Secure fine time measurement for wireless communication protocols

In general, techniques are described by which to perform secure fine time measurement for wireless communication protocols. An initiating station comprising wireless communication circuitry may be configured to perform the techniques. The wireless communication circuitry may be configured to receive, in accordance with a wireless networking protocol for communicating between the initiating station and a responding station, a first fine time measurement specifying a first time. The wireless communication circuitry may also be configured to receive, in accordance with the wireless networking protocol and for the corresponding first time, a first message integrity code. The wireless communication circuitry may next be configured to authenticate, based on the first message integrity code, the responding station to establish that the fine time measurement is from a trusted responding station.

TECHNICAL FIELD

This disclosure relates to wireless communication protocols, and more specifically, techniques for providing secure fine time measurement via the wireless communication protocols.

BACKGROUND

The Internet of Things (IoT) refers to a broad category of technology that enables interactions, via network protocols, between devices, including so-called smart devices such as smart speakers, smart plugs, smart lights, smart televisions, smartphones, smart locks, smart doorbells, etc., as well as other devices, such as keyless entry systems for homes and/or vehicles, cameras, and the like. In some instances, wireless networking protocols that conform to an Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (which may be referred to as WiFi™) are employed to facilitate wireless interactions between the devices.

In some contexts, determining the proximity of the devices (which may be referred to as an initiating station and a responding station) to one another may be desirable prior to permitting the interactions between the initiating station and the responding station, especially when such interactions permit physical access to an underlying resource, such as a home and/or a vehicle. While wireless networking protocols may provide for accurate distance determination of the responding station relative to the initiating station via a process known as fine time measurement, such fine time measurement processes may be easily compromised via inadvertent or malicious operation of the responding station.

SUMMARY

In general, techniques are described for secure fine time measurement for wireless networking protocols. A responding station may respond to an initiating station, and in doing so, the responding station may not only transmit the fine time measurement, but may also transmit a message integrity code that the initiating station may use to authenticate the fine time measurement as being sent by an authorized responding station. That is, the initiating station may be initially associated with a given responding station, where such association may involve agreement on a shared key that the responding station may use to generate the message integrity code. The initiating station may then authenticate the message integrity code (using the associated shared key) sent by the responding station in order to establish a secure session between the responding station and the initiating station for purposes of performing round trip time fine time measurement (RTT FTM). In this way, the initiating station may determine that the fine time measurement is from a valid initiating station, thereby potentially providing secure fine time measurement for wireless communication protocols.

In some examples, various aspects of the techniques may enable more secure interactions via wireless communication protocols that potentially require accurate proximity detections. While global positioning systems (GPS) and other conventional processes may enable device distance determination, such processes are not as accurate as that provided by way of fine time measurement as described herein. As such, various aspects of the techniques described in this disclosure may enable responding stations and initiating stations to establish a secure session by which FTM may be performed to facilitate instances in which accurate positioning of stations is required prior to permitting access to underlying resources, such as a house and/or a vehicle.

In one example, aspects of the techniques are directed to a method comprising: receiving, in accordance with a wireless networking protocol for communicating between an initiating station and a responding station, a first fine time measurement specifying a first time; receiving, in accordance with the wireless networking protocol and for the corresponding first time, a first message integrity code; and authenticating, based on the first message integrity code, the responding station to establish that the fine time measurement is from a trusted responding station.

In another example, aspects of the techniques are directed to a method comprising: transmitting, in accordance with a wireless networking protocol for communicating between an initiating station and a responding station, a first fine time measurement specifying a first time; transmitting, in accordance with the wireless networking protocol and for the corresponding first time, a first message integrity code; and receiving, responsive to the first message integrity code, an acknowledgement indicating that a secure session has been established between the initiating station and the responding station.

In another example, aspects of the techniques are directed to a system comprising: an initiating station; and a responding station, the responding station comprising: first wireless communication circuitry configured to: transmit, in accordance with a wireless networking protocol for communicating between the initiating station and the responding station, a first fine time measurement specifying a first time; transmit, in accordance with the wireless networking protocol and for the corresponding first time, a first message integrity code; wherein the initiating station comprises: second wireless communication circuitry configured to: receive, in accordance with a wireless networking protocol for communicating between the initiating station and a responding station, the first fine time measurement specifying the first time; receive, in accordance with the wireless networking protocol and for the corresponding first time, the first message integrity code; authenticate, based on the first message integrity code, the responding station to establish a secure session between the initiating station and the responding station; and transmit, in accordance with the wireless networking protocol, an acknowledgement indicating that a secure session has been established between the initiating station and the responding station, wherein the responding station further comprises processing circuitry configured to access, based on receipt of the acknowledgment, a resource associated with the initiating station.

The details of one or more aspects of the techniques are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of these techniques will be apparent from the description and drawings, and from the claims.

DETAILED DESCRIPTION

Wireless networking protocols provide for a process referred to as fine time measurement (FTM). For example, the Institute of Electrical and Electronics Engineers (IEEE) 802.11mc standard defines a round trip time (RTT) FTM to facilitate indoor positioning, which may enable wireless access points (as initiating stations) to better manage delivery of wireless networking services to responding stations (e.g., a smartphone, laptop, portable gaming systems, and/or other portable devices) as the responding stations move between the access points.

That is, wireless access points may initiate RTT FTM (thereby acting as so-called “initiating stations”) to identify a position of the responding stations relative to the initiating stations. The initiating stations may then determine the wireless access points to which the responding station should connect in order to receive wireless networking services having the highest signal to noise ratio (or other metric associated with wireless networking services).

While RTT FTM may provide for accurate identification of receiver station position, RTT FTM may be relatively unsecure as there is no need to properly authenticate that the RTT FTM data is valid. In other words, the IEEE 802.11 standard does not provide for securing RTT FTM data used by initiating and responding station.

In some contexts, the accurate identification of receiver station position may be desirable, especially when such position is relevant prior to permitting access to the initiating station (e.g., for remote keyless entry systems in vehicles and/or smart locks for homes or other uses). Positioning processes, such as angle of arrival (AoA) provided by some personal area network (PAN) protocols or global positioning system (GPS), are only accurate up to a couple (e.g., five or more) meters while RTT FTM may be accurate down to one meter.

In accordance with various aspects described in this disclosure, the initiating station may perform secure fine time measurement. A responding station may not only transmit the fine time measurement, but may also transmit a message integrity code that the initiating station may use to authenticate the fine time measurement as being sent by an authorized responding station. That is, the initiating station may be initially associated with a given responding station, where such association may involve agreement on a shared key that the responding station may use to generate the message integrity code. The initiating station may then authenticate the message integrity code sent by the responding station (using the shared shared key) in order to establish a secure session between the responding station and the initiating station for purposes of performing RTT FTM. In this way, the initiating station may determine that the fine time measurement is from a valid responding station, thereby providing secure fine time measurement for wireless networking protocols in contexts requiring secure proximity detection prior to granting access to resources.

