NZ761966B2 - Leveraging flexible distributed tokens in an access control system - Google Patents

Abstract

method according to one embodiment includes determining whether a guest associated with a guest device is authorized to control an access control device based on an access control list, generating a caveated cryptographic bearer token in response to determining the guest is authorized to control the access control device, the caveated cryptographic bearer token including a time-based caveat defining a time limit for control of the access control device, transmitting the caveated cryptographic bearer token to the guest device in response to generating the caveated cryptographic bearer token, transmitting, in response to receiving the caveated cryptographic bearer token, a request including the caveated cryptographic bearer token to control the access control device to the access control device, and authenticating the request based on the received caveated cryptographic bearer token, a base cryptographic bearer token stored on the access control device, and a real-time clock of the access control device. he access control device, the caveated cryptographic bearer token including a time-based caveat defining a time limit for control of the access control device, transmitting the caveated cryptographic bearer token to the guest device in response to generating the caveated cryptographic bearer token, transmitting, in response to receiving the caveated cryptographic bearer token, a request including the caveated cryptographic bearer token to control the access control device to the access control device, and authenticating the request based on the received caveated cryptographic bearer token, a base cryptographic bearer token stored on the access control device, and a real-time clock of the access control device.

Description

W0 2019/018842 PCT/USZOIS/(HJZW LEVERAGING LE DISTRIBUTED TOKENS IN AN ACCESS CONTROL SYSTEM BACKGROUND Access control systems typically involve the use of tials to manage the operation of an access control device (e.g., a lock device). Such credentials may be assigned to a particular user or device and are often al in nature. forming at least a portion of, for example, a smartcard, proximity card, key fob, token , or mobile device. Additionally, an access control database that identifies which credentials (e.g., which user devices) are ted control over the access control device (e.g., lock/unlock ons) is typically stored on the access control device or a server in communication with the access control device. As such, an update to the access control database to change the credentials associated with the access control device, if even possible, often involves an update (or even a factory reset) of the access control device itself.

SUMMARY According to one aspect, a method includes determining, by a server, whether a guest associated with a guest device is authorized to control an access control device based on an access control list stored on the server; generating, by the server, a caveated graphic bearer token in response to a determination that the guest is authorized to control the access control device, wherein the caveated cryptographic bearer token includes a time-based caveat that defines a time limit for control ofthe access control device; transmitting, by the server, the caveated cryptographic bearer token to the guest device in se to generation of the caveated cryptographic bearer token; transmitting, by the guest device and in response to receipt of the caveated cryptographic bearer token from the , a request to control the access control device to the access control device, n the request es the caveated cryptographic bearer token; and authenticating, by the access control device, the request based on the received caveated cryptographic bearer token, a base cryptographic bearer token stored on the access l device, and a real-time clock of the access control device.

In some embodiments, the method may further include requesting, by the guest device, the caveated cryptographic bearer token from the server. Further, determining whether W0 18842 PCT/U32018/043277 the guest is authorized to control the access control device may include determining whether the guest is authorized to control the access control device in response to receipt of the request for the caveated cryptographic bearer token by the server. In some embodiments, authenticating the request may include determining whether the caveated cryptographic bearer token was derived from the base cryptographic bearer token, and comparing the time-based caveat to the real-time clock of the access control device to determine whether a current time is within the time limit.

In some embodiments, the caveated graphic bearer token may be or may include a macaroon. Further, in some embodiments, generating the caveated cryptographic bearer token may include generating the caveated cryptographic bearer token based on the base cryptographic bearer token. In some embodiments, the method may further include transmitting by the guest , a command to control a function of the access control device in response to successful authentication of the t by the access l device; and performing, by the access control device, the function based on the command.

In some ments, the access control list identifies one or more access control devices and guest access control permissions for each of the one or more access control s, and the access control list is modifiable by an owner device authenticated via a separate security domain. In sonre embodiments, the method may further include verifying, by the server, an fier of an owner associated with the owner device via the separate security domain; determining, by the server, a guest access control permission for one of the one or more access control devices to revoke; and updating, by the sewer, the access control list to revoke the guest access control sion. Further, revocation of the guest access control permission may prevent the server front subsequently issuing a caveated cryptographic bearer token to a corresponding guest device to control a corresponding access control .

In some embodiments, the method may further include verifying, by the , an identifier of an owner associated with the owner device via the separate security domain; transmitting, by the server and to a target guest device associated with a target guest, an invitation to control the access control device; verifying, by the , a guest identifier of the target guest via the separate security domain; and updating, by the server, the access control list to te that the target guest is authorized to have time-limited and pemrission-limited control the access control device in se to successful ation of the guest identifier.

W0 2019/018842 PCT/U52018/043277 In some embodiments, the method may further include registering an owner of the access control device with the server via the separate security domain; providing a programming code of the access control device to the owner ; transmitting the base cryptographic bearer token generated by the access control device from the owner device to the sewer; and updating the access l list to identify ownership of the access l device by the owner Further, the base cryptographic bearer token stored on the access l device may be the base cryptographic bearer token generated by the access control device and transmitted to the server.

In some embodiments, the mming code is identified on at least one of a component of the access control device or paperwork provided with the access control device upon purchase of the access control device, In some embodiments, the access control device is a lock device, the server is a cloud-based server, and the guest device is a mobile device. In some embodiments. the guest device is a user interface that permits a guest user to interact with the server and the access control device. ing to another aspect, an access control system may include a server, a guest device, and a lock device. Funher, the server may include a first processor and a first memory comprising a first plurality of instructions stored n that, in se to execution by the first processor, causes the server to determine whether a guest associated with a guest device is authorized to control a lock device based on an access control list stored on the server, generate a caveated cryptographic bearer token in response to a determination that the guest is authorized to control the lock device, wherein the caveated cryptographic bearer token includes a time~based caveat that defines a time limit for control of the lock device, and transmit the caveated cryptographic bearer token to the guest device in response to generation of the caveated cryptographic bearer token. The guest device may include a second processor and a second memory comprising a second ity of instructions stored thereon that, in response to execution by the second processor, causes the guest device to receive the caveated cryptographic. bearer token from the server and it a request to control the lock device to the lock device in response in response to receipt of the caveated cryptographic bearer token, wherein the request es the caveated cryptographic bearer token. The lock device may include a lock mechanism to control access to a passageway, a third processor, and a third memory comprising a third plurality of instructions stored n that, in response to execution by the third processor, causes the lock device to authenticate the request based on the received caveated W0 2019/018842 PCT/U52018/043277 cryptographic bearer token, a base cryptographic bearer token stored on the lock device, and a real—time clock of the lock device.

In some ments, to authenticate the request may include to determine whether the caveated cryptographic bearer token was derived from the base cryptographic bearer token and to compare the time-based caveat to the real-time clock of the lock device to determine whether a current time is within the time limit. r, in some embodiments, the caveated cryptographic bearer token may be or may include a macaroon, the access control list may identify one or more lock devices and guest access control permissions for each of the one or more lock devices, and the access control list may be modifiable by an owner device ticated via a separate security . In some embodiments, the caveated cryptographic bearer token is generated based on the base cryptographic bearer token. Further, in some embodiments, the second ity of instructions may further cause the guest device to transmit a command to unlock the lock mechanism of the lock device in response to successful authentication of the request by the lock device, and the third plurality of instructions may further cause the lock device to unlock the lock mechanism in response to the command.

