Abstract:
An access control system securely transfers identification and transaction information between an access reader and a contactless smart card over a contactless radio frequency link via an RF modem. The access reader contains a programmable microcontroller, DC/DC converter, regulator, Opto-Isolators and LEDS, and an RF modem. The smart cards contain identification or transaction data as well as reader programming and de-programming software, which is protected by appropriate security keys. An access reader having the appropriate security keys performs a one to one verification of data stored in the smart card to data from an identification device coupled to the access reader. Upon verification of the validity of the smart card, the access reader transfers identification and transaction information over a data link to any external processor or controller which controls access to a secured area. Both the data format/protocol and operating state out of the access reader is programmable and configurable at any time. The access reader and access cards are compatible with any existing Wiegand, magnetic stripe, and serial based access control systems, and are configurable to emerging Biometric system designs.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of priority under 35 U.S.C. 119(e) to Provisional U.S. Patent Application No. 60/289,039 filed May 4, 2001 and Provisional U.S. Patent Application No. 60/318,385 filed September 10, 2001 which are incorporated herein by reference in their entirety. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of Invention  
           [0003]    This invention relates generally to access systems for accessing restricted areas, and more specifically to a one to one comparison access card reader utilizing security keys for true authenticated verification of the identity of an access card holder attempting to gain access to a restricted area.  
           [0004]    2. Background  
           [0005]    Access readers typically are small boxes located proximate to the entrances to restricted, or secured, areas. To gain access to an area, an access card holder must present an access card to the access reader, which in turn verifies the information on the card with a central computer. Commonly used access cards include both contact and contactless smart cards. In the prior art systems, the central computer stores data files associated with each access card holder, including information regarding employee identification, card validity, and access rules. The verification process of the prior art requires an initial communication between the access card and the access card reader, communication between the access reader and the central computer, verification of card holder data and access card data at the central computer, communication of the results from the central computer to the access reader, and communication of the results to the access card holder by allowing or denying access to the restricted area.  
           [0006]    The verification process of the prior art is sufficient for low traffic entrances, such as a gated entrances for a small office building, wherein the additional time required for the verification process does not cause long queues of employees waiting to pass through the gate. However, even a slight delay required to swipe a contact card and to verify card holder data at the central computer may be inconvenient for “high traffic” entrance ways. Further, complex comparisons such as biometric identification, requires a complex decision process and associated software that must be performed by the central computer as the currently available access readers and access cards have limited storage capacity and processing capability. In addition, the central computer must have updated information for each person, including infrequent visitors, who have clearance to enter a secured area. The data bases stored at the central computer for these entrance ways have the potential to be unmanageable, particularly for multi-story, multi-company office buildings. Security necessarily is augmented through use of security personnel stationed at the gates to check and/or verify identification of employees as they enter the gates.  
           [0007]    Installations of the prior art access control systems are costly. Each new access gate or entrance way requires installation of communication lines to the central computer. For multi-story or expansive buildings, the wiring and/or re-wiring process is both time-consuming and expensive. These factors often present cost-prohibitive blocks to converting rooms, labs, or designated areas into secured access areas. In addition, because each door or gate may have different access rights, the central computer also must keep track of personnel access rights for every door or gate. Installation of a new gated entrance requires update of the central computer data bases. In addition, each change in personnel or a change in personnel access to restricted areas requires an update to the data bases, and for large companies, the changes may be required daily.  
           [0008]    The prior art also presents security issues. For example, an access card holder user can enter a secured area with an unreported stolen card if the verification process is for validity of the card, only. Thus, for security purposes, entrance ways are often manned to verify the identity of a person holding the card with a picture identification on the access card. One way to eliminate the requirement of security personnel at each entrance way, is through the use of automatic identification systems connected to the central computer. Biometric systems such as fingerprint identification systems are becoming increasingly popular as the biometric technology develops to further identify an access card holder as he or she passes through the secured entrance way. Although the biometric systems may add security of verification and eliminate additional security personnel, the central computer is further burdened with storage of the biometric information. Biometric systems typically employ the concept of a “one to many” comparison, that is, an access card holder presents his fingertip for fingerprint imaging, and this one image is transmitted to a central computer for comparison to many fingerprints to find a matching print. The comparison and search time further slows down the identification process to add delays to the time required to pass through a secure entrance way.  
