Patent Publication Number: US-2023155813-A1

Title: Vehicle Certificate Application Method, Vehicle-Mounted Device, and Roadside Unit

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of International Patent Application No. PCT/CN2020/104556, filed on Jul. 24, 2020, the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to the field of internet of vehicles technologies, and in particular, to a vehicle certificate application method, a vehicle-mounted device, and a roadside unit. 
     BACKGROUND 
     Long-Term Evolution vehicle-to-everything (LTE-V2X) includes vehicle to network (V2N) communication, vehicle-to-vehicle (V2V) communication, vehicle-to-infrastructure (V2I) connection, vehicle-to-pedestrian (V2P) communication. 
     When a vehicle communicates with another device, a sent message may be signed by using a short-term identity certificate, so that a receive device can determine whether the message is valid. The short-term identity certificate may be a pseudonym certificate or a real-name certificate. The pseudonym certificate is a pseudonym used by the vehicle in communication, and may be continuously changed to protect user privacy. 
     Usually, the vehicle may have at most one real-name certificate. The real-name certificate may be used to prove a real identity of the vehicle to a roadside unit (RSU) or a service provider (SP) to obtain a specific internet of vehicles application service provided by the service provider. 
     Usually, the real-name certificate of the vehicle does not exist in the vehicle for a long time. When the vehicle requires a real-name certificate, the vehicle needs to apply for the real-name certificate from a certificate authority (CA). Currently, the vehicle interacts with the certificate authority through a universal mobile telecommunications system (UMTS) air (Uu) interface to apply for the real-name certificate. The Uu interface is an interface used for communication between user equipment (UE) and a UMTS terrestrial radio access network. In some cases, the Uu interface may be in an unavailable state. For example, the Uu interface of the vehicle fails, or the vehicle is at a location with poor signal quality, for example, in a tunnel or a basement. Therefore, a solution for applying for the real-name certificate when the Uu interface is unavailable is urgently required. 
     SUMMARY 
     Embodiments of the present disclosure provide a vehicle certificate application method, a vehicle-mounted device, and a roadside unit, so that a vehicle-mounted device may apply for an identity certificate through a proximity communication five (PC5) interface when a Uu interface is unavailable or signal quality of the Uu interface is poor. 
     According to a first aspect, an embodiment of the present disclosure provides a vehicle certificate application method including: when a Uu interface of a vehicle-mounted device is unavailable or signal quality of the Uu interface is lower than a threshold, the vehicle-mounted device sends a certificate proxy application message to a roadside unit RSU, where the certificate proxy application message includes certificate application information of a vehicle to which the vehicle-mounted device belongs, and the certificate application information is forwarded by the RSU to a third-party authority; and the vehicle-mounted device receives a certificate proxy application response from the RSU, where the certificate proxy application response includes an identity certificate of the vehicle, and the identity certificate is generated by the third-party authority based on the certificate application information and sent to the RSU. In an example, the third-party authority may be a certificate authority. 
     That is, when the vehicle-mounted device cannot send the certificate application information through the Uu interface, the vehicle-mounted device may send the certificate application information by using the roadside unit to obtain a required certificate through application. 
     In a possible implementation, the certificate application information includes identity information of the vehicle and a public key of the vehicle, and the identity certificate of the vehicle is generated by the third-party authority based on the identity information and the public key of the vehicle. Before the vehicle-mounted device sends the certificate proxy application message to the roadside unit RSU, the method further includes: the vehicle-mounted device determines that the vehicle enters a first usage scenario, where a service in the first usage scenario needs to be obtained by the vehicle based on the identity certificate. 
     That is, in this implementation, when a specific identity certificate of the vehicle is required for obtaining a corresponding service, if a certificate application information cannot be sent through the Uu interface, the identity certificate may be obtained by using the roadside unit. 
     In a possible implementation, that the vehicle-mounted device determines that the vehicle enters a first usage scenario includes: the vehicle-mounted device determines, based on a user input, that the vehicle enters the first usage scenario; or the vehicle-mounted device determines, based on an operating status of a first device on the vehicle, that the vehicle enters the first usage scenario. For example, the vehicle may be a police car, and the first device may be an alarm or an alarm light; or the vehicle may be an ambulance, and the first device may be any one or more of a ventilator, a blood oxygen monitor, an alarm, and an alarm light. 
     That is, in this implementation, the vehicle-mounted device can flexibly determine whether the vehicle enters a corresponding usage scenario. 
     In a possible implementation, the certificate proxy application message further includes a registration certificate of the vehicle, the certificate application information is signed by using the registration certificate, and the registration certificate is forwarded by the RSU to the third-party authority, and is used by the third-party authority to verify the certificate application information. 
     That is, in this implementation, the third-party authority may obtain the registration certificate of the vehicle, to verify, by using the registration certificate of the vehicle, whether the certificate application information is valid. 
     In a possible implementation, the certificate proxy application message further includes a message type indicator, and the message type indicator is used to indicate that a message carrying the message type indicator is a certificate proxy application message. 
     That is, in this implementation, the message type indicator may be carried in a message to indicate that the message is a certificate proxy application message, so that the roadside unit performs corresponding processing. 
     In a possible implementation, before the vehicle-mounted device sends the certificate proxy application message to the roadside unit RSU, the method further includes: the vehicle-mounted device sends a connection setup request to the RSU, where the connection setup request includes first check information, and the first check information is encrypted by using a public key of the RSU. That the vehicle-mounted device sends a certificate proxy application message to a roadside unit RSU includes: when the vehicle-mounted device receives a connection setup response from the RSU and the connection setup response includes a second check information, sending the certificate proxy application message to the RSU, where the second check information is generated based on the first check information. 
     That is, in this implementation, a check information is set, so that a receive device can verify that information received by the receive device is truly sent by a related device, thereby improving security of information exchange. 
     In a possible implementation, the certificate application information in the certificate proxy application message is encrypted by using a public key of the third-party authority; and/or the identity certificate in the certificate proxy application response is encrypted by using the public key of the vehicle. 
     That is, in this implementation, the roadside unit can be prevented from excessively obtaining messages exchanged between the vehicle-mounted device and the third-party authority, thereby improving communication security. 