According to yet another aspect, an access control system may include at least one processing device and at least one memory including a plurality of ctions stored thereon that, in response to execution by the at least one processing device, causes the access control system to request, by a guest device, a derived macaroon from a cloud system. wherein the derived macaroon includes a time-based caveat that restricts l of the access control device beyond a defined time; detennine, by the cloud , whether the guest is ized to control the access control device based on an access l list stored on the cloud system; generate, by the cloud system, the derived macaroon in response to a determination that the guest is authorized to control the access control device; it, by the cloud system, the derived macaroon to the guest device in response to generation of the derived macaroon; transmit, by the guest device and in se to receipt of the derived macaroon from the cloud system, a request to control the access control device to the access control device, wherein the request includes the derived macaroon; and authenticate, by the access control device, the request based on the received derived macaroon, a base macaroon stored on the access control , and a real-time clock of the access control device.

WO 18842 In some embodiments, to authenticate the request may include to ine r the derived on was derived from the base macaroon, and to compare the time- based caveat to the real-time clock of the access control device to determine whether a current time is within the time limit. In some embodiments, the derived macaroon may further include at least one of a permission-based caveat or a location-based caveat. In some embodiments, the cloud system may be configured to execute a ity of virtual functions. [0011a] In another aspect, there is provided a method, comprising: determining, by a server, whether a guest associated with a guest device is authorized to control an access control device based on an access control list stored on the server; deriving, by the , a caveated cryptographic bearer token from a base cryptographic bearer token in response to a determination that the guest is authorized to control the access control device, wherein the base cryptographic bearer token includes a base set of caveats and a first keyed cryptographic hash of the base set of caveats, wherein the caveated cryptographic bearer token es a guest set of caveats including a time-based caveat that defines a time limit for control of the access control device and a second keyed cryptographic hash based on the first keyed cryptographic hash and the guest set of caveats, and n the first keyed cryptographic hash is a key for the second keyed cryptographic hash; transmitting, by the server, the caveated graphic bearer token to the guest device in response to derivation of the caveated cryptographic bearer token; transmitting, by the guest device and in response to receipt of the caveated cryptographic bearer token from the server, a request to l the access control device to the access control device, wherein the request includes the caveated cryptographic bearer token; and authenticating, by the access control device, the request based on the received caveated cryptographic bearer token, the base cryptographic bearer token stored on the access l device, and a real-time clock of the access control device. [0011b] In another aspect there is provided, an access control system, comprising: a server ing a first processor and a first memory sing a first plurality of instructions stored thereon that, in response to execution by the first processor, causes the server to (i) determine whether a guest associated with a guest device is authorized to control a lock device based on an access l list stored on the server, (ii) derive a caveated cryptographic bearer token from a base graphic bearer token in response to a ination that the guest is authorized to control the lock device, wherein the base cryptographic bearer token includes a base set of caveats and a first keyed cryptographic hash of the base set of caveats, and wherein the caveated cryptographic bearer token includes a guest set of caveats including a time-based caveat that defines a time limit for l of the lock device and a second keyed cryptographic hash based on the first keyed cryptographic hash and the guest set of caveats, and wherein the first keyed graphic hash is a key for the second keyed graphic hash, and (iii) transmit the caveated cryptographic bearer token to the guest device in response to derivation of the caveated cryptographic bearer token; a guest device including a second processor and a second memory comprising a second plurality of instructions stored thereon that, in response to execution by the second processor, causes the guest device to (i) receive the caveated cryptographic bearer token from the server and (ii) transmit a request to control the lock device to the lock device in response in response to receipt of the caveated cryptographic bearer token, wherein the request includes the caveated cryptographic bearer token; and a lock device including a lock ism to control access to a passageway, a third processor, and a third memory comprising a third plurality of instructions stored thereon that, in response to execution by the third processor, causes the lock device to authenticate the request based on the received caveated cryptographic bearer token, the base cryptographic bearer token stored on the lock device, and a real-time clock of the lock device. [0011c] In another aspect, there is provided an access control system, comprising: at least one processing device; and at least one memory comprising a plurality of instructions stored thereon that, in response to execution by the at least one processing device, causes the access control system to: request, by a guest device, a derived cryptographic bearer token from a cloud system, wherein the derived cryptographic bearer token includes a guest set of caveats including a time-based caveat that restricts control of the access control device beyond a defined time; determine, by the cloud system, whether the guest is authorized to control the access control device based on an access l list stored on the cloud system; derive, by the cloud system, the derived cryptographic bearer token from a base cryptographic bearer token in response to a ination that the guest is authorized to control the access control device, wherein the base cryptographic bearer token includes a base set of caveats and a first keyed cryptographic hash of the base set of caveats, wherein the derived cryptographic bearer token includes the guest set of caveats and a second keyed cryptographic hash based on the first keyed graphic hash and the guest set of caveats, and wherein the first keyed graphic hash is a key for the second keyed cryptographic hash; transmit, by the cloud system, the derived cryptographic bearer token to the guest device in response to derivation of the derived cryptographic bearer token; transmit, by the guest device and in response to receipt of the derived graphic bearer token from the cloud , a t to control the access control device to the access control device, wherein the request includes the derived cryptographic bearer token; and authenticate, by the access l device, the request based on the received derived cryptographic bearer token, the base cryptographic bearer token stored on the access control device, and a real-time clock of the access control device.

Further embodiments, forms, features, and aspects of the present application shall become apparent from the description and figures provided herewith.

BRIEF DESCRIPTION OF THE DRAWINGS The concepts described herein are illustrative by way of example and not by way of limitation in the accompanying figures. For simplicity and clarity of illustration, elements illustrated in the figures are not necessarily drawn to scale.

Where considered appropriate, references labels have been repeated among the figures to indicate corresponding or analogous elements.

FIG. I is a simplified block diagram of at least one ment of an access control system for leveraging flexible distributed tokens; is a simplified block diagram of at least one ment of a computing system; is a simplified block diagram of at least one embodiment of a method for ering a lock device; is a simplified block diagram of at least one embodiment of a method for updating an access control list; and is a fied block diagram of at least one embodiment of a method for controlling a lock device by a guest device.

DETAILED DESCRIPTION Although the ts of the present disclosure are susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described herein in . It should be tood, however, that there is no intent to limit the concepts of the present disclosure to the particular forms disclosed, W0 2019/018842 PCT/U32018/043277 but on the contrary, the intention is to cover all modifications, equivalents, and alternatives consistent with the present disclosure and the appended claims.

References in the specification to "one embodiment; an embodiment," "an rative embodiment," etc., indicate that the embodiment described may e a particular feature, stmcture, or characteristic, but every embodiment may or may not necessarily include that particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. It should further be iated that although reference to a "preferred” component or feature may indicate the desirability of a panicular component or feature with respect to an embodiment, the disclosure is not so limiting with respect to other embodiments, which may omit such a component or e. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one d in the art to implement such feature, structure, or characten'stic in connection with other embodiments r or not explicitly described.

Additionally, it should be appreciated that items included in a list in the form of "at least one of A, B, and C" can mean (A); (B); (C); (A and B); (B and C); (A and C); or (A, B, and C).

Similarly, items listed in the form of "at least one of A, B, or C" can mean (A); (B); (C); (A and B); (B and C); (A and C); or (A, B, and C). Further, with respect to the claims, the use of words and phrases such as “a,” “an," “at least one,” and/or “at least one portion" should not be interpreted so as to be limiting to only one such element unless specifically stated to the contrary. and the use of phrases such as “at least a portion” and/or “a portion“ should be interpreted as assing both embodiments including only a portion of such element and embodiments including the entirety of such element unless specifically stated to the contrary.

