Patent Publication Number: US-11023875-B2

Title: Electronic credential management system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a divisional of U.S. patent application Ser. No. 14/728,701 filed on Jun. 2, 2015 and issued as U.S. Pat. No. 10,257,706, which claims the benefit of U.S. Provisional Patent Application No. 62/006,836 filed on Jun. 2, 2014, the contents of each application hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     Embodiments of the present application generally relate to electronic credential management for lock systems. More specifically, embodiments of the present invention relate to the secure distribution and management of electronic credentials. 
     Credentials used to manage the operation of lock systems are often physical in nature such as, for example, being at least part of a card, fob, token, or mobile device to be read at a lock device. Thus, current credential systems typically require that the interaction between the credential and the lock device occur at, or at least near, the lock device. For example, when interaction between the credential and lock device is needed, a user may need to swipe a credential containing card through, or present the credential near, a card reader associated with the lock device. 
     Similarly, when a new credential is being added to a lock system, the credential typically needs to be received by, and/or otherwise be in the possession of, a user. The user may then need to manually add the credential to the system such as, for example, by presenting the physical form of the credential at the actual location of each lock device in the lock system that is to be associated with the credential. With the physical credential presented at the location of the lock device(s), the credential may be manually added to an access control portion of the lock device. 
     BRIEF SUMMARY 
     An aspect of the present invention is directed to a method for credential management that includes inputting a master key and a mobile device identifier into a diversification algorithm to generate a diversification key, the mobile device identifier including information that identifies a mobile device. Further, a control system payload is encrypted using the diversification key, the control system payload including at least one or more unique credential identifiers. An access control system may communicate the encrypted control system payload to the mobile device. Additionally, a lock device receives the encrypted control system payload from the mobile device and may retrieve the master key from a memory of the lock device. The lock device may also decrypt the encrypted control system payload using the retrieved master key and the mobile device identifier. 
     Another aspect of the present invention is directed to a method for managing a system that includes receiving, by an access control system, a mobile device identifier from a mobile device. The mobile device identifier and a master key are applied to a diversification algorithm to generate a diversification key, with the diversification key being used to encrypt a mobile device payload that includes one or more credential identifiers. Additionally, the one or more credential identifiers may include information regarding a permission level of the mobile device. The access control system may communicate the encrypted mobile device payload to the mobile device. Further, a look device may receive the encrypted mobile device payload from the mobile device. The lock device may also decrypt the encrypted mobile device payload and extract the one or more credential identifiers from the decrypted encrypted mobile device payload. Additionally, the lock device may identify the permission level of the mobile device using the extracted one or more credential identifiers and determine, using the identified permission level, whether the mobile device has authority to complete an action. 
     Additionally, an aspect of the present invention is directed to a method for revocation of one or more credential identifiers stored on a mobile device. The method includes communicating, by the access control system, a first credential identifier for storage on the mobile device. An encrypted revocation request payload may also be received by a lock device, the encrypted revocation request payload including a second credential identifier that is related to the first credential identifier. The lock device may decrypt the encrypted revocation request payload and extract the second credential identifier from the decrypted encrypted revocation request payload. The lock device may also identify the second credential identifier as being a revoked identifier. Additionally, the lock device may receive a communication from the mobile device that includes the first credential identifier. The lock device may further identify whether the received first credential identifier is related to the revoked identifier. 
     A further aspect of the present invention is directed to a method for revocation of credential identifiers stored on a mobile device, the method including communicating, by an access control system, a credential identifier for storage on the mobile device and communicating, by the access control system, a revocation request to the mobile device. The revocation request may request that the stored credential identifier be removed from the mobile device. The method may further include the access control system receiving a notification that the stored credential identifier has been removed from the mobile device. 
     Another aspect of the present invention is directed to a method for removing an administrative mobile device from an enrolled lock device that includes notifying an access control system that a first administrative mobile device is being removed from the access control system. Additionally, a replacement administrative mobile device may be enrolled with the access control system, and a field device reset may be performed on the enrolled lock device of the of a credential management system. An encrypted lock device payload may be received by the access control system, the encrypted lock device payload including a replacement field device reset identifier. The access control system may extract from the encrypted lock device payload the replacement field device reset identifier, and communicate the extracted replacement field device reset identifier to one or more user mobile devices that are to be used with the enrolled lock device. 
