WO2022067815A1 - 一种通信方法、装置及设备 - Google Patents

一种通信方法、装置及设备 Download PDF

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Publication number
WO2022067815A1
WO2022067815A1 PCT/CN2020/119746 CN2020119746W WO2022067815A1 WO 2022067815 A1 WO2022067815 A1 WO 2022067815A1 CN 2020119746 W CN2020119746 W CN 2020119746W WO 2022067815 A1 WO2022067815 A1 WO 2022067815A1
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Prior art keywords
security
communication system
network device
contexts
security contexts
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PCT/CN2020/119746
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English (en)
French (fr)
Inventor
李洪
孙兵
Original Assignee
华为技术有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to PCT/CN2020/119746 priority Critical patent/WO2022067815A1/zh
Priority to CN202080015319.5A priority patent/CN114642014B/zh
Publication of WO2022067815A1 publication Critical patent/WO2022067815A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W12/00—Security arrangements; Authentication; Protecting privacy or anonymity
    • H04W12/06—Authentication

Definitions

  • the present application relates to the field of communication technologies, and in particular, to a communication method, apparatus, and device.
  • both the non-access stratum (NAS) of the terminal device and the NAS layer of the core network in the communication system maintain a set of security contexts.
  • the security context includes a NAS count (count).
  • the terminal device needs to perform an inter-system handover from the first communication system to the second communication system
  • the terminal device and the core network need to map the first set of security contexts in the first communication system to generate the second communication system the second set of security contexts, and only after the terminal device and the second communication system successfully perform secure docking according to the second set of security contexts, the terminal device can switch to the second communication system, and the second communication system realizes the business transmission.
  • the first communication system and the second communication system are communication systems of different standards, for example, the first communication system is a 5G communication system, and the second communication system is a 4G communication system.
  • mapping protocol for the security context
  • the NAS count in the second set of security contexts obtained by mapping the NAS counts in the first set of security contexts with different protocol versions may be different. Therefore, if the terminal device and the core network use different mapping protocol versions to map the first set of security contexts, it may cause the second set of security contexts maintained by the NAS layer of the terminal device to be different from the first set of security contexts maintained by the NAS layer of the core network.
  • the NAS count is one of the input parameters for encryption and decryption, integrity protection (referred to as complete protection), and deintegration protection, if the NAS count in the second set of security contexts maintained by the terminal device and the core network is inconsistent, it will cause the terminal device to The security connection with the core network fails, and the terminal device cannot be successfully switched to the second communication system, and the second communication system cannot provide transmission services for the terminal device, which seriously affects the service of the terminal device.
  • the present application provides a communication method, apparatus and device to solve the problem that the terminal device cannot successfully switch the communication system due to inconsistent versions of the security context mapping protocol used by the terminal device and the core network in the process of switching between different systems.
  • an embodiment of the present application provides a communication method, and the method includes the following steps:
  • the terminal device obtains a first set of security contexts; wherein, the first set of security contexts is used for the security verification between the terminal device and the first network device, so The first network device is located in the second communication system; when the terminal device fails to perform security verification with the first network device using the first set of security contexts, the terminal device sends a message to the first network device. Initiate the registration process.
  • the terminal device acquires a security context for performing security verification with the network device in the second communication system during the process of switching from the first communication system to the second communication system; when the UE uses the security context
  • the security verification with the network device in the second communication system fails, initiate a registration process to the network device in the second communication system, so that both the UE and the network device in the second communication system can be registered in the process.
  • the terminal device when the number of times that the terminal device uses the first set of security context and the first network device to fail in security verification is greater than or equal to a set threshold, the terminal device sends a message to the first network device.
  • the network device initiates the registration process.
  • the terminal device fails to perform security verification with the first network device using the first set of security contexts, including the following situations:
  • Case 1 The terminal device uses the first set of security contexts to decrypt the encrypted downlink message from the first network device, and the decryption fails;
  • Case 2 The terminal device uses the first set of security contexts to perform integrity protection verification on the downlink message after integrity protection processing from the first network device, and the integrity protection verification fails;
  • Scenario 3 The terminal device uses the first set of security contexts to perform decryption processing and integrity protection verification on the encrypted and integrity protected downlink messages from the first network device, and the decryption fails or completes Sexual protection check failed;
  • Case 4 The terminal device uses the first set of security contexts to perform integrity protection processing on the uplink message, and sends the integrity-protected uplink message to the first network device, and the terminal device does not receive it A response message to the uplink message from the first network device.
  • the terminal device can determine that the security verification using the first set of security contexts has failed in various situations.
  • the downlink message is any one of the following: a security mode command, a tracking area update accept message, a radio resource control RRC security mode command, and an attach accept message;
  • the uplink message is any of the following: Tracking area update request message, attach request message.
  • the first network device includes: a core network device or an access network device located in the second communication system.
  • the terminal device initiates a registration process to the first network device in the second communication system, including:
  • the terminal device sends an attach request message or a registration request message to the first network device, where the attach request message or the registration request message includes the International Mobile Subscriber Identity IMSI of the terminal device.
  • the first set of security contexts includes a non-access stratum count value NAS count.
  • the terminal device obtains the first set of security contexts, including:
  • the terminal device calculates the second set of security contexts according to the set security context mapping algorithm to generate the first set of security contexts; wherein the second set of security contexts is used for the terminal device and the second network device For security verification, the second network device is located in the first communication system.
  • the first communication system is a fifth-generation 5G communication system
  • the second communication system is a fourth-generation 4G communication system.
  • an embodiment of the present application provides a communication method, and the method includes the following steps:
  • the terminal device acquires multiple sets of alternative security contexts; the terminal device determines, in the multiple sets of alternative security contexts, the first set of security that has passed the security verification test context; the terminal device activates the first set of security contexts, and uses the first set of security contexts to perform security verification with a first network device, where the first network device is located in the second communication system.
  • the terminal device can acquire multiple sets of alternative security contexts during the process of switching from the first communication system to the second communication system; and determine a set of security contexts that have passed the security verification test from the multiple sets of alternative security contexts context; the UE activates the set of security contexts for subsequent security verification with the network device of the second communication system. Since the set of security contexts activated by the terminal device has passed the security verification test, that is, the set of security contexts is consistent with the security context maintained by the network device in the second communication system, the terminal device uses this set of security contexts to communicate with the second set of security contexts. The network device of the communication system performs security verification, which can realize successful security verification, thereby ensuring that the terminal device can be successfully switched to the second communication system.