The sed embodiments may, in some cases, be implemented in hardware, firmware, sofiware, or a combination f. The disclosed embodiments may also be implemented as instructions carried by or stored on one or more transitory or non-transitory e-readable (e.g., computer-readable) storage media, which may be read and executed by one or more processors. A machine-readable e medium may be embodied as any storage device, mechanism, or other physical structure for storing or transmitting information in a form le by a machine (e.g., a le or latile memory, a media disc, or other media device).

PCT/U52018/043277 In the drawings, some structural or method features may be shown in specific arrangements and/or orderings. However, it should be iated that such specific arrangements and/or ngs may not be required. Rather, in some embodiments, such es may be arranged in a different manner and/or order than shown in the rative figures unless ted to the contrary Additionally, the inclusion of a structural or method e in a particular figure is not meant to imply that such feature is required in all embodiments and, in some embodiments, may not be included or may be combined with other features.

Referring now to in the illustrative embodiment, an access control system 100 for ging flexible distributed tokens includes a lock device 102, an owner device 104, a cloud server 106, and a guest device 108. Additionally, in some embodiments. the access control system 100 may also include a gateway device I 10.

As bed in detail below, the access control system 100 allows for flexible access control over offline lock devices 102 and/or other access control devices. For example, in some embodiments, the owner of a lock device 102 may invite others (guests) to gain entry to a facility without having a connection to the facility‘s locks and/or readers. To do so, the access control system 100 may utilize connectivity to a cloud server 106 that distributes caveated graphic bearer tokens (e.g., macaroons) to the owner device 104 and/or guest devices 108 for use with a specified lock device 102. It should be further appreciated that the lock device 102 of the access control system 100 is not limited, for example, in the number of guests that can control the lock device 102 and/or other limitations associated with finite onboard memory, because the lock device 102 is not required to locally store an access control list of authorized users. Instead, as described herein, the lock device 102 may store a base macaroon (or other base cryptographic bearer token), which may be ed (e.g., directly or indirectly) to derived macaroons or contextual cryptographic bearer tokens to determine whether a particular user/device should be granted access/control.

In the illustrative embodiment, the access control system 100 ges the flexibility associated with contextual cryptographic bearer tokens ( e. g, macaroons) for access control. For example, as described below, the lock device 102 and the owner device 104 may communicate with one another during a setup or registration s in which a base cryptographic bearer token (e.g., a base macaroon) with a base set of restrictions is generated (_e.g., a valid after ime, a particular security model, etc). Once generated and submitted to PCT/U82018/0-13277 the cloud server 106, the cloud server 106 may append additional caveats to the base cryptographic bearer token and its restrictions, for example, to reduce the duration the token is valid or limit the sions given to a particular user/guest. In particular, in doing so, the cloud server 106 may employ a cryptographic hash function (e.g., an HMAC) to hash the additional caveats to the base cryptographic bearer token to generate a derived or caveated cryptographic bearer token (e.g, a d macaroon). It should be appreciated that, in the illustrative embodiment, the additional caveats may only modify the base token to be more restrictive than the base token, which prevents a guest, for example, from obtaining greater privileges than the owner of the lock device 102.

As shown in the illustrative owner device 104 includes an application 1 12 that enables the lock owner to register an t with the cloud server 106 or cloud service associated therewith. In the illustrative embodiment, it should be appreciated that the owner’s secure login (e.g., usemame and password) to the cloud /service constitutes a separate security domain from the security domain associated with the flexible tokens described herein.

The application 1 12 further provides a user ace by which the owner may enter user input associated with registering a particular lock device 102 to the owner. Additionally, in some embodiments, after the base cryptographic bearer token (e.g., base macaroon) is generated and stored to the lock device 102 and the cloud server 106, the token may be removed from the owner device 104. In such embodiments, the owner may subsequently use the application I 12 to retrieve a caveated bearer token to access/control the lock device 102 in a manner similar to that described below in reference to a guest. |0027| The guest device 108 similarly includes an application 1 14 that enables a particular guest to register an account with the cloud server/service, t and/or receive an invitation from the owner to access/control a ular lock device 102, t and/or receive caveated cryptographic bearer tokens (e.g., macaroons) for access/control of particular lock s 102, and interact with the lock devices 102.

The ations 1 12, 1 14 may be embodied as any suitable applications for performing the functions described herein. For example, in some embodiments, the owner device 104 and the guest device 108 are embodied as mobile devices. In such embodiments, the applications 1 12, 114 may be embodied as mobile applications (e.g., smartphone ations).

In some embodiments, it should be appreciated that one or more of the applications 1 12, 1 14 W0 2019/018842 PCT/U32018/043277 may serve as a client-side user interface for a web-based ation or service of the cloud server 106. |0029| As shown in the cloud server 106 includes an access control list 1 16. In the illustrative embodiment, the access control list 1 16 identifies each lock device 102 registered to the cloud server/service, the ownership of each of those lock devices 102, and the guests (if any) permitted access to each of those lock devices 102. In some embodiments, each user (e.g., owner/guest) may be associated with a sally unique identifier (UUID) generated during the secure login with the cloud server 106 (e. g., generated as a JWT token). In such embodiments, it should be appreciated that the owner and guests of a particular lock device 102 may be identified in the access control list 1 16 by the corresponding UUID of that owner or guest. Each lock device 102 may be similarly identified based on a lock mming/security code and/or a unique lock identifier. For example, in some embodiments, each lock device 102 may be identified based on a lock programming code ly identified on a component of the lock device 102 ( e.g, the back of the lock device 102), included on paperwork provided with the lock device 102 upon se of the lock device 102, and/or stored in a memory of the lock device 102 and securely errable. [0030I In some embodiments, the access control list I 16 may identify a memory location of the cloud server 106 from which the base cryptographic bearer token (e.g., base macaroon') ponding with each of the registered lock devices 102 can be retrieved. In distributed environments, the access control list 1 16 may further identify, for example, the IP address and/or physical s of the device storing the token. It should be appreciated that the access control list I 16 may be embodied as a table (e.g, an association table), a database, or any other data stmcture or collection of data structures suitable for performing the functions bed herein. |0031| As described in detail below, in the illustrative embodiment, the owner device 104 and the guest device 108 are embodied as mobile devices, and the lock device 102 may communicate with the owner device 104 and the guest device 108 over any suitable wireless communication tion (e.g., Bluetooth, Wi-Fi, etc.) established between the lock device 102 and the device 104, 108. Additionally, in the illustrative embodiment, the owner device 104 and the guest device 108 may communicate with the cloud server 106 using any suitable wireless communication connection. For example, in various embodiments, the owner device 104 and/or the guest device 108 may communicate with the cloud server 106 over Wi-Fi, WiMAX, a WAN W0 2019/018842 PCT/U52018/043277 (e.g., the Internet), and/or a suitable telecommunications network/protocol, As such, it should be appreciated that the illustrative cloud server 106 is located at one or more remote locations relative to the devices 102, 104, 108. In other ments, it should be appreciated that one or more of the communication connections may be wired.