     Other aspects of the present invention will become apparent by consideration of the detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a schematic diagram of an exemplary system that includes one or more mobile devices, one or more lock devices, and an access control system according to an illustrated embodiment of the present invention. 
         FIG. 2A  illustrates a flow diagram of an exemplary process for enrolling an administrative mobile device and lock device with the access control system according to an illustrated embodiment of the present invention. 
         FIG. 2B  illustrates a schematic representation for generating a diversification key using the diversification algorithm, a master key, and an identifier of an administrative mobile device, user mobile device, and/or lock device. 
         FIG. 3  illustrates a flow diagram of an exemplary process for creating and distributing credential identifiers to user mobile devices according to an illustrated embodiment of the present invention. 
         FIG. 4  illustrates a flow diagram of an exemplary process for manually revoking a credential identifier(s) for user mobile devices according to an illustrated embodiment of the present invention. 
         FIG. 5  illustrates a flow diagram of an exemplary process for automatically revoking a credential identifier(s) for user mobile devices according to an illustrated embodiment of the present invention. 
         FIG. 6  illustrates a flow diagram of an exemplary process for removing an administrative mobile device from an enrolled lock device according to an illustrated embodiment of the present invention. 
     
    
    
     The foregoing summary, as well as the following detailed description of certain embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings, certain embodiments. It should be understood, however, that the present invention is not limited to the arrangements and instrumentalities shown in the attached drawings. 
     DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
       FIG. 1  illustrates a schematic diagram of an exemplary system  100  that includes one or more mobile devices  102 , one or more lock devices  104 , and an access control system  106  according to an illustrated embodiment of the present invention. A variety of mobile devices  102  may be utilized, including, for example, a mobile telephone smartphone, tablet, personal computing device, and/or a proprietary hand-held device, among other devices. According to the illustrated embodiment, the mobile device  102  may have one or more transceivers  108  for communicating data with other devices, including the lock device  104  and the access control system  106 . Additionally, a variety of different types of transceivers  108  may be used, including, for example, active and passive transceivers that may communicate via Bluetooth (including Bluetooth low energy) and/or WiFi. The mobile device  102  may also include an input/output device  110  such as, for example, a keypad, display, and/or touch screen among other input/output devices. Additionally, the mobile device  112  may include may include one or more different processing devices  112  such as, for example, programmable, dedicated, and/or hardwired state machine types of processors, as well as any combination thereof. For example, according to certain embodiments, the processing device  112  may include multiple processors and may be of a programmable variety that executes algorithms and processes data in accordance with an operating logic  114  as defined by programming instructions (such as software or firmware) stored in a memory  116 . 
     As discussed in further detail below, in the illustrated embodiment, an administrative mobile device  102   a  may be granted authority or a permission level in connection with administrative tasks relating to managing and/or configuring the lock devices  104  of the system  100 , while user mobile devices  102   b  may be configured for general use of the lock devices  104  such as, for example, at least day-to-day routine operation or use of the lock devices  104 . 
     The lock device  104  may be a lock, reader device, a payment terminal, and/or any other type of device that can communicate with the mobile device  102 . For example, in the embodiment shown in  FIG. 1 , the lock device  104  is an electronic lock device having one or more transceivers  118 , a processing device  120 , a memory  122 , a reader  124 , and a lock mechanism  126  such as, for example, a bolt and/or latch. The memory  122  may or may not be part of the processing device  120 . The mobile device  102  and the lock device  104  may be adapted to communicate with each other using one or more of a variety of different wireless communication technologies. For example, according to certain embodiments, the lock device  104  may have a transceiver  118  that allows for Bluetooth low energy communication between the mobile device  102  and the lock device  104 . Further, according to certain embodiments, the mobile device  102  and the lock device  104  may communication via NFC and/or WiFi (such as WiFi Direct). 