     In a possible implementation, the certificate proxy application message is a basic safety message BSM, and/or the certificate proxy application response is a BSM or a road safety message (RSM). 
     According to a second aspect, an embodiment of the present disclosure provides a vehicle certificate application method, including: a roadside unit RSU receives a certificate proxy application message from a vehicle-mounted device, where the certificate proxy application message includes certificate application information of a vehicle in which the vehicle-mounted device is located, and the certificate proxy application message is sent by the vehicle-mounted device when a Uu interface of the vehicle-mounted device is unavailable or signal quality of the Uu interface is lower than a threshold; the RSU sends a certificate application information to a third-party authority, where the certificate application information is used by the third-party authority to generate an identity certificate; the RSU receives the identity certificate from the third-party authority; and the RSU sends a certificate proxy application response to the vehicle-mounted device, where the certificate proxy application response includes the identity certificate. 
     In a possible implementation, the certificate proxy application message further includes a registration certificate of the vehicle, and the certificate application information is signed by using the registration certificate. The method further includes: the RSU sends the registration certificate to the third-party authority, where the registration certificate is used by the third-party authority to verify the certificate application information. 
     In a possible implementation, the certificate proxy application message further includes a message type indicator, and the message type indicator is used to indicate that a message carrying the message type indicator is a certificate proxy application message. 
     In a possible implementation, before the RSU receives the certificate proxy application message from the vehicle-mounted device, the method further includes: the RSU receives a connection setup request from the vehicle-mounted device, where the connection setup request includes first check information, and the first check information is encrypted by using a public key of the RSU; and the RSU sends a connection setup response to the vehicle-mounted device in response to the connection setup request, where the connection setup response is used to indicate the vehicle-mounted device to send the certificate proxy application message to the RSU, the connection setup response includes a second check information, and the second check information is generated based on the first check information. 
     In a possible implementation, the certificate application information in the certificate proxy application message is encrypted by using a public key of the third-party authority; and/or the identity certificate in the certificate proxy application response is encrypted by using a public key of the vehicle. 
     In a possible implementation, the certificate application information includes the public key of the vehicle and identity information of the vehicle, the identity certificate is obtained by the third-party authority by encrypting the public key of the vehicle and the identity information of the vehicle by using a first private key, and the first private key is a private key of the third-party authority. 
     According to a third aspect, an embodiment of the present disclosure provides a vehicle certificate application apparatus, configured in a vehicle-mounted device. The apparatus includes a sending unit and a receiving unit. The sending unit is configured to: when a Uu interface of the vehicle-mounted device is unavailable or signal quality of the Uu interface is lower than a threshold, send a certificate proxy application message to a roadside unit RSU, where the certificate proxy application message includes certificate application information of a vehicle to which the vehicle-mounted device belongs, and the certificate application information is forwarded by the RSU to a third-party authority. The receiving unit is configured to receive a certificate proxy application response from the RSU, where the certificate proxy application response includes an identity certificate of the vehicle, and the identity certificate is generated by the third-party authority based on the certificate application information and sent to the RSU. In an example, the third-party authority may be a certificate authority. 
     According to a fourth aspect, an embodiment of the present disclosure provides a vehicle certificate application apparatus, configured in a roadside unit RSU. The apparatus includes a receiving unit and a sending unit. The receiving unit is configured to receive a certificate proxy application message from a vehicle-mounted device, where the certificate proxy application message includes certificate application information of a vehicle in which the vehicle-mounted device is located, and the certificate proxy application message is sent by the vehicle-mounted device when a Uu interface of the vehicle-mounted device is unavailable or signal quality of the Uu interface is lower than a threshold. The sending unit is configured to send a certificate application information to a third-party authority, where the certificate application information is used by the third-party authority to generate an identity certificate. The receiving unit is further configured to receive the identity certificate from the third-party authority. The sending unit is further configured to send a certificate proxy application response to the vehicle-mounted device, where the certificate proxy application response includes the identity certificate. 
     According to a fifth aspect, an embodiment of the present disclosure provides a vehicle-mounted device, including a processor, a memory, and a transceiver. The memory is configured to store computer instructions. When the vehicle-mounted device runs, the processor executes the computer instructions, so that the vehicle-mounted device performs the method provided in the first aspect. 
     According to a sixth aspect, an embodiment of the present disclosure provides a roadside unit, including a processor, a memory, and a transceiver. The memory is configured to store computer instructions. When the roadside unit runs, the processor executes the computer instructions, so that the roadside unit performs the method provided in the second aspect. 
     According to a seventh aspect, an embodiment of the present disclosure provides a computer storage medium. The computer storage medium includes computer instructions. When the computer instructions are run on an electronic device, the electronic device is enabled to perform the method provided in the first aspect or the method provided in the second aspect. 
     According to an eighth aspect, an embodiment of the present disclosure provides a computer program product. When program code included in the computer program product is executed by a processor in an electronic device, the method provided in the first aspect or the method provided in the second aspect is implemented. 
     In the vehicle certificate application method provided in embodiments of the present disclosure, when a Uu interface of a vehicle-mounted device is unavailable or signal quality of the Uu interface is poor, an identity certificate may be applied for through a PC5 interface, so that a required certificate can be obtained through application when a vehicle is in an environment in which signal quality of a Uu interface is poor, for example, in a tunnel or an underground garage. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic diagram of a network system according to an embodiment of the present disclosure; 
         FIG.  2    is a schematic diagram of a structure of a vehicle-mounted device according to an embodiment of the present disclosure; 
         FIG.  3 A  is a flowchart of a vehicle certificate application method according to an embodiment of the present disclosure; 
         FIG.  3 B  is a flowchart of information exchange between a vehicle-mounted device and a roadside unit according to an embodiment of the present disclosure; 
         FIG.  3 C  is a flowchart of information exchange between a vehicle-mounted device and a roadside unit according to an embodiment of the present disclosure; 
         FIG.  3 D  is a flowchart of information exchange between a vehicle-mounted device and a roadside unit according to an embodiment of the present disclosure; 
         FIG.  3 E  is a flowchart of information exchange between a roadside unit and a certificate authority according to an embodiment of the present disclosure; 
         FIG.  3 F  is a flowchart of information exchange between a roadside unit and a certificate authority according to an embodiment of the present disclosure; 
         FIG.  4    is a schematic diagram of a structure of a vehicle-mounted device according to an embodiment of the present disclosure; and 
         FIG.  5    is a schematic diagram of a structure of a roadside unit according to an embodiment of the present disclosure. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The following describes technical solutions of embodiments in the present disclosure with reference to accompanying drawings. It is clear that the described embodiments are merely some but not all of embodiments of the present disclosure. 