  • the terminal device may select the first set of security contexts that pass the security verification test from the multiple sets of candidate security contexts through the following steps:
  • the terminal device selects a set of security contexts to be tested from the multiple sets of candidate security contexts, wherein the security context to be tested is any set of candidate security contexts in the multiple sets of candidate security contexts;
  • the terminal device uses the security context to be tested to decrypt the encrypted downlink message from the first network device, and the decryption succeeds to obtain the downlink message; or the terminal device uses the security context to be tested. security context, performing integrity protection verification on the downlink message after the integrity protection processing from the first network device, and the integrity protection verification is successful, to obtain the downlink message; or the terminal device uses the pending message testing the security context, performing decryption processing and integrity protection verification on the downlink message after encryption and integrity protection processing from the first network device, and the decryption and integrity protection verification are successful to obtain the downlink message;
  • the terminal device determines that the security context to be tested is the first set of security contexts.
  • the terminal device can determine the first set of security contexts that have passed the security verification test.
  • the downlink message is any one of the following: a security mode command, a tracking area update accept message, a radio resource control RRC security mode Command, Attach Accept message.
  • the first network device includes: a core network device or an access network device located in the second communication system.
  • the first set of security contexts includes a non-access stratum count value NAS count.
  • the terminal device acquires multiple sets of alternative security contexts, including:
  • the terminal device calculates the second set of security contexts according to the security context mapping algorithms of multiple versions respectively, and generates the multiple sets of candidate security contexts; wherein, the second set of security contexts is used for the terminal device to communicate with the security context.
  • the second network device performs security verification, and the second network device is located in the first communication system.
  • the first communication system is a fifth-generation 5G communication system
  • the second communication system is a fourth-generation 4G communication system.
  • an embodiment of the present application provides a communication method, and the method includes the following steps:
  • the core network equipment located in the second communication system receives a tracking area update request message or an attach request message from the terminal equipment; the core network equipment When the device determines that the RRC connection of the terminal device is in an idle state, it activates a new set of security contexts; wherein the new set of security contexts is used for the first network device to perform security verification with the terminal device, and the first set of security contexts is used for security verification between the first network device and the terminal device.
  • a network device is located in the second communication system; the core network device sends an authentication request message to the terminal device, so that the terminal device activates a new set of security contexts.
  • the terminal device in the process of switching from the first communication system to the second communication system, can trigger the TAU process or the attachment process, so that the terminal device and the core network device in the second communication system are in the TAU A new set of security contexts are activated in the process or attached process. Since the new set of security contexts activated by the two are consistent, the two subsequently use the new set of security contexts for security verification, which can achieve successful security verification, thereby ensuring that the terminal device can be successfully switched to the second set of security contexts. Communication Systems.
  • the core network device may also send the new set of security contexts to the access network device in the second communication system, so that the access network device can use the A new set of security contexts performs security authentication with the terminal device.
  • the new set of security contexts includes a non-access stratum count value NAS count.
  • the core network device may further determine, according to the tracking area update request message or the status indication information UE status carried in the attach request message, that the terminal device is from the first communication system Switch to the second communication system.
  • the first communication system is a fifth-generation 5G communication system
  • the second communication system is a fourth-generation 4G communication system.
  • an embodiment of the present application provides a communication method, and the method includes the following steps:
  • the terminal device sends a tracking area update request message or an attach request message to the core network device in the second communication system;
  • the authentication request message of the network device the terminal device activates a new set of security contexts according to the authentication request message; wherein, the new set of security contexts is used for the terminal device to communicate with the first network device
  • the first network device is located in the second communication system; the terminal device uses the new set of security contexts to perform security verification with the first network device.
  • the terminal device in the process of switching from the first communication system to the second communication system, can trigger the TAU process or the attachment process, so that the terminal device and the core network device in the second communication system are in the TAU A new set of security contexts are activated in the process or attached process. Since the new set of security contexts activated by the two are consistent, the two subsequently use the new set of security contexts for security verification, which can achieve successful security verification, thereby ensuring that the terminal device can be successfully switched to the second set of security contexts. Communication Systems.
  • the terminal device sends a tracking area update request message or an attach request message to the core network device in the second communication system, including:
  • the terminal device uses the first set of security contexts to perform integrity protection processing on the tracking area update request message or the attach request message; the first set of security contexts is used for the terminal device and the second network device to perform integrity protection processing. Security verification, the second network device is located in the first communication system;
  • the terminal device sends the tracking area update request message or the attach request message after integrity protection processing to the core network device.
  • the new set of security contexts includes a non-access stratum count value NAS count.
  • the tracking area update request message or the attach request message carries status indication information
  • the status indication information UE status is used to instruct the terminal device to switch from the first communication system to the second communication system.
  • the first communication system is a fifth-generation 5G communication system
  • the second communication system is a fourth-generation 4G communication system.
  • an embodiment of the present application provides a communication method, and the method includes the following steps:
  • the first core network device acquires multiple sets of alternative security contexts; wherein the first core network device is located in the second communication system; the The first core network device determines, among the multiple sets of candidate security contexts, a first set of security contexts that pass the security verification test; the first core network device activates the first set of security contexts, and uses the first set of security contexts
  • the security context performs security authentication with the terminal device.
  • the core network device located in the second communication system can obtain multiple sets of alternative security contexts; and in the multiple sets of alternative security contexts A set of security contexts that pass the security verification test is determined in the second communication system; the core network device located in the second communication system activates the set of security contexts for subsequent security verification with the terminal device.
  • the core network device in the second communication system can use This set of security contexts performs security verification with the terminal device, so that the security verification can be successful, thereby ensuring that the terminal device can be successfully switched to the second communication system.
  • the first core network device may obtain multiple sets of alternative security contexts in the following manner:
  • Manner 1 the first core network device receives the multiple sets of alternative security contexts from the second core network device; wherein the multiple sets of alternative security contexts are the second core network device based on multiple versions of the security context.