     A variety of different types of processing devices may be employed for the processing device  120  of the lock device  104  such as, for example, a programmable, dedicated, and/or hardwired state machine, or any combination thereof. The processing device  120  may further include multiple processors such as, for example, Arithmetic-Logic Units (ALUs), Central Processing Units (CPUs), Digital Signal Processors (DSPs), or the like. Processing devices  120  with multiple processing units may also utilize distributed, pipelined, and/or parallel processing. The processing device  120  may also be dedicated to the performance of just the operations described herein, or may be utilized in one or more additional applications. In the depicted form, the processing device  120  is of a programmable variety that executes algorithms and processes data in accordance with operating logic  128  as defined by programming instructions (such as software or firmware) stored in the memory  122  of the lock device  104 . Alternatively or additionally, the operating logic  128  is at least partially defined by hardwired logic or other hardware. The processing device  120  may include one or more components of any type suitable to process the signals received from an input/output device  130  of the lock device  104  such as, for example, the keypad, reader  124 , or elsewhere, and to provide desired output signals. Such components may include digital circuitry, analog circuitry, or a combination of both. 
     The memory  122  of the lock device  104  may be included with the processing device  120  and/or coupled to the processing device  120 . Further, the memory  122  may be of one or more types, such as a solid-state variety, electromagnetic variety, optical variety, or a combination of these forms. Additionally, the memory  122  can be volatile, nonvolatile, or a combination of these types, and some or all of the memory  122  can be of a portable variety, such as a disk, tape, memory stick, cartridge, or the like. In addition, according to certain embodiments, the memory  122  can store data that is manipulated by the operating logic  128  of processing device  120 , such as data representative of signals received from and/or sent to the input/output device  130  in addition to, or in lieu of, storing programming instructions defining the operating logic  128 . 
     The access control system  106  may include one or more servers  132  such as, for example, a cloud based server and/or a web based server, that may communicate with the mobile device  102  and/or the lock device  104  in a variety of different manners including, for example, over the Internet, a cellular data network, or any combination, thereof. Further, according to certain embodiments, different servers  132  may be used for different purposes such as, for example, a cloud-based server  132   a  for installation, maintenance, and/or management of, or relating to, the access control system  106 , lock device  104 , and/or the mobile device  102 , and another, different server  132   b  such as, for example, a web-based server, for other purposes such as, for example, general day-to-day usage and/or operation of the lock device  104 . The access control system  106  may also include one or more databases  134  or other record systems. A variety of different types and combination of types databases  134  may be utilized. For example, the one or more servers  132  may include databases  134   a  and/or be in operable communication with auxiliary databases such as, for example, auxiliary databases  134   b  for a manufacturer, producer, and/or assembler of the lock device  104 . 
       FIG. 2  illustrates a flow diagram of an exemplary process  200  for enrolling an administrative mobile device  102   a  and lock device  104  with the access control system  106  according to an illustrated embodiment of the present invention. At step  202 , the administrative mobile device  102   a  connects to the access control system  106  such as, for example, by connecting to a server  132  so that communications may be transmitted between, and received by, the administrative mobile device  102   a  and the access control system  106 . At step  204 , the user may enroll in, or otherwise access, a registered user account with the access control system  106 . For example, the user of the mobile administrative mobile device  102   a  may enter various different types of information into the access control system  106  including, for example, information relating to the user or an associated institution, the administrative mobile device  102   a , and/or the lock device(s)  104  associated with the user/institution, among other information. The control access system  106  may then enroll the user and/or the administrative mobile device  102   a  that is associated with the registered user account. At step  206 , the access control system  106  will communicate a control system payload to the administrative mobile device  102   a . The control system payload may contain a variety of different types of information such as, for example, one or more unique credential identifiers, access permissions, and/or a configuration permission. Additionally, the access control system  106  may encrypt the control system payload using an administrative diversification key. As shown by  FIG. 2B , according to certain embodiments, the administrative diversification key may be generated by applying at least a master key which may be known by the access control system  106  and the lock device  104 , but not the administrative mobile device  102   a , and an administrative mobile device identifier such as, for example, a serial number, production code, product number, and/or universal unique identifier (UUID) of the administrative mobile device, among other identifiers, to a diversification algorithm. Further, as discussed below, diversification keys for other components of the system  100  may also be generated in a similar manner such as, for example, supplying the master key and an identifier associated with the particular component such as, for example, a mobile device  102  or lock device  104 , to the diversification algorithm to generate the associated diversification key. At step  208 , the administrative mobile device  102   a  receives the communicated control system payload. 