           [0009]    Therefore, a need remains for an access control system that does not require connection to a central computer, but which provides verification of the validity of the access card as well as identification of the access card holder. A further need remains for access readers and access cards that have expanded storage and processing capability for performing complex decision processes and comparisons, such as biometric identification. Yet a further need remains for an access control system which minimizes installation time and cost, which is compatible with existing access control systems, and which may be updated to accommodate changes in secure area entrance rules and locations.  
         SUMMARY OF THE INVENTION  
         [0010]    It is an advantage of the present invention to provide an access control system that does not require communication to a central computer for activation, access card verification, and reconfiguration.  
           [0011]    It is another advantage to provide an access control system which employs a one to one verification process at the access card reader and does not require data storage for every access card holder.  
           [0012]    Still another advantage is to provide an access control system that may be configured to emulate a variety of access cards to allow compatibility with existing access systems.  
           [0013]    It is yet another advantage to provide an access control system which may be configured to allow different access rights to a variety of gated entrances.  
           [0014]    A further advantage is to provide an access control system having the option for an unattended or attended secured entrance way.  
           [0015]    In an exemplary embodiment of the present invention an access control system includes a access reader having an RF interface for communication with a contactless smart card, at least one serial connection to an identification (ID) device, and data output lines for controlling access to a secured entrance. The contactless smart card includes memory divided into a number of blocks, wherein each block is further divided into pages of a predetermined number of bytes. At least one page of each block is utilized to store an application type number key, a read key, and a write key. The access reader communicates with the smart card providing the access reader is supplied with the keys of at least one memory bock of the smart card. The use of keys provides an authenticated read of data from the access card that is not provided in prior art access control systems.  
           [0016]    The access control system of the exemplary embodiment of the present invention utilizes four types of contactless smart cards including activation cards, access cards, deactivation cards, and update cards. In an exemplary embodiment of the invention, the access readers are pre-programmed during manufacture with an initial activation key. The access readers may then be initialized by reading data from an activation card encoded with the same key. The deactivation card returns the access reader to a production state awaiting an activation card. Modifications in access reader data, such as keys, are downloaded to the access reader utilizing an update card. In one embodiment of the invention, the access reader includes a serial port for connection with a personal computer (PC) device. The PC device may be used for initializing or updating the access reader, or for collecting transaction, or “log” , data from the access reader.  
           [0017]    Access cards are presented to the access readers to gain entrance to secured areas. The access cards are further formatted to contain application specific data in a designated memory blocks. Each memory block has an application type number key, a read key, and a write key. The application specific data is the data required by the access reader to verify the identity of the access card holder against data received from an identification device. Identification devices of the exemplary embodiment, such as keypads and biometric identification devices, may vary according to the use of the access reader. The access reader includes a microprocessor for comparing the application specific data from the access card with the data received from the identification device. Upon verification of a match of the data, the access reader permits the access card holder to enter the secured area.  
           [0018]    The access reader of an exemplary embodiment of the present invention receives identification data from biometric devices for comparison to identification data contained on the access cards. The biometric devices provide biometric images, e.g., fingerprint images, retinal images, and/or facial images, as well as template minutia of the actual images. The template minutia may be used by an access reader for automatic comparison of the template minutia from the biometric device with the template minutia stored on an access card. The actual images from the access card and the biometric device may be used by security personnel to make decisions whether to permit an access card holder access to the secured area. Thus, the access control system of the exemplary embodiment provides means for both attended and unattended identification verification.  