In this way, various aspects of the techniques described herein may ensure backwards compatibility allowing stations that do not implement secure RTT FTM to perform unsecure RTT FTM consistent with the wireless networking protocol (e.g., the above noted IEEE 802.11mc or other FTM wireless networking protocol standards). In some examples, the initiating station may specify a burst duration that is longer than a standard burst duration for performing unsecure RTT FTM (e.g., 2-4 times longer than is normally specified for unsecure RTT FTM) in order to permit delivery of one or more message integrity codes in addition to the FTM. A responding station may compare this burst duration to a threshold burst duration and perform secure RTT FTM when the burst duration is longer than the threshold burst duration. However, if the responding station is not configured to implement secure RTT FTM, the responding station may only send FTM specifying the one or more times without providing any message integrity codes consistent with unsecure RTT FTM, thereby permitting backward compatibility with existing unsecure RTT FTM specified in various wireless network protocol standards.

FIG.1is a block diagram illustrating an example keyless access system configured to perform secure fine time measurement in accordance with various aspects of the techniques described in this disclosure. As shown in the example ofFIG.1, a system100includes a vehicle102and a keyless access device104.

Vehicle102may represent any type of vehicle capable of acting as an initiating station for purposes of performing secure fine time measurement (FTM), such as round trip time (RTT) FTM as set forth in IEEE 802.11mc. Vehicle102may represent any type of vehicle, including an automobile, a truck, farm equipment, a motorcycle, a bike (including electronic bikes), a scooter, construction equipment, a semi-truck, an airplane, a helicopter, a military vehicle, robot, or any other type of vehicle capable of acting as the initiating station.

Keyless access device104may represent any device capable of acting as a responding station for purposes of performing secure FTM, such as RTT FTM as set forth in IEEE 802.1mc. Keyless access device104may include a so-called “key fob,” a smartphone, a laptop computer, a tablet computer, or any other portable device capable of interfacing with the initiating station, i.e., vehicle102in the example ofFIG.1, to perform RTT FTM. Furthermore, keyless access device104may allow an occupant of vehicle102to gain access to an interior of vehicle102(e.g., one or more of a passenger compartment, a glove box or other console compartment, a trunk, or any other compartment or interior of vehicle102) and potentially operate vehicle102.

While described with respect to a keyless access system100, the techniques described in this disclosure may be performed with respect to any system in which secure FTM may be performed in order to potentially more accurately detect a proximity of a responding station to an initiating station in order to permit the responding station to access, control, or otherwise manipulate the initiating station.

For example, various aspects of the techniques may be performed with respect to smartlocks acting as the initiating station with respect to a smartphone acting as a responding station in order to access a house, garage, shed, or other compartment secured by the smartlock.

In some examples, vehicle102may, as shown in the example ofFIG.1, include a transceiver unit110, an antenna selector unit112, processing circuitry114, a storage unit116, a wireless communication protocol (WCP) unit118, and a bus119. Transceiver unit110may represent a unit configured transmit and receive radio frequency (RF) signals according to one or more communication protocols.

When operating as a receiver, transceiver unit110may process received RF signals in the analog domain, perform analog-to-digital signal processing to convert the RF signals into digital signals (or, in other words, digital data), and demodulate the digital data to provide binary data for further processing (e.g., packet processing) by WCP unit118. When operating as a transmitter, transceiver unit110may perform operations reciprocal to those performed when operating as a receiver, receiving digital data from WCP unit118, performing digital-to-analog signal processing to convert the digital data into analog signals, and outputting the analog signals for transmission by one or more of antennas111. As such, transceiver unit110may include circuitry or a combination of software (firmware, middleware, etc. or any other form of instructions or bytecode) for performing analog-to-digital conversion, and digital-to-analog conversion, modulation, demodulation and other forms of signal processing for sending and receiving RF signals via antennas111.

Antenna selector unit112may represent a hardware unit (e.g., circuitry) configured to select one or more antennas111and couple the selected antennas of antennas111to transceiver unit110. In some examples, each of antennas111may represent one or more antennas. Antenna selector unit112may, in some examples, operate as switch circuitry to couple transceiver unit110to one or more antennas111(e.g., a phased array and/or antenna clusters—such as six or eight antennas).

Processing circuitry114may represent any type of circuitry configured to process data. For example, processing circuitry114may represent any combination of one or more of a central processing unit (CPU), a microprocessor, a graphics processing unit, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), a dedicated integrated circuit, a digital signal processor (DSP), an electronic control unit (ECU, which reside, for example, in vehicles), a control unit (which reside, for example, in networking equipment), general circuitry coupled to a printed circuit board (PCB), analog circuitry, and the like.

In instances in which processing circuitry114may represent a CPU, microprocessor or other type of programmable processor that executes instructions, the programmable processor may have a single processing core (which may be referred to as a “core”), or multiple cores that are included in a single package or housing. In some instances, processing circuitry114may include multiple different processors (e.g., a GPU, a CPU, one or more sensors, video and/or audio processors—for compression, rendering, etc., memory, and the like) that reside in a single so-called system-on-a-chip. In some instances, processing circuitry114may be a dedicate integrated circuit that implements a programmable processor along with each of transceiver unit110, antennas111, antenna selector unit112, storage unit116, and WCP unit118.

Storage unit116may represent a non-transitory computer-readable storage media configured to store instructions (although not shown in the example ofFIG.1for ease of illustration purposes) that, when executed, cause processing circuitry114to perform operations attributed to processing circuitry114throughout this disclosure. Storage unit116may include any combination of volatile memory and non-volatile memory. Volatile memory may include dynamic random access memory (DRAM) and/or static RAM (SRAM), while non-volatile memory may include read only memory (ROM, such as erasable programmable ROM—EPROM, electrically EPROM—EEPROM, Flash memory), non-volatile RAM (NVRAM), hard disk drives, solid state drives, optical discs, and the like.

WCP unit118may represent one or more elements configured to implement one or more wireless communication protocols. WCP unit118may be implemented as wireless communication circuitry that performs operations attributed throughout this disclosure to WCP unit118. In any event, WCP unit118may implement wireless communication protocols, including a wireless networking protocol, such as one or more versions of WiFi™ defined in a suite of standards generally denoted as IEEE 802.11 standards, for establishing a wireless local area network (WLAN) connection between a wireless access point and a computing device. Wireless communication protocols may also include wireless personal area network (WPAN) protocols, such as the IEEE 802.15 suite of standards (which define to some extent operation of Bluetooth®), for establishing WPAN connections directly between two computing devices.

That is, wireless networking protocols operate according to a network stack having multiple layers. The layers of any given implementation of a wireless network protocol may include all of or some subset of the layers defined by the Open Systems Interconnect (OSI) model, which includes a physical layer, a data link layer (e.g., Ethernet), a network layer (e.g., Internet protocol—IP), a transport layer (e.g., a transport control protocol—TCP), a session layer, a presentation layer, and an application layer (e.g., hyper-text transfer protocol—HTTP).

WPAN protocols do not generally implement a network stack, but instead provide for a short, direct connection in which a host device (which may also be referred to as a source device) may manage WPAN connections between one or more client devices (which may also be referred to as a sink device). WPAN connections provide for proximate (meaning such connections are generally short range, e.g., 10 meters), low data communication between the host device and the one or more client devices. WPAN connections may access network connections (including wireless network connections) in which one of the devices participating in the WPAN connection acts as a gateway to facilitate forwarding of communications via wireless networking protocols to the LAN and/or WLAN.