     With the administrative mobile device  102   a  enrolled with the access control system  106 , the administrative mobile device  102   a  may be presented to the lock device  104 . Therefore, at step  210 , the lock device  104  may be put into an enrollment mode such as, for example, via receipt of a communication by the processing device  120  the lock device  104  such as, for example, a communication made via entry of code into a keypad of the input/output device  130 , recognition of data by card reader of the lock device  104 , an enrollment credential, or communication from the administrative mobile device  102   a  to the transceiver  118  of the lock device  104 . It is contemplated that a variety of operations may occur in connection with the lock device  104  being put into the enrollment mode such as, for example, the lock device  104  authenticating information received by the lock device  104  before the lock device  104  may enter into the enrollment mode. At step  212 , with the lock device  104  in the enrollment mode, and a connection between the lock device  104  and the administrative mobile device  102   a  is established, the administrative mobile device  102   a  may be used in the communication of the encrypted control system payload from the administrative mobile device  102   a  to the lock device  104 . 
     At step  214 , using the master key contained in the memory  122  and/or an administrative mobile device identifier, the lock device  104  will attempt to decrypt the received control system payload. If the lock device  104  is unable to decrypt the control system payload, then at step  216 , the connection between the lock device  104  and the administrative mobile device  102   a  is terminated. However, if the lock device  104  is able to decrypt the control system payload, then at step  218 , the lock device  104  transmits a lock device payload to the administrative mobile device  102   a . The lock device payload may include a variety of information such as, for example, a field device reset identifier and one or more lock device identifiers such as, for example, a lock device UUID, serial number, and or a production code, among other types of identifiers. Additionally, the lock device payload may also be encrypted using the administrative diversification key. At step  220 , the administrative mobile device  102   a  receives the communicated encrypted lock device payload from the lock device  104 . According to certain embodiments, the administrative mobile device  102   a  may then have control of the lock device  104  via the access and configuration permissions provided by the access control system  106 . 
     At step  222 , the administrative mobile device  102   a  may communicate the lock device payload information to the access control system  100 . At step  224 , alto access system  106  may register, or otherwise record or store information received from the communicated lock device payload. Such registering may associate the received information from the lock device payload with the associated register user account and/or the look device  104 . For example, according to certain embodiments, the access control system  100  may register information from the lock device payload such as for example, the one or more lock device identifier such as, for example, a field device reset identifier, in a database  134 . Additionally, the registering of the information may include recording the information in one or more databases  134   a ,  134   b , or operably accessible to the server(s)  132  of the access control system  106 . 
     By using the diversification algorithm in the manner described herein to generate, and use diversification keys, information encrypted within the payloads that are communicated between the lock device  104  and the access control system  106  may not be accessible to the mobile devices  102 . Additionally, the inclusion of the identifiers relating to at least the mobile devices  102  in generating diversification keys may preclude and/or decrease the likelihood of success of the security of the system  100  being compromised by a playback attack. 
       FIG. 3  illustrates a flow diagram of an exemplary process  300  for creating and distributing, credential identifiers to user mobile devices  102   b  according to an illustrated embodiment of the present invention. Credential identifiers for user mobile devices  102   b  may be generated in a variety of manners including, for example, through use of an application  136  on the administrative mobile device  102   a , or by accessing the access control system  106  via a web portal. For example, an application  136  that may be installed on the administrative mobile device  102   a  may process, receive and/or store data relating to/from the access control system  106 , the administrative mobile device  102   a , user mobile devices  102   b , and/or the lock device  104 . For example, according to certain embodiments, the application  128  may be used in connection with communicating information such as, for example, encrypted security and/or authentication information or data, via the administrative mobile device  102   a  to/from the access control system  106  and the lock device  104 . Further, as discussed above, the application  136 , and thus the administrative mobile device  102   a , may not be configured to decrypt at least information that is passed along through the administrative mobile device  102   a  that is encrypted with a diversification key. Further, credential identifiers for mobile devices  104   b , as well as for administrative mobile devices  104   a , may be stored on the mobile devices  104   a ,  104   b  such as, for example, being stored by the application  136 . 