     “An embodiment”, “some embodiments”, or the like in descriptions of this specification means that one or more embodiments of the present disclosure include a specific feature, structure, or characteristic described with reference to the embodiment. Therefore, statements such as “in an embodiment”, “in some embodiments”, “in some other embodiments”, and “in other embodiments” that appear at different places in this specification do not necessarily mean referring to a same embodiment. Instead, the statements mean “one or more but not all of embodiments”, unless otherwise specifically emphasized in another manner. 
     In the descriptions of this specification, “/” means “or” unless otherwise specified. For example, AB may represent A or B. In this specification, “and/or” describes only an association relationship for describing associated objects and represents that three relationships may exist. For example, A and/or B may represent the following three cases: only A exists, both A and B exist, and only B exists. In addition, in the descriptions in embodiments of the present disclosure, “a plurality of” means two or more. 
     In the descriptions of this specification, the terms “first” and “second” are merely intended for description, and shall not be understood as an indication or implication of relative importance or implicit indication of a quantity of indicated technical features. Therefore, a feature limited by “first” or “second” may explicitly or implicitly include one or more such features. The terms “include”, “have”, and their variants all mean “include but are not limited to”, unless otherwise specifically emphasized in another manner. 
     Embodiments of the present disclosure provide a vehicle certificate application method, and the method may be applied to a network system  100  shown in  FIG.  1   . The network system  100  may include a vehicle  110 , a base station  120 , a certificate authority  130 , and a roadside unit  140 . 
     The vehicle  110  may be an automobile or a motor vehicle in another form. For example, the vehicle may be a police car, an ambulance, a bus, a truck, an agricultural vehicle, a parade float, a ride in an amusement park, or a vehicle in another form. 
     The vehicle may be equipped with a vehicle-mounted device  111 . The vehicle-mounted device  111  may be a device that is disposed in the vehicle  110  and that has data processing and data sending functions, for example, an on-board unit (OBU) or a telematics box (T-BOX). 
       FIG.  2    shows a possible structure of the vehicle-mounted device  111 . As shown in  FIG.  2   , the vehicle-mounted device  111  may include components such as a processor  1111 , a memory  1112 , a wireless communication interface  1113 , a wired communication interface  1114 , and an input component  1115 . 
     The memory  1112  may be configured to store a software program, instructions, and related information. For example, the memory  1112  may be configured to store a program for implementing, on the vehicle-mounted device side, the vehicle certificate application method provided in embodiments of the present disclosure. 
     The processor  1111  may invoke the software program and the instructions stored in the memory  1112 , to control the vehicle-mounted device  111  to implement a related function. For example, the processor  1111  may invoke the program, stored in the memory  1112 , for implementing, on the vehicle-mounted device side, the vehicle certificate application method provided in embodiments of the present disclosure, to control the vehicle-mounted device  111  to perform implementation steps of the method on the vehicle-mounted device. 
     The wireless communication interface  1113  may include a Uu interface and a PC5 interface. The Uu interface is used for communication between the vehicle-mounted device  111  and the base station  120 , and the PC5 interface is used for communication between the vehicle-mounted device  111  and the roadside unit  140 . 
     The wired communication interface  1114  may be used for communication between the vehicle-mounted device  111  and another device (for example, an alarm or an alarm light) in the vehicle  110 . 
     The input component  1115  may receive input initiated by a user. In an example, the input component  1115  may be a touchscreen, and may receive a touch operation initiated by a user. In an example, the input component  1115  may be a microphone, and may receive voice input of a user. 
     The base station  120  may communicate with the vehicle-mounted device  111  through the Uu interface, and communicate with the certificate authority  130  by using a wired network. For example, the base station  120  may be an evolved NodeB (eNodeB), an access network device in a 5th generation (5G) mobile communication technology, an access network device in a 3rd generation (3G) mobile communication technology, or an access network device in a 2nd generation (2G) mobile communication technology. 
     The roadside unit  140  may also be referred to as a roadside station, and may communicate with the vehicle-mounted device  111  through the PC5 interface, and communicate with the certificate authority  130  by using a wired network. For example, the roadside unit  140  may include a high-gain directional beam control read/write antenna and a radio frequency controller. The high-gain directional beam control read/write antenna is a microwave transceiver module, and is responsible for signal and data transmission/reception, modulation/demodulation, encoding/decoding, and encryption/decryption. The radio frequency controller is a module for controlling data transmission and reception, and processing information transmission to a host computer and information reception from the host computer. 
     The certificate authority  130  may generate a digital certificate based on an application of a certificate applicant. For example, the certificate authority  130  may encrypt a public key and other information of the certificate applicant by using a private key of the certificate authority  130 , to obtain a digital certificate that the certificate applicant applies for. 
     Then, with reference to the network system shown in  FIG.  1   , the vehicle certificate application method provided in embodiments of the present disclosure is described by using an example. 
     In general, in the vehicle certificate application method provided in embodiments of the present disclosure, the vehicle-mounted device  111  in the vehicle  110  may determine that the vehicle  110  enters a usage scenario A 1 , where the vehicle  110  can obtain a related service in the usage scenario A 1  only based on an identity B 1 . Therefore, the vehicle-mounted device  111  needs to apply for an identity certificate B 11  of the identity B 1 . Usually, if the Uu interface between the vehicle-mounted device  111  and the base station  120  is available or signal quality is good (for example, higher than a threshold C 1 ), the vehicle-mounted device  111  may exchange information with the certificate authority  130  through the Uu interface, to apply for the identity certificate B 11 . If the Uu interface of the vehicle device  111  fails (the Uu interface is unavailable) or signal quality of the Uu interface is poor (for example, lower than the threshold C 1 ), the vehicle-mounted device  111  may send a certificate proxy application message to the roadside unit  140 , to request the roadside unit  140 , in place of the vehicle-mounted device  111 , to apply for the identity certificate B 11  from the certificate authority  130 . 