In this respect, WLAN protocols are separate and distinct from WPAN protocols, although WLAN protocols may share some resources in common with WPAN protocols, such as RF spectrum. As such, when referring to wireless networking protocols, including WLAN protocols, WPAN protocols (and PAN protocols generally) should be understood to be excluded, in some examples, from wireless network protocols. Although described as being separate, WPAN protocol may, in other examples, be included within WLAN protocols, and the techniques described in this disclosure may apply to both WLAN protocols and WPAN protocols, and more generally to any wireless communication protocols, such as protocols defined in accordance with WiFi™ standards, Bluetooth® standards, Zigbee standards (as defined in IEEE 802.15.4 specifications or, in other words, standards), etc.

Bus119may represent a communication medium that interconnects one or more, and possibly all (as shown in the example ofFIG.1), of transceiver unit110, antenna selector unit112, processing circuitry114, storage unit116, and WCP unit118to one or more, and possibly each, every one of units110-118. Bus119may include inter-chip busses, intra-chip busses, coexistence busses, or any other communication lines that connect the circuits and/or logic represented by units110-118, which may be disposed within an integrated circuit chip or discrete integrated circuit chip.

As further shown in the example ofFIG.1, keyless access device104may include a transceiver unit120, an antenna selector unit122, processing circuitry124, a storage unit126, a WCP unit128, and a bus129. Each of units120-128may be similar to, if not substantially the same as, units110-118described above with respect to vehicle102. Moreover, keyless access device104may include antennas121, which may be similar, if not substantially similar, to antennas111. Bus129may also be similar, if not substantially similar, to bus119.

As noted above, wireless networking protocols provide for a process referred to as fine time measurement (FTM). For example, the IEEE 802.11mc standard defines a round trip time (RTT) FTM to facilitate indoor positioning, which may enable wireless access points (as initiating stations) to better manage delivery of wireless networking services to responding stations (e.g., a smartphone, laptop, portable gaming systems, and/or other portable devices) as the responding stations move between the access points.

In some examples, wireless access points may initiate RTT FTM (thereby acting as so-called “initiating stations”) to identify a distance (and possibly position) of the responding stations from (or in the case of position, relative) to the initiating stations. The initiating stations may then determine which of the wireless access points to which the responding station should connect in order to receive wireless networking services having the highest signal to noise ratio (or other metric associated with wireless networking services).

While 802.11 RTT FTM may provide for accurate identification of receiver station distance from the initiating station, RTT FTM may be relatively unsecure as there is no authentication ensuring that the RTT FTM data is valid. As such, RTT FTM data is sent in the clear without any encryption or other authentication data.

In some contexts, such as keyless access system100, the accurate identification of receiver station distance from the initiating station may be important especially when such distance is relevant prior to permitting access to the initiating station (e.g., for remote keyless entry systems in vehicles and/or smart locks for homes or other usesPositioning processes, such as angle of arrival (AoA) provided by some personal area network (PAN) protocols or a global positioning system (GPS), are only accurate up to a couple (e.g., five or more) meters while RTT FTM may be accurate down to one meter.

Consider example keyless access system100shown in the example ofFIG.1in which vehicle102may act as the initiating station (and, as such, may be referred to as initiating station102) while keyless access device104may act as the responding station (and, as such, may be referred to as responding station104). Vehicle102may determine a distance between vehicle102and keyless access device104so as to only enable access to vehicle102when the distance between keyless access device104and vehicle102is below a threshold distance. Such distance between vehicle102and keyless access device104may be a criterion for enabling access to vehicle102for safety and/or security reasons.

For example, allowing keyless access device104to access vehicle102to open a door may result in a door being opened that harms a person, an adjacent vehicle, a shopping cart, a pet, or other individual, animal or property that is not visible or noticeable from relatively larger distances (e.g., above the threshold distance). As another example, allowing keyless access device104to access vehicle102to unlock or open a door may result in unauthorized entry of persons that may steal or otherwise harm personal property stored in vehicle (or harm the interior of vehicle itself).

Furthermore, large inaccuracies in determining the distance between keyless access device104and vehicle102may result in allowing keyless access device104to access vehicle102when such access should have been denied. That is, having an error on the order of several meters when computing the distance between vehicle102and keyless access device104may enable access in instances for which access should have been denied (due to the actual distance being greater than that determined).

In accordance with various aspects described in this disclosure, initiating station102may perform secure fine time measurement. Responding station104may not only transmit the fine time measurement (FTM) data130, but may also transmit a message integrity code (MIC)132that initiating station102may use to authenticate keyless access device104as sending secure FTM data130. That is, initiating station102may be initially associated with a given responding station, i.e., responding station104in the example ofFIG.1, where such association may involve agreement on a shared key (SK)134that responding station104may use to generate MIC132. Examples of shared key134include a group temporal key (GTK), a unicast key (e.g., a pairwise transit key—PTK), and the like.

Initiating station102may then authenticate MIC132sent by responding station104(using shared SK134) in order to establish a secure session between responding station10and initiating station102for purposes of performing RTT FTM. In this way, initiating station102may determine that FTM data130is from a valid responding station, thereby potentially providing secure FTM for wireless networking protocols in contexts requiring secure proximity detection prior to granting access to resources (e.g., vehicle102).

In operation, initiating station102may initially specify, in a first frame of FTM frames136, a request for RTT FTM that includes a burst duration (that is above a threshold burst duration in order to signal that FTM is to be authenticated via MIC132(or, in other words, that secure FTM is to be performed). Although described with respect to the burst duration being above the threshold burst duration in order to signal that secure FTM is to be performed, initiating station102may specify, as an alternative to, or in conjunction with, the burst duration being above the threshold burst duration, an indication that secure FTM is to performed in which FTM data130is to be authenticated via MIC132.

In either event, initiating station102may provide the first frame of FTM frames136to transceiver unit110, which may transmit the first frame via antennas111(or some subset of antennas111selected by antenna selector unit112). It should be noted that the term “frame” refers to an Ethernet frame consistent with layer two communications via layer two of the foregoing network stack, where WCP unit118may generate the first frame (and for that matter, all of FTM frames136) in accordance with the IEEE 802.11mc standard defining RTT FTM for the Ethernet protocol (and possibly other layer two networking protocols).

In any event, responding station104may receive the first frame of FTM frames136requesting RTT FTM and specifying the burst duration that is above the threshold burst duration. Responding station104may receive the first frame as an RF signal via antenna121(or some subset of antennas121selected by antenna selector unit122). More specifically, transceiver120may receive the first frame of FTM frames136, converting as noted above, the first frame into a digital representation of the first frame of FTM frames136. Transceiver unit120may pass the first frame of FTM frames136to WCP unit128, which may process the first frame to parse the burst duration from the first frame.

