the first embodiment; 
           [0022]      FIGS. 10A to 10D  are diagrams illustrating a relationship in rotations of humans hands between a small person and a large person, where FIGS. A and B illustrate a small person&#39;s case and FIGS. C and D illustrate a large person&#39;s case; and 
           [0023]      FIG. 11  is a diagram illustrating a configuration example of a biometric authentication system in a second embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0024]    In the following, a detailed description is given of embodiments with reference to the accompanying drawings. Note that in the drawings, components having the same functions are provided with the same reference numbers, and a duplicated description is omitted from the specification. 
       First Embodiment 
     Outline of Biometric Authentication System  
       [0025]      FIG. 1  is a diagram illustrating a configuration example of a biometric authentication system in a first embodiment. The first embodiment illustrates an example of the biometric information using fingerprints of both the left and the right hands and palm veins of both the left and the right hands. As illustrated in  FIG. 1 , the biometric authentication system in the first embodiment includes a client  1 , a reading sensor  2 , a server  3 , a communications channel  4  connecting the client  1  and the reading sensor  2 , and a communications channel  5  connecting the client  1  and the server  3 . 
         [0026]    The client  1  may, for example, be a personal computer (PC). The client  1  includes a client controller  11 , a left-or-right hand input checker  12 , a left-right corresponding table  13 , a rotation predicting part  14 , a fingerprint matching part  15 , a vein matching part  16 , a memory part  17 , a communications part  18 , and a bus  19 . The client controller  11  is configured to control the client  1 . The left-or-right hand input checker  12  is configured to check which one of the left and right hands of the person to be authenticated is used to input biometric information. The left-right corresponding table  13  is configured to store a relationship between the left and right hands in terms of shapes of the left and the right hands of the person to be authenticated. The rotation predicting part  14  is configured to predict an input angle of biometric information of one of the left and right hands of the person to be authenticated relative to an input angle of the biometric information of the other hand. The fingerprint matching part  15  is configured to match characteristics of fingerprints of the person to be authenticated. The fingerprint matching part  15  is used for a later-described left or right hand input check. The vein matching part  16  is configured to match characteristics of veins of the person to be authenticated. The vein matching part  16  is used for the later-described left or right hand input check. The memory part  17  is used as a work area for maintaining images associated with the captured biometric information or a later-described matching process. The communications part  18  is configured to perform communications processes with the communications channel  5  and/or the server  3 . The bus  19  is configured to connect the client controller  11 , the left-or-right hand input checker  12 , the left-right corresponding table  13 , the rotation predicting part  14 , the fingerprint matching part  15 , the vein matching part  16 , the memory part  17 , and the communications part  18  with one another. 
         [0027]    The reading sensor  2  includes a fingerprint sensor part  21  and a vein sensor part  22 . The fingerprint sensor part  21  is configured to read the fingerprints of the person to be authenticated as an image. The vein sensor part  22  is configured to read the veins of the person to be authenticated as an image. 
         [0028]    The server  3  may, for example, be a server (SV), a computer, or a personal computer (PC). The server  3  includes a storage part  30 , a server controller  31 , a fingerprint matching part  35 , a vein matching part  36 , a memory part  37 , a communications part  38 , and a bus  39 . 
         [0029]    The storage part  30  is configured to save a registration template of biometric information. The server controller  31  is configured to control the entire server  3 . The fingerprint matching part  35  is configured to match characteristics of the fingerprints of the person to be authenticated. The vein matching part  16  is configured to match characteristics of veins of the person to be authenticated. The memory part  37  is used as a work area for maintaining images associated with the captured biometric information or a later-described matching process. The communications part  38  is configured to perform communications processes with the communications channel  5  and/or the client  1 . The bus  39  is configured to connect the storage part  30 , the server controller  31 , the fingerprint matching part  35 , the vein matching part  36 , the memory part  37 , and the communications part  38  with one another. 
         [0030]    The communications channel  4  may be wired or wireless, and configured to enable communications between the client  1  and the reading sensor  2 . Various types of the communications channel  4  may be used including a USB cable, FireWire (registered trademark), the Internet, a local area network, Wi-Fi (registered trademark), and Bluetooth (registered trademark). 
         [0031]    The communications channel  5  may be wired or wireless, and configured to enable communications between the client  1  and the server  3 . Various types of the communications channel  4  may be used including a USB cable, FireWire (“FireWire” is a registered trademark), the Internet, a local area network, Wi-Fi (“Wi-Fi” is a registered trademark), and Bluetooth (“Bluetooth” is a registered trademark). 
         [0032]    An illustration is given of an example of the reading sensor  2  with reference to  FIGS. 2 and 3 .  FIG. 2  is a side view illustrating the example of the reading sensor  2 .  FIG. 3  is a top view illustrating the example of the reading sensor  2 . The reading sensor  2  further includes a guide  23 , a case  24 , a fingerprint reading range  25 , and a vein reading range  26 , in addition to the fingerprint sensor part  21  and the vein sensor part  22  illustrated in  FIG. 1 . The guide part  23  is configured to guide the hand to be held at an appropriate position over the fingerprint sensor part  21  or the vein sensor part  22  for capturing the biometric information. For example, a wall may be provided at each side of the hand as the guide  23  so as not to move the hand toward left or right. The case  24  is configured to house the fingerprint sensor part  21 , the vein sensor part  22 , and the guide  23 . The fingerprint reading range  25  is located above the fingerprint sensor part  21 , and is configured to read a fingerprint upon placing a ball of a finger in the fingerprint reading range  25 . The vein reading range  26  is located above the vein sensor part  22 , and configured to read an image of palm veins upon placing a palm of a hand in the vein reading range  26 . 