  • the security context mapping algorithm calculates and generates a second set of security contexts, and the second set of security contexts is used for the security verification between the second core network device and the terminal device, and the second core network device is located in the in the first communication system;
  • Manner 2 The first core network device receives the second set of security contexts from the second core network device; the first core network device calculates the second set of security contexts according to multiple versions of security context mapping algorithms , and generate the multiple sets of alternative security contexts; wherein, the second set of security contexts is used for the second core network device to perform security verification with the terminal device, and the second core network device is located in the first in the communication system.
  • the first core network device may determine the first set of security contexts that pass the security verification test among the multiple sets of candidate security contexts by performing the following steps:
  • the first core network device selects a set of security contexts to be tested from the multiple sets of alternative security contexts, wherein the security context to be tested is any set of alternative security contexts in the multiple sets of alternative security contexts context;
  • the first core network device uses the security context to be tested to decrypt the encrypted uplink message from the terminal device, and the decryption succeeds to obtain the uplink message; or the first core network device uses In the security context to be tested, integrity protection verification is performed on the uplink message after integrity protection processing from the terminal device, and the integrity protection verification is successful, and the uplink message is obtained; or
  • the first core network device uses the security context to be tested to perform decryption processing and integrity protection verification on the encrypted and integrity-protected uplink message from the terminal device, and decrypt and integrity-protect the uplink message. If successful, the uplink message is obtained;
  • the first core network device determines that the security context to be tested is the first set of security contexts.
  • the first core network device can determine the first set of security contexts that pass the security verification test.
  • the uplink message is any one of the following: a tracking area update request message and an attach request message.
  • the first core network device may also send the first set of security contexts to the access network device in the second communication system, so that the access network device can use all the security contexts.
  • the first set of security contexts perform security verification with the terminal device.
  • the first set of security contexts includes a non-access stratum count value NAS count.
  • the first communication system is a fifth-generation 5G communication system
  • the second communication system is a fourth-generation 4G communication system.
  • an embodiment of the present application provides a communication method, and the method includes the following steps:
  • the terminal device acquires multiple sets of alternative security contexts
  • the terminal device selects a set of candidate security contexts from the multiple sets of candidate security contexts to perform integrity protection processing on the uplink message, and sends the integrity protection processed uplink message to the first network device, and the first network device.
  • a network device is located in the second communication system; when the terminal device does not receive a response message to the uplink message from the first network device, the terminal device is in the multiple sets of alternative security contexts. Select the next set of alternative security contexts to perform integrity protection processing on the uplink message until a response message for the uplink message from the first network device is received.
  • the terminal device can attempt to use the next set of alternative security contexts for the uplink message after using a set of alternative security contexts to perform integrity protection processing on the uplink message and fail to receive a response message for the uplink message.
  • the message is subjected to integrity protection processing until a response message of the uplink message is received, so that the uplink message can be safely and successfully transmitted to the first network device.
  • the terminal device may further select a set of alternative security contexts from the multiple sets of alternative security contexts
  • the security context performs integrity protection verification on the response message after integrity protection processing, and if the integrity protection verification is successful, activate the alternative security context used this time;
  • the terminal device may also select a set of alternative security contexts from the multiple sets of alternative security contexts for encryption and integrity protection The response message after the security protection processing is decrypted and verified for integrity protection. If the decryption and integrity protection verification are successful, the alternative security context used this time is activated; otherwise, the terminal device is in the multiple sets of In the alternative security context, select the next set of alternative security contexts to perform decryption processing and integrity protection verification on the response message after encryption and integrity protection processing, until the decryption and integrity protection verification are successful, the terminal device Activate the last used alternate security context.
  • the terminal device can acquire multiple sets of alternative security contexts in the process of switching from the first communication system to the second communication system; and determine a set of security contexts that have passed the security check in the multiple sets of alternative security contexts context; the terminal device activates the set of security contexts for subsequent security verification with the network device of the second communication system. Since the set of security contexts activated by the terminal device has passed the security check, that is, the set of security contexts is consistent with the security context maintained by the network device in the second communication system, the terminal device uses the set of security contexts to communicate with the second set of security contexts. The network device of the communication system performs security verification, which can realize successful security verification, thereby ensuring that the terminal device can be successfully switched to the second communication system.
  • the terminal device is in the connected state of the RRC connection, and the uplink message is any one of the following: a tracking area update request message, an attach request message; the response message is any one of the following Items: Tracking Area Update Accept Message, Attach Accept Message, Security Mode Command, Radio Resource Control RRC Security Mode Command.
  • the terminal device acquires multiple sets of alternative security contexts, including:
  • the terminal device calculates the first set of security contexts according to the security context mapping algorithms of multiple versions respectively, and generates the multiple sets of candidate security contexts; wherein, the first set of security contexts is used for the terminal device to communicate with the security context.
  • the second network device performs security verification, and the second network device is located in the first communication system.
  • any set of alternative security contexts includes the non-access stratum count NAS count.
  • the first communication system is a fifth-generation 5G communication system
  • the second communication system is a fourth-generation 4G communication system.
  • an embodiment of the present application provides a communication apparatus, including a unit for performing each step in any of the above aspects.
  • an embodiment of the present application provides a communication device, comprising at least one processing element and at least one storage element, wherein the at least one storage element is used to store programs and data, and the at least one processing element is used to read and execute Programs and data stored by the storage element, so that the method provided by any of the above aspects of the present application is implemented.
  • an embodiment of the present application further provides a computer program, which, when the computer program runs on a computer, causes the computer to execute the method provided in any of the foregoing aspects.
  • an embodiment of the present application further provides a computer-readable storage medium, where a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a computer, the computer is made to execute any one of the above methods provided.
  • an embodiment of the present application further provides a chip, where the chip is configured to read a computer program stored in a memory and execute the method provided in any of the foregoing aspects.
  • an embodiment of the present application further provides a chip system, where the chip system includes a processor for supporting a computer device to implement the method provided in any of the foregoing aspects.
  • the chip system further includes a memory for storing necessary programs and data of the computer device.
  • the chip system can be composed of chips, and can also include chips and other discrete devices.
  • FIG. 1A is a schematic diagram of a confidentiality protection process provided by an embodiment of the present application.
  • FIG. 1B is a schematic diagram of an integrity protection process provided by an embodiment of the present application.
  • FIG. 2 is an architectural diagram of a communication system provided by an embodiment of the present application.
  • 3A is a flowchart of a communication method provided by an embodiment of the present application.
