Abstract:
An authenticating method includes enabling a transponder to receive a read request that contains an authentication code, enabling the transponder to extract the authentication code from the read request, enabling the transponder to generate and wirelessly transmit a reply signal that contains the authentication code, and enabling a reader to authenticate the transponder based on the authentication code contained in the reply signal. An identification system, which includes the transponder and the reader is also disclosed.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to an authenticating method for authenticating a transponder, such as a radio frequency identification (RFID) tag, of an identification system. 
         [0003]    2. Description of the Related Art 
         [0004]    When a reader reads a radio frequency identification (RFID) tag, the RFID tag sends a unique identifier thereof back to the reader. 
         [0005]    The aforementioned conventional RFID tag is disadvantageous in that, since the unique identifier thereof is fixed, a counterfeit thereof can be easily fabricated by simply eavesdropping on the reader. 
       SUMMARY OF THE INVENTION 
       [0006]    Therefore, the main object of the present invention is to provide an authenticating method that can overcome the aforesaid drawback of the prior art. 
         [0007]    Another object of the present invention is to provide an identification system that can overcome the aforesaid drawback of the prior art. 
         [0008]    According to an aspect of the present invention, an authenticating method comprises enabling a transponder to receive a read request that contains an authentication code, enabling the transponder to extract the authentication code from the read request, and enabling the transponder to generate and wirelessly transmit a reply signal that contains the authentication code extracted thereby from the read request. The transponder is authenticated based on the authentication code contained in the reply signal transmitted thereby. 
         [0009]    According to another aspect of the present invention, an identification system comprises a transponder. The transponder receives a read request that contains an authentication code, extracts the authentication code from the read request, and generates and wirelessly transmits a reply signal that contains the authentication code extracted thereby from the read request. The transponder is authenticated based on the authentication code contained in the reply signal transmitted thereby. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawings, of which: 
           [0011]      FIG. 1  is a block diagram of the first preferred embodiment of an identification system according to this invention; 
           [0012]      FIGS. 2A and 2B  are flow charts of the first preferred embodiment of an authenticating method to be implemented using the identification system shown in  FIG. 1  according to this invention; 
           [0013]      FIG. 3  is a block diagram of the second preferred embodiment of an identification system according to this invention; and 
           [0014]      FIGS. 4A and 4B  are flow charts of the second preferred embodiment of an authenticating method to be implemented using the identification system shown in  FIG. 3  according to this invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0015]    Before the present invention is described in greater detail, it should be noted that like elements are denoted by the same reference numerals throughout the disclosure. 
         [0016]    Referring to  FIG. 1 , the first preferred embodiment of an identification system according to this invention is shown to include a transponder  1  and a reader  2 . 
         [0017]    The transponder  1 , such as a radio frequency identification (RFID) tag, includes a database  11  in which a unique identifier thereof is stored. 
         [0018]    The reader  2  includes a code generator  21  that generates first and second authentication codes. In this embodiment, the reader  2  authenticates the transponder  1  based on the first and second authentication codes generated by the code generator  21  thereof, in a manner that will be described hereinafter. 
         [0019]    The reader  2  generates and wirelessly transmits a read request that contains the first authentication code. 
         [0020]    In this embodiment, the code generator  21  of the reader  2  generates the first authentication code based on a first varying value. Preferably, the first varying value is the date and time at which the code generator  21  of the reader  2  generates the first authentication code. For example, when the code generator  21  of the reader  2  generates the first varying value on Jul. 15, 2008 at 11:07:08am, the first varying value may be 20080715110708. 
         [0021]    The transponder  1  receives the read request, extracts the first authentication code from the read request, and generates and wirelessly transmits a reply signal that contains the first authentication code extracted thereby from the read request and the unique identifier of the transponder  1 . 
         [0022]    The reader  2  receives the reply signal, extracts the first authentication code and the unique identifier of the transponder  1  from the reply signal, and obtains a difference between the first authentication code extracted thereby from the reply signal and the second authentication code generated by the code generator  21  thereof. 
         [0023]    In this embodiment, the code generator  21  of the reader  2  generates the second authentication code based on a second varying value. Preferably, the second varying value is the date and time at which the reader  2  receives the reply signal. For example, when the reader  2  receives the reply signal on Jul. 15, 2008 at 11:07:16am, the second varying value may be 20080715110716. 
         [0024]    The reader  2  compares the difference between the first and second authentication codes obtained thereby, i.e., eight, with a predetermined index, e.g., ten. When the result of comparison indicates that the difference obtained thereby is less than the predetermined index, which is the case in this example, the reader  2  verifies the transponder  1  to be authentic. On the other hand, when the result of comparison indicates that the difference obtained thereby is greater than the predetermined index, the reader  2  identifies the transponder  1  to be a counterfeit. 
         [0025]    In an alternative embodiment, the first varying value is the amount of a count, such as of a counter, at a time point when the code generator  21  of the reader  2  generates the first authentication code, and the second varying value is the amount of a count at a time point when the reader  2  receives the reply signal. 
         [0026]    It is noted that when the transponder  1  is verified to be authentic by the reader  2 , the unique identifier of the transponder  1  extracted by the reader  2  from the reply signal is forwarded by the reader  2  to an external computer (not shown). Otherwise, i.e., when the transponder  1  is identified by the reader  2  to be a counterfeit, the reply signal is simply ignored by the reader  2 . 