WCP unit128may compare the burst duration specified in the first frame to the burst duration threshold (BDT)138in order to determine whether to perform secure FTM. Assuming for purposes of illustration that the parsed burst duration is greater than BDT138, WCP unit128may determine that secure FTM is to be performed. As such, WCP unit128may access storage unit126to obtain SK134, and determine, based on SK134, MIC132.

WCP unit128may also determine FTM data130, which may include a first indication of a fine time measurement specifying a first time (and possibly a second time). That is, FTM data130may specify a time a subsequent frame of FTM frames136specifying FTM data130from responding station104was sent by responding station104and a time the subsequent frame of FTM frames136specifying FTM data130from initiating station102was received. However, considering the first frame of FTM frames136only specifies a request for FTM and did not include any FTM data130, and that this is the first frame of FTM frames136that includes FTM data130, WCP unit128may specify FTM data130as null for both times. In any event, WCP unit128may transmit FTM data130to WCP unit118in this manner for one or more additional iterations, as will be described in greater detail with respect to the example ofFIG.2.

In some examples, WCP unit118may receive, in accordance with a wireless networking protocol for communicating between initiating station102and responding station104, FTM data130specifying at least a first time (e.g., a time a subsequent frame of FTM frames136specifying FTM data130from responding station104was sent by responding station104and a time the subsequent frame of FTM frames136specifying FTM data130from initiating station102was received). After the iterations of providing FTM frames136specifying FTM data130has concluded, WCP unit128may generate one or more FTM frames136that specify MIC132generated using SK134.

As further shown in the example ofFIG.1, WCP unit128may include a MIC generation (GEN) unit150configured to generate, based on SK134, MIC132. As discussed above, WCP unit128may initially execute a WPAN or other wireless communication protocol to establish an association with initiating station102. In some examples, WCP unit128may execute the WPAN to detect, prior to establishing communication via the wireless network protocol, initiating station102(or vice versa, where initiating station102may execute WPAN to detect responding station104). WCP unit128may utilize WPAN protocols to detect initiating station102as the WPAN protocol may utilize less energy or otherwise consume less processing or other computing resources of responding station104(which may operate via a battery or other portable power source that has a limited duration compared to wired power sources). WCP unit128may then enable, responsive to detecting initiating station102via the WPAN, the communication via the wireless network protocol between initiating station102and responding station104.

In any event, WCP unit128may initially execute the WPAN to establish a WPAN connection (or in other words, session) with initiating station102to exchange SK134. SK134may represent a key by which to generate MIC132that is specific to the wireless networking session to be established between responding station104and initiating station102. MIC generation unit150may then utilize SK134to generate MIC132, or in other words, generate, based on SK134, MIC132. WCP unit128may then generate FTM frames136to include MIC132(where FTM frames136may include a MIC frame formatted in accordance with the wireless networking protocol in which the FTM frame136wraps the MIC frame or portions thereof as described in more detail below). WCP unit128may next transmit the FTM frames136to initiating station102.

Initiating station102may, as a result, receive, in accordance with the wireless networking protocol and for the corresponding first time, the authentication frames specifying MIC132. Initiating station102may associate any given MIC132to each of the subsequent frames of the FTM frames136specifying FTM data130based on a time specified in the authentication frames of FTM frames136. That is, WCP unit128may generate each authentication frame to include a time at which each of the corresponding FTM frames136was sent, thereby allowing WCP unit118to determine to which of FTM frames136each authentication frame corresponds in order to authenticate responding station104as a valid responding station.

WCP unit118may thereby authenticate, based on MIC132, responding station104to establish a secure session between initiating station102and responding station104and thereby establish that FTM data130is from a trusted (or valid) responding station. To authenticate responding station104based on MIC132, initiating station102may apply SK134to some base value (e.g., a time at which WCP unit128received the subsequent frame specifying FTM data130, FTM data130, etc.) in order to reconstruct a comparison MIC (which is shown in the example ofFIG.1as authentication MAC—AMAC—141). WCP unit118may include a MIC generation (GEN) unit140configured to generate, based on SK134, AMIC141. Initiating station102may then compare the AMAC141to MIC132specified in the corresponding frame of FTM frames136.

When AMIC141is different from MIC132, initiating station102may determine that responding station104is not a valid or, in other words, authorized (or, in other words, trusted or valid) responding station and may revoke access to vehicle102. When AMIC141is the same as MIC132, initiating station102may determine that responding station104is a trusted or, in other words, authorized responding station, and may permit responding station104to access initiating station102. Initiating station102may, in other words, permit, based on successful authentication of responding station104, responding station104to access a resource144associated with initiating station102(e.g., where resource144may represent a lock or other resources associated with a door, trunk or other compartment, etc. or generally operation of vehicle102).

In some instances, initiating station102may not permit access to resource144even after authenticating responding station104when responding station104is not within a set distance threshold (DT)145. WCP unit118may include, as further shown in the example ofFIG.1, a conversion (CONV) unit142configured to convert FTM data130into one or more distances (DIST)143according to the IEEE 802.11mc standard. Conversion unit142may determine, based on FTM data130(e.g., one or more FTMs representative of times), distance143. WCP unit118may next compare distance143to distance threshold145. When distance143is greater than distance threshold145, WCP unit118may not permit responding station104to access resource144associated with initiating station102. When distance143is less than or equal to distance threshold145, WCP unit118may permit responding station104to access resource144associated with initiating station102.

In this respect, WCP unit128normally has WiFi™ interfaces turned off, and periodically turns on the Bluetooth® low energy (BLE) interface to detect if any initiating stations, such as initiating station102, (to which WCP unit128has been previously associated) is close to initiating station102(or the underlying resource144). WCP unit128may operate in this manner to preserve battery power as the WiFi™ interface may consume more power than BLE. When BLE interfaces of WCP unit128detects BLE interface of WCP unit118, WCP units118and128may enable respective WiFi™ interfaces for quick distance measurement using the secure FTM techniques described in this disclosure to verify that responding device104is in close range (within distance threshold145) to resource144.

In some examples, various aspects of the techniques may enable more secure interactions via wireless communication protocols that potentially require accurate proximity detection. While personal area networks (PAN) or global positioning systems (GPS) may provide distance determination of devices, such distance determination of devices provided by PANs or GPS is not as accurate as that provided by way of FTM in accordance with wireless networking protocols. As such, various aspects of the techniques described in this disclosure may enable responding station104and initiating station102to establish a secure session by which FTM may be performed to facilitate instances in which accurate positioning of stations is required prior to permitting access to underlying resources, such as a house and/or a vehicle102.

Furthermore, various aspects of the techniques described herein may ensure backwards compatibility allowing stations that do not implement secure RTT FTM to perform unsecure RTT FTM consistent with the wireless networking protocol (e.g., the above noted IEEE 802.11mc or other FTM wireless networking protocol standards). That is, initiating station102may specify a burst duration that is longer than a standard burst association for performing unsecure RTT FTM (e.g., 2-4 times longer than is normally specified for unsecure RTT FTM) in order to permit delivery of one or more MICs132in addition to the FTM data130specifying one or more times. Responding station104may compare this burst duration to BDT138and perform secure RTT FTM when the burst duration is longer than BDT138. However, if responding station104is not be configured to implement secure RTT FTM, responding station104may only send FTM data130specifying the one or more times without providing any MIC132consistent with unsecure RTT FTM, thereby permitting backward compatibility with existing unsecure RTT FTM specified in various wireless network protocol standards.