         [0033]    The reading sensor  2  is configured to image fingerprints of three fingers (forefinger, middle finger and annular finger) and palm veins of the hand. In a sensor using two or more types of biometric information (a multimodal type) such as the fingerprints and the palm veins of the hand, authentication may be accurately conducted by improving the matching accuracy. 
       Registration Process of Biometric Information 
       [0034]    An illustration is given below of an example of authentication using biometric information of both the left and right hands in order to more accurately perform large-scale 1:N authentication by improving the matching accuracy without increasing FAR. Of the biometric information, a characteristics amount subject to comparison includes fingerprints of both hands (left and right hands), palm veins of both hands (left and right hands), or a combination of the fingerprints of both hands (left and right hands) and the palm veins of both hands (left and right hands). 
         [0035]      FIG. 4  is a flowchart illustrating a registration process of the biometric information in the first embodiment. The flowchart illustrated in  FIG. 4  intends that the first data acquisition is performed by inputting biometric information from one of the hands (first hand) of the person to be authenticated. Likewise, it intends that the second data acquisition is performed by inputting biometric information from the other hand (second hand) of the person to be authenticated. However, despite the above intentions, the first data and the second data may be acquired by the biometric information input from the same hand of the person to be authenticated. In such a case, the biometric information fails to be registered with accuracy. 
         [0036]    Hence, the following process may be performed, an example of which is illustrated in  FIG. 4 . Note that V 1 , V 2 , F 1 , F 2 , and F 1 ′ may be defined as follows. V 1  indicates authentication characteristics data (characteristics data of fingerprints of three fingers and palm veins) acquired for registration in the first data acquisition. V 2  indicates authentication characteristics data (characteristics data of fingerprints of three fingers and palm veins) acquired for registration in the second data acquisition. F 1  indicates shape characteristics data of an outer shape of a hand acquired in the first data acquisition. F 2  indicates shape characteristics data of an outer shape of a hand acquired in the second data acquisition. F 1 ′ indicates reversed shape characteristics data extracted by mirror reversing the shape characteristics data of the outer shape of the hand acquired in the first data acquisition (N. B., “mirror reverse” is synonymous with “left-right image reverse”). Note that the characteristics data indicate information necessary for authentication or information necessary for comparisons of shapes that is extracted from images. Examples of the authentication characteristics include palm vein patterns, characteristics points (minutiae) of the fingerprint, and the like. Examples of the shape characteristics include a length of a finger, a width or a contour of a hand, and the like. 
         [0037]    For example, steps S 101  and S 102  are performed by the reading sensor  2 . Steps S 103  to S 107  are performed by the client  1 . Step S 108  is performed by the server  3 . 
         [0038]    In step S 101 , the first data acquisition is performed by the reading sensor  2 . The authentication characteristics data acquired in this step are V 1 . Further, the shape characteristics data acquired in this step are F 1 . 
         [0039]    In step S 102 , the second data acquisition is performed by the reading sensor  2 . The authentication characteristics data acquired in this step are V 2 . Further, the shape characteristics data acquired in this step are F 2 .  FIG. 5  is a diagram illustrating a model of the registration process of the biometric information in the first embodiment. As illustrated in  FIG. 5 , right hand data are acquired in the first data acquisition, and left hand data are acquired in the second data acquisition, for example. In this case, in both the first right hand data acquisition and the second left hand data acquisition, the hands are disposed approximately in parallel with a longitudinal direction of the reading sensor  2  to acquire the first and second data. 
         [0040]    Note that the first and second data acquisition in steps S 101  and S 102  may be performed by a different reading sensor or the like other than the reading sensor  2 . 
         [0041]    In step S 103 , the fingerprint matching part  15  and the vein matching part  16  determine whether the authentication characteristics data V 1  and the authentication characteristics data V 2  are identical. When the determination indicates that the authentication characteristics data V 1  and the authentication characteristics data V 2  are identical (“YES” in step S 103 ), step S 104  is processed. When the determination indicates that the authentication characteristics data V 1  and the authentication characteristics data V 2  are not identical (“NO” in step S 103 ), step S 105  is processed. 
         [0042]    In step S 104 , the client controller  11  determines that the first and second data acquisition are performed by the same-side hand of the same person being held twice, and hence, the client controller  11  determines that the same data are acquired twice. Thus, the client controller  11  determines the above data acquisition as an error to terminate the process. 
         [0043]    In step S 105 , the client controller  11  or the left-or-right hand input checker  12  calculates the reversed shape characteristics data F 1 ′ to obtain the calculated result. The reversed shape characteristics data F 1 ′ are calculated by mirror reversing (left-right image reversing) the shape characteristics data F 1  of the hand acquired in the first data acquisition in step S 101 . 