           [0019]    The access reader of the exemplary embodiment may be integrated with existing access control systems by programming the access reader to output a data stream required by the existing system upon verification of the identification data from an ID device with the application data from the access card. For example, access control systems that utilize key pads and swipe cards, and which output Wiegand bit streams, may be updated by providing access readers that output the same Wiegand bit streams upon a positive comparison of the key pad entries to the entries stored on the contactless access card. The access reader may be configured to be compatible with other existing access readers, such as magnetic stripe and serial based access control systems in the same manner. The ability to integrate the access reader of the exemplary embodiment with existing systems, enables the existing system to be updated for contactless smart card operation without a shut down of the exiting system. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    The present invention will be better understood from the following detailed description of a preferred embodiment of the invention, taken in conjunction with the accompanying drawings in which like reference numerals refer to like parts and in which:  
         [0021]    [0021]FIG. 1 is an illustration of the initialization components for a smart card access control system of a preferred embodiment;  
         [0022]    [0022]FIG. 2 is a block diagram of the access reader states and card types of the preferred embodiment;  
         [0023]    [0023]FIG. 3 is an illustration of the components of an access reader of a first embodiment of the present invention;  
         [0024]    [0024]FIG. 4 is an illustration of a preferred physical configuration of an access reader;  
         [0025]    [0025]FIG. 5 is an illustration of an access control system of a preferred embodiment;  
         [0026]    [0026]FIG. 6 is an illustration of a biometric access control system of a preferred embodiment;  
         [0027]    [0027]FIG. 7 is an illustration of example equipment that may employ the use of the access control system of a preferred embodiment of the present invention;  
         [0028]    [0028]FIG. 8 is an illustration of a memory block of a contactless smart card of the preferred embodiment; and  
         [0029]    [0029]FIG. 9 is a flow diagram of a method of the preferred embodiment for an access control system. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0030]    [0030]FIG. 5 illustrates the smart card access control system  200  of a preferred embodiment of the present invention. The system  200  includes an access control unit (ACU), also referred to as an access reader  202 , which communicates by radio frequency  228  to an access card, e.g., a contactless smart card  208 . The access reader may be used for basic applications such as transit access, loyalty transactions, and health care benefits which utilizes a contactless smart card. However, this basic system has minimum use as the access reader  202  is limited to verifying the validity of the smart card  208  rather than further identifying the access card holder. Thus, the access control system  200  of the preferred embodiment further includes an identification device  204 , such as a keypad or a biometric device. A biometric device includes, e.g., a camera and processor for facial or retinal recognition, or a fingerprint pad and processor for fingerprint identification. In other embodiments of the invention, the identification device  204  can be incorporated into the access reader  202 . The output data  220  from the identification device  204  is sent to the access reader  220  which performs a one-to-one (1:1) comparison of the output data  220  with card data read from the access card  208 . A positive verification may be indicated by the illumination of an indicator and/or by the output of a control signal  222  to a secured device  206  such as a door lock or a gate turnstile.  
         [0031]    Continuing with FIG. 5, the access reader  202  of a preferred embodiment may include a serial port  230  for connection with a personal computer-type (PC) device  212 . The PC device  212  may be utilized with the access reader  202  to program standard production smart cards  208 . The programmed smart cards  208 , then are utilized to program an access reader  202  for a desired mode of operation. The PC device  212 , or a contactless update card  62 , as shown in FIG. 2, may be used to download database material to the access reader  202 . Similarly, the PC device  212  or a contactless memory device  232  may be utilized to upload log lists from the access reader  202 . Log lists may include data collected from access cards  208  that are presented to the access reader  202 , as well as data identifying the access reader  230 . The access reader  202  of the preferred embodiment is connected via another serial connection  226  to a central computer  210 . The access reader  202  performs the access identification process in real time, and uploads the results of the “transactions” to the central computer at a later time, for example, each night after a business day.  
         [0032]    [0032]FIG. 3 illustrates the electrical hardware components of an access reader  100  of a preferred embodiment of the present invention. The access reader  100  includes a microcontroller  104  for performing the access verification processes, and an RF modem  102  for communicating with a contactless smart card. Unit power  116  is connected to a DC to DC converter  108  which supplies 5 volts internal power  128  to the RF modem  102 . The DC to DC converter  108  is connected to a regulator  110  which supplies power  120  to the microcontroller  104 . The RF modem  102  of the preferred embodiment generates a 13.56 MHZ RF field  126 , and reads standard smart cards at distances up to 10 cm. The microcontroller  104  outputs data signals  124  for controlling the secured device  206 , as shown in FIG. 5, for illuminating an indicator, such as an LED  112 , or for communicating with the central computer  210  or the PC device  212 . The microcontroller  104  includes memory for storing data such as software applications for validation processes, and negative lists of invalid access cards. Additional input data lines  136  may be required to communicate with multiple identification devices  204  or with an existing access control system reader.  
         [0033]    Continuing with FIG. 3, in one embodiment of the present invention, the access reader  100  includes an opto-isolater  106  for isolating the microcontroller  104  from the unit power  116  and the internal power  118 . A terminal block  130  of the preferred embodiment utilizes at least eight connections as shown in Table 1. Additional connectors/terminals X, Y, etc. may be necessary for data communications to existing devices (not shown) and external devices  204 ,  206 ,  212 ,  210 , as shown in FIG. 5. If the microcontroller  104  does not require optical isolation, the unit power  116  and the external power  120  may be provided from the same power source by connecting terminals  2  and  8 , and by connecting terminals  6  and  7 , for the terminal block  130  configuration shown in FIG. 3. This configuration uses the external power  120  for the optical isolator and the LED  106 , but defeats the optical isolation by connecting the signal ground  132  to the power ground  134 .  