FIG.2is a timing diagram illustrating example negotiation and frame exchange sequence between an initiating station and a responding station when performing various aspects of the secure fine time measurement techniques described in this disclosure. As shown in the example ofFIG.2, secure FTM system200may include an initiating station202and a responding station204. Vehicle102ofFIG.1may represent an example of initiating station202, while keyless access device104may represent an example of responding station204.

In any event, initiating station202may initially generate frame136A in accordance with the wireless networking protocol that requests FTM (“initial FTM request” frame136A). Frame130A may also specify a burst duration205capable of accommodating multiple times (e.g., 3 to 4 times) the duration needed for FTM measurement frames per burst to allow responding station204to send back FTM frames specifying FTM data130(or, in other words, times) followed by FTM frames specifying corresponding MICs132. Responding station204may receive frame136A and generate an FTM frame136B specifying acknowledgement of frame136A (“ACK” frame136B).

Responding station204may next generate an initial FTM frame136C (“initial FTM_1(0,0)” frame136C) specifying FTM data130, which may include a time of departure of a subsequently sent FTM frame and a time of arrival of an ACK frame acknowledging the subsequently sent FTM frame. As frame136C is the initial FTM frame, responding station204determines that there is no subsequent FTM frame specifying FTM data130, and sets the time of departure of the subsequently sent FTM frame to zero (“0”) and the time of arrival of the ACK frame acknowledging the subsequently sent FTM frame to zero (“0”). Initiating station202may receive frame136C and generate an FTM frame136D specifying acknowledgement of frame136D (“ACK” frame136D).

Responding station204may next generate an FTM frame136E (“FTM_2(T1_1,T4_1)” frame136E) specifying FTM data130, which may include a time of departure of subsequently sent FTM frame136C specifying FTM data130(which is shown as “T1_1” in the example ofFIG.2) and a time of arrival of ACK frame136D acknowledging subsequently sent FTM frame136C (which is shown as “T4_1” in the example ofFIG.2). That is, the notation on the left and right sides along the lines denoted “responding STA204” and “initiating STA202” indicate the time of departure (TOD) for packets sent by responding station204and initiating station202and a time of arrival (TOA) for packets received by responding station204and initiating station202. In any event, responding station204sends FTM frame136E to initiating station202, which may receive frame136E and generate an FTM frame136F specifying acknowledgement of frame136F (“ACK” frame136F).

Responding station204may next generate an FTM frame136G (“FTM_3(T1_2,T4_2)” frame136G) specifying FTM data130, which may include a time of departure of subsequently sent FTM frame136E specifying FTM data130(which is shown as “T1_w” in the example ofFIG.2) and a time of arrival of ACK frame136F acknowledging subsequently sent FTM frame136E (which is shown as “T4_2” in the example ofFIG.2). Responding station204sends FTM frame136G to initiating station202, which may receive frame136G and generate an FTM frame136H specifying acknowledgement of frame136G (“ACK” frame136H).

Up to this point in the exchange of FTM frames136A-136H, responding station204may have operated in accordance with unsecure FTM as set forth by the wireless networking protocol, while initiating station202may have only differed from unsecure FTM by way of specifying burst duration205that is multiple times the duration necessary to accommodate unsecure FTM. In this respect, secure FTM is backwards compatible and standard compliant with unsecure FTM as set forth by the wireless networking protocol.

If responding station204implements secure FTM in accordance with various aspects of the techniques described herein, responding station204may, upon receiving initial FTM frame136A specifying burst duration205, parse an indication of burst duration205from initial FTM frame136A and compare burst duration205to BDT138. As noted above, when burst duration205is less than BDT138, responding station204implements the foregoing exchange to perform unsecure FTM. However, when burst duration205is greater than BDT138, responding station204implements secure FTM.

In some examples, to implement secure FTM, responding station204generates MIC132for each of FTM frames136C,136E, and136G using SK134. Responding station204and initiating station202may exchange SK134in the most recent successful associating between initiating station202and responding station204. Both of stations202and204store SK134for the most recent associations with all other stations in storage unit126, where each SK134for each association is identified by the media access control (MAC) address for the other station.

For example, responding station204may parse a MAC address associated with initiating station202from a frame header on initial FTM request frame136A. Using the MAC address associated with initiating station202, responding station204may perform a lookup in a table storing GTKs, accessing SK134identified by the MAC address associated with initiating station202. Using the lookup table (or other data structure) may avoid responding station204and initiating station202from having to perform an association each time responding station204attempts to access initiating station202(which may conserve computing resources and avoid unnecessary operations that would otherwise consume processing cycles, memory, bus bandwidth and associated power or other computing resources).

Responding station204may generate FTM frame136I that includes MIC132(“FTM_4(initial FTM MIC)” frame136I). Responding station204may indicate that MIC132corresponds to initial FTM frame136C by specifying, in FTM frame136I, a TOD equal to the TOD for initial FTM frame136C (which in this example is denoted as “0”). Responding station204may transmit FTM frame136I to initiating station202, which may parse the TOD and MIC132from FTM frame136I.

Initiating station202may then access FTM data130associated with FTM frame136C (stored to storage unit116) to identify which FTM data130is being authenticated. Initiating station202may generate a comparison MIC (or, in other words, an authentication MIC) using SK134and compare the authentication MIC to MIC132parsed from frame136I. If the authentication MIC matches MIC132, initiating station202may authenticate FTM data130provided by FTM frame136C as coming from a valid responding station. If the authentication MIC does not match MIC132, initiating station202may not authenticate FTM data130as coming from a valid responding station (possibly removing FTM data130associated with responding station204from storage unit116).

Responding station204and initiating station202may continue in this manner with responding station204generating and transmitting FTM frames136K and136M having MIC132associated with FTM frames136E and136G respectively by way of TOD specified in FTM frames136K and136M of “T1_1” and “T1_2.” In each instance, initiating station202may respond to receipt of FTM frames136I,136K, and136M with ACK FTM frames136J,136L, and136N, while also authenticating FTM data130associated with each of the identified FTM frames136E,136G as being generated by a valid responding station.

After authenticating all of the FTM data130using MIC132, initiating station202may convert FTM data130into an approximate distance from initiating station202to responding station204using standard unsecured FTM distance conversion processes set forth in the wireless networking protocol. As noted above, when this distance is below a distance threshold, initiating station202may permit responding station204to access initiating station202. In this respect, initiating station202may permit, based on successful authentication of MIC132for FTM frames130received from responding station204, responding station to access initiating station202.

FIGS.3A and3Bare conceptual diagrams showing examples of fine time measurement frames that stations shown in the example ofFIGS.1and2may generate in order to perform various aspects of the secure fine time measurement techniques. Referring first to the example ofFIG.3A, FTM frame300may conform to the wireless networking protocol specified by the IEEE 802.11mc standard, and may represent an example of FTM frames136. FTM frame300may have a general form in which an element identifier (ID)302identifies a type of frame, followed by a length304that identifies a length of the following field, which in this instance is an FTM parameters field306. Initiating station202may specify element ID302to indicate that FTM parameters are defined in FTM parameters field306(e.g., set element ID302to a value of 206 as set forth in the above noted IEEE 802.11mc standard).