         [0044]    In step S 106 , the client controller  11  or the left-or-right hand input checker  12  compares the reversed shape characteristics data F 1 ′ and the shape characteristic data F 2  to determine whether the reversed shape characteristics data F 1 ′ match the shape characteristic data F 2  in a predetermined range. When the reversed shape characteristics data F 1 ′ do not match the shape characteristic data F 2  in the predetermined range (“NO” in step S 106 ), step S 107  is processed. When the reversed shape characteristics data F 1 ′ match the shape characteristic data F 2  in the predetermined range (“YES” in step S 106 ), step S 108  is processed. In step S 106  (“YES”), the lengths of the fingers or the shape of the hand such as the contour are compared after reversing the shape characteristics of the hand. When the reversed shape characteristics data F 1 ′ match the shape characteristics data F 2 , it is determined that the shape characteristics data of both the left and the right hands of the same person are acquired. In this process, the authentication characteristics data V 1  and the authentication characteristics data V 2  of the hands of the same person, an ID specifying the person subject to the acquisition of the authentication characteristics data V 1  and the authentication characteristics data V 2 , and information identifying which of the authentication characteristics data V 1  and the authentication characteristics data V 2  correspond to the left or the right hand are transmitted from the client  1  via the communications part  18  to the server  3 . Note that at registration, it may be predetermined that the first data are acquired from the right hand, and the second data are acquired from the left hand. 
         [0045]    In step S 107 , the client controller  11  determines that the first data and the second data are acquired from hands of different persons. Thus, the client controller  11  determines the above data acquisition as an error to terminate the process. 
         [0046]    In step S 108 , in the server  3 , the authentication characteristics data V 1  and the authentication characteristics data V 2  are registered in association with IDs. The server controller  31  registers in the storage part  30  the authentication characteristics data V 1  and the authentication characteristics data V 2  in association with a corresponding ID. 
         [0047]    In step S 109 , the server  3  sends a report of completion of registration to the client  1 . The registration process is thus completed. 
         [0048]    In the following, an illustration is given of the calculation of mirror reversing (left-right image reversing) the shape characteristics data F 1  of the hand performed in step S 105 , and determination of whether the reversed shape characteristics data F 1 ′ match the shape characteristics data F 2  in step S 106 . 
         [0049]    First, the shape characteristics data F 1  are described. In this embodiment, the shape characteristics data F 1  are acquired based on an image captured by the fingerprint sensor part  21  and an image captured by the vein sensor part  22 . Specifically, the lengths of fingers, the width of the palm, and the width of the wrist may be used as the shape characteristics data. 
         [0050]    An illustration is given of an example of utilizing respective lengths of the forefinger, middle finger and annular finger as the shape characteristics data F 1  with reference to  FIG. 3 . 
         [0051]    In  FIG. 3 , T 1  indicates coordinates of a fingerprint center of the first finger (forefinger) from the left. T 2  indicates fingerprint central coordinates of the second finger (middle finger) from the left. T 3  indicates fingerprint central coordinates of the third finger (annular finger) from the left. BA indicates coordinates of the left-side base of the first finger (forefinger) from the left. BB indicates coordinates of the right-side base of the first finger (forefinger) from the left, and the left-side base of the second finger (middle finger) from the left. BC indicates coordinates of the right-side base of the second finger (middle finger) from the left, and the left-side base of the third finger (annular finger) from the left. BD indicates coordinates of the right-side base of the third finger (annular finger) from the left. 
         [0052]    The lengths of the fingers are calculated based on the respective differences between the fingerprint central coordinates T 1 , T 2 , and T 3  acquired from the fingerprints, and the finger base coordinates BA, BB, BC, and BD acquired from the vein image. Note that the length of a finger includes the lengths of two sides of the finger. The left side length L 1 L of the first finger (forefinger) from the left is obtained by T 1 -BA. The right side length L 1 R of the first finger (forefinger) from the left is obtained by T 1 -BB. The left side length L 2 L of the second finger (middle finger) from the left is obtained by T 2 -BB. The right side length L 2 R of the second finger (middle finger) from the left is obtained by T 2 -BC. The left side length L 3 L of the third finger (annular finger) from the left is obtained by T 3 -BC. The right side length L 3 R of the third finger (annular finger) from the left is obtained by T 3 -BD. 
         [0053]      FIG. 6  is a left-right corresponding table illustrating an example of shape characteristics data in the first embodiment. The shape characteristics data F 1  may include the above-described lengths L 1 L, L 1 R, L 2 L, L 2 R, L 3 L, and L 3 R of the fingers, the width of the palm, and the width of the wrist. The lengths L 1 L, L 1 R, L 2 L, L 2 R, L 3 L, and L 3 R of the fingers, the width of the palm, and the width of the wrist are provided with respective identification numbers  1  to  8  of the shape characteristics data. 