In some embodiments, the access control system 100 may e the gateway device 1 10. For example, in some embodiments, the gateway device 1 10 may be used in conjunction with third-party integrations with the access control system 100. In some embodiments, a registered gateway device 1 10 may be treated as an additional owner of the lock device 102 with privileges similar to the owner. As such, unlike guests, the gateway device 110 may receive a cryptographic bearer token that is not time-limited and/or permission-limited in some embodiments. In embodiments that include the gateway device 110, it should be appreciated that the gateway device 1 10 may communicate with other devices of the access control system 100 over any suitable wired or wireless communication network and associated protocol.

Further, in some embodiments, one or more of the owner s 104 and/or guest devices 108 may be embodied as a shared device or user interface device that permits a user to ct with the cloud server 106, the lock device 102, and/or cloud-based solutions. For example, one or more of the devices 104, 108, l 10 may be embodied as a home assistant device or smart home hub. In some embodiments, the access control system 100 may e an ambient voice ace or other shared user ace instead of a wned graphical user interface. Further, in some embodiments, the access control system 100 may be accessed by virtue of a to-cloud integration with a third party integrator. |0034| It should be appreciated that each of the lock device 102, the owner device 104, the cloud server 106, the guest device 108, and/or the gateway device 1 10 may be embodied as a ing device similar to the computing device 200 described below in reference to For example, in the illustrative embodiment, each of the lock device 102, the owner device 104, the cloud server 106, the guest device 108, and the gateway device 1 10 includes a processing device 202 and a memory 206 having stored thereon operating logic 208 for execution by the processing device 202 for operation of the corresponding device. Additionally, although the lock device 102 is described herein for clarity of the description as a “lock device," it should be appreciated that, in other ments, the lock device 102 may be embodied as any access PCT/USZOIS/(HJZW control device suitable for perfomiing the functions described herein. As such, the description of the lock device 102 is equally able to embodiments of the access control system 100 having a different type of access control device.

It should be further appreciated that, although the cloud server 106 is described herein as a cloud-based device or collection of devices, in other embodiments, the cloud server 106 may be embodied as one or more devices outside of a cloud computing environment.

Further, in some embodiments, the cloud server 106 may be embodied as a “serverless” or -ambiguous computing solution, for example, that executes a plurality of instructions on- demand, ns logic to execute instructions only when prompted by a particular activity/trigger, and does not consume computing resources when not in use. That is, the cloud server 106 may be embodied as a virtual computing environment residing “on” a computing system (e.g., a distributed network of devices) in which various virtual ons (e.g., Lamba functions, Azure functions, Google cloud functions, and/or other suitable l functions) may be ed corresponding with the functions of the cloud server 106 described herein. For example. when an event occurs (e.g, a user presses a button in an application to unlock the lock device 102), the application may contact the l computing environment (e.g., via an HTTPS request to an API of the virtual computing environment), whereby the API may route the request to the correct virtual function (_e.g., a particular server-ambiguous computing resource) based on a set ofrules. As such, when a request for a caveated cryptographic bearer token is made, the appropriate l function(s) may be executed to determine if that user should receive access to the lock device 102, mint the appropriate ed cryptographic bearer token, and transmit that ation back to the user before eliminating the instance of the virtual function(s). gh only one lock device 102, one owner device 104, one cloud server 106, one guest device 108, and one gateway device 1 10 are shown in the illustrative embodiment of the access control system 100 may include multiple lock devices 102, owner s 104 cloud servers 106, guest s 108, and/or gateway devices 1 10 in other embodiments. For example, as described herein, a ular owner may have multiple owner devices 104 that the owner may use to securely connect with the cloud server 106 (e.g., via secure login over a security domain separate from the cryptographic bearer tokens) in order to register a lock device 102 and/or invite/revoke access control permissions of a particular guest for the lock device 102. rly, a guest with permission to access/control a particular lock device 102 may securely PCT/USZOIfl/(N3277 connect with the cloud server 106 via any suitable guest device 108 to request and receive a caveated cryptographic bearer token for access to the lock device 102. Further, in some embodiments, a particular owner and/or guest may have access to multiple lock devices 102. As such, it should be appreciated that, in some embodiments, a ular user may be an owner of one lock device 102 and a guest with respect to another look device 102. Similarly, a particular device may be an owner device 104 or a guest device 108 depending on the particular person (and login tials thereof) using the device. In some ments, it should be appreciated that the cloud server 106 may be embodied as multiple s in a cloud computing environment. Accordingly. in such embodiments. the access control list 1 16 and/or other data used by the access control system 100 may be distributed among multiple servers.

Referring now to a simplified block diagram of at least one embodiment ofa computing device 200 is shown. The illustrative computing device 200 s at least one embodiment of a lock device, owner device, cloud server, guest device, and/or gateway device that may be utilized in connection with the lock device 102, the owner device 104, the cloud server 106, the guest device 108, and/or the y device 1 10 illustrated in Depending on the particular ment, computing device 200 may be embodied as a reader device, credential device, access control device, , desktop er, laptop computer, tablet computer, notebook, netbook, UltrabookTM, mobile computing device, ar phone, smartphone, wearable computing device, personal l assistant, Internet of Things (IoT') device, control panel, processing system, router, gateway, and/or any other computing, processing, and/or communication device capable of performing the functions described herein.

The computing device 200 includes a processing device 202 that executes algorithms and/or processes data in accordance with operating logic 208, an input/output device 204 that enables communication n the computing device 200 and one or more external devices 210, and memory 206 which stores. for example, data received from the external device 210 via the input/output device 204.

The input/output device 204 allows the computing device 200 to communicate with the external device 210. For example, the input/output device 204 may include a eiver, a network adapter, 3 network card, an interface, one or more communication ports (e.g., a USB port, serial pon, parallel port, an analog port, a digital port, VGA, DVI, HDMI, FireWire, CAT 5, or any other type of communication port or interface), and/or other PCT/U32018/043277 communication circuitry. Communication circuitry of the computing device 200 may be configured to use any one or more communication technologies (e.g., wireless or wired communications) and ated protocols (cg, Ethemet, Bluetooth®, Wi-Fi®, WiMAX, etc.) to effect such communication depending on the particular computing device 200. The input/output device 204 may e hardware, software, and/or firmware suitable for performing the techniques described herein.

The extemal device 210 may be any type of device that allows data to be inputted or outputted from the computing device 200. For example, in s embodiments, the external device 210 may be embodied as the lock device 102. the owner device 104, the cloud server 106. the guest device 108, and/or the gateway device I 10. Further, in some embodiments, the external device 210 may be embodied as another computing device, switch, diagnostic tool, controller, printer, display, alarm, peripheral device (e.g., rd, mouse, touch screen display. etc), and/or any other computing, processing, and/or communication device capable of performing the functions described herein. Furthermore, in some embodiments, it should be iated that the external device 210 may be integrated into the computing device 200. |004l| The processing device 202 may be embodied as any type of sor(s) capable of performing the functions described herein. In particular, the processing device 202 may be embodied as one or more single or multi-core processors, microcontrollers, or other processor or processing/controlling circuits. For example, in some embodiments, the processing device 202 may include or be ed as an arithmetic logic unit (ALU), l processing unit (CPU), digital signal processor (DSP), and/or another le sor(s). The processing device 202 may be a programmable type, a dedicated red state machine, or a combination thereof.