     Then, the vehicle certificate application method provided in embodiments of the present disclosure is described by using an example. 
     With reference to  FIG.  3 A , the vehicle-mounted device  111  may perform step  301  to determine that the vehicle  110  enters the usage scenario A 1 . 
     The usage scenario A 1  may be understood as a scenario in which the vehicle  110  is performing a special task. For example, the vehicle  110  may be a police car, and the usage scenario A 1  is a scenario in which the police car performs a call-out task. For another example, the vehicle  110  may be an ambulance, and the usage scenario A 1  may be a scenario in which the ambulance performs a call-out task. 
     It can be understood that, when the vehicle  110  does not perform the special task, the vehicle  110  may be a common vehicle on a road, that is, the vehicle  110  is in a common scenario. For example, a police car that does not perform a call-out task may travel on a road as a common vehicle. When the vehicle  110  performs the special task, the vehicle  110  may enter the usage scenario A 1 . 
     In some embodiments, a driver (user) may perform scenario setting input to notify the vehicle-mounted device  111  that the vehicle  110  enters the usage scenario A 1 . That is, the vehicle-mounted device  111  may receive the scenario setting input of the user, and determine accordingly that the vehicle  110  enters the usage scenario A 1 . As described above, the vehicle-mounted device  111  may include the input component  1115 , and the input component  1115  may receive the scenario setting input of the user, and determine accordingly that the vehicle  110  enters the usage scenario A 1 . For example, the input component  1115  may be a touchscreen, and the scenario setting input may be touch input generated on the touchscreen. For another example, the input component  1115  may be a microphone, and the scenario setting input may be language input. 
     In some embodiments, the vehicle-mounted device  111  may determine, based on an operating status of another device in the vehicle  110 , that the vehicle  110  enters the usage scenario A 1 . It can be understood that starting, by a device that is in the vehicle  110  and that is related to the usage scenario A 1 , to operate may indicate that the vehicle  110  enters the usage scenario A 1 . For example, the vehicle  110  may be a police car, and the usage scenario A 1  is a scenario in which the police car performs a call-out task. The device that is in the vehicle  110  and that is related to the usage scenario A 1  may include an alarm, an alarm light, or the like. When the alarm and the alarm light start to operate, the vehicle enters the usage scenario A 1 . For another example, the vehicle  110  may be an ambulance, and the usage scenario A 1  is a scenario in which the ambulance performs a call-out task. The device that is in the vehicle  110  and that is related to the usage scenario A 1  may include a ventilator, a blood oxygen monitor, an alarm, an alarm light, or the like. The vehicle-mounted device  111  may obtain the operating status of the device that is in the vehicle  110  and that is related to the usage scenario A 1 . For example, as described above, the vehicle-mounted device  111  may communicate with the another device in the vehicle  110  through the wired communication interface  1114 , to obtain the operating status of the another device. For example, when the device that is in the vehicle  110  and that is related to the usage scenario A 1  starts, a notification message may be sent to the vehicle-mounted device  111 , to notify the vehicle-mounted device  111  that the device that is in the vehicle  110  and that is related to the usage scenario A 1  starts to operate. 
     Therefore, the vehicle-mounted device  111  may determine that the vehicle  110  enters the usage scenario A 1 . 
     It can be understood that, when the vehicle  110  is in the usage scenario A 1 , for ease of performing a related task, the vehicle  110  should obtain one or more internet of vehicles application services, and the one or more internet of vehicles application services should not be obtained by a common vehicle (for example, a vehicle not in the usage scenario A 1 ). For example, when a police car performs a call-out task, that is, when the police car is in a scenario of performing a call-out task, traffic lights should provide a traffic light controllable service for the police car. When the police car obtains the traffic light controllable service, the police car may control the traffic lights, so that the police car can conveniently perform the call-out task. In this embodiment of the present disclosure, a service that should be obtained by a vehicle in the usage scenario A 1  and should not be obtained by a common vehicle may be referred to as a service in the usage scenario A 1 . 
     It can be understood that the vehicle  110  in the usage scenario A 1  can obtain a service in the usage scenario A 1  only based on the specific identity B 1  (for example, a real identity). Therefore, when the vehicle  110  enters the usage scenario A 1 , the vehicle  110  needs to apply for the identity certificate B 11  (for example, a real-name certificate) corresponding to the identity B 1 . 
     The vehicle-mounted device  111  may perform step  302  to determine that the Uu interface is unavailable or signal quality of the Uu interface is lower than the threshold C 1 . 
     In some embodiments, the vehicle-mounted device  111  may detect whether the Uu interface of the vehicle-mounted device  111  fails, and if the Uu interface fails, may determine that the Uu interface is unavailable. 
     In some embodiments, the vehicle-mounted device  111  may determine that the vehicle-mounted device  111  cannot connect to the base station  120  through the Uu interface, and then determine that the Uu interface is unavailable. For example, the vehicle-mounted device  111  may determine that an attempt of the vehicle-mounted device  111  to connect to the base station  120  fails, and then determine that the Uu interface is unavailable. For example, the vehicle-mounted device  111  may attempt to connect to the base station  120  by using a random access program. In the random access procedure, if the vehicle-mounted device  111  has not received a random access response (RAR) or a contention resolution result when a timer expires, the attempt to connect to the base station  120  fails, that is, the vehicle-mounted device  111  cannot connect to the base station  120  through the Uu interface. 
     In some embodiments, when the vehicle-mounted device  111  is connected to the base station  120 , the vehicle-mounted device  111  may determine signal quality of the Uu interface of the vehicle-mounted device  111 . In this embodiment of the present disclosure, signal quality of the Uu interface of the vehicle-mounted device  111  may be signal quality of a cellular cell in which the vehicle-mounted device  111  resides. The vehicle-mounted device  111  may measure, according to a related protocol of the 3rd generation partnership project (3GPP), the signal quality of the cell in which the vehicle-mounted device  111  resides. In an example, the signal quality of the cell may be represented by a reference signal received power (RSRP). In another example, the signal quality of the cell may be represented by reference signal received quality (RSRQ). In another example, the signal quality of the cell may be represented by a signal-to-interference-plus-noise ratio (SINR). In another example, the signal quality of the cell may be represented jointly by two or more of an RSRP, RSRQ, an SINR, and a received signal strength indicator (RSSI). Therefore, the signal quality of the cell in which the vehicle-mounted device  111  resides may be obtained, that is, the signal quality of the Uu interface of the vehicle-mounted device  111  may be obtained. 