         [0054]    The calculation of mirror reversing (left-right image reversing) the characteristics data F 1  in step S 105  is performed on the basis of the assumption of an image of the hand illustrated in  FIG. 3  being plane-symmetrical relative to plane of the palm. The reversed shape characteristics data F 1 ′ have the following features. The reversed shape characteristics data F 1 ′ indicate no change in the width of the palm and the width of the wrist of the respective identifications numbers  7  and  8 . Thus, in the reversed shape characteristics data F 1 ′, reverse identification numbers  7  and  8  that are the same as the identification numbers are assigned to the width of the palm and the width of the wrist. On the other hand, the lengths of the first finger, the second finger, and the third finger from the left correspond to the lengths of the annular finger, the length of the middle finger, and the length of the forefinger, which indicates that the reversed shape characteristics data F 1 ′ differ from the shape characteristics data F 1 . Hence, as illustrated in  FIG. 6 , the lengths L 1 L, L 1 R, L 2 L, L 2 R, L 3 L, and L 3 R of the fingers for the reversed shape characteristics data F 1 ′ are provided with reverse identification numbers  6  to  1 . Accordingly, the reversed shape characteristics data F 1 ′ are acquired as data having the respective lengths of the fingers corresponding to the reverse identification numbers. 
         [0055]    In step S 106 , the left-or-right hand input checker  12  determines whether the hand shape characteristics data F 2  acquired in the second data acquisition match the reversed shape characteristics data F 1 ′ obtained as described above. The left-or-right hand input checker  12  compares the shape characteristics data F 2  and the reversed shape characteristics data F 1  having the reverse identification numbers identical to the identification numbers of the shape characteristics data F 2 . When the shape characteristics data F 1  match the shape characteristics data F 2  in a predetermined range, the left-or-right hand input checker  12  determines that the reversed shape characteristics data F 1 ′ match the shape characteristics data F 2  (“YES” in step S 106 ). 
         [0056]    Note that the first embodiment has described an example of determining whether the reversed shape characteristics data F 1 ′ match the shape characteristics data F 2  utilizing the left-right corresponding table  13  (step S 106 ). However, the characteristics amount may be extracted by mirror reversing the first input image. 
         [0057]    In the first embodiment, whether the reversed shape characteristics data F 1 ′ match the shape characteristics data F 2  (step S 106 ) is determined by the client  1 . The loads on the communications channel  5  such as the network and the server  3  may be reduced by causing the client  1  to determine whether the reversed shape characteristics data F 1 ′ match the shape characteristics data F 2 . However, the invention is not limited to this example. The server  3  may instead determine whether the reversed shape characteristics data F 1 ′ match the shape characteristics data F 2  (step S 106 ). 
         [0058]      FIG. 7  is a flowchart illustrating a matching process of the biometric information in the first embodiment. 
       Mathcing Process of Biometric Information 
       [0059]    For example, steps S 201  and S 203  are performed by the reading sensor  2 . Steps S 203  to S 207 , step S 209 , and steps S 211  to S 213  are performed by the client  1 . Steps S 202  and S 211  are performed by the server  3 . 
         [0060]    In step S 201 , the first data acquisition is performed by the reading sensor  2 . The authentication characteristics data acquired in this step are V 10 . Further, the shape characteristics data acquired in this step are F 10 . The acquired authentication characteristics data V 10  are transmitted to the server  3 . 
         [0061]    In step S 202 , the server  3  identifies the acquired authentication characteristics data V 10 . The fingerprint matching part  35  and the vein matching part  36  of the server  3  perform the matching process of extracting registration authentication characteristics data that match the acquired authentication characteristics data V 10  in a predetermined range from the registration authentication characteristics data V 1  stored in a storage. From the registration authentication characteristics data V 1  that match the acquired authentication characteristics data V 10 , an ID corresponding to a person to be authenticated, and left-right information indicating that the registration authentication characteristics data V 1  are associated with one of the left and right hand of the person are specified. Then, the ID of the person to be authenticated corresponding to the authentication characteristics data V 10 , and the left-right information of the hand are transmitted from the server  3  to the client  1 . 
         [0062]    In step S 203 , the second data acquisition is performed by the reading sensor  2 . The authentication characteristics data acquired in this step are V 20 . Further, the shape characteristics data acquired in this step are F 20 .  FIG. 8  is a diagram illustrating a model of the matching process of the biometric information in the first embodiment. As illustrated in  FIG. 8 , right hand data are acquired in the first data acquisition, and left hand data are acquired in the second data acquisition, for example. In this case, in the first right hand data acquisition, the right hand is disposed approximately in parallel with a longitudinal direction of the reading sensor  2  to acquire data. However, in the second left hand data acquisition, a longitudinal direction of the left palm may likely be disposed oblique so as to form an angle relative to the longitudinal direction of the reading sensor  2 . 
         [0063]    That is, in the registration process of the biometric information illustrated in  FIG. 5 , the highly accurate authentication characteristics data V 1  and V 2  are acquired for reducing FAR. Hence, an operator intervenes in carefully arranging each of the left and right hands of the person to be authenticated such that the longitudinal direction of the corresponding palm is approximately in parallel with the longitudinal direction of the reading sensor  2  to acquire data. By contrast, in the matching process of the biometric information illustrated in  FIG. 8 , the person to be authenticated is unlikely to hold his or her hand slowly and carefully. That is, the person to be authenticated may hold the hand over the reading sensor  2  for acquiring the second data while continuously standing in the standing position determined in the first data acquisition. As a result, in the second left hand data acquisition, a longitudinal direction of the left palm may likely be disposed oblique so as to form an angle θ relative to the longitudinal direction of the reading sensor  2 . 