Processing devices 202 with multiple processing units may utilize distributed, pipelined, and/or parallel processing in various embodiments. Further, the processing device 202 may be dedicated to performance ofjust the operations described herein, or may be utilized in one or more additional applications. In the illustrative embodiment, the processing device 202 is programmable and executes algorithms and/or processes data in accordance with operating logic 208 as defined by programming instructions (such as re or re) stored in memory 206. Additionally or alternatively. the operating logic 208 for processing device 202 may be at least lly defined by hardwired logic or other hardware. Further, the processing device 202 may include one or more components of any type suitable to process the signals received from PCT/U52018/043277 input/output device 204 or from other components or devices and to provide desired output signals. Such components may include digital circuitry, analog circuitry, or a combination thereof.

The memory 206 may be of one or more types transitory computerreadable media, such as a solid-state memory, electromagnetic memory, optical , or a combination thereof. Furthermore, the memory 206 may be volatile and/or nonvolatile and, in some embodiments, some or all of the memory 206 may be of a portable type, such as a disk, tape. memory stick, cartridge, and/or other suitable portable memory. In operation, the memory 206 may store various data and software used during operation of the computing device 200 such as operating systems, ations, programs, ies, and drivers. It should be appreciated that the memory 206 may store data that is manipulated by the operating logic 208 of processing device 202, such as, for example, data representative of signals received from and/or sent to the input/output device 204 in addition to or in lieu of storing programming instmctions defining operating logic 208. As shown in the memory 206 may be included with the processing device 202 and/or coupled to the processing device 202 depending on the particular embodiment.

For example, in some embodiments, the processing device 202, the memory 206, and/or other components of the computing device 200 may form a portion of a system-on-a-chip (80C) and be incorporated on a single integrated circuit chip.

In some embodiments, various components of the computing device 200 (e.g., the processing device 202 and the memory 206) may be communicatively coupled via an input/output subsystem, which may be embodied as try and/or components to facilitate input/output operations with the processing device 202, the memory 206, and other components ofthe computing device 200. For example, the input/output subsystem may be embodied as, or otherwise include, memory controller hubs, input/output control hubs, e devices, communication links (i.e., point-to—point links, bus links, wires, cables, light guides, printed t board , etc.) and/or other ents and subsystems to facilitate the output operations.

The computing device 200 may include other or additional components, such as those ly found in a typical computing device (e.g., various input/output devices and/or other components). in other embodiments. It should be further appreciated that one or more of the components of the computing device 200 described herein may be buted across multiple PCT/U52018/1l43277 computing devices. In other words, the techniques described herein may be employed by a computing system that includes one or more computing devices. Additionally, although only a single processing device 202, [/0 device 204, and memory 206 are illustratively shown in it should be appreciated that a particular computing device 200 may include multiple sing devices 202, I/O s 204, and/or memories 206 in other embodiments Further, in some embodiments, more than one external device 210 may be in communication with the computing device 200.

In some embodiments, the illustrative lock device 102 includes a lock mechanism that is configured to l access through a passageway. For example, in some embodiments, the lock ism may be configured to be positioned in a locked state in which access to the eway is denied, or may be positioned in an unlocked state in which access to the passageway is permitted. In some embodiments, the lock mechanism includes a deadbolt, latch bolt, lever, and/or other mechanism adapted to move between the locked and unlocked state and otherwise perform the functions bed herein. However, it should be appreciated that the lock mechanism may be embodied as any another mechanism suitable for controlling access through a passageway in other embodiments.

Referring now to in use, the access control system 100 may execute a method 300 for registering a lock device 102. It should be appreciated that the particular blocks of the method 300 are illustrated by way of e, and such blocks may be ed or divided, added or removed, and/or reordered in whole or in part ing on the particular embodiment. unless stated to the contrary. The illustrative method 300 begins with block 302 in which a lock owner ishes a communication connection with the cloud server 106 via an owner device 104, and the cloud server 106 determines r the lock owner is a new lock owner or a registered lock owner. It should be appreciated that the cloud server 106 may employ any suitable technique to do so. For example, in some embodiments, a user interface presented on the owner device 104 may ask the user whether the user is a registered lock owner (e. g, whether the user has an ng cloud server account) and, if so, prompt the user/owner for secure login information to the cloud server account. In such circumstances, the method 300 advances to block 308.

However, if the cloud server 106 determines that the user/owner is a new lock owner (e.g., a lock owner without an existing cloud server account), the method 300 advances to PCT/U52018/043277 block 304 in which the lock owner is registered with the cloud server 106. In particular, in block 306, the owner may create a cloud server account and secure login to the cloud server 106 or associated cloud sen/ice. As described above. in the illustrative embodiment, it should be appreciated that the secure login is associated with a security domain different from the graphic bearer tokens. For example, as described above, each user (cg, owner/guest) may be associated with a UUID generated during the secure login with the cloud server 106 (e.g.. generated as a JWT token) for identification of the user by the cloud server 106. In some embodiments, the UUID may be based in pan on the e and/or primary phone number of the user. It should be appreciated that, in some embodiments. the secure login may require multi factor authentication.

In block 308, the cloud server [06 determines whether to register a particular lock device 102 to the owner. If so, the method 300 advances to block 310 in which the owner enters a lock programming code into the application 1 12 of the owner device 104. As indicated above, in some ments, each lock device 102 may be identified, for example. based on a lock programming code visually fied on a component of the lock device 102 (e.g., the back of the lock device 102) or ed on paperwork provided with the lock device 102 upon purchase of the lock device 102. As such, the owner may copy the programming code into the application 1 12 of the owner device 104. Additionally, in some embodiments, it should be appreciated that the programming code may be programmed into the memory of the lock device 102. In such ments, the programming code may be securely transmitted to the owner device 104, for example, for comparison to programming code manually entered by the owner into the application 112. l0049| It should be appreciated that the lock programming code may serve as proof to the lock device 102 and the application 1 12 that the owner has possession of and/or is authorized to setup/register the lock device 102. In some embodiments, entry ofthe lock programming code initiates a session to establish a secure pairing between the lock device 102 and the owner device 104 (or the application 1 12, in particular). For example, in some ments, the lock device 102 and the owner device 104 may perform a secure password authenticated key exchange ) based on the lock programming code (e.g., in which the lock mming code serves as a SPAKE2 password), which may include the generation of one or more base cryptographic bearer tokens (cg, macaroons) as described below. In particular, in some embodiments, the W0 2019/018842 PCT/U52018/0-13277 lock device 102 may mint a client authentication token and a server authentication token, which may be included in or form a portion of one or more base cryptographic bearer tokens. The server authentication token may be subsequently used to ensure that a device is actually communicating with the appropriate lock device 102 and the lock device 102, for example, is not being “spoofed“ by a nefarious actor. The client authentication token may be used for secure access to the lock device 102 and, for simplicity, may be referred to herein simply as the graphic bearer token (despite some ments of the bearer tokens including both the server authentication token and the client authentication token).

As ted above, in block 312, a base cryptographic bearer token (e.g.. a base macaroon) is generated by the lock device 102, for example, as part of a secure pairing n the lock device 102 and the owner device 104 (or the application 1 12, in particular). As described above, in the illustrative embodiment, the base cryptographic bearer token is generated by the lock device 102 and securely transmitted to the owner device 104 (e. g., encrypted by a SPAKE key). However, in other embodiments, it should be appreciated that the token may alternatively be generated by the owner device 104 and transmitted to the lock device 102. In block 314, the base cryptographic bearer token is stored to the lock device 102 and the cloud server 106. For example, in the rative embodiment, the owner device 104 securely transmits the base cryptographic bearer token to the cloud server 106 (e.g., via the application 1 12) and the deletes the token from the memory of the owner device 104. In block 316, the access control list 1 16 of the cloud server 106 is updated to identify the base cryptographic bearer token and ownership of the lock device 102 by the registered owner. For e, as indicated above, in some embodiments, the access control list 1 16 may be updated to identify a memory location of the cloud server 106 from which the base cryptographic bearer token can be retrieved. Additionally, the access l list 1 16 may be updated to associate the owner with the lock device 102 (e.g., by mapping the owner’s UUlD to a lock identifier ofthe lock device 102).