     The vehicle-mounted device  111  may determine whether the signal quality of the Uu interface is lower than the threshold C 1 . If the signal quality of the Uu interface is lower than the threshold C 1 , the signal quality of the Uu interface is poor, and it is difficult for the vehicle-mounted device  111  and the base station  120  to perform effective communication. The threshold C 1  may be a preset value. 
     When the Uu interface of the vehicle-mounted device  111  is unavailable or the signal quality of the Uu interface is lower than the threshold C 1 , the vehicle-mounted device  111  may exchange information with the roadside unit  140  through the PC5 interface, so that the roadside unit  140 , in place of the vehicle-mounted device  111 , applies for the identity certificate B 11  from the certificate authority  130 . 
     Still with reference to  FIG.  3 A , when the Uu interface of the vehicle-mounted device  111  is unavailable or the signal quality of the Uu interface is lower than the threshold C 1 , the vehicle-mounted device  111  may perform step  305  to send a certificate proxy application message to the roadside unit  140 , where the certificate proxy application message includes certificate application information. 
     In some embodiments, before performing step  305 , the vehicle-mounted device  111  may perform a communication handshake with the roadside unit  140 . Specifically, as shown in  FIG.  3 A , the vehicle-mounted device  111  may perform step  303  to send a connection setup request to the roadside unit  140 . The roadside unit  140  may send a connection setup response to the vehicle-mounted device  111  in response to the connection setup request. Therefore, a connection between the vehicle-mounted device  111  and the roadside unit  140  may be established, to facilitate subsequent information exchange between the vehicle-mounted device  111  and the roadside unit  140 . 
     Still with reference to  FIG.  3 A , after receiving the certificate proxy application message, the roadside unit  140  may respond to the certificate proxy application message, extract the certificate application information from the certificate proxy application message, and send the certificate application information to the certificate authority  130  in step  306 . 
     When receiving the certificate application information, the certificate authority  130  may generate the identity certificate B 11  based on the certificate application information, and then may send the identity certificate B 11  to the roadside unit  140  in step  307 . 
     When receiving the identity certificate B 11 , the roadside unit  140  may add the identity certificate B 11  to a certificate proxy application response, and send the certificate proxy application response to the vehicle-mounted device  111  in step  308 . 
     The vehicle-mounted device  111  receives the certificate proxy application response, and may extract the identity certificate B 11  from the certificate proxy application response. Therefore, the identity certificate B 11  may be obtained, so that the vehicle-mounted device can obtain the identity certificate B 11  through application through the PC5 interface when the Uu interface is unavailable or the signal quality of the Uu interface is poor. 
     Then a process of information exchange between the vehicle-mounted device  111  and the roadside unit  140  is specifically described in different embodiments. 
     In some embodiments, with reference to  FIG.  3 B , the connection setup request sent in step  303  may include a message type indicator D 1 . The message type indicator D 1  may be a preset character string or bit string, and is used to indicate that a message carrying the message type indicator D 1  is a connection setup request, so as to indicate the roadside unit  140  to perform an operation based on the message, for example, send the connection setup request to the vehicle-mounted device  111 . Usually, after the roadside unit receives a message sent by the vehicle-mounted device, if the message has no related indicator, the roadside unit may directly forward the message to another device, without further processing the message. Therefore, in this embodiment, the vehicle-mounted device  111  adds the message type indicator D 1  to the connection setup request, to indicate the roadside unit  140  to further parse and respond to the connection setup request instead of directly forwarding the connection setup request to another device. 
     Still with reference to  FIG.  3 B , the connection setup request sent by the vehicle-mounted device  111  in step  303  may further include check information E 1 . For example, the check information may be a random number, for example, may be a random number generated by a rand(1) function. The check information E 1  may be encrypted by using a public key of the roadside unit  140 , so that the roadside unit  140  can decrypt the check information E 1 , and therefore may generate check information E 1 ′ corresponding to the check information E 1 . Details are described below, and details are not described herein. 
     For example, the connection setup request may be signed by using a registration certificate of the vehicle  110  (to be specific, the connection setup request is signed by using a private key corresponding to a public key F 1  in the registration certificate), and the registration certificate, together with the connection setup request, is sent to the roadside unit  140 . The roadside unit  140  may obtain the public key F 1  from the registration certificate by using a public key of the certificate authority. Then whether the connection setup request is sent by the vehicle-mounted device  111  may be verified by using the public key F 1 . 
     The registration certificate of the vehicle may be identification information applied for from an internet of vehicles when the vehicle is registered with the internet of vehicles for the first time, and is a unique identity of the vehicle  110  in the internet of vehicles. The registration certificate of the vehicle is equivalent to a passport of the vehicle, has a validity period, and can be revoked. 
     For example, the connection setup request may be a BSM. To be specific, related information such as the message type indicator D 1  and the check information E 1  may be encapsulated into fields in the basic safety message. 
     It should be noted that a format of the connection setup request is not limited in this embodiment of the present disclosure. In another embodiment, the connection setup request may have another message type, for example, a message type that appears in the future. 
     Still with reference to  FIG.  3 B , the connection setup response sent by the roadside unit  140  in step  304  may include a message type indicator D 2 . The message type indicator D 2  may be a preset character string or bit string, and is used to indicate that a message carrying the message type indicator D 2  is a certificate application—related message, so as to indicate the vehicle-mounted device  111  to perform an operation based on the message, for example, send the certificate proxy application message to the roadside unit  140 . 
     The connection setup response may further include a key K. The key K may be generated by the roadside unit  140 , and is carried in the connection setup response, so that after receiving the connection setup response, the vehicle-mounted device  111  may extract the key K, and perform communication between the vehicle-mounted device  111  and the roadside unit  140  by using the key K. In an example, the roadside unit  140  may encrypt the key K by using the public key of the vehicle  110 , and the public key may be the foregoing public key F 1 . 