         [0034]    As shown in Table 1 for one embodiment of the access reader  100 , terminals 3 and 4 are data outputs. Other embodiments of the invention may require more or fewer data outputs. For example, if the access reader  100  is programmed by activation card to output Wiegand data, the data appears on terminals 3 and 4. If the unit is programmed to output serial or magnetic-stripe data the data appears on pin 3, only.  
                             TABLE 1                           Terminal Block Connections for an Access Reader            Terminal   Function   Comment               1   Internal 5 Volts; or   Provides +5 Volts at up to 100 mA;           Test Terminal   or for production testing       2   External 5 to 28 Volts   Isolator and LED power (Requires +5               to +28 Volts at 20 mA)       3   Data 1   Optically isolated data out       4   Data 0   Optically isolated data out       5   LED   High = Red, low = Green,               unconnected = Yellow       6   External Common   Isolator and LED power and data               signal common       7   Power Common   Unit power and internal +5 Volt               common       8   Unit Power   Requires from +8 to +28 Volts at               up to 2.5 Watts                  
 
         [0035]    [0035]FIG. 4 illustrates a packaging configuration  150  for the electrical components of the access reader  100  of FIG. 3. The packaged access reader  150  of a preferred embodiment of the invention utilizes the same area footprint as a single-gang wall plate having a width, W, of 2.75 inches (6.98 cm) and a length, L, of 4.5 inches (11.43 cm). The packaged access reader  150  is mounted onto a surface using two mounting holes  158  that match the holes in a single-gang electrical utility box. Another embodiment of the packaged access reader  150  replaces or fits inside the electrical utility box. The packaged access reader  150  of the preferred embodiment has a depth, D, of 1.5 inches (3.81 cm), be configured for any necessary thickness. The packaged access reader  150  has a faceplate area  154  which provides a target for the presentation of an access card. At least one LED  152  on the faceplate  154  illuminates to red to signal an invalid card or a read error. A valid card and a successful identification of the access card holder is indicated by the LED  152  illuminating to green. The LED  152  provides the access card holder with an indication that the access reader  100  is operational. In other embodiments, the packaging configuration be of any form factor desired by a customer.  
         [0036]    [0036]FIG. 6 illustrates a biometric configuration  300  of one embodiment of the invention. The access card reader  304  is installed adjacent a door and controls the door reader  308 . An access card holder presents his access card  306  to the access card reader  304 , which reads pre-stored access data from the access card  306 . In this configuration  300 , a camera  302  sends an image and/or image minutia of the access card holder to the access card reader  304 . The access card reader  304  compares the data from the camera  302  with the pre-stored access data on the access card  306  to verify identification of the access card holder. If the image data matches the pre-stored access data, then the identification of the access card holder may be guaranteed to a higher degree than existing control systems that verify one data component, only. This validation is a one to one comparison, and does not require communication with a data base of a central computer.  
         [0037]    To prevent security breaches, the access card reader  304  of the preferred embodiment performs additional verifications before or after the identification process. For example, the access card reader  304  must first establish communication with the access card  306  utilizing specific protocols. The communication protocols may also identify particular information about the access card  306 , such as the serial number of the access card  306 . If the access card  306  does not respond to the required communication protocols transmitted by the access reader  304 , then the access card  306  is not valid for that particular entrance way  308 . Once communication is established between the access card  306  and the access reader  304 , the access reader  304  can read data from the access card  306  only if it knows at least one application key and read key stored on the access card  306 . In an alternate embodiment, the access card reader  304  further compares the access card information, such as the serial number, with access card holder data, such as negative lists, that are downloaded to the access reader  304  at regular intervals by means of the PC Device  212 , the central computer  210 , or an update card  62  as illustrated in FIG. 5. If any of the validation processes have a negative result, the access card reader  304  denies access to the secured area.  
         [0038]    In an alternate embodiment of the invention, the access card reader  304  may also write an invalidation code to the access card  306  providing the access card reader  304  has a correct write key. The invalidation code on the smart card may be recognized by all or specific access readers. Access readers that recognize the invalidation code may then deny access to corresponding secured areas until the access card  306  is re-validated by security personnel.  