         [0064]    In step S 204 , whether the authentication characteristics data V 10  and the authentication characteristics data V 20  are identical is determined by the fingerprint matching part  15  and the vein matching part  16 . When the determination indicates that the authentication characteristics data V 10  and the authentication characteristics data V 20  are identical (“YES” in step S 204 ), step S 205  is processed. When the determination indicates that the authentication characteristics data V 10  and the authentication characteristics data V 02  are not identical (“NO” in step S 204 ), step S 206  is processed. 
         [0065]    In step S 205 , the client controller  11  determines that the first and second data are acquired from the same-side hand of the same person, so that the same data are acquired twice. Thus, the client controller  11  determines the above data acquisition as an error to terminate the process. At this time, the reading sensor  2  may display a message such as “Please hold the other hand over the reading sensor”. The person to be authenticated may be likely to mistake input operations by alternately placing the left hand and the right hand because the person to be authenticated is generally not accustomed to such operations. Hence, the above message or the like is prepared for appropriately guiding the person to be authenticated when the person wrongly holds the same hand over the reading sensor  2  twice. Accordingly, the biometric authentication system having superior usability may be provided. 
         [0066]    Note that the biometric authentication system may further include a configuration to compare the shape characteristics data F 1  subject to the first data acquisition and the shape characteristics data F 2  subject to the second data acquisition. That is, the shape characteristics data F 1  may be compared with the shape characteristics data F 2  without mirror reversing (left-right image reversing) the shape characteristics data F 1 . When the first and second shape characteristics data are input by using the same hand twice, the first and second shape characteristics data are matched. However, when the first and second shape characteristics data do not match despite the fact that the first and second authentication characteristics data are matched, it may be determined that some kind unauthorized operation is performed. In this case, a warning may be generated. 
         [0067]    In step S 206 , the client controller  11  or the left-or-right hand input checker  12  calculates the reversed shape characteristics data F 10 ′. The reversed shape characteristics data F 10 ′ are calculated by mirror reversing (left-right image reversing) the shape characteristics data F 10  of the hand acquired in the first data acquisition in step S 201 . The calculation of the reversed shape characteristics data F 10  is similar to the calculation of the reversed shape characteristics data in the registration process in  FIG. 4 , and a duplicated illustration is omitted from the specification. 
         [0068]    In step S 207 , the client controller  11  or the left-or-right hand input checker  12  compares the shape characteristics data F 10 ′ and the shape characteristic data F 20  to determine whether the shape characteristics data F 10 ′ match the shape characteristic data F 20  in a predetermined range. When the shape characteristics data F 10 ′ do not match the shape characteristic data F 20  in the predetermined range (“NO” in step S 207 ), step S 208  is processed. When the shape characteristics data F 10 ′ match the shape characteristic data F 20  in the predetermined range (“YES” in step S 207 ), step S 208  is processed. 
         [0069]    In step S 208 , the client controller  11  determines that the first data and the second data are acquired from the hands of different persons, and generates an error to terminate the process. At this time, the reading sensor  2  may display a message such as “Please replace the hand with a hand of yourself”. It may be assumed that an input operation differing from the original operation be intentionally performed. Such input operations may be performed for the purpose of spoofing or simple mischief. In this case, unintended load may be applied to the system. Further, it may be necessary to prepare for an attack such as temporarily or indefinitely interrupting or suspending services of a server by simultaneously transmitting a large amount of inappropriately acquired data. The display of the above message may improve the convenience of the person to be authenticated as well as reducing the system load by eliminating spoofing, mischief, and the attack in the early stage. 
         [0070]    In step S 209 , the rotation predicting part  14  calculates a prediction rotational angle θ. The rotation predicting part  14  predicts an approximate rotational angle of a longitudinal direction of one hand (e.g., a left hand) subject to the second data acquisition relative to a longitudinal direction of the other hand (e.g. a right hand) subject to the first data acquisition.  FIG. 9  is a diagram illustrating a rotation of a hand in the first embodiment. The prediction rotational angle θ indicates a rotational angle of one hand (e.g., a left hand) subject to the second data acquisition that is predicted relative to the other hand (e.g., a right hand) subject to the first data acquisition. The rotational angle is provided with a plus (+) sign when one hand subject to the second data acquisition rotates relative to the other hand subject to the first data acquisition in a clockwise direction in  FIG. 9 , whereas the rotational angle is provided with a minus (−) sign when one hand subject to the second data acquisition rotates relative to the other hand subject to the first data acquisition in a counterclockwise direction in  FIG. 9 . In this case, the rotational angle indicates a rotational angle in a plane when the center of the palm is positioned approximately at an axis of rotation, as illustrated in  FIG. 9 . 