     According to the illustrated embodiment, at step  302 , the application  136  or a web portal may be used to establish an operable connection with the access control system  106 . At step  304 , using the connection, information pertaining to establishing new credential identifiers for a user of the system  100  may be communicated to the access control system  106 . A variety of different types of information may be provided and/or selected for the new credential identifiers including, for example, a selection of the permission level or authorization that is to be given for the new credential. A variety of different permission levels may be offered for selection such as, for example, simple access, one-time access, the ability to request other new credential identifiers, and/or the ability to configure a lock device(s)  104 , among other permissions. Additionally, the access control system  106  may be provided with identification information relating to the user mobile device  102   b  and/or the associated user such as, for example, contact information such as a phone number or email address associated with the user and/or user mobile device  102   b , among other information. 
     At step  306 , an invitation to join the system  100  from the access control system  106  and/or the administrative mobile device  102   a  may be communicated to the user mobile device  102   b . According to certain embodiments, the invitation may be communicated to a phone number or email address associated with the user and/or the user mobile device  102   b . The invitation may include a variety of information including, for example, an invitation to download an application  136  onto the user mobile device  102   b  and/or to register with the access control system  106 , lf the user elects to join the system  100 , then at step  308 , the application  136  may be downloaded to the user mobile, device  102   b , and the user may enroll in the access control system  106 . At step  310 , the access control system  106  may receive a user mobile device identifier such as, for example, as serial number, production code, product number, and/or universal unique identifier (UUID) for the user mobile device  102   b , among other identifiers, According to certain embodiments, the user mobile device identifier may be communicated to the access control system  106  during the enrollment process at step  308 . 
     At step  312 , the access control system  106  may encrypt a user mobile device payload. For example, according to certain embodiments, the access control system  106  may encrypt the user mobile device payload using the master key and a user mobile device identifier. Moreover, according to certain embodiments, the access control system  106  may encrypt the user mobile device payload using the master key, a user mobile device identifier, and the diversification algorithm to generate the user diversification key. The encrypted user mobile device payload may include a variety of information including, for example, one or more user mobile device identifiers and other information needed for the user mobile device  102   b  to work with the lock device  104  including, for example, information indicating the permission level assigned to the user mobile device  102   b , credential identifiers, a lock identifier, and/or a field device reset identifier, among other information. Further, according to illustrated embodiments, the encrypted user mobile device payload may be stored on the user mobile device  104   b , thereby allowing for the associated credential identifiers to be stored in the user mobile device  104   b.    
     At step  314 , the user mobile device  102   b  may establish a connection with the lock device  104 , With the connection established, at step  316  the user mobile device  102   a  can communicate the user mobile device payload to the lock device  104 . 
     At step  318 , using the master key contained in the memory  122  and/or one or more mobile device identifier(s), the lock device  104  will attempt to decrypt the received user mobile device payload such as, for example, decrypting the user mobile device payload that had been encrypted using the user diversification key. If the lock device  104  is unable to decrypt the user mobile device payload, then at step  320  the lock device  104  may deny the user mobile device  102   b  access to the lock device.  104  and nor the connection between the lock device  104  and the user mobile device  102   b  is terminated. However, if the lock device  104  is able to decrypt the user mobile device payload then, according to certain embodiments, the user mobile device  102   b  is authorized to communicate with the lock device  104 . 
     If the lock device  104  was able to decrypt the user mobile device payload, then at step  322  the lock device  104  may compare information that was encrypted in the user mobile device payload with information stored in or otherwise accessible to the lock device  104 , including information or data stored in the memory  122  of the lock device  104 . For example, the lock device  104  may compare one or more lock device identifiers that had been encrypted in the user mobile device payload with similar types of lock device identifiers that are stored in the memory  122  of the lock device  104 . If the comparison indicates that the lock device identifiers from the decrypted user mobile device payload are not the same, similar, and/or related to lock device identifiers that are stored in the memory  122  of the lock device  104 , then at step  324  the lock device  104  may terminate communication with the user mobile device  102   b  and/or deny the user mobile device  102   b  access to the lock device  104 . 