Referring next to the example ofFIG.3B, FTM parameters field306is shown in more detail. FTM parameters field306may include a status field310, a value field312, a reserved field314, a number of burst exponent (NBEX) field316, a burst duration (BD) field318, a minimum delta FTM (“MIN D FTM320”), a partial timing synchronization function (TSF) timer field322(“P TSF TIMER322”), a partial TSF timer number preference field324(“P TSF TIMER NO PREF324”), an as-soon-as-possible (ASAP) capable field326, an ASAP field328, an FTM per burst field330(“FTM/BURST330”), a reserved (RSVP) field332, a format and bandwidth (FAB) field334, and a burst period field336.

For purposes of explaining secured FTM, a full explanation of each of fields310-336is not provided in this disclosure. Instead, each of these fields310-336are defined in more detail in section 9.4.2.168 of the IEEE standard 802.11-2016 entitled “Part11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications,” prepared by the 802.11 Working Group of the LAN/MAN Standards Committee of the IEEE Computer Society, and approved Dec. 7, 2016 (hereinafter referred to as the “IEEE standard 802.11-2016”).

To the extent FTM parameters306related to secured FTM, initiating station202may, when negotiating an FTM session, include FTM parameters306in initial FTM request frame136A. Initiating station202may specify burst duration205in burst duration field318, setting burst duration205to multiple times the duration that normally accommodates the specified number of FTMs per burst set forth in FTM per burst field330. In this way, initiating station202may signal to responding station204that responding station204should perform secure FTM by sending FTM frames136C,136E, and136G specifying FTM data130followed by FTM frames136I,136K, and136N specifying MIC132.

FIGS.4A and4Bare conceptual diagrams showing additional examples of fine time measurement frames that stations shown in the example ofFIGS.1and2may generate in order to perform various aspects of the secure fine time measurement techniques. Referring first to the example ofFIG.4A, MIC frame400may conform to the wireless networking protocol specified by the IEEE 802.11mc standard. MIC frame400may have a general form in which an element identifier (ID)402identifies a type of frame (which is set to a value of 76 to signal this is a management MIC frame), followed by a length404that identifies a length of the following fields, which in this instance is a key ID field406, an integrity shared key packet number (IPN) field408, and a MIC field410. Again, each of these fields are defined in more detail in the IEEE 802.11-2016 standard.

MIC frame400may represent a management MIC frame used during normal operation of the wireless networking protocol (e.g., during normal frame delivery to ensure message integrity and prevent forgery and replay). That is, MIC frame400may protect data frames unassociated with FTM processes, as the IEEE 802.11-2016 standard does not provide for MIC frames400for FTM frames136. MIC frame400may be of variable length as MIC field410may be 8 octets or 16 octets long depending on the extent of authentication required (with longer MICs being more difficult to spoof or otherwise crack). The total length of MIC frame400may be between 18-26 octets. In order to insert MIC frame400into FTM frames136, responding station204may adapt FTM frames136to carry MIC frame400(either in its entirety or as one or more portions in successive FTM frames).

Referring next to the example ofFIG.4B, an example FTM frame420is shown that conforms to the wireless networking protocol specified by the IEEE 802.11mc standard, and may represent an example of FTM frames136, such as FTM frames136C,136E, and136G that specify FTM data130. FTM frame420includes a category field422, a public (“PUB”) action field424, a dialog token (“TKN”) field428, a TOD field430, a TOA field432, a TOD error field434, a TOA error field436, a location configuration information (LCI) report field438, a location civic (LC) report field440, an FTM parameters field442, and a FTM synchronization information (SI) field444. Again, each of these fields are defined in more detail in the IEEE 802.11-2016 standard.

Responding station204may generate FTM frame420and may specify the TOD, in TOD field430, for the subsequent FTM frame136specifying FTM data130sent by responding station204and a TOA, in TOA field432, for an ACK FTM frame136sent in response to the subsequent FTM frame136specifying FTM data130received by responding station204. However, to maintain backwards compatibility, responding station204may repurpose FTM frame420to specify portions of MIC frame400, and thereby provide secure FTM.

To repurpose FTM frame420, responding station204may replace TOA field432, TOD error field434, and TOA error field436with a portion of MIC frame400. As such, responding station204may sent multiple FTM frames420having different portions of MIC frame400in order to specify MIC frame400across multiple FTM frames420.

To illustrate, consider that responding station204may generate MIC132using a short management element (e.g., for broadcast integrity protocol-cipher-based message authentication code-128 bit—BIP-CMAC-128). Using this short management element, responding station204may generate MIC frame420having 18 octets. Responding station204may specify the first 10 octets in the 10 octets represented by TOA field432, TOD error field434, and TOA error field436of a first FTM frame420. Responding station204may next specify the remaining 8 octets in the 10 octets represented by TOA field432, TOD error field434, and TOA error field436of a second FTM frame420(which may be padded to 10 octets to avoid parsing errors). In this respect, initiating station202may specify a burst duration of three times the normal burst duration for unsecured FTM as three FTM frames136are sent to authenticate each FTM frame136specifying FTM data130.

When responding station204uses a larger management element in which MIC132is an additional 8 octets (such as when using BIP-CMAC-256), responding station204generates three FTM frames420to specify the longer MIC frame400(as both the first and second FTM frames420specify a full 10 octets and the third FTM frame420is required to send the remaining 6 octets—which may be padded to 10 octets to avoid potential parsing errors). In this instance, initiating station202may specify a burst duration that is four times the normal burst duration for unsecured FTM, as three additional FTM frames420are required to authenticate FTM frames420specifying MIC frames400.

FIG.5is a flowchart illustrating example operations or methods of the keyless access system ofFIG.1in performing various aspects of the secure fine time measurement techniques described in this disclosure. Initiating station102may initially specify, in a first frame of FTM frames136, a request for RTT FTM that includes a burst duration205(FIG.2) (500). Initiating station102may transmit the request for FTM to responding station104(502).

Responding station104may receive the first frame of FTM frames136requesting RTT FTM and parse burst duration205from the first frame (504). Responding station104may compare burst duration205specified in the first frame to the burst duration threshold (BDT)138(506) in order to determine whether to perform secure FTM. When parsed burst duration205is less than or equal to BDT138(“NO”506), responding device102may perform unsecured FTM (508).

When parsed burst duration205is greater than BDT138(“YES”506), responding station104may determine whether a shared key exists in storage unit126for initiating station102(or, in other words, whether responding station104has been previously associated with initiating station102) (509). When responding station104does not include a shared key in storage unit126that corresponds to initiating station102, responding station104may perform unsecured FTM (508). When responding station104includes a shared key in storage unit126that corresponds to initiating station102(e.g., SK134), responding station104may obtain SK134, and determine, based on SK134, MIC132(510).