         [0071]    The prediction accuracy may be improved by determining the prediction rotational angle θbased on a function having a size of the hand SH as an input as noted below in a formula (1). In this formula (1), SH indicates a value representing the size of the palm, an example of which may be an area of the palm. 
         [0000]      Formula (1) 
         [0000]      θ= F ( S   H )= aS   H   +b    (1)
 
         [0072]    In this formula (1), a and b indicate coefficients previously set by conducting an experiment or the like. Note that when SH represents an area of the palm, an area such as an area of the palm may be calculated based on an overall contour of the shape characteristics data F 10  acquired in the first data acquisition in step S 201 , or the shape characteristics data F 20  acquired in the second data acquisition in step S 203 . 
         [0073]    The prediction rotational angle θ may be calculated based on the value SH representing the size of the hand of the person to be authenticated because it is experimentally known that the person to be authenticated tends to have a larger size of the body as he or she has a larger size of the hand, and the prediction rotational angle θ tends to be greater as the person to be authenticated has a larger size of the body.  FIGS. 10A to 10D  are diagrams illustrating a relationship of the size of the body and the rotation of the hand between persons having different sizes of the body. 
         [0074]    The following illustration describes a reason indicating that the prediction rotational angle θ increases as the size of the body increases. As illustrated in  FIG. 10A , when the person to be authenticated has a small size body, the reading sensor  2  is located at an approximately the same height as the position of the shoulder of the person. As illustrated in  FIG. 10C , when the person to be authenticated has a large size body, the reading sensor  2  is located below the shoulder of the person. 
         [0075]    It is assumed that the reading sensor  2  is located at the same height as the position of the shoulders of both the person having a large size body and the person having a small size body. That is, it is assumed that the person having a large size body is also in a state illustrated in  FIG. 10A . This indicates that the overall image in the  FIG. 10A  is equally enlarged. In this case, an angle θ formed when the left hand is held over the reading sensor  2  (corresponding an angle θ1 in  FIG. 10B ) may be the same regardless of the large and small sizes of the bodies. This is because sizes (lengths) of the respective portions of the body appear to be proportionally increased as a whole. 
         [0076]    However, in most cases, the reading sensor  2  is placed at a predetermined height in practical operations. Hence, the person having a large size body needs to stand closer to the reading sensor  2  than the person having a small size body to eliminate the difference in height between the shoulder and the reading sensor  2 . As a result, the angle θ for the person having a large size body is greater than that for the person having a small size body. The reason for this is illustrated below. 
         [0077]    In the example of the person having a small size body illustrated in  FIG. 10A , when R 1  represents the length of the arm, the distance D 1  of the horizontally stretched arm is approximately the same as the length R 1  (D 1 ≈R 1 ). On the other hand, in the example of the person having a large size body illustrated in  FIG. 10C , when R 2  represents the length of the arm, the distance D 2  of the horizontally stretched arm is shorter than the length R 2  (D 2 &lt;R 2 ). This is because the person having a large body needs to downwardly stretch the arm. In this case, an angle θ formed when the left hand is held over the reading sensor  2  is calculated as follows. 
         [0000]      θ1=arctan( S 1/ D 1)≈atan( S 1/ R 1)
 
         [0000]      θ2=arctan( S 2/ D 2)≈atan( S 2/ R 2)
 
         [0078]    In the above formulas, proportions of the lengths of the arm (R 1 , R 2 ) to the widths of the bodies (S 1 , S 2 ) appear to be relatively constant, and hence, there is a relationship represented by S 1 /R 1 ≈S 2 /R 2 . Accordingly, the relationship represented by θ1&lt;θ2 is finally obtained. Further, the coefficients a and b in the formula (1) may be varied between the case where the person to be authenticated uses the reading sensor  2  while standing and the case where the person to be authenticated uses the reading sensor  2  while sitting. That is, the prediction rotational angle θ may be more likely to be increased due to an increase in the size (height) of the body in the case where the person to be authenticated uses the reading sensor  2  while standing compared to the case where the person to be authenticated uses the reading sensor  2  while sitting. Hence, highly accurate biometric authentication may be carried out by applying appropriate values to the coefficients a and b depending on the case where the person is standing and the case where the person is sitting. 
         [0079]    Further, a fixed value may be set in the prediction rotational angle θ. For example, the prediction rotational angle θ may be less likely to be increased due to an increase in the size (height) of the body in the case where the person to be authenticated uses the reading sensor  2  while sitting compared to the case where the person to be authenticated uses the reading sensor  2  while standing. Thus, a fixed value may be set as the prediction rotational angle θ when the person to be authenticated uses the reading sensor  2 . 
         [0080]    The direction of the prediction rotational angle θ, that is, a rotational direction of the hand in the second data acquisition may vary according to one of the left and the right hands being first held over the reading sensor  2 . The direction of the prediction rotational angle θ may be reversed between the case where the right hand is held first and the left hand is held next and the case where the left hand is held first and the right hand is held next. 