         [0039]    For additional security, it is possible to require the access card holder to present the access card  306  before exiting the same, or another, entrance. Because the identification of the access card holder and the validity of the access card  306  is determined by the access card reader  304  immediately upon presentation of the access card  306 , the access card holder may gain entrance into a secured area using an access card  306  that is invalid. However, a further validation may be performed for access card readers  202  that are connected to a central computer  210 , as shown in FIG. 5. The transaction log data, including, for example, the access card serial number and time of entrance is uploaded to the central computer  210  or a memory device  232  at regular intervals and/or after a pre-determined number of identification verifications. The central computer performs a validity check of the transaction data for each access card  208  against data stored in the central computer. If the card is determined to be invalid, the central computer  210  then downloads updated information to the access readers  202  of the secured area to deny exit for the access card holder, and alerts security. The preferred embodiment of the access reader  202  also includes an additional security measure for notifying security personnel of an attempted removal of the access reader  202 . For example, upon the detection of a loss of power, the access reader  202  sends an identifying signal to the central computer  210 .  
         [0040]    [0040]FIG. 1 illustrates the initialization components  10  for the smart card access control system of a preferred embodiment. The components  10  include an access reader  14 , a standard production smart card  16 , and a personal computer device  12 . The access reader  14  includes a serial port for data communication  18  between the access reader  14  and the PC device  12 , e.g., a laptop or hand held computer device. In an alternate embodiment of the invention, a central computer, as shown in FIG. 5, that is hardwired to the access reader  14  may perform the installation and configuration processes of the PC device  12 . Continuing with FIG. 1, the PC device  12  together with the access reader  14  are utilized to create various card types  54  from standard production smart cards  16 . FIG. 2 illustrates the access reader states  52  and card types  54  of the preferred embodiment. The different card types  54  are used with the access reader  14  for activation, access, deactivation, and update purposes.  
         [0041]    Continuing with FIG. 2, the access reader  14  has two operational reader states  52  which are the deactivated operational state and the activated operational state. Upon power-up, the access reader  14  of the preferred embodiment indicates its operational state by, for example, beeping three times to indicate that it is in the deactivated operational state. In the deactivated operational state, the access reader  14  waits for an activation card  56  to lock it into the activated state. When a valid activation card  56  is presented to the access reader  14 , the access reader  14  is locked into the activated operational state using the application type number, the read key, and output format specified by the activation card  56 . If a production smart card  16  is presented to the access reader  14  while the reader is in the deactivated operational state  52 , and the smart card is not a valid activation card  56 , the access reader  14  will signal an error condition, e.g., two beeps.  
         [0042]    The activated operational state of the access reader  14  utilizes customer specific application type keys which are pre-loaded into the access reader  14 . Upon power-up, the access reader  14  of the preferred embodiment indicates that it is in an activated operational state by, for example, beeping once for a duration of one second. Table 2 lists the actions that an access reader  14  of the preferred embodiment takes upon presentation/detection of an access card  16 . In the activated operational state, the access reader  14  only reads access cards  58  that are encoded by a customer with an appropriate read key in order to prevent unauthorized cards from communicating data to the access reader  14  In the preferred embodiment, the read key of the access card  58  is encrypted to produce a hash key. The access reader  14  reads the hash key and uses the encryption code to determine whether the read key of the access card  58  is valid. The use of the read/hash key provides an authenticated security which is not found in current access systems. Other systems which provide un-authenticated Wiegand identification numbers can easily be replicated via playback attack.  
         [0043]    As shown in Table 2, if the read key is invalid, the access reader  14  beeps twice to indicate the invalidity of the access card  58  and no data is output to control access to the secured area. In the preferred embodiment, the serial card number or any other identifying data of the invalid access card  58 , if available, is stored in a log file in the access reader for subsequent uploading to a PC device  212 , a central computer  212 , or contactless memory device  232 . The information them may be utilized to perform actions such as alerting security or placing the access card  212  on a negative list. If the read key stored in the access reader  14  is correct, the access reader  14  can attempt to read data from the access card  58 . If data is not available, the access reader  14  signals access card  58  invalidity by beeping twice. If data is available, the access reader  14  performs a cyclic redundancy check (CRC) on the data to determine whether parity is correct. If all three conditions are met, then the access card  58  is valid and the access reader  14  outputs formatted data to perform actions to allow the access card holder to gain access to the secured area. Security may be increased by maintaining the secrecy of the hash key and/or the CRC.  