  • 3B is a flowchart of a communication example provided by an embodiment of the present application.
  • 4A is a flowchart of a communication method provided by an embodiment of the present application.
  • 4B is a flowchart of a communication example provided by an embodiment of the present application.
  • 5A is a flowchart of a communication method provided by an embodiment of the present application.
  • 5B is a flowchart of a communication example provided by an embodiment of the present application.
  • 6A is a flowchart of a communication method provided by an embodiment of the present application.
  • 6B is a flowchart of a communication example provided by an embodiment of the present application.
  • FIG. 7A is a flowchart of a communication method provided by an embodiment of the present application.
  • FIG. 7B is a flowchart of a communication example provided by an embodiment of the present application.
  • FIG. 8 is a structural diagram of a communication device provided by an embodiment of the present application.
  • FIG. 9 is a structural diagram of a communication device according to an embodiment of the present application.
  • the present application provides a communication method, apparatus and device to solve the problem that the terminal device cannot successfully complete the communication system switching due to inconsistent versions of the security context mapping protocol used by the terminal device and the core network during the process of switching between different systems.
  • the method and the device are based on the same technical concept. Since the principles of the method and the device for solving problems are similar, the implementation of the device and the method can be referred to each other, and repeated descriptions will not be repeated.
  • a terminal device is a device that provides voice and/or data connectivity to users.
  • a terminal device may also be called a user equipment (user equipment, UE), a mobile station (mobile station, MS), a mobile terminal (mobile terminal, MT), and the like.
  • UE user equipment
  • MS mobile station
  • MT mobile terminal
  • only a terminal device is taken as an example of UE for description.
  • the terminal device may be a handheld device with a wireless connection function, a vehicle-mounted device, or the like.
  • some examples of terminal devices are: mobile phone (mobile phone), tablet computer, notebook computer, PDA, mobile internet device (MID), smart point of sale (POS), wearable device, Virtual reality (VR) equipment, augmented reality (AR) equipment, wireless terminals in industrial control, wireless terminals in self driving, remote medical surgery wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, wireless terminals in smart homes, Class smart meters (smart water meter, smart electricity meter, smart gas meter), etc.
  • a communication system which is used to connect the terminal equipment to the data network by using the 3rd generation partnership project (3GPP) access technology when the terminal equipment requests services, and realize the connection between the terminal equipment and the data network.
  • 3GPP 3rd generation partnership project
  • the transmission of user plane data between them can realize corresponding services.
  • the communication systems involved in the following embodiments of the present application are all 3GPP communication systems.
  • the communication system is divided into an access network (AN) and a core network (core network, CN).
  • the access network is used to converge terminal equipment into the core network through 3GPP access technology.
  • the core network is used to connect terminal devices to different data networks.
  • the core network can be further divided into a control plane and a user plane.
  • this application does not limit the format of the communication system, which may be a third generation ( 3rd generation, 3G) communication system, a fourth generation ( 4th generation, 4G) communication system (ie, long term evolution (long term evolution). , LTE) communication system), the fifth generation ( 5th generation, 5G) communication system (ie new radio (new radio, NR) communication system), or a future communication system, or a communication system evolved based on any generation of communication systems.
  • 3rd generation, 3G) communication system ie, long term evolution (long term evolution). , LTE) communication system
  • the fifth generation ( 5th generation, 5G) communication system ie new radio (new radio, NR) communication system
  • a future communication system ie new radio (new radio, NR) communication system
  • an access network may also be referred to as an evolved universal mobile telecommunications system (UMTS) terrestrial radio access network (evolved-UMTS terrestrial radio access network, E-UTRAN), a core network It can also be called an evolved packet core (EPC).
  • UMTS evolved universal mobile telecommunications system
  • E-UTRAN evolved-UMTS terrestrial radio access network
  • EPC evolved packet core
  • the access network may also be referred to as a 5G radio access network (NG-radio access network (RAN), or NG-RAN), and the core network may also be referred to as a 5G core network (5G core, 5GC).
  • NG-radio access network RAN
  • NG-RAN 5G radio access network
  • 5G core 5G core network
  • a network device which is a network element located in the communication system.
  • the network device may be an access network device (AN device) in an access network, or a core network device in a core network. This application does not limit this.
  • the AN device is a device that connects the terminal device to the wireless network in the communication system.
  • the access network device as a node in the radio access network, may also be referred to as a base station, and may also be referred to as a radio access network (radio access network, RAN) node (or device).
  • RAN radio access network
  • AN devices are: gNB, transmission reception point (TRP), evolved Node B (evolved Node B, eNB), radio network controller (radio network controller, RNC), Node B (Node B) B, NB), access point (access point, AP) base station controller (base station controller, BSC), base transceiver station (base transceiver station, BTS), home base station (for example, home evolved NodeB, or home Node B, HNB), or base band unit (BBU), enterprise LTE discrete narrowband aggregation (Enterprise LTE Discrete Spectrum Aggregation, eLTE-DSA) base station, etc.
  • TRP transmission reception point
  • eNB evolved Node B
  • RNC radio network controller
  • Node B Node B
  • RNC radio network controller
  • Node B Node B
  • AP access point
  • base station controller base station controller
  • BTS base transceiver station
  • home base station for example, home evolved NodeB, or home Node B,
  • the AN device may include a centralized unit (centralized unit, CU) node and a distributed unit (distributed unit, DU) node.
  • CU centralized unit
  • DU distributed unit
  • This structure separates the protocol layers of the eNB in the long term evolution (LTE) system. The functions of some protocol layers are centrally controlled by the CU, and the remaining part or all of the functions of the protocol layers are distributed in the DU, which is controlled by the CU. Centralized control of DU.
  • LTE long term evolution
  • the AN device in a 4G communication system, is called an eNB; in a 5G communication system, the AN device may be called a gNB.
  • core network equipment a network element located in the core network, used to realize the functions of the core network, for example, responsible for connecting the terminal equipment to different data networks according to the call request or service request sent by the terminal equipment through the access network , as well as services such as billing, mobility management, and session management. Since the method provided by the embodiment of the present application is in the scenario where the terminal device performs inter-system handover, the core network device involved in the present application is the network element in the core network responsible for the mobility management function of the terminal device.
  • the core network equipment responsible for the mobility management function can also be called a control plane network element or a control plane. surface equipment.