         [0081]    Hence, whether the hand subject to the first data acquisition is the left or the right hand is determined. In this case, whether the hand subject to the first data acquisition is the left or the right hand is determined based on the shape characteristics data F 10 . However, the accuracy in the determination of the left or the right hand based on the shape characteristics data is not high. Hence, in the first embodiment, whether the hand subject to the first data acquisition is the left or the right hand is determined based on the shape characteristics data F 10 . As described above, since the operator intervenes in the registration, the operator or the like may save in the server  3  the authentication characteristics data V 1  in association with the left-right information. Alternatively, it may be predetermined that the data are acquired in the order from the right hand to the left hand at the registration. The authentication characteristics data may differ between the right hand and the left hand. Thus, the authentication characteristics data V 10  in the first data acquisition and the registered authentication characteristics data V 1  are compared to determine whether the matched authentication characteristics data belongs the left or the right hand. As a result, whether the hand subject to the first data acquisition is the left or the right hand is determined. When the hand subject to the first data acquisition is the right hand, the second data acquisition is performed by using the left hand. Hence, the prediction rotational angle θ is +. When the hand subject to the first data acquisition is the left hand, the second data acquisition is performed by using the right hand. Hence, the prediction rotational angle θ is −. 
         [0082]    In step S 210 , the server  3  identifies the acquired authentication characteristics data V 10 . The fingerprint matching part  35  and the vein matching part  36  of the server  3  may turn the matching authentication characteristics data V 20  by the prediction rotational angle θ before the second matching process (offset setting). 
         [0083]    The matching may be susceptible to failing when the rotational angle between the registered authentication characteristics data and the matching authentication characteristics data increases. A search range of the rotational angle at the matching process may be increased; however, this may increase the load of the authentication process. Further, when matching is performed by increasing the search range of the rotational angle, respective data of different third parties may be matched with each other with high probability. As a result, a false acceptance rate “FAR” may be raised. That is, despite the fact that the authentication characteristics data respectively belong to the different third parties, similarities between the two units of the authentication characteristics data may be increased with high probability by applying different rotational angles to match the two units of the authentication characteristics data. 
         [0084]    Hence, when it may be predicted that the authentication characteristics data V 20  subject to the second data acquisition are rotated by +20 degrees based on the authentication characteristics data V 1  subject to the first data acquisition, the authentication characteristics data V 20  may be corrected by turning −20 degrees, and the turned authentication characteristics data V 20  are matched with the registration authentication characteristics data V 2  while searching the neighboring range (e.g., ±5 degrees). Further, a similar process may be applied to the shape characteristics data. 
         [0085]    As described above, it may be possible to reduce the calculation time, enhance responsiveness to the person to be authenticated, and improve the convenience of the biometric authentication system by applying the offset setting. In this configuration, the process requiring similar processing time may be performed by a server having less processing capability. Hence, cost-effective performance may be improved. Further, it may be possible to decrease the search range of the rotational angle as well as reducing FAR. 
         [0086]    The fingerprint matching part  35  and the vein matching part  36  of the server  3  perform the matching process of extracting data that match the acquired authentication characteristics data V 20  turned by the prediction rotational angle θ in a predetermined range from the registration authentication characteristics data V 2  registered in a storage. Hence, the time required for the extraction of the match may be reduced, thereby accurately performing a matching process at a high speed. From the registration authentication characteristics data V 2  that match the acquired authentication characteristics data V 20 , an ID corresponding to a person to be authenticated, and left-right information indicating that the registration authentication characteristics data V 1  are associated with one of the left and right hand of the person is specified. Then, the ID of the person to be authenticated corresponding to the authentication characteristics data V 20 , and the left-right information of the hand are transmitted from the server  3  to the client  1 . 
         [0087]    In step S 211 , the client controller  11  performs authentication. In step S 202 , the ID of the person to be authenticated and the left-right information of the hand corresponding to the authentication characteristics data V 10  transmitted to the client  1 , and the ID of the person to be authenticated and the left-right information of the hand corresponding to the authentication characteristics data V 20  transmitted to the client  1  are determined. When the two IDs of the person to be authenticated are matched and the respective left-right information of the hand indicate opposite hands, the person subject to the first data acquisition and the person subject to the second data acquisition are determined to be an identical person to be authenticated (“YES” in step S 211 ). 
         [0088]    When the determination indicates a successful authentication, the matching process ends as the authentication being succeeded (step S 212 ). On the other hand, when the determination indicates a unsuccessful authentication, the matching process ends as the authentication being a failure (step S 213 ). 
         [0089]    The input order of the left and the right hands to be authenticated may be the right hand first and the left hand next, or the left hand first and the right hand next. 
         [0090]    The first embodiment describes a combination of the fingerprints and the palm veins as the biometric information. However, the biometric information is not limited to this example, and may be a recombination of finger veins or palm prints, or a combination of the finger veins and the palm prints. 
         [0091]    Further, step S 207  is processed by the client  1  in order to reduce the process load imposed on the server  3  and the communications channel  5  such as a network, and hence, step S 207  may be processed by the server  3 . 
         [0092]    Moreover, the registration process in steps S 101  and S 102  and the registration process in steps S 201  and S 202  may be performed different reading sensors. Further, the matching process in steps S 103  to S 107  and step S 109 , the matching process in steps S 203  to S 207 , step S 209 , and steps S 211  to S 213  may be performed by different clients. 