                                                               TABLE 2                           Access Reader Actions for an Activated State                Correct   Data   Valid   Access Reader Action                Read Key   Read   CRC   Beeps   Output               1   N   N   N   2   none       2   Y   N   N   2   none       3   Y   Y   N   2   none       4   Y   Y   Y   1   Formatted Data       5   Other   Reader   Errors   2   none                  
 
         [0044]    Referring to FIGS. 2 and 5, the access cards  58  of the preferred embodiment are standard production contactless smart cards formatted for use with the access control system  200 . If desired, these cards  58  can be securely shared among multiple systems, such as transit system fare-card applications, building physical access control applications,equipment access applications and loyalty applications. The memory in a standard production smart card  208  is divided into blocks. Each block  400 , as shown in FIG. 8, contains multiple pages of read/write memory for storage of application data  408 , and an associated page for storing a read key  404  and a write key  406 . Each block  400  is assigned an application type number (ATN)  402 , e.g., transit or access control.  
         [0045]    For example, in a standard memory smart card, there are a number of available memory blocks  400 . A set of one or more blocks  400  of memory on a smart card  208  used for an application is referred to as a customer memory area (CMA). Each customer memory area can use up to the total number of blocks available on the smart card  208 . For access control applications, the customer memory area can vary from 16 bytes for simple identification to up to 32 Kbytes for intensive biometric identification since access reader  202  uses only one application type number  402 . and read key  404  from cards that it has been programmed to use. Since each customer memory area uses customer specified read and write cryptographic keys  404 ,  406  to secure the card, each customer memory area is both secure and inaccessible to anyone, i.e., an access card reader, that does not have the correct cryptographic keys  404 ,  406 .  
         [0046]    Adding access control capabilities to an existing smart card requires at least one application block  400  to be unused and available in the smart card memory. This allows multiple applications, such as transit for subway and buses, loyalty, payment systems, identity, and/or additional physical access control applications, to be loaded seamlessly and securely onto the same contactless smart card. FIG. 7 illustrates example applications of the access control system  200 . Each application may be connected  382  to a central computer  380 . A first application for physical access control is illustrated as a door  370  controlled by an access reader  372  having a keypad ID device  374 . An employee presents his or her access card  58  to the access reader  372  and enters a code on the keypad  374 . The code is verified with identification data  408  stored on the smart card to determine the validity of the smart card. In an alternate embodiment of the invention, other identification devices may be used in place of, or in addition to, the key pad  374 . For example, in an alternate embodiment of the invention, the access reader  372 ,  352 ,  360  may require more than one identification device. In such an embodiment, the smart card application data  408  contains the identification data for comparison with the data received from each identification device. The access control system may also be used to control access to equipment such as personal computers  350 . For example, an access reader  352  having an RF interface  354  for reading a smart card, and a fingerprint pad  356  for identifying the access card holder, may be used with security software installed on the personal computer  350  to limit access to the computer  350 . The smart card may also contain an application type number  402  that is utilized by access readers  360  at transit gates  358 .  
         [0047]    A method for smart card access control  400  is illustrated in FIG. 9, with reference to system components of FIG. 5. In a first step  452 , the access reader  202  establishes communication with a smart card  208  configured as an access card. If communication is established successfully, then the smart card  208  has responded to a communication protocol used by the access reader  202 . In step  454 , the access reader  202  reads and stores access card application data from the access card. The access reader determines whether the access card is valid in step  456 . If the access card is invalid, step  458 , for example, parity is incorrect or the read keys used by the access reader  202  are invalid, access to the secured area is denied, step  464 .  
         [0048]    The preferred embodiment of the invention provides the optional steps of recording the access card data in a log file, step  460 , and writing an invalid flag to the access card, step  462 , providing the access reader  202  knows a required write key for the access card  208 . In step  466 , the access reader  202  receives identification data from an ID device  204 , and compares the application data with the identification data, step  468 . A data match in step  470  results in the access reader  202  outputting a signal  222  to a secured device  206  to allow an access card holder access to a secured area. In optional steps  472  and  474 , the access reader  202  stores the transaction data to a log file and updates a status on the access card  208 .  
         [0049]    Although a preferred embodiment of the invention has been described above by way of example only, it will be understood by those skilled in the field that modifications may be made to the disclosed embodiment without departing from the scope of the invention, which is defined by the appended claims.