     If the lock device identifiers in the decrypted user mobile device payload are the same, similar, and/or related to lock device identifiers that are stored in the memory  122  of the lock device  104 , then at step  320  the lock device  104  may compare other information from the decrypted user mobile device payload with information stored in, or otherwise accessible to, the lock device  104  such as, for example, the field device reset identifier from the user mobile device payload with the field device reset identifier stored by the lock device  104 . In such an example, if the compared field device reset identifiers are not the same, similar, and/or related, then at step  328  the lock device  104  may terminate communication with the user mobile device  102   b  and/or deny the user mobile device  102   b  access to the lock device  104 . Further, such comparisons between field device reset identifiers may provide a level of security in the event the administrative mobile device  102   a  is lost or changed, since performing a field device reset will change the field device reset identifier on the lock device  104 . 
     If, however, the comparison(s) performed at step  322  indicates that the compared information or data is the same, similar, and/or related, then at step  330  the lock device  104  may evaluate the permission level of the user mobile device  102   b  that was contained in the encrypted user mobile device payload and validate that the user mobile device  102   b  has the permission or authority to complete the action that the user mobile device  102   b  is attempting to complete. If the user mobile device  102   b  does not have permission or authority to complete the action, then at step  332  the lock device  104  may terminate communications With the user mobile device  102   b  and/or deny the user mobile device  102   b  access to the lock device  104 . If, however, the lock device  104  determines that the user mobile device  102   b  authorized to complete the action, then at step  334  communication between the lock device  104  and the user mobile device  102   b  may continue as needed to complete the authorized action. 
       FIG. 4  illustrates a flow diagram of an exemplary process  400  for manually revoking a credential identifier(s) for user mobile devices  102   b  according to an illustrated embodiment of the present invention. At step  402 , the administrative mobile device  102   a  may make a determination, or otherwise be instructed, that the user mobile device  102   b  is to no longer be allowed access to the lock device  104 . At step  404 , a request for revocation of the current credential identifier of the user mobile device  102   b  generated. The request for revocation may be generated in a number of different ways. For example, according to embodiments, the request may be generated through use of the application on the administrative mobile device  102   a , or via a web portal connection the access control system  106 . 
     At step  406 , a command for revocation of the credential identifier of the user mobile  102   b  is communicated to the user mobile device  102   b . According to certain embodiments, revocation command may be generated and communicated to the user mobile device  102   b  by the access control system  106 , the administrative mobile device  102   a , or a combination thereof. According to certain embodiments, the revocation command may be sent to an email address(es) or telephone number(s) associated with the user mobile device  102   b.    
     At step  408 , the access control system  106  may a communicate a revocation response pal load to the administrative mobile device  102   a . According to certain embodiments, the access control system  106  may send the revocation response payload to the administrative mobile device  102   a  regardless of whether the response has been received from the user mobile device  102   b . The revocation response payload may contain a variety of information such as, for example, the credential identifier that is to be revoked along with information necessary for communication with the lock device  104 , among other information. Additionally, the revocation response payload may be encrypted such as, for example, through use of the administrative diversification key, which may be generated by supplying the master key from the access control system  106  and one or more of the administrative mobile device identifiers to the diversification algorithm. 
     At step  410 , the administrative mobile device  102   a  may communicate the revocation response payload to the lock device  104 . According to certain embodiments, the revocation response payload may be communicated to the lock device  104  upon the establishment of the next, subsequent communication between the administrative mobile find the lock device  104 . At step  412 , the lock device  104  may decrypt the revocation response payload such as, for example, in a manner similar to those previously discussed. At step  414 , upon determining that the revoked credential identifier is intended to be associated at least in-part, with the lock device  104  that received the revocation response payload, that lock device  104  will identity the credential identifier as being revoked. For example, according certain embodiments, the lock device  104  may assign the revoked credential identifier to a record or list of revoked credential identifiers, or otherwise or assign the credential identifier a revoked status. 