Although the blocks 302-316 are described in a relatively serial manner, it should be appreciated that various blocks of the method 300 may be performed in el in some embodiments. |0052| Referring now to in use, the access control system 100 may execute a method 400 for ng an access control list 1 16. It should be appreciated that the particular W0 2019/018842 PCT/U32018/043277 blocks of the method 400 are illustrated by way of example, and such blocks may be combined or divided, added or removed, and/or reordered in whole or in part depending on the particular embodiment, unless stated to the contrary. The illustrative method 400 begins with block 402 in which the access control system 100 determines r an owner s to update access l permissions for a particular lock device 102. For example, in some embodiments, an owner may indicate a desire to update the lock permissions via an application 1 12 executing on an owner device 104 (e.g., by selecting a particular option on the application, by initiating a secure login, etc.) In block 404, the cloud server 106 es the lock owner via secure login in a manner similar to that described above (e.g., via usemame/password over a separate security domain from the graphic bearer tokens). As indicated above, in some embodiments, the lock owner may be required to securely login using multifactor authentication and, therefore, may be required to, for example, enter a security code received via text message or email, provide biometric input, and/or otherwise provide proof of identity, Assuming the lock owner has been verified, in block 406, the cloud server 106 determines (e.g., based on a user selection in the application 1 12 of the owner device 104) whether the owner desires to invite a guest to have access control of the lock device 102 or revoke a particular guest's access control permissions for a particular lock device 102.

If the owner is inviting a guest to have access control over a particular lock device 102 (e.g., based 0n user input), in block 408, the cloud server 106 transmits an tion to a guest device 108 associated with the guest. It should be appreciated that the owner may identify the guest and/or guest device 108 using any suitable identifier. For example, in some embodiments, the owner may provide the guest’s phone number and/or email address to which the cloud server 106 may address the invitation (e.g., via voice, SMS, or email). Upon ing the invitation, in block 410, the guest may securely login to the cloud server 106 or associated cloud service as bed above. In particular, in some embodiments, upon selecting a link provided in the invitation, the guest may be prompted to securely login to the cloud server 106 or create a new account. In block 412. the cloud server 106 updates the access control list 1 16 to permit the guest to have access control of the lock device 102. As described above, in the Illustrative ment, guests are ed time-limited and permission-limited access control relative to the owner, which may have full access control over the lock device 102 that is not time-bounded (or time-bounded with a greater time limit). Having updated the access control list 116 to permit the guest access to the lock device 102, the cloud server 106 may subsequently issue temporary tokens (e. g., caveated cryptographic bearer tokens) to be given to the guest for access to the lock device 102 as described . In some ments, it should be appreciated that the temporary token may provide schedule-based access to the guest. For example, the token may include a modified and/or additional ased caveat that sets a time at which the token becomes valid, thereby providing a window within which the temporary token may be used (e. g., between the time at which it becomes valid and the time at which it expires).

Returning to block 406, if the owner is ng a guest’s access control permissions for a particular lock device 102, in block 414, the cloud server 106 determines (e.g.. based on user input of the owner) the particular lock device 102 registered to the owner (if multiple lock devices 102 are registered to the owner) for which access ls are to be modified, and the particular guest that currently has access control permissions to that lock device 102 to be d. In other words, in some embodiments, the cloud server 106 determines the guestflock combination for which to revoke access. In other ments, it should be iated that the cloud server 106 may revoke a particular guest’s access to all lock devices 102 of the owner and/or revoke access of all guests to a ular lock device 102. In block 416, the cloud server 106 updates the access control list 1 16 to revoke the guest’s access control of the ular lock device 102. For example, in some embodiments, the cloud server 106 deletes the guest from an entry associated with the lock device 102 or otherwise disassociates the guest with the lock device 102. However, it should be appreciated that the cloud server 106 may update the access control list I 16 to reflect the revocation using any suitable technique, which may vary depending on the particular embodiment (e.g., depending on the particular data structure of the access control list I 16). It should be appreciated that, in the illustrative embodiment, revocation of the guest access control permission prevents the cloud server 106 from subsequently issuing/transmitting a caveated cryptographic bearer token to a guest device 108 of the guest (unless currently associated with a different authorized guest as described above) to access the lock device 102.

In some embodiments. the cloud server 106 may update the access control list 1 16 to grant and/or revoke multiple access control permissions concurrently depending on the user input of the owner. In some embodiments, the access control list 1 16 may also include a ist that defines one or more devices that are unauthorized to receive a cryptographic bearer W0 2019/018842 PCT/U52018/043277 token under any circumstances. Further, it should be appreciated that the techniques described herein allow the owner to update the access control list 116 that defines access controls for the lock device 102 without interacting with the lock device 102 for which access controls are being modified.

Although the blocks 402-416 are described in a relatively serial manner, it should be appreciated that various blocks of the method 400 may be perfonned in parallel in some embodiments.

Referring now to in use, the access control system 100 may execute a method 500 for controlling a lock device 102 by a guest device 108. It should be appreciated that the particular blocks of the method 500 are illustrated by way of example, and such blocks may be combined or divided, added or removed, and/or reordered in whole or in part depending on the particular embodiment, unless stated to the ry The illustrative method 500 begins with block 502 in which the cloud server 106 determines whether a guest is ting access control over a particular lock device 102. For example, in some embodiments, the guest may request access control over the lock device 102 via the application 1 14 on the guest device 108.

In particular, in some embodiments, the application 1 14 may include a graphical user ace that fies each of the lock devices 102 for which the guest has access control permissions.

In some embodiments, the application 114 may fy those lock devices 102 for which the guest has ownership and, therefore, has owner-level access control permissions in addition to the lock s 102 for which the guest has guest-level access permissions. Depending on the particular embodiment, the application 1 14 may or may not cally distinguish the lock devices 102 that have owner-level permissions from those having guest-level permissions. |0059| Upon identifying the particular lock device 102 for which access control is desired, in block 504, the guest device 108 requests a caveated cryptographic bearer token from the cloud server 106. In block 506, the cloud server 106 ines whether the guest using the guest device 108 is authorized to control the lock device 102 based on the access control list 116 stored in the cloud server 106. For example, as described above, the guest may be required to securely login to the cloud server 106 or associated cloud service through a ty domain separate from the token-based security in order to prove the guest’s identity. Further, in the illustrative embodiment, the cloud server 106 compares the s identity (e.g., the guest UUID generated during the secure login) to the access control list I 16 to confirm that the guest W0 2019/018842 PCT/U52018/043277 identifier is associated with the lock device 102 that the guest desires to /control. If the guest’s identity cannot be verified by secure login and/or the guest identifier is not associated with control of the lock device 102 in the access control list 1 16, the access control system 100 performs one or more error handling procedures in block 508. For example, in some embodiments, the cloud server 106 drops its communication tion with the guest device 108, alerts the owner of the error. and/or records the error in an audit file. Further, the application 1 14 may alert the user of the guest device 108 of the error. It should be appreciated, however, that the access control system 100 may, additionally or alternatively, m other suitable error ng procedures.