Responding station104may also determine FTM data130(512), which may include a first indication of a fine time measurement specifying a first time (and possibly a second time). Responding station104may transmit FTM data130to initiating station102(514) in this manner for one or more additional iterations. As such, initiating station102may receive, in accordance with a wireless networking protocol for communicating between initiating station102and responding station104, FTM data130specifying at least a first time (516).

Responding station104may also transmit MIC132. That is, after the iterations of providing FTM frames136specifying FTM data130has concluded, responding station104may generate one or more FTM frames136that specify MIC132generated using SK134. Responding station104may transmit the FTM frames136to initiating station102. In this manner, responding station104may transmit FTM data130and MIC132to initiating station102(514), where initiating station102may receive FTM data130and MIC132(516).

Initiating station102may thereby authenticate MIC132(518) to establish a secure session between initiating station102and responding station104. To authenticate MIC132, initiating station102may apply SK134to some base value (e.g., a time at which WCP unit128received the subsequent frame specifying FTM data130, FTM data130, etc.) in order to reconstruct a comparison MIC (which is not shown in the example ofFIG.1for ease of illustration purposes). Initiating station102may then compare the comparison MIC to MIC132specified in the corresponding frame of FTM frames136.

When the comparison MIC is different from MIC132, initiating station102may determine that responding station104is not a valid or, in other words, authorized responding station and may revoke access to vehicle102. When the comparison MIC is the same as MIC132, initiating station102may determine that responding station104is a valid or, in other words, authorized responding station, and may permit responding station104to access initiating station104. Initiating station102may, in other words, permit, based on authentication of the MIC132, responding station104to access initiating station102(e.g., to initiate an unlock door, trunk or other compartment, or potentially open a door, trunk, etc) (520). Responding station104may then access initiating station102(522).

The following clauses may illustrate one or more aspects of the disclosure.

Clause 1A. A method comprising: receiving, in accordance with a wireless networking protocol for communicating between an initiating station and a responding station, a first fine time measurement specifying a first time; receiving, in accordance with the wireless networking protocol and for the corresponding first time, a first message integrity code; and authenticating, based on the first message integrity code, the responding station to establish that the fine time measurement is from a trusted responding station.

Clause 2A. The method of clause 1A, further comprising: specifying, in a first frame that conforms to the wireless networking protocol, an indication that the fine time measurement is to be authenticated via one or more message integrity codes that includes the first message integrity code; and transmitting, via the wireless networking protocol, the first frame to the responding station.

Clause 3A. The method of clause 2A, wherein specifying the indication comprises specifying, in the first frame that conforms to the wireless networking protocol, a burst duration along with a request for performing fine time measurement, wherein the burst duration is above a threshold burst duration to indicate that the responding station is to be authenticated via one or more message integrity codes that includes the first message integrity code.

Clause 4A. The method of any combination of clauses 1A-3A, further comprising: generating a first frame in accordance with the wireless networking protocol that requests fine time measurement; sending, to the responding station, the first frame, wherein receiving the first fine time measurement for the first time comprises receiving a second frame that includes the first fine time measurement specifying the first time, wherein the method further comprises: generating a third frame specifying an acknowledgement to the second frame; and sending, to the responding station, the third frame.

Clause 5A. The method of any combination of clauses 1A-4A, wherein authenticating the responding station comprises: computing, based on a shared key, an authentication message integrity code; comparing the authentication message integrity code to the first message integrity code; and authenticating, based on the comparison of the authentication message integrity code to the first message integrity code, the responding station to establish the secure session between the responding station and the initiating station.

Clause 6A. The method of any combination of clauses 1A-5A, further comprising: receiving, in accordance with the wireless networking protocol, a second fine timing measurement specifying a second time; and receiving, in accordance with the wireless networking protocol and for the corresponding second time, a second message integrity code, wherein authenticating the responding station comprises authenticating, based on the first message integrity code and the second message integrity code, the responding station to establish the secure session between the initiating station and the responding station.

Clause 7A. The method of any combination of clauses 1A-6A, further comprising associating, via a personal area network, the initiating station to the responding station to exchange a shared key by which to generate the first message integrity code.

Clause 8A. The method of any combination of clauses 1A-7A, further comprising: detecting, via the personal area network and prior to enabling communication via the wireless network protocol, the responding station; and enabling, responsive to detecting the responding station via the personal area network, the communication via the wireless network protocol between the initiating station and the responding station.

Clause 9A. The method of any combination of clauses 1A-8A, further comprising: converting, based on successful authentication of the first message integrity code, the fine time measurement into a distance; and permitting, when the distance is less than a threshold distance, the responding station to access a resource associated with the initiating station.

Clause 10A. The method of clause 9A, wherein permitting the responding station to access the initiating station comprises allowing, based on successful authentication of the first message integrity code, the responding station to unlock a lock coupled to the initiating station.

Clause 11A. The method of any combination of clauses 1A-10A, wherein the wireless networking protocol comprises a wireless networking protocol that conforms to an Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard.

Clause 12A. An initiating station comprising: wireless communication circuitry configured to: receive, in accordance with a wireless networking protocol for communicating between the initiating station and a responding station, a first fine time measurement specifying a first time; receive, in accordance with the wireless networking protocol and for the corresponding first time, a first message integrity code; and authenticate, based on the first message integrity code, the responding station to establish that the fine time measurement is from a trusted responding station.

Clause 13A. The initiating station of clause 12A, wherein the wireless communication circuitry is further configured to: specify, in a first frame that conforms to the wireless networking protocol, an indication that the fine time measurement is to be authenticated via one or more message integrity codes that includes the first message integrity code; and transmit, via the wireless networking protocol, the first frame to the responding station.

Clause 14A. The initiating station of clause 13A, wherein the wireless communication circuitry is, when specifying the indication, configured to: specify, in the first frame that conforms to the wireless networking protocol, a burst duration along with a request for performing fine time measurement, wherein the burst duration is above a threshold burst duration to indicate that the responding station is to be authenticated via one or more message integrity codes that includes the first message integrity code.

Clause 15A. The initiating station of any combination of clauses 12A-14A, wherein the wireless communication circuitry is further configured to: generate a first frame in accordance with the wireless networking protocol that requests fine time measurement; transmit, to the responding station, the first frame, wherein the wireless communication circuitry is, when receiving the first fine time measurement for the first time, configured to receive a second frame that includes the first fine time measurement specifying the first time, wherein the wireless communication circuitry is further configured to: generate a third frame specifying an acknowledgement to the second frame; and transmit, to the responding station, the third frame.

Clause 16A. The initiating station of any combination of clauses 12A-15A, wherein the wireless communication circuitry is, when authenticating the responding station, configured to: compute, based on a shared key, an authentication message integrity code; compare the authentication message integrity code to the first message integrity code; and authenticate, based on the comparison of the authentication message integrity code to the first message integrity code, the responding station to establish the secure session between the responding station and the initiating station.