     For example, the connection setup response may further include the check information E 1 ′. The check information E 1 ′ is information that corresponds to the check information E 1  and that is generated by the roadside unit  140  based on the check information E 1 . When the connection setup response includes the check information E 1 ′, the connection setup response is truly sent by the roadside unit  140  and is sent in response to the connection setup request in step  303 . 
     Specifically, as described above, the connection setup request sent by the vehicle-mounted device  111  to the roadside unit  140  in step  303  may include the check information E 1 , and the check information is encrypted by using the public key of the roadside unit  140 . The roadside unit  140  may decrypt the check information E 1  by using a private key of the roadside unit  140 , and then may obtain content of the check information E 1 , and accordingly generate the check information E 1 ′ corresponding to the check information E 1 . For example, devices (for example, the vehicle-mounted device  111 , the roadside unit  140 , and other vehicle-mounted devices or roadside units) in the internet of vehicles may agree upon a response rule for check information. When obtaining check information, a device may generate, according to the response rule, check information’ corresponding to the check information. For example, the check information is a random number, and the following may be agreed upon: the check information is added to n (n may be a natural number) to obtain the check information’. The roadside unit  140  may generate, according to the response rule, the check information E 1 ′ corresponding to the check information E 1 . It can be understood that, because the check information E 1  is encrypted by using the public key of the roadside unit  140 , only the roadside unit  140  (to be specific, a device with the private key of the roadside unit  140 ) can decrypt the check information E 1 , and may generate the check information E 1 ′ corresponding to the check information E 1 . However, other devices do not have the private key of the roadside unit  140 , and therefore cannot decrypt the check information E 1 , and therefore cannot generate check information E 1 ′, in other words, cannot generate correct check information E 1 ′. Therefore, when receiving the connection setup response, the vehicle-mounted device  111  may determine, based on whether the connection setup response includes the check information E 1 ′ (in other words, correct check information E 1 ′), whether the connection setup response is a message sent by the roadside unit  140 , and whether the connection setup response is a message sent in response to the connection setup request in step  303 . In an example, the roadside unit  140  may encrypt the check information E 1 ′ by using the public key of the vehicle  110 , and the public key may be the foregoing public key F 1 . 
     For example, the connection setup response may further include check information E 2 . For example, the check information may be a random number, for example, may be a random number generated by a rand(2) function. The check information E 2  may be encrypted by using the public key of the vehicle  110  (for example, the public key F 1 ), so that the vehicle-mounted device  111  can decrypt the check information E 2 , and therefore may generate check information E 2 ′ corresponding to the check information E 2 . Details are described below, and details are not described herein. 
     For example, the roadside unit  140  may sign the connection setup response by using an application certificate of the roadside unit  140  (to be specific, sign the connection setup response by using a private key corresponding to a public key in the application certificate), and send the application certificate together with the connection setup response to the vehicle-mounted device  111 . The vehicle-mounted device  111  may obtain the public key of the application certificate from the application certificate by using the public key of the certificate authority. Then whether the connection setup response is sent by the roadside unit  140  may be verified by using the public key. 
     For example, the connection setup response may be a BSM. To be specific, related information such as the message type indicator D 2 , the check information E 2 , and the check information E 1 ′ may be encapsulated into fields in the basic safety message. 
     For example, the connection setup response may be a RSM. To be specific, related information such as the message type indicator D 1 , the check information E 2 , and the check information E 1 ′ may be encapsulated into fields in the road safety message. 
     It should be noted that a format of the connection setup response is not limited in this embodiment of the present disclosure. In another embodiment, the connection setup response may have another message type, for example, a message type that appears in the future. 
     In step  303  and step  304 , a security connection is established between the vehicle-mounted device  111  and the roadside unit  140 , and the key K is exchanged. Then step  305  and subsequent steps may be performed. 
     Still with reference to  FIG.  3 B , in response to the connection setup response received in step  304 , the vehicle-mounted device  111  may perform step  305  to send the certificate proxy application message to the roadside unit  140 . The certificate proxy application message may include the certificate application information. Content and functions of the certificate application information are described below, and details are not described herein. 
     For example, when the connection setup response received in step  304  includes the check information E 1 ′, the vehicle-mounted device  111  may perform step  305 . As described above, when the connection setup response includes the check information E 1 ′ (in other words, correct check information E 1 ′), the connection setup response is truly sent by the roadside unit  140  and is sent in response to the connection setup request in step  303 . The connection setup response may trigger, only in this case, the vehicle-mounted device  111  to send the certificate proxy application message, so as to avoid an unauthorized attack (for example, a replay attack) that triggers the vehicle-mounted device  111  to frequently send certificate proxy application messages. 
     For example, the vehicle-mounted device  111  may sign the certificate application information by using the registration certificate of the vehicle  110 . The certificate proxy application message may include the registration certificate of the vehicle  110 . 
     For example, the vehicle-mounted device  111  may encrypt the certificate application information by using the key K. 
     For example, the certificate proxy application message may further include a message type indicator D 3 . The message type indicator D 3  may be a preset character string or bit string, and is used to indicate that a message carrying the message type indicator D 3  is a certificate proxy application message, so as to indicate the roadside unit  140  to perform an operation based on the message, for example, forward the certificate application information to the certificate authority  130 . 
     For example, the certificate proxy application message may further include check information E 2 ′. The check information E 2 ′ is information that corresponds to the check information E 2  and that is generated by the vehicle-mounted device  111  based on the check information E 2 . When the certificate proxy application message includes the check information E 2 ′, the certificate proxy application message is truly sent by the vehicle-mounted device  111  and is sent in response to the connection setup response in step  304 . For details, refer to the foregoing descriptions of the check information E 1 ′. Details are not described herein again. In an example, the check information E 2 ′ may be encrypted by using the key K. 
     For example, the certificate proxy application message may be signed by using the registration certificate of the vehicle  110 , and the registration certificate, together with the certificate proxy application message, is sent to the roadside unit  140 , so that the roadside unit  140  verifies whether the certificate proxy application message is sent by the vehicle-mounted device  111 . 
     For example, the certificate proxy application message may be a BSM. To be specific, related information such as the certificate application information, the message type indicator D 3 , and the check information E 2 ′ may be encapsulated into fields in the basic safety message. 
     It should be noted that a format of the certificate proxy application message is not limited in this embodiment of the present disclosure. In another embodiment, the certificate proxy application message may have another message type, for example, a message type that appears in the future. 