     At step  416 , when a user mobile device  102   b  subsequently attempts to access the lock device  104  using, at least in part, the revoked credential identifier, and the lock device  104  decrypts the payload and determines that the credential identifier is for that particular lock device  104 , the lock device  104  will check as to whether the credential identifier for that user mobile device  102   b  has been listed, designated and/or recorded by the lock device  104  as having a revoked status. For example, according to certain embodiments, the lock device  104  may access a listing of revoked credential identifiers that are stored by the lock device  104  such as, for example, in the memory  122  of the lock device  104 , and determine whether the credential identifier being presented is on a record or list of revoked credential identifiers. If the lock device  104  recognizes that the credential identifier being presented is a revoked credential identifier, then at step  418  the lock device  104  will deny the mobile device  102  access to the device  104 . Additionally, at step  420  the lock device  104  may transmit a command to the application  136  on the user mobile device  1020  to remove the credential identifier. At step  422 , the application  136  may proceed with removing the credential identifier from user mobile device  102   b . The application  136  on the user mobile device  102   b  may also generate a notification that the user mobile device  102   b  transmits to notify the access control system  106  and/or the application  136  on the administrative mobile device  102   a  that the credential identifier has been removed from the user mobile device  102   b.    
       FIG. 5  illustrates a flow diagram of an exemplary process  500  for automatically revoking a credential identifier(s) for user mobile devices  102   b  according to an illustrated embodiment of the present invention. At step  502 , the administrative mobile device  102   a  may make a determination, or otherwise be instructed, that the user mobile device  102   b  is to no longer be allowed access to the lock device  104 . At step  504 , a request for revocation of the current credential identifier for the user mobile device  102   b  is generated. The request for revocation may be generated in a number of different ways. For example, according to certain embodiments, the request may be generated through use of the application on the administrative mobile device  102   a , or via a web portal connection to the access control system  106 . 
     At step  506 , command for revocation of the credential identifier of the user mobile device  102   b  is communicated to the user mobile device  102   b . According to certain embodiments, the revocation command may be generated and communicated to the user mobile device  102   b  by the access control system  106 , the administrative mobile device  102   a , or a combination thereof. According to certain embodiments, the revocation command may be sent to an email address(es) or telephone number(s) associated with the user mobile  102   b.    
     At step  508 , upon receiving the revocation command, the application  136  on the user mobile device  102   b  may remove the credential identifier from the user mobile device  102   b . For example, according to certain embodiments, the application  136  on the user mobile device  102   b  may permanently remove the credential identifier from the user mobile device  102   b . At step  510 , the application  136  on the user mobile device  102   b  may then generate a communication that is provided to the access control system  106  and/or the administrative mobile device  102   a  that provides notification or verification that the credential identifier(s) has been removed from the user mobile device  102   b . Such a notification may be sent to the access control system  106  at various time periods including, for example, upon completion of the removal of the credential identifier from the user mobile device  102   b , and/or upon the occurrence of the first opportunity for the notification to be transmitted. For example, if the user mobile device  102   b  is powered-off before the notification is sent, then the notification may be transmitted when the user mobile device  102   b  is powered back on. 
     Upon removal of the credential identifier(s), if the user mobile device  102   b  attempts to communicate with the lock device  104 , the user mobile device  102   b  may be unable to communicate payload information that the lock device  104  will be expecting. Accordingly, the user mobile device  102   b  may either receive a denied response from the lock device  104 , or the connection will time out. 
     According to certain embodiments, the exemplary manual and automatic processes  400 ,  500  discussed above for revoking credential identifiers may be run in parallel or in series. For example, according to certain embodiments, the manual process  400  may be used if the automatic, process  500  is unable to result in the revocation of credential identifiers, or vice versa. According to other embodiments, both the manual and automatic processes  400 ,  500  may be used in parallel as a further attempt to prevent breaches in security. 