Returning to block 506. if the cloud server 106 determines that the guest is authorized to l the lock device 102, the method 500 advances to block 5 10 in which the cloud server 106 generates a caveated cryptographic bearer token and transmits the generated token to the guest device 108. In particular, in block 512, the cloud server 106 may generate a caveated cryptographic bearer token ing a time-based caveat that s a time limit for control of the lock device 102 and a permission-based caveat that defines a permission level of the bearer of the token as described herein. In particular, in the illustrative embodiment, the cloud server 106 retrieves the base cryptographic bearer token associated with the lock device 102 (see block 316 of and generates a caveated cryptographic bearer token based on that base cryptographic bearer token. In other embodiments, the cloud server 106 may, additionally or alternatively, include other caveats. For example, in some embodiments, the ted caveated cryptographic bearer token may include a location—based caveat that defines a al location, region. boundary. and/or radius within which the token is valid (e.g., for mobile lock devices 102 such as bicycle locks).

As described above, it should be appreciated that the cryptographic bearer tokens described herein may include or be embodied as macaroons. It should be appreciated that a on is a data structure that can have caveats appended to it, for example, to limit time access and privilege level ofa user of a lock device 102. When the lock device 102 is paired with the owner device 104 (e.g., during a one-time action unless a factory default reset occurs to reset data on the lock device 102), the lock device 102 may generate a macaroon that is transmitted to the owner device 104 and forwarded to the cloud server 106 (see blocks 314, 316 of . The macaroon may be composed of a security key and caveats associated with a W0 2019/018842 PCT/U52018/043277 macaroon type (e. g., owner, admin/manager, and user/guest) and a timestamp indicating a creation time of the macaroon. Further, in some embodiments, the macaroon may include a caveat ated with a function of the macaroon (e.g, what the macaroon is intended to do).

The security key may be based, for example, on the SPAKE key generated during the g between the lock device 102 and the owner device 104. In other embodiments, another suitable key may be used for the macaroon. The permitted values for the time-based caveat may vary depending on the particular embodiment. For example, in some embodiments, the time-based caveat may allow ti the/expiration limits of one hour, twenty-four hours, thirty days, or absolute/non-expiring. In other embodiments, any suitable time limits may be used. It should be appreciated that, in the illustrative embodiment, the time limits define the amount of time that may elapse from the tion of the on (e.g., defined by a timestamp in the on) before the macaroon is considered to be expired.

In some embodiments, the base macaroon, base, may be generated according to base : ‘base_caveats| liaseJag}, where base caveats is a concatenated string of the caveats of the base macaroon, ag = HMACUrevase_caveats), and HMAC is a keyed-hash message authentication code of the base caveats using key as the cryptographic key for the hash As indicated above, it should be appreciated that any suitable keys may be used for the generation of the base macaroon. Further, as described herein, a macaroon may also be derived from the base macaroon (eg, for transmittal to a guest device 108) thereby narrowing the permissions of the base macaroon (e.g., further including imiting and/or permission- limiting caveats). In particular, a derived macaroon, guest, may be generated according to guest = HMA(‘(base_/ag,guest_caveat.s) = HMA('(HMA( ‘(ke_v_,ba.s'e -caveats),guest ‘caveam, where guest caveats is a enated string of the additional caveats defining the guest’s access control permissions. It should be further appreciated that the macaroons may further incorporate caveats associated with a particular session and/or other suitable information. ing back to in block 514, the guest device 108 ishes a secure communication session with the lock device 102 and, in block 516, the guest device 108 securely transmits a request to control the lock device 102 including the ed cryptographic bearer token to the lock device 102. In block 518, the lock device 102 authenticates the access control request based on the ed caveated cryptographic bearer token, the base cryptographic bearer token stored on the lock device 102 (see block 316 of , and the real-time clock of the lock PCT/U52018/043277 device 102. In particular, in block 520, the lock device 102 compares the ed cryptographic bearer token to the base cryptographic bearer token to determine whether the caveated cryptographic bearer token is associated with the base graphic bearer token. It should be appreciated that the tokens may be compared directly or ctly depending on the ular embodiment. For example, in the illustrative embodiment, the lock device 102 determines whether caveated cryptographic bearer token was derived from the base cryptographic bearer token using a suitable technique or algorithm (eg, using the appropriate keys and the HMAC as described above). Additionally, in block 522, the lock device 102 compares the time-based caveat to the real-time clock of the lock device 102 to determine whether the current time is within the time limit defined by the time-based caveat.

If the caveated cryptographic bearer token is not properly associated with the base cryptographic bearer token or the current time is e the time period for control ized by the time-based caveat, for e, the authentication fails and the guest device 108 is determined to be unauthorized to control the lock device 102. If the lock device 102 ines, in block 524. that the access control is unauthorized, the access control system 100 performs one or more error handling procedures in block 526. For example, the access control system 100 may handle the error in a manner similar to that described above in reference to block 508. In particular, the lock device 102 may drop its communication tion with the guest device 108 and/or record the error in an audit tile that may be subsequently retrieved (e.g, by an owner device 104). Further, the application 1 14 may alert the user ofthe guest device 108 of the error.

It should be appreciated, however, that the access control system 100 may, additionally or alternatively, perform other suitable error handling procedures.

It should be further appreciated that, in some embodiments, the access control system 100 may perform an error handling procedure ifa guest token is presented and the real- time clock of the lock device 102 has not been set (e.g., due to a power reset). To do so, in some embodiments, the access l system 100 may perfonn one or more of the techniques described in reference to US. Patent ation No. 15/656,678 filed on July 21, 2017, the entirety of which is incorporated herein by reference.

However, if the access control is authorized, the method 500 advances to block 528 in which the guest device 108 may transmit a command to control a function of the lock device 102. in particular, in some embodiments, the guest device 108 may transmit a command PCT/U52018/043277 to the lock device 102 to unlock a lock mechanism of the lock device 102. in other embodiments, however, the guest device 108 may transmit a command to perform any suitable function depending on the type of access control device being controlled. In block 530, the lock device 102 ds to the command. For e, the lock device 102 may perform the requested function in response to receiving the command to do so (e.g., unlock a lock mechanism). Further, in block 532, in some embodiments, the lock device 102 may transmit a status message to the guest device 108 based on the success or failure of the requested fimcti on.

For example, in the illustrative embodiment, if the guest has delayed issuing a command such that the time limit det'r ned by the time-based caveat is no longer satisfied, the access control attempt will be denied by the lock device 102.

It should be appreciated that the owner may utilize an owner device 104 to retrieve an owner-level contextual cryptographic bearer token for access to a lock device 102 of the owner in a manner similar to that described above in reference to a guest obtaining a token.

However, in some ments, the owner’s token ted by the cloud server 106 does not include a time-based caveat or may be less time-bounded than the guests token. In other embodiments, the owner may retrieve and use the base cryptographic bearer token for access to the lock device 102. In the illustrative embodiment, r, the owner device 104 does not perpetually store the base cryptographic bearer token as doing so could pose a ty risk to the Although the blocks 502-532 are described in a relatively serial manner, it should be appreciated that various blocks of the method 500 may be perfomred in parallel in some embodiments.