Clause 17A. The initiating station of any combination of clauses 12A-16A, wherein the wireless communication circuitry is further configured to: receive, in accordance with the wireless networking protocol, a second fine timing measurement specifying a second time; and receive, in accordance with the wireless networking protocol and for the corresponding second time, a second message integrity code, wherein the wireless communication circuitry is, when authenticating the responding station, configured to authenticate, based on the first message integrity code and the second message integrity code, the responding station to establish the secure session between the initiating station and the responding station.

Clause 18A. The initiating station of any combination of clauses 12A-17A, wherein the wireless communication circuitry is further configured to associate, via a personal area network, the initiating station to the responding station to exchange a shared key by which to generate the first message integrity code.

Clause 19A. The initiating station of any combination of clauses 12A-18A, wherein the wireless communication circuitry is further configured to: detect, via the personal area network and prior to enabling communication via the wireless network protocol, the responding station; and enable, responsive to detecting the responding station via the personal area network, the communication via the wireless network protocol between the initiating station and the responding station.

Clause 20A. The initiating station of any combination of clauses 12A-19A, wherein the wireless communication circuitry is further configured to: convert, based on successful authentication of the first message integrity code, the fine time measurement into a distance; and permit, when the distance is less than a threshold distance, the responding station to access a resource associated with the initiating station.

Clause 21A. The initiating station of clause 20A, wherein the wireless communication circuitry is, when permitting the responding station to access the initiating station, configured to allow, based on successful authentication of the responding station, the responding station to unlock a lock coupled to the initiating station.

Clause 22A. The initiating station of any combination of clauses 12A-21A, wherein the wireless networking protocol comprises a wireless networking protocol that conforms to an Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard.

Clause 23A. A non-transitory computer-readable storage media storing instructions that, when executed, cause one or more processors to perform each step of the method recited in any combination of clauses 1A-11A.

Clause 1B. A method comprising: transmitting, in accordance with a wireless networking protocol for communicating between an initiating station and a responding station, a first fine time measurement specifying a first time; transmitting, in accordance with the wireless networking protocol and for the corresponding first time, a first message integrity code; and receiving, responsive to the first message integrity code, an acknowledgement indicating that a secure session has been established between the initiating station and the responding station.

Clause 2B. The method of clause 1B, further comprising receiving a first frame in accordance with the wireless networking protocol, the first frame including an indication that fine time measurement is to be authenticated via one or more message integrity codes that includes the first message integrity code.

Clause 3B. The method of clause 2B, wherein the indication comprises a burst duration that is above a threshold burst duration to signal that the fine time measurement is authenticated via one or more message integrity codes that includes the first message integrity code.

Clause 4B. The method of any combination of clauses 1B-3B, further comprising receiving a first frame that conforms to the wireless networking protocol that requests fine time measurement, wherein transmitting the first fine time measurement for the first time comprises transmitting a second frame that includes the first fine time measurement specifying the first time, and wherein the method further comprises receiving a third frame specifying an acknowledgement to the second frame that includes a second time representative of when the second frame was received and a third time representative of when the third frame was sent.

Clause 5B. The method of any combination of clauses 1B-4B, further comprising: transmitting, in accordance with the wireless networking protocol, a second fine timing measurement specifying a second time; and transmitting, in accordance with the wireless networking protocol and for the corresponding second time, a second message integrity code to establish the secure session between the initiating station and the responding station.

Clause 6B. The method of any combination of clauses 1B-5B, further comprising associating, via a personal area network, the initiating station with the responding station to exchange a shared key by which to generate the first message integrity code.

Clause 7B. The method of any combination of clauses 1B-6B, further comprising accessing, based on receipt of the acknowledgement, a resource associated with the initiating station.

Clause 8B. The method of any combination of clauses 1B-7B, further comprising: detecting, via the personal area network and prior to enabling communication via the wireless network protocol, the initiating station; and enabling, responsive to detecting the initiating station via the personal area network, the communication via the wireless network protocol between the initiating station and the responding station.

Clause 9B. A responding station comprising: wireless communication circuitry configured to: transmit, in accordance with a wireless networking protocol for communicating between an initiating station and the responding station, a first fine time measurement specifying a first time; transmit, in accordance with the wireless networking protocol and for the corresponding first time, a first message integrity code; and receive, responsive to the first message integrity code, an acknowledgement indicating that a secure session has been established between the initiating station and the responding station.

Clause 10B. The responding station of clause 9B, wherein the wireless communication circuitry is further configured to receive a first frame in accordance with the wireless networking protocol, the first frame including an indication that fine time measurement is to be authenticated via one or more message integrity codes that includes the first message integrity code.

Clause 11B. The responding station of clause 10B, wherein the indication comprises a burst duration that is above a threshold burst duration to signal that the fine time measurement is authenticated via one or more message integrity codes that includes the first message integrity code.

Clause 12B. The responding station of any combination of clauses 9B-11B, wherein the wireless communication circuitry is further configured to: receive a first frame that conforms to the wireless networking protocol that requests fine time measurement, wherein the wireless communication circuitry is, when transmitting the first fine time measurement for the first time, configured to transmit a second frame that includes the first fine time measurement specifying the first time, and further configured to receive a third frame specifying an acknowledgement to the second frame that includes a second time representative of when the second frame was received and a third time representative of when the third frame was sent.

Clause 13B. The responding station of any combination of clauses 9B-12B, further configured to: transmit, in accordance with the wireless networking protocol, a second fine timing measurement specifying a second time; and transmit, in accordance with the wireless networking protocol and for the corresponding second time, a second message integrity code to establish the secure session between the initiating station and the responding station.

Clause 14B. The responding station of any combination of clauses 9B-13B, further configured to associate, via a personal area network, the initiating station with the responding station to exchange a shared key by which to generate the first message integrity code.

Clause 15B. The responding station of any combination of clauses 9B-14B, further comprising processing circuitry configured to access, based on receipt of the acknowledgement, a resource associated with the initiating station.

Clause 16B. The responding station of any combination of clauses 9B-15B, further configured to: detect, via the personal area network and prior to enabling communication via the wireless network protocol, the initiating station; and enable, responsive to detecting the initiating station via the personal area network, the communication via the wireless network protocol between the initiating station and the responding station.

Clause 17B. A non-transitory computer-readable storage media storing instructions that, when executed, cause one or more processors to perform each step of the method recited in any combination of clauses 1B-8B.

1C. A system comprising: an initiating station; and a responding station, the responding station comprising: first wireless communication circuitry configured to: transmit, in accordance with a wireless networking protocol for communicating between the initiating station and the responding station, a first fine time measurement specifying a first time; transmit, in accordance with the wireless networking protocol and for the corresponding first time, a first message integrity code; wherein the initiating station comprises: second wireless communication circuitry configured to: receive, in accordance with a wireless networking protocol for communicating between the initiating station and a responding station, the first fine time measurement specifying the first time; receive, in accordance with the wireless networking protocol and for the corresponding first time, the first message integrity code; authenticate, based on the first message integrity code, the responding station to establish a secure session between the initiating station and the responding station; and transmit, in accordance with the wireless networking protocol, an acknowledgement indicating that a secure session has been established between the initiating station and the responding station, wherein the responding station further comprises processing circuitry configured to access, based on receipt of the acknowledgment, a resource associated with the initiating station.