  • the core network equipment responsible for the mobility management function may be referred to as a mobility management entity (mobility management entity, MME); in the 5G mobile communication system, the core network equipment responsible for the mobility management function It can be called an Access and Mobility Management Function (AMF) network element, or AMF for short.
  • MME mobility management entity
  • AMF Access and Mobility Management Function
  • this application does not limit the name of the core network device responsible for the mobility management function, it can also implement other functions or integrate with other functional network elements, and can also be called other names.
  • Security verification also known as security docking, security verification, etc., is used to realize the confidentiality protection and/or integrity protection of the receiver and the sender.
  • Inter-system handover which is to switch the UE from a communication system of one standard to a communication system of another standard.
  • the UE can implement the inter-system handover through various handover mechanisms, such as: handover mechanism, redirection mechanism, blind redirection mechanism, network search mechanism, reselection mechanism, and the like.
  • the handover mechanism is performed when the UE is in the RRC connected state, and the other mechanisms are performed when the UE is in the RRC idle state.
  • the attach (attach) process, the tracking area update (TAU) process, the security mode command (security mode command, SMC) process, and the authentication (authentication) process involved in the embodiments of the present application may be communication Standard procedures specified in a standard, such as those specified in Communications Standard 24.301.
  • the messages and timers involved in the above process can also refer to the definitions in this communication standard.
  • the radio resource control (radio resource control, RRC) SMC process involved in the embodiments of this application may also be a standard process specified in a communication standard, such as a process specified in communication standard 36.331.
  • the messages involved in this process may also refer to the definitions in this communication standard.
  • the UE and the network equipment in the communication system perform secure connection through a set of security contexts, so as to realize the transmission security of signaling.
  • the security verification includes confidentiality protection (ie encryption, decryption) and integrity protection (ie complete protection, uncompleted protection/integrity protection verification).
  • confidentiality protection ie encryption, decryption
  • integrity protection ie complete protection, uncompleted protection/integrity protection verification.
  • the NAS count in the security context is one of the parameters of encryption and decryption, security and de-security.
  • the UE may perform encryption and/or security processing on the uplink message according to the maintained security context, and the core network device may decrypt and/or perform security processing on the received uplink message according to the maintained security context. Or after the guarantee processing is completed, the upstream message is obtained.
  • the core network device can encrypt and/or secure the downlink message according to the maintained security context, and the terminal device can decrypt and/or decrypt the received downlink message after encryption and/or secure processing according to the maintained security context. After the guarantee processing is completed, the downlink message is obtained.
  • the security contexts maintained by the two need to correspond, that is, the UE and the core network.
  • the NAS count in the security context maintained by both devices is the same.
  • Figure 1A shows the process that the receiver and the sender use the NAS count to protect the confidentiality of the message.
  • the input parameters of the cryptographic algorithm include: a 128-bit (bit) confidentiality key (key) , a 32-bit count value (that is, NAS count, which is essentially a message sequence number), a 5-bit bearer identifier (that is, bearer), a 1-bit transmission direction indication (that is, direction), and the length of the required key stream block (that is, length).
  • a 128-bit (bit) confidentiality key key
  • a 32-bit count value that is, NAS count, which is essentially a message sequence number
  • a 5-bit bearer identifier that is, bearer
  • a 1-bit transmission direction indication that is, direction
  • the length of the required key stream block that is, length
  • Figure 1B shows the process that the receiver and the sender use the NAS count to protect the integrity of the message.
  • the input parameters of the integrity algorithm include: a 128-bit integrity key (key), a 32-bit count value (that is, NAS count, Its essence is the message sequence number), a 5-bit bearer identifier (ie bearer), a 1-bit transmission direction indication and the message to be transmitted itself (ie message). Wherein, when the value of the direction indication is 0, it indicates the upward direction, and when the value of the direction indication is 1, it indicates the downward direction.
  • the sender can generate a check code (ie MAC-I/NAS-MAC) based on the message to be transmitted and a series of other parameters according to the integrity algorithm in the figure, and then send the message and check code to the receiver at the same time .
  • the receiver According to the same integrity algorithm, the receiver generates the check code to be verified (XMAC-I/XNAS-MAC) based on the received message and a series of other local parameters;
  • the verification code to be verified is compared, if the two are the same, it means that the message is complete and has not been tampered with, the integrity of the message is verified successfully, and the receiver has successfully solved the guarantee; if the two are different, it means the message is complete.
  • the message may be tampered with, the integrity verification of the message fails, and the receiver fails to release the guarantee.
  • the NAS count in the security context is one of the parameters for encryption and decryption, security and de-security, and the NAS maintained by the sender and the receiver The count value must be the same to ensure successful connection.
  • each set of security contexts includes uplink security contexts and downlink security contexts. Both the uplink security context and the downlink security context consist of the NAS count, and some other parameters.
  • the UE can use the uplink security context to perform encryption and/or security processing on uplink messages (such as uplink signaling), and send the encrypted and/or fully processed uplink messages to the core network equipment;
  • the core network device can use the uplink security context to decrypt and/or de-encrypt the received uplink message after encryption and/or security processing, so as to obtain the uplink message.
  • the core network device may use the downlink security context to encrypt and/or secure downlink messages (such as downlink signaling), and send the encrypted and/or secure downlink messages to the UE;
  • the UE can use the downlink security context to decrypt and/or de-encrypt the received downlink message after encryption and/or security processing, so as to obtain the downlink message.
  • the terminal device when the terminal device resides in the communication system, the terminal device and the network device of the communication system only maintain the same security context, in order to realize the secure connection between the two, so that the communication system can provide services for the terminal device. Otherwise, the two cannot transmit messages, resulting in terminal device access failure.
  • the terminal device and the core network need to map the first set of security contexts in the first communication system to generate the second set of security contexts in the second communication system, and only when the terminal device After the device and the second communication system are successfully connected securely according to the second set of security contexts, the terminal device can be switched to the second communication system, and the service transmission of the terminal device can be realized through the second communication system.
  • the first communication system and the second communication system are communication systems of different standards, for example, the first communication system is a 5G communication system, and the second communication system is a 4G communication system.