       FIG. 6  illustrates a flow diagram of an exemplary process  600  for removing an administrative mobile device  102   a  from an enrolled lock device  104  according to an illustrated embodiment of the present invention. According to certain embodiments, a field device reset may be performed on the lock device(s)  104 , which may in turn allow for a change as to which mobile device  102  is to be the administrative mobile device  102   a  that is enrolled with the lock device  104 . Further, the use of field device reset may allow for a changing of which mobile devices  102  are an administrative mobile device  102   a  without requiring the presence of the existing administrative mobile device  102   a , thereby allowing for such changes in the event that the current administrative mobile device  102   a  is lost or otherwise inoperable. Additionally, when a field device reset is performed, the field device reset identifier is modified in a known way, and any previously stored credential identifier(s) may be removed from the lock device  104 . 
     The field device reset and designation of another mobile device  102  as the administrative mobile device  102   c , as shown in  FIG. 1 , may be performed in a number of different ways. For example, according to the illustrated embodiment, at step  602  the access control system  106  may be notified that that an administrative mobile device  102   a  is being removed from the system  100  such as, for example, due to the administrative mobile device  102   a  being lost or inoperable. At step  604 , a field device reset may be performed such as, for example, at the lock device  104 , which may, then remove credential identifiers from the lock device  104  and modify the field device reset identifier. Accordingly, the lock device  104  may not be of via the user mobile device  102   b  as the new field device reset identifier of the lock device  104  may not match, or be similar to, a credential identifier(s) stored on the user mobile device  102   b . For at least similar reasons, in the event the lost or inoperable administrative mobile device  102   a  becomes usable, that administrative mobile device  102   a  may also be unable to be used with the lock device  104 . 
     At step  606 , the mobile device  102  that is to become the replacement administrative mobile device  102   c  is connected to and enrolled with the access control system  106 , and subsequently is associated with being an administrative mobile device  102   c . According to certain embodiments, the process for enrolling the replacement administrative mobile device  102   c  may be similar to exemplary process  200  discussed above with respect to  FIG. 2A . At step  608 , the replacement administrative mobile device  102   c  may be presented to the lock device  104 , and may communicate a replacement control system payload that has been encrypted by a replacement administrative mobile device diversification key that was generated using the master key, a replacement administrative mobile device identifier, and the diversification algorithm. 
     At step  610 , using the master key contained in the memory  122  and the replacement administrative mobile device identifier, the lock device  104  will attempt to decrypt the received replacement control system payload. It the lock device  104  is unable to decrypt the control system payload, then at step  612  the connection between the lock device  104  and the replacement administrative mobile device  102   c  is terminated. However, if the lock device  104  is able to decrypt the replacement control system payload, then at step  614  the lock device  104  communicates a lock device payload to the replacement administrative mobile device  102   c , which is subsequently received by replacement administrative mobile device  102   c . The lock device payload may again include a variety of information such as, for example, a replacement field device reset identifier and one or more lock device identifiers. Additionally, the lock device payload may also be encrypted using the replacement administrative diversification key. According to certain embodiments, the replacement administrative mobile device  102   c  may then have control of the lock device via the access and configuration permissions provided by the access control system  106 . 
     At step  616 , the replacement administrative mobile device  102   c  may communicate the encrypted lock device payload to the access control system  106 . According to certain embodiments, the access control system  106  may then acknowledge the update such as, for example, by communicating an update reply notification to the replacement administrative mobile device  102   c  and/or the lock device  104 . At step  618 , using the access control system  106 , the user associated with the registered user account may indicate or identify which distributed credential identifiers tire to be updated such as, for example, which user mobile devices  102   b  are to receive updated credential identifiers. At step  620 , the access control system  106  may then communicate updated credential identifiers, which may include the updated field device reset identifier, to user mobile devices  102   b  that are registered or otherwise enrolled for use with the lock device(s)  104  and/or the particular lock device  104 . 
     Various features and advantages of the present invention are set forth in the following claims. Additionally, changes and modifications to the described embodiments described herein will be apparent to those skilled in the art, and such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its intended advantages. While the present invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered illustrative and not restrictive in character, it being understood that only selected embodiments have been shown and described and that all changes, equivalents, and modifications that come within the scope of the inventions described herein or defined by the following claims are desired to be protected. Further, the steps illustrated herein are understood to be exemplary only, and steps may be combined or divided, and added or removed, as well as re-ordered in whole or in part. 
     While the invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.