     After receiving the certificate proxy application message, the roadside unit  140  may extract the certificate application information from the certificate proxy application message, and send the certificate application information to the certificate authority  130 . The certificate authority  130  may generate the identity certificate B 11  based on the certificate application information. The certificate authority  130  may send the identity certificate B 11  to the roadside unit  140 . The certificate application information and a process of generating the identity certificate B 11  by the certificate authority  130  based on the certificate application information are specifically described below, and details are not described herein. 
     After receiving the identity certificate B 11  from the certificate authority  130 , the roadside unit  140  may perform step  308  to send the certificate proxy application response to the vehicle-mounted device  111 . The certificate proxy application response includes the identity certificate B 11 . In an example, the identity certificate B 11  may be encrypted by using the key K. 
     For example, the certificate proxy application response may further include a message type indicator D 4 . The message type indicator D 4  may be a preset character string or bit string, and is used to indicate that a message carrying the message type indicator D 4  is a certificate application—related message, so as to indicate the vehicle-mounted device  111  to perform an operation based on the message, for example, extract the identity certificate B 11  from the certificate proxy application response. 
     For example, the certificate proxy application response may further include check information E 2 ″. The check information E 2 ″ is information that corresponds to the check information E 2 ′ and that is generated by the roadside unit  140  based on the check information E 2 ′, and is used to indicate that the certificate proxy application response is truly sent by the roadside unit  140 , and is sent after the certificate proxy application message in step  305  is received. Therefore, this further indicates that the identity certificate B 11  is a certificate that the roadside unit  140  applies for from the certificate authority based on the certificate proxy application message in step  305 , to further ensure reliability of a source of the identity certificate B 11 . In an example, the check information E 2 ″ may be encrypted by using the key K. 
     Therefore, the vehicle-mounted device  111  may obtain the identity certificate B 11 . 
     In some embodiments, with reference to  FIG.  3 C , the vehicle-mounted device  111  may perform step  303  to send the connection setup request to the roadside unit  140 , where the connection setup request includes the key K. That is, in the embodiment shown in  FIG.  3 C , the key K may be generated by the vehicle-mounted device  111 , and sent to the roadside unit  140  in step  303 . 
     The connection setup request may further include a message type indicator D 1  and check information E 1 . For the message type indicator D 1  and the check information E 1 , refer to the foregoing descriptions of the embodiment shown in  FIG.  3 B . Details are not described herein again. 
     For a message format of the connection setup request in the embodiment shown in  FIG.  3 C , refer to the foregoing descriptions of the embodiment shown in  FIG.  3 B . Details are not described herein again. 
     As shown in  FIG.  3 C , the roadside unit  140  may perform step  304  to send a connection setup response to the vehicle-mounted device  111 . The connection setup response may not include the key K, but may include a message type indicator D 2 , check information E 2 , and check information E 1 ′. For details about the message type indicator D 2 , the check information E 2 , and the check information E 1 ′, refer to the foregoing descriptions of the embodiment shown in  FIG.  3 B . Details are not described herein again. 
     For a message format of the connection setup response in the embodiment shown in  FIG.  3 C , refer to the foregoing descriptions of the embodiment shown in  FIG.  3 B . Details are not described herein again. 
     For step  305  and step  308  in the embodiment shown in  FIG.  3 C , refer to the foregoing descriptions of the embodiment shown in  FIG.  3 B . Details are not described herein again. 
     Therefore, the vehicle-mounted device  111  may obtain the identity certificate B 11 . 
     In some embodiments, with reference to  FIG.  3 D , the vehicle-mounted device  111  may perform step  303 , and the roadside unit  140  may perform step  304 . For details, refer to the foregoing descriptions of the embodiment shown in  FIG.  3 B  or  FIG.  3 C . Details are not described herein again. 
     Still with reference to  FIG.  3 D , the vehicle-mounted device  111  may perform step  305  to send a certificate proxy application message to the roadside unit  140 . Certificate application information in the certificate proxy application message is encrypted by using the public key of the certificate authority  130 . Therefore, content of the certificate application information can be prevented from being disclosed to the roadside unit. 
     Still with reference to  FIG.  3 D , the roadside unit  140  may perform step  308  to send a certificate proxy application response to the vehicle-mounted device  111 . An identity certificate B 11  in the certificate proxy application message is encrypted by using the public key F 1  of the vehicle-mounted device  111  (a public key in the registration certificate of the vehicle  110 ). Therefore, the identity certificate B 11  can be prevented from being disclosed to the roadside unit  140 . 
     Therefore, the vehicle-mounted device  111  may obtain the identity certificate B 11 . 
     Then a process of information exchange between the roadside unit  140  and the certificate authority  130  is described in different embodiments. 
     In some embodiments, with reference to  FIG.  3 E , the roadside unit  140  may extract the certificate application information from the certificate proxy application message, and perform step  306  to send the certificate application information to the certificate authority  130 . 
     The certificate application information may include a public key F 2  of the vehicle  110  and identity information of the vehicle  110 . For example, the public key F 2  and the public key F 1  (the public key in the registration certificate of the vehicle  110 ) may be the same or different. For example, the identity information of the vehicle  110  may include vehicle information of the vehicle  110  or information about a user to whom the vehicle  110  belongs. It can be understood that, when a certificate applied for is a real-name certificate (an identity certificate corresponding to a real identity), the identity information of the vehicle  110  in the certificate application information may be real identity information of the vehicle  110 . For example, the real identity information of the vehicle may include real vehicle information or real information about the user to whom the vehicle belongs. 
     For example, as described above, the certificate application information sent in step  305  may be information encrypted by using the public key of the certificate authority  130 . After receiving the certificate application information, the certificate authority  130  may decrypt the certificate application information by using the private key of the certificate authority  130 , to obtain a decrypted certificate application information. 
     For example, the certificate application information sent in step  305  may be information signed by using the registration certificate of the vehicle  110 . The roadside unit  140  may further forward the registration certificate to the certificate authority  130 . The registration certificate is received by the roadside unit  140  from the vehicle-mounted device  111 . The certification authority  130  may verify whether the registration certificate is valid, for example, whether the registration certificate is in a validity period, or whether the registration certificate is revoked. If the registration certificate is valid, the certificate authority  130  may extract the public key F 1  from the registration certificate, and decrypt the certificate application information. 