  • mapping protocol for the security context
  • the NAS count in the second set of security contexts obtained by mapping the NAS counts in the first set of security contexts with different protocol versions may be different. Therefore, if the terminal device and the core network use different mapping protocol versions to map the first set of security contexts, it may cause the second set of security contexts maintained by the NAS layer of the terminal device to be different from the first set of security contexts maintained by the NAS layer of the core network.
  • the NAS count is one of the input parameters for encryption and decryption, complete protection (that is, integrity protection), and complete protection, if the NAS count in the second set of security contexts maintained by the terminal device and the core network is inconsistent, it will cause the terminal device and the core network.
  • the security connection of the core network fails, thereby causing the terminal device to fail to successfully switch to the second communication system, and the second communication system cannot provide transmission services for the terminal device, which seriously affects the services of the terminal device.
  • a security context mapping protocol is 3GPP protocol 33501_CR0611r1, which is used to map the security context corresponding to the 5G communication system to the security context corresponding to the 4G communication system.
  • 3GPP protocol 33501_CR0611r1 3GPP protocol 33501_CR0611r1
  • 5G security context the security context corresponding to the 5G communication system
  • 4G security context the security context corresponding to the 4G communication system
  • the protocol has two versions, the previous version and the refreshed version.
  • the following two versions of the protocol are used as examples for description.
  • the NAS count (referred to as NR count) in the 5G security context will be mapped to the initial value of 0, that is, the NAS count (referred to as LTE count) in the generated 4G security context. is 0.
  • the NAS count (that is, the NR count) in the 5G security context does not change, that is, the NAS count (that is, the LTE count) in the generated 4G security context is equal to the NR count.
  • FIG. 2 shows a communication architecture to which the communication method provided by the embodiment of the present application is applicable.
  • FIG. 2 only takes the 5G communication system and the 4G communication system as examples for description.
  • this application does not limit the communication architecture used by the method provided in this application, and the architecture can also include at least any of the following two communication systems: 5G communication system, 4G communication system, future new generation communication system, global mobile communication system Communication (Global System of Mobile communication, GSM) system, Code Division Multiple Access (Code Division Multiple Access, CDMA) system, Wideband Code Division Multiple Access (Wideband Code Division Multiple Access, WCDMA) system, General Packet Radio Service (General Packet Radio) Service, GPRS), Advanced Long Term Evolution (LTE-A) system, Universal Mobile Telecommunication System (UMTS), and The 3rd Generation Partnership Project (3GPP) Related cellular systems, and communication systems evolved based on the above communication systems.
  • GSM Global System of Mobile communication
  • CDMA Code Division Multiple Access
  • WCDMA Wideband Code Division Multiple Access
  • GPRS General Packet Radio Service
  • LTE-A Advanced Long Term Evolution
  • UMTS Universal Mobile Telecommunication System
  • 3GPP 3rd Generation Partnership Project
  • the communication architecture described in the embodiments of the present application is for the purpose of illustrating the technical solutions of the embodiments of the present application more clearly, and does not constitute a limitation on the technical solutions provided by the embodiments of the present application.
  • the development of the network and the evolution of the network architecture, the technical solutions provided by the embodiments of the present application are also applicable to similar technical problems and scenarios.
  • the UE can switch from one communication system to another communication system through inter-system handover.
  • the 4G communication system includes two parts: an access network and a core network.
  • the access network is the E-UTRAN shown in the figure, and the core network includes the following network elements: a mobility management entity (MME), a serving gateway (SGW), Packet data network gateway (PGW), policy and charging rules function (policy and charging rules function, PCRF) network element (referred to as PCRF), home subscriber server (home subscriber server, HSS), etc.
  • MME mobility management entity
  • SGW serving gateway
  • PGW Packet data network gateway
  • PCRF policy and charging rules function
  • HSS home subscriber server
  • PCRF home subscriber server
  • HSS home subscriber server
  • the PGW can be further divided into: PGW control plane (PGW-control, PGW-C) network element (referred to as PGW-C) and PGW user plane (PGW-user, PGW-U) ( Referred to as PGW-U).
  • PGW control plane PGW control plane
  • PGW-C PGW control plane
  • PGW-user PGW-U
  • the 5G communication system also includes two parts: the access network and the core network.
  • the access network is the NG-RAN shown in the figure, AMF network element (referred to as AMF), user plane function (user plane function, UPF) network element (referred to as UPF), session management function (session management function) management function, SMF) network element (referred to as SMF), policy and charge function (policy and charge function, PCF) network element (referred to as PCF), unified data management (unified data management, UDM) network element (referred to as UDM) network element )Wait.
  • AMF AMF network element
  • UPF user plane function
  • UPF session management function
  • SMF session management function
  • PCF policy and charge function
  • PCF policy and charge function
  • PCF policy and charge function
  • UDM unified data management
  • UDM unified data management
  • SMF and PGW-C can be integrated in the same network element, or can be separately set in different devices
  • UPF and PGW-U, HSS and UDM, and PCF and PCRF network elements are also the same, and their composition modes are not specifically limited in the embodiments of the present application.
  • Communication between two network devices in the 4G communication system may be implemented through corresponding interfaces, as shown in FIG. 2 for details. And two network devices in the 5G communication system can also communicate through corresponding interfaces, as shown in FIG. 2 for details. It should be noted that, in order to realize the inter-system handover of the UE between the 5G communication system and the 4G communication system, the AMF in the 5G communication system and the MME in the 4G communication system can also communicate through the interface N26 to realize signaling and The transmission of the security context ensures seamless handover of the UE.
  • the above network elements in a 4G communication system or a 5G communication system can be either network elements implemented on dedicated hardware, software instances running on dedicated hardware, or virtualized platforms (such as An instance of a virtualized function on a cloud platform).
  • the embodiments of the present application do not limit the distribution form of each network element in the communication system.
  • each of the above network elements may be deployed in different physical devices, or multiple network elements may be integrated into the same physical device.
  • each network element may have other names; for example, when multiple network elements are integrated into the same physical device , the physical device can also have another name.
  • the security contexts maintained by the two may be inconsistent (the security context maintained by the two is in the security context).
  • the included NAS count is inconsistent), which eventually causes the UE to fail to successfully switch to the new communication system.
  • an embodiment of the present application provides a communication method, which can be applied to the communication system as shown in FIG. 2 .
  • the source communication system for the UE to perform the inter-system handover is referred to as the first communication system
  • the destination communication system for the UE to perform the inter-system handover is referred to as the second communication system.