         [0093]    Within the first embodiment, the number of the characteristics data for one person may be increased by using one sensor for performing the biometric authentication on both the left and right hands. Hence, it possible to reduce a false acceptance rate “FAR”. 
       Second Embodiment 
       [0094]    Within the second embodiment, only the vein sensor part  22  is used as the reading sensor  2 .  FIG. 11  is a diagram illustrating a configuration example of a biometric authentication system in the second embodiment. An illustration is given of the configuration example of the biometric authentication system in the second embodiment with reference to  FIG. 11 . 
         [0095]    In  FIG. 11  for describing the second embodiment, components having functions the same as  FIG. 1  are provided with reference numbers identical to those of  FIG. 1 , and a duplicated description is omitted from the specification. The second embodiment differs from the first embodiment in that the second embodiment of the biometric authentication system does not include the fingerprint sensor part  21 , the fingerprint matching part  15 , the left-right corresponding table  13 , or the fingerprint matching part  35 , and includes a left-right image reversing part  131 . 
         [0096]    The left-right image reversing part  131  is configured to mirror reverse (left-right image reverse) the shape characteristics data subject to the data acquisition in step S 105  in  FIG. 4  and in step S 206  in  FIG. 7 . The shape characteristics data handled by the left-right image reversing part  131  may be obtained by a contour shape of the palm, for example. Specifically, an image of the contour of the palm is traced, and a Fourier descriptor of a contour line may be used as the shape characteristics data. Alternatively, moment is calculated based on an image of an overall shape of the palm, and the calculated moment may be used as the shape characteristics data. The reference for the characteristics amount of the image of the hand shape may, for example, be cited on pages 246 to 253 of “R. M. Luque, D. Elizondo, E. Lopez-Rubio and E. J. Palomo, “GA-Based Feature Selection Approach In Biometric Hand Systems”, Proceedings of International Joint Conference on Neural Networks, San Jose, Calif., USA, Jul. 31-Aug. 5, 2011, 2011IEEE″. The characteristics amounts may be used as the shape characteristics. 
         [0097]    The left-right image reversing part  131  may apply mirror reverse (left-right image reverse) of the shape characteristics data obtained from the above-described image to the subject of the first data acquisition or to the subject of the second data acquisition. When a reverse process is performed on the shape characteristics data F 1  or F 10  subject to the first data acquisition, the shape characteristics data F 2  or F 20  subject to second data acquisition may be acquired in parallel with performing the reversing process on the shape characteristics data F 1  or F 10  subject to the first data acquisition. As a result, a response may be quickened so as to perform the authentication of the person to be authenticated in a short time. 
         [0098]    In step S 106  of  FIG. 4 , the client controller  11  and the left-or-right hand input checker  12  compare the shape characteristics data reversed by the left-right image reversing part  131  and the shape characteristics data of the other hand to see whether the reversed shape characteristics data match the shape characteristics data of the other hand in a predetermined range. When the reversed shape characteristics data do not match the shape characteristics data of the other hand in the predetermined range (“NO” in step S 106 ), step S 107  is processed. When the reversed shape characteristics data F 1 ′ match the shape characteristic data F 2  in the predetermined range (“YES” in step S 106 ), step S 108  is processed. 
         [0099]    Further, in step S 207  of  FIG. 7 , the client controller  11  and the left-or-right hand input checker  12  compare the reversed shape characteristics data and the shape characteristics data of the other hand to see whether the reversed shape characteristics data match the shape characteristics data of the other hand in a predetermined range. When the reversed shape characteristics data F 10 ′ do not match the shape characteristic data F 20  in the predetermined range (“NO” in step S 207 ), step S 208  is processed. When the reversed shape characteristics data F 10 ′ match the shape characteristic data F 20  in the predetermined range (“YES” in step S 207 ), step S 209  is processed. Although an illustration of other steps is omitted, these steps are conducted to perform the authentication by following the flowchart of the matching process in  FIG. 7 . 
         [0100]    Note that the person to be authenticated may have defects in his or her fingers, so that fingerprints are not available as the biometric information in such a case. Even in such a case, the biometric system according to the second embodiment may be able to perform the authentication with higher accuracy by using the biometric information of the identical portions of both hands to increase the matching accuracy, thereby reducing the false acceptance rate FAR. 
         [0101]    In the above embodiments, the fingerprints and the palm veins are illustrated as examples of the biometric information to be matched. However, the biometric information is not limited to these examples. For example, palm prints or finger veins may be used as the biometric information. 
         [0102]    Further, in the above embodiments, the shape characteristics data are used for determining whether the hand held over the reading sensor is the left hand or the right hand. However, the shape characteristics data of the left hand and those of the right hand may be configured to be used in the authentication process. 
         [0103]    According to the biometric system of the above-described embodiments, the biometric authentication of both hands may be performed by one sensor. 
         [0104]    As described above, the examples and embodiments have been described in detail; however, it should not be construed that the present invention is limited to those specific examples and embodiments described above. Various changes or alternations may be made within the scope of the invention. 
         [0105]    All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.