Claims (18)

1. A method, comprising: ining, by a , whether a guest ated with a guest device is authorized to control an access control device based on an access control list stored on the server; deriving, by the server, a caveated cryptographic bearer token from a base cryptographic bearer token in response to a determination that the guest is authorized to control the access control device, wherein the base cryptographic bearer token includes a base set of caveats and a first keyed cryptographic hash of the base set of caveats, wherein the caveated cryptographic bearer token includes a guest set of caveats including a time-based caveat that defines a time limit for control of the access control device and a second keyed graphic hash based on the first keyed cryptographic hash and the guest set of caveats, and wherein the first keyed cryptographic hash is a key for the second keyed cryptographic hash; itting, by the server, the caveated cryptographic bearer token to the guest device in response to tion of the caveated cryptographic bearer token; transmitting, by the guest device and in response to receipt of the caveated cryptographic bearer token from the server, a request to control the access l device to the access control device, wherein the request includes the caveated graphic bearer token; and authenticating, by the access control device, the request based on the received caveated cryptographic bearer token, the base cryptographic bearer token stored on the access control device, and a real-time clock of the access control device.

2. The method of claim 1, further comprising requesting, by the guest , the caveated cryptographic bearer token from the server; and wherein ining whether the guest is authorized to control the access control device comprises determining whether the guest is authorized to control the access control device in response to t of the request for the caveated cryptographic bearer token by the server.

3. The method of claim 1, wherein authenticating the request comprises: determining whether the caveated cryptographic bearer token was derived from the base cryptographic bearer token; and comparing the time-based caveat to the real-time clock of the access control device to determine whether a current time is within the time limit.

4. The method of claim 1, further comprising: itting, by the guest device, a command to control a function of the access l device in response to successful authentication of the request by the access control device; and performing, by the access control device, the function based on the command.

5. The method of claim 1, wherein the access control list identifies one or more access control devices and guest access control permissions for each of the one or more access control devices; and wherein the access l list is modifiable by an owner device authenticated via a separate security domain.

6. The method of claim 5, further comprising: verifying, by the server, an identifier of an owner associated with the owner device via the separate security domain; determining, by the server, a guest access control sion for one of the one or more access control s to revoke; and ng, by the server, the access control list to revoke the guest access control permission; wherein revocation of the guest access control permission prevents the server from subsequently issuing a caveated cryptographic bearer token to a corresponding guest device to control a corresponding access control device.

7. The method of claim 5, further comprising: verifying, by the server, an fier of an owner associated with the owner device via the separate security domain; transmitting, by the server and to a target guest device associated with a target guest, an invitation to control the access control device; verifying, by the server, a guest identifier of the target guest via the te security domain; and ng, by the server, the access control list to indicate that the target guest is ized to have time-limited and sion-limited control the access control device in response to successful verification of the guest identifier.

8. The method of claim 5, further sing: registering an owner of the access control device with the server via the separate security domain; ing a programming code of the access control device to the owner device; transmitting the base cryptographic bearer token generated by the access control device from the owner device to the server; and updating the access control list to identify ownership of the access control device by the owner.

9. The method of claim 8, wherein the base cryptographic bearer token stored on the access control device is the base cryptographic bearer token generated by the access control device and transmitted to the server.

10. The method of claim 8, wherein the programming code is identified on at least one of a component of the access control device or paperwork provided with the access control device upon purchase of the access control device.

11. An access control system, comprising: a server including a first processor and a first memory comprising a first plurality of ctions stored thereon that, in response to execution by the first processor, causes the server to (i) determine whether a guest associated with a guest device is authorized to control a lock device based on an access control list stored on the server, (ii) derive a caveated cryptographic bearer token from a base cryptographic bearer token in response to a determination that the guest is authorized to control the lock device, wherein the base cryptographic bearer token includes a base set of caveats and a first keyed graphic hash of the base set of caveats, and wherein the caveated graphic bearer token includes a guest set of caveats including a ased caveat that defines a time limit for control of the lock device and a second keyed cryptographic hash based on the first keyed cryptographic hash and the guest set of caveats, and wherein the first keyed cryptographic hash is a key for the second keyed cryptographic hash, and (iii) transmit the caveated graphic bearer token to the guest device in se to derivation of the caveated cryptographic bearer token; a guest device including a second processor and a second memory comprising a second plurality of instructions stored thereon that, in response to execution by the second processor, causes the guest device to (i) receive the caveated cryptographic bearer token from the server and (ii) transmit a request to l the lock device to the lock device in response in response to receipt of the caveated graphic bearer token, wherein the t es the caveated graphic bearer token; and a lock device including a lock mechanism to control access to a passageway, a third processor, and a third memory comprising a third plurality of instructions stored thereon that, in response to execution by the third processor, causes the lock device to authenticate the request based on the received caveated cryptographic bearer token, the base cryptographic bearer token stored on the lock device, and a real-time clock of the lock device.

12. The access control system of claim 11, wherein to authenticate the request comprises to: determine r the caveated cryptographic bearer token was derived from the base cryptographic bearer token; and compare the time-based caveat to the real-time clock of the lock device to determine whether a current time is within the time limit.

13. The access control system of claim 12, wherein the access control list identifies one or more lock devices and guest access control permissions for each of the one or more lock devices; and wherein the access control list is modifiable by an owner device ticated via a separate security domain.

14. The access control system of claim 13, wherein the second plurality of instructions further causes the guest device to transmit a command to unlock the lock ism of the lock device in response to successful authentication of the request by the lock device; and wherein the third plurality of instructions further causes the lock device to unlock the lock mechanism in response to the command.

15. The access control system of claim 11, wherein the lock mechanism comprises at least one of a deadbolt or latch bolt.

16. An access control system, comprising: at least one processing device; and at least one memory comprising a plurality of instructions stored thereon that, in response to execution by the at least one processing device, causes the access control system to: t, by a guest , a derived cryptographic bearer token from a cloud system, wherein the derived cryptographic bearer token includes a guest set of caveats including a time-based caveat that restricts control of the access l device beyond a defined time; determine, by the cloud , whether the guest is authorized to control the access control device based on an access control list stored on the cloud system; derive, by the cloud system, the derived cryptographic bearer token from a base cryptographic bearer token in response to a determination that the guest is authorized to control the access control device, wherein the base cryptographic bearer token es a base set of caveats and a first keyed cryptographic hash of the base set of caveats, wherein the derived cryptographic bearer token includes a second keyed cryptographic hash based on the first keyed cryptographic hash and the guest set of caveats, and wherein the first keyed cryptographic hash is a key for the second keyed cryptographic hash; transmit, by the cloud system, the derived graphic bearer token to the guest device in response to derivation of the derived graphic bearer token; transmit, by the guest device and in response to receipt of the derived graphic bearer token from the cloud , a request to control the access control device to the access control device, wherein the request includes the derived cryptographic bearer token; and authenticate, by the access control device, the request based on the received derived cryptographic bearer token, the base cryptographic bearer token stored on the access control device, and a real-time clock of the access l device.

17. The access control system of claim 16, wherein to ticate the request comprises to: determine whether the derived cryptographic bearer token was derived from the base cryptographic bearer token; and e the ased caveat to the real-time clock of the access control device to determine whether a current time is within the time limit.

18. The access control system of claim 16, wherein the derived cryptographic bearer token further includes at least one of a permission-based caveat or a location-based caveat. W0 018842 PC'I‘IUSZHIR/043277 mm>mmw .53 wmmoo< 03040 405.200 vor 2075x039”; MOSNO