  • the network device located in the first communication system is referred to as the first network device
  • the network device located in the second communication system is referred to as the second network device.
  • the first network device may include a first core network device and a first AN device located in the first communication system
  • the second network device may include a second core network located in the second communication system network equipment and the second AN equipment.
  • the respective embodiments of the present application do not limit the systems of the first communication system and the second communication system.
  • the first communication system may be a 5G communication system
  • the second communication system may be a 4G communication system
  • the first communication system may be a 4G communication system
  • the second communication system may be a 5G communication system communication system
  • the first communication system may be a 6G communication system
  • the second communication system may be a 5G communication system or the like.
  • S301a When the UE resides in the first communication system, the UE performs security verification with the first network device located in the first communication system using the first set of security contexts.
  • the NAS layer in the UE and the first network device maintains the first set of security contexts respectively, and uses the first set of security contexts maintained by them to perform confidentiality protection and integrity on the transmitted messages
  • the NAS layer in the UE and the first network device maintains the first set of security contexts respectively, and uses the first set of security contexts maintained by them to perform confidentiality protection and integrity on the transmitted messages
  • S302a When the current network environment satisfies the inter-system handover condition, trigger the inter-system handover of the UE; the UE starts to perform the inter-system handover to switch from the first communication system to the second communication system. During the inter-system handover process, the UE successfully camps on the second communication system. The UE acquires a second set of security contexts to perform security authentication with a second network device located in a second communication system using the second set of security contexts.
  • the communication system may use a handover mechanism, a redirection mechanism, a blind redirection mechanism, or a network search mechanism. , reselection mechanism, etc., to realize the inter-system handover of the UE.
  • the UE may trigger an inter-system handover process of switching from the first communication system to the second communication system when determining that the inter-system handover condition is satisfied; or the first network device determines that the system handover is satisfied.
  • a notification message is sent to the UE, instructing the UE to perform an inter-system handover procedure of handover from the first communication system to the second communication system.
  • the UE when it acquires the second set of security contexts, it may calculate the first set of security contexts maintained by itself according to a locally saved set security context mapping algorithm to generate the second set of security contexts. security context.
  • S303a The UE uses the second set of security contexts to perform security authentication with the second network device.
  • the second network device may also obtain a third set of security contexts in the following two ways:
  • Manner 1 During the process of the UE performing the inter-system handover, the first network device calculates the first set of security contexts maintained by itself according to the set security context mapping algorithm saved locally, and generates the third set of security contexts. Set of security contexts. The first network device may send the third set of security contexts to the second network device through the interface N26.
  • the second set of security contexts generated by the UE is the same as the set security context mapping algorithm locally stored by the first network device.
  • the third set of security contexts generated by the first network device are the same.
  • the set security context mapping algorithm stored locally by the UE is different from the set security context mapping algorithm stored locally by the first network device, the second set of security contexts generated by the UE is different from the set security context generated by the first network device.
  • the third set of security contexts may be different.
  • Manner 2 During the process of the UE performing the inter-system handover, the first network device sends the first set of security contexts maintained locally to the second network device.
  • the second network device generates the third set of security contexts by calculating the received first set of security contexts according to the set security context mapping algorithm stored locally.
  • the first network device may send the first set of security contexts to the second network device through the interface N26.
  • the second set of security contexts generated by the UE is the same as the set security context mapping algorithm locally stored by the second network device.
  • the third set of security contexts generated by the second network device are the same.
  • the set security context mapping algorithm stored locally by the UE is different from the set security context mapping algorithm stored locally by the second network device, the second set of security contexts generated by the UE is different from the set security context generated by the second network device.
  • the third set of security contexts may be different.
  • the UE uses the second set of security contexts to perform security with the second network device
  • the verification means that the security verification is successful, that is, the UE is successfully connected with the second network device, so as to ensure that the UE can be successfully switched to the second communication system.
  • the UE uses the second set of security contexts to communicate with the second network device.
  • the security verification will lead to a failure of the security verification, that is, the UE fails to securely connect with the second network device, and thus the UE cannot be successfully handed over to the second communication system.
  • S304a When the second set of security contexts generated by the UE is different from the third security context obtained by the second network device, and the UE fails to perform security verification with the second set of security contexts using the second set of security contexts , the UE initiates a registration process to the second network device, so that the UE and the second network device can activate a new set of security contexts at the same time.
  • the UE when the number of times that the UE fails to perform security verification with the second network device using the second set of security contexts is greater than or equal to a set threshold, the UE initiates the second network device registration process. In this way, signaling overhead and delay caused by the UE initiating the registration process can be avoided when a small number of security verifications fail due to other reasons.
  • the value of the set threshold may be specifically set according to an actual application or a specific scenario, which is not limited in this embodiment of the present application.
  • the set threshold may be 2, 3, 4, or the like.
  • the UE fails to perform security verification with the second network device using the second set of security contexts, which may include, but is not limited to, the following situations:
  • Case 1 The UE uses the second set of security contexts to decrypt the encrypted downlink message from the second network device, and the decryption fails.
  • Case 2 The UE uses the second set of security contexts to perform integrity protection verification on the downlink message after integrity protection processing from the second network device, and the integrity protection verification fails.
  • Case 3 The UE uses the second set of security contexts to decrypt the encrypted and integrity-protected downlink messages from the second network device and perform integrity protection verification, and the decryption fails or the integrity Protection verification failed.
  • Case 4 The UE uses the second set of security contexts to perform integrity protection processing on uplink messages, and sends the integrity-protected uplink messages to the second network device, and the UE does not receive any The response message of the uplink message of the second network device.
  • the downlink message involved in the above case may be, but is not limited to, any of the following: a security mode command (security mode command), a tracking area update accept message (tracking area update accept), an RRC security mode command ( security mode command), attach accept message (attach accept);
  • the uplink message involved in the above case can be, but is not limited to, any of the following: tracking area update request message (tracking area update request), attachment request message (attach request).
  • the UE initiates a registration process to the second network device, which may, but is not limited to, include the following steps:
  • the UE deletes the second set of security contexts, and releases the RRC connection of the UE;
  • the UE sends an attach request message (attach request) to the second network device, where the attach request message includes an international mobile subscriber identification number (international mobile subscriber identification number, IMSI) of the UE.