         [0027]    The external computer is operable to retrieve information, such as price or size, related to a product (not shown) on which the transponder  1  is attached based on the unique identifier of the transponder  1  forwarded thereto by the reader  2 , in a manner well known in the art. 
         [0028]    The first preferred embodiment of an authenticating method to be implemented using the aforementioned identification system according to this invention will now be described with further reference to  FIGS. 2A and 2B . 
         [0029]    In step  21 , the code generator  21  of the reader  2  generates a first authentication code that is based on the first varying value. 
         [0030]    In step  22 , the reader  2  generates and wirelessly transmits a read request that contains the first authentication code. 
         [0031]    In step  23 , the transponder  1  receives the read request. 
         [0032]    In step  24 , the transponder  1  extracts the first authentication code from the read request. 
         [0033]    In step  25 , the transponder  1  generates and wirelessly transmits a reply signal that contains the first authentication code extracted thereby from the read request in step  24  and the unique identifier thereof. 
         [0034]    In step  26 , the reader  2  receives the reply signal. 
         [0035]    In step  27 , the reader  2  extracts the first authentication code and the unique identifier of the transponder  1  from the reply signal. 
         [0036]    In step  28 , the code generator  21  of the reader  2  generates a second authentication code based on the second varying value. 
         [0037]    In step  29 , the reader  2  obtains a difference between the first authentication code extracted thereby from the reply signal in step  27  and the second authentication code generated by the code generator  21  thereof in step  28 . 
         [0038]    In step  30 , the reader  2  compares the difference obtained thereby in step  29  to the predetermined index. 
         [0039]    In step  31 , when the result of comparison in step  30  indicates that the difference obtained in step  29  is less than the predetermined index, the flow proceeds to step  32 . Otherwise, when the result of comparison in step  30  indicates that the difference obtained in step  29  is greater than the predetermined index, the flow proceeds to step  34 . 
         [0040]    In step  32 , the reader  2  verifies the transponder  1  to be authentic. 
         [0041]    In step  33 , the reader  2  forwards the unique identifier of the transponder  1  extracted thereby from the reply signal in step  27  to the external computer. Thereafter, the flow is terminated. 
         [0042]    In step  34 , the reader  2  identifies the transponder  1  to be a counterfeit. Thereafter, the flow is terminated. 
         [0043]      FIG. 3  illustrates the second preferred embodiment of an identification system according to this invention. When compared to the previous embodiment, in this embodiment, the unique identifier of the transponder  1  stored in the database  11  is an encrypted unique identifier. The reader  2  further includes an encrypting unit  22  and a decrypting unit  23 . The encrypting unit  22  is connected to the code generator  21  of the reader  2 , and encrypts the first authentication code prior to the transmission of the read request. The decrypting unit  23  decrypts the first authentication code and the unique identifier of the transponder  1  extracted by the reader  2  from the reply signal. 
         [0044]    The second preferred embodiment of an authenticating method to be implemented using the aforementioned identification system according to this invention will now be described with further reference to  FIGS. 4A and 4B . 
         [0045]    In step  41 , the code generator  21  of the reader  2  generates a first authentication code based on the first varying value. 
         [0046]    In step  42 , the encrypting unit  22  of the reader  2  encrypts the first authentication code to obtain an encrypted first authentication code. 
         [0047]    In step  43 , the reader  2  generates and wirelessly transmits a read request that contains the encrypted first authentication code obtained in step  42 . 
         [0048]    In step  44 , the transponder  1  receives the read request. 
         [0049]    In step  45 , the transponder  1  extracts the encrypted first authentication code from the read request. 
         [0050]    In step  46 , the transponder  1  generates and wirelessly transmits a reply signal that contains the encrypted first authentication code extracted thereby from the read request in step  45  and the encrypted unique identifier thereof. 
         [0051]    In step  47 , the reader  2  receives the reply signal. 
         [0052]    In step  48 , the reader  2  extracts the encrypted first authentication code and the encrypted unique identifier of the transponder  1  from the reply signal. 
         [0053]    In step  49 , the decrypting unit  23  of the reader  2  decrypts the encrypted first authentication code and the encrypted unique identifier of the transponder  1  extracted by the reader  2  in step  48  to obtain the first authentication code and the unique identifier of the transponder  1 . 
         [0054]    In step  50 , the code generator  21  of the reader  2  generates a second authentication code based on the second varying value. 
         [0055]    In step  51 , the reader  2  obtains a difference between the first authentication code obtained in step  49  and the second authentication code generated by the code generator  21  thereof in step  50 . 
         [0056]    In step  52 , the reader  2  compares the difference obtained thereby in step  51  to the predetermined index. 
         [0057]    In step  53 , when the result of comparison in step  52  indicates that the difference obtained in step  51  is less than the predetermined index, the flow proceeds to step  54 . Otherwise, when the result of comparison in step  52  indicates that the difference obtained in step  51  is greater than the predetermined index, the flow proceeds to step  56 . 
         [0058]    In step  54 , the reader  2  verifies the transponder  1  to be authentic. 
         [0059]    In step  55 , the reader  2  forwards the unique identifier of the transponder  1  obtained in step  49  to the external computer. Thereafter, the flow is terminated. 
         [0060]    In step  56 , the reader  2  identifies the transponder  1  to be a counterfeit. Thereafter, the flow is terminated. 
         [0061]    While the present invention has been described in connection with what are considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.