     The certificate authority  130  may sign the certificate application information by using the private key of the certificate authority  130 , to obtain the identity certificate B 11 . Then the certificate authority  130  may perform step  307  to send the identity certificate B 11  to the roadside unit  140 . For example, the certificate authority  130  may first encrypt the identity certificate B 11  by using the public key F 1  of the vehicle  110 , and then perform step  307  to send an encrypted identity certificate B 11  to the roadside unit  140 , so that the roadside unit  140  may forward the encrypted identity certificate B 11  to the vehicle-mounted device  111 . The vehicle-mounted device  111  may decrypt the identity certificate B 11  by using a private key corresponding to the public key F 1 . Therefore, the vehicle-mounted device  111  may obtain the identity certificate B 11 . 
     In some embodiments, with reference to  FIG.  3 E , the certificate authority  130  may include an application registration authority (ARA)  131  and an application certificate authority (ACA)  132 . 
     With reference to  FIG.  3 E , the roadside unit  140  may perform step  306  to send the certificate application information to the ARA  131 . The ARA  131  may forward the certificate application information to the ACA  132 . For example, when the certificate request information is information signed by using the registration certificate of the vehicle  110 , the roadside unit  140  may forward the registration certificate to the ARA  131 . The ARA  131  may verify whether the registration certificate is valid. If the registration certificate is valid, the ARA  131  forwards the certificate application information to the ACA  132 . 
     The ACA  132  may generate the identity certificate B 11  based on the certificate application information. For example, the certificate application information may be signed by using the private key of the ACA  132  to obtain the identity certificate B 11 . 
     The ACA  132  may send the identity certificate B 11  to the ARA  131 . When or after receiving the identity certificate B 11 , the ARA  131  may perform step  307  to send the identity certificate B 11  to the roadside unit  140 . Therefore, the roadside unit  140  may forward the identity certificate B 11  to the vehicle-mounted device  111 . 
     To sum up, in the vehicle certificate application method provided in embodiments of the present disclosure, when a Uu interface of a vehicle-mounted device is unavailable or signal quality of the Uu interface is poor, an identity certificate may be applied for through a PC5 interface, so that a required certificate can be obtained through application when a vehicle is in an environment in which signal quality of a Uu interface is poor, for example, in a tunnel or an underground garage. 
     With reference to  FIG.  4   , an embodiment of the present disclosure provides a vehicle-mounted device  400 . The vehicle-mounted device  400  may include a processor  410 , a memory  420 , and a transceiver  430 . The memory  420  stores instructions, and the instructions may be executed by the processor  410 . When the instructions are executed by the processor  410 , the vehicle-mounted device  400  may perform the operations performed by the vehicle-mounted device  111  in the foregoing method embodiments, for example, the operations performed by the vehicle-mounted device  111  in  FIG.  3 A  to  FIG.  3 D . Specifically, the processor  410  may perform a data processing operation, and the transceiver  430  may perform a data sending operation and/or a data receiving operation. 
     Therefore, when a Uu interface of a vehicle-mounted device is unavailable or signal quality of the Uu interface is poor, an identity certificate may be applied for through a PC5 interface, so that a required certificate can be obtained through application when a vehicle is in an environment in which signal quality of a Uu interface is poor, for example, in a tunnel or an underground garage. 
     With reference to  FIG.  5   , an embodiment of the present disclosure provides a roadside unit  500 . The roadside unit  500  may include a processor  510 , a memory  520 , and a transceiver  530 . The memory  520  stores instructions, and the instructions may be executed by the processor  510 . When the instructions are executed by the processor  510 , the roadside unit  500  may perform the operations performed by the roadside unit  140  in the foregoing method embodiments, for example, the operations performed by the roadside unit  140  in  FIG.  3 A  to  FIG.  3 F . Specifically, the processor  510  may perform a data processing operation, and the transceiver  530  may perform a data sending operation and/or a data receiving operation. 
     Therefore, when a Uu interface of a vehicle-mounted device is unavailable or signal quality of the Uu interface is poor, an identity certificate may be applied for through a PC5 interface, so that a required certificate can be obtained through application when a vehicle is in an environment in which signal quality of a Uu interface is poor, for example, in a tunnel or an underground garage. 
     The method steps in embodiments of the present disclosure may be implemented in a hardware manner, or may be implemented in a manner of executing software instructions by the processor. The software instructions may include corresponding software modules. The software modules may be stored in a random-access memory (RAM), a flash memory, a read-only memory (ROM), a programmable ROM (PROM), an erasable PROM (EPROM), an electrically EPROM (EEPROM), a register, a hard disk, a removable hard disk, a compact disc read-only memory (CD-ROM), or any other form of storage medium well-known in the art. For example, a storage medium is coupled to a processor, so that the processor can read information from the storage medium or write information into the storage medium. Certainly, the storage medium may be a component of the processor. The processor and the storage medium may be disposed in an application-specific integrated circuit (ASIC). 
     All or some of the foregoing embodiments may be implemented by using software, hardware, firmware, or any combination thereof. When software is used to implement the embodiments, all or a part of the embodiments may be implemented in a form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on the computer, the procedures or functions according to the embodiments of the present disclosure are all or partially generated. The computer may be a general-purpose computer, a dedicated computer, a computer network, or another programmable apparatus. The computer instructions may be stored in a computer-readable storage medium or may be transmitted by using the computer-readable storage medium. The computer instructions may be transmitted from a website, computer, server, or data center to another website, computer, server, or data center in a wired (for example, a coaxial cable, an optical fiber, or a digital subscriber line (DSL)) or wireless (for example, infrared, radio, or microwave) manner. The computer-readable storage medium may be any usable medium accessible by the computer, or a data storage device, for example, a server or a data center, integrating one or more usable media. The usable medium may be a magnetic medium (for example, a floppy disk, a hard disk, or a magnetic tape), an optical medium (for example, a digital versatile disc (DVD)), a semiconductor medium (for example, a solid-state disk (SSD)), or the like. 
     It may be understood that various numbers in embodiments of the present disclosure are merely used for differentiation for ease of description, and are not used to limit the scope of embodiments of the present disclosure.