  • attach request message includes an international mobile subscriber identification number (international mobile subscriber identification number, IMSI) of the UE.
  • IMSI international mobile subscriber identification number
  • the second network device after receiving the attach request message sent by the UE in the registration process, the second network device will activate a new set of security contexts locally when it is determined that the attach request message contains the IMSI of the UE , and instruct the UE to activate a new set of security contexts.
  • the security contexts maintained by the two are consistent (the NAS counts included in the security contexts maintained by the two are all initial values (for example, 0), which are consistent) . Therefore, the UE and the second network device can use the new set of security contexts to perform security verification subsequently, and can ensure that the security verification is successful.
  • S305a The UE and the second network device use a new set of security contexts to perform security verification.
  • the UE and the second network device can be securely connected to each other, thereby ensuring that the UE can be successfully handed over to the second communication system.
  • the embodiments of the present application provide a communication method, in which, during the process of switching from the first communication system to the second communication system, the UE obtains the network equipment used for communicating with the second communication system.
  • a security context for security verification when the UE fails to perform security verification with the network device in the second communication system using the security context, a registration process is initiated to the network device in the second communication system, so that the UE and the network device in the second communication system fail to perform security verification. All the network devices in the second communication system can activate a new set of security contexts in the registration process. Since the new set of security contexts activated by the two are consistent, the two subsequently use the new set of security contexts for security verification, which can achieve successful security verification, thereby ensuring that the UE can successfully switch to the second communication system.
  • the present application also provides a communication example, which will be described in detail below with reference to the flowchart of the communication example shown in FIG. 3B .
  • This example is described by taking the UE switching from the 5G communication system to the 4G communication system as an example.
  • the security context corresponding to the 5G communication system is abbreviated as 5G security context
  • the security context corresponding to the 4G communication system is abbreviated as 4G security context.
  • S301b When the UE resides in the 5G communication system, and the current network environment satisfies the conditions for triggering the inter-system handover from the 5G communication system to the 4G communication system (for example, the signal quality of the 5G communication system is reduced, while the signal quality of the 4G communication system is higher) , triggering the inter-system handover of the UE.
  • the conditions for triggering the inter-system handover from the 5G communication system to the 4G communication system for example, the signal quality of the 5G communication system is reduced, while the signal quality of the 4G communication system is higher
  • S302b The UE uses the security context mapping algorithm 1 to calculate the 5G security context maintained by the UE to obtain the 4G security context 1.
  • the security context mapping algorithm 1 used by the UE may be the 33501_CR0611r1 protocol of the previous version, or the 33501_CR0611r1 protocol of the refreshed version.
  • the NAS count (referred to as NR count) in the 5G security context will be mapped to the initial value of 0, that is, the NAS count in the generated 4G security context 1 (referred to as NR count) LTE count) is 0.
  • the NAS count (that is, the NR count) in the 5G security context does not change, that is, the NAS count (that is, the LTE count) in the generated 4G security context 1 is equal to the NR count.
  • S303b The AMF in the 5G communication system uses the security context mapping algorithm 2 to calculate the 5G security context maintained by the AMF, and obtains the 4G security context 2.
  • the security context mapping algorithm 2 used by the AMF may also be the 33501_CR0611r1 protocol of the previous version, or the 33501_CR0611r1 protocol of the updated version.
  • the different security context mapping algorithms used by the UE and the AMF are used as an example, that is, the 4G security context 1 obtained by the UE and the 4G security context 2 obtained by the calculation by the AMF are used as an example. different.
  • S304b The AMF sends the calculated 4G security context 2 to the MME in the 4G communication system through the interface N26.
  • the UE fails to perform security verification with the network device in the 4G communication system using the generated 4G security context 1. Since the 4G security context 1 used by the UE is different from the 4G security context 2 used by the network device in the 4G communication system, it will occur. A condition where security verification fails.
  • the following describes the security verification failure in detail according to Scenario 1 to Scenario 4. It should be noted that Scenario 1 to Scenario 4 are only a few examples of security verification failures, which do not limit the security verification failure scenarios involved in this example. In addition, scenarios such as UE attachment process failure are also applicable to this example. Since the attachment process is similar to these example processes, they can be referred to each other, and are not repeated in this example.
  • Scenario 1 The SMC process fails.
  • S305b After the UE successfully resides in the 4G communication system, the UE sends a tracking area update request message (Tracking area update request) to the MME in the 4G communication system to realize registration in the 4G communication system.
  • Tracking area update request a tracking area update request message
  • S306b The MME selects to trigger the SMC process of the NAS layer, selects a new set of algorithms, and generates a security mode command (Security mode command), wherein the key set identifier (key set identifier) in the security mode command is set to Identifier indicating 4G security context 2.
  • the MME uses the locally maintained 4G security context 2 to perform integrity protection processing on the security mode command, and sends the integrity protection processed security mode command to the UE.
  • S308b According to the provisions of protocol 24.301, the UE notifies the MME that the current SMC process fails to the MME security mode reject message (Security mode reject).
  • Scenario 2 The UE fails to decrypt and unlock the security.
  • S310b The MME generates a tracking area update accept message (Tracking area update accept), and uses the locally maintained 4G security context 2 to encrypt and integrity-protect the tracking area update accept message; the MME sends the UE a Send an encrypted and integrity protected Tracking Area Update Accept message.
  • Tracking area update accept a tracking area update accept message
  • 4G security context 2 a tracking area update accept message
  • S311b Since the 4G security contexts maintained by the UE and the MME are inconsistent (the NAS counts in the 4G security contexts maintained respectively are inconsistent), the UE uses the locally maintained 4G security context 1 to encrypt and complete the received encryption Decryption and integrity protection verification of the tracking area update acceptance message after performance protection processing may occur, and decryption failure or integrity protection verification failure may occur. At this time, the UE will receive the encrypted and integrity protection processed tracking area. The update accept message is discarded.
  • the MME may autonomously choose to execute the above-mentioned scenario one or the second scenario.
  • Scenario 3 The connection state MME fails to release the security.
  • S312b When the UE is in the RRC connection state, according to protocol 24.301, the NAS layer of the UE uses 4G security context 1 to perform integrity protection processing on the tracking area update request message (Tracking area update request); the UE sends the MME to the The tracking area update request message after integrity protection is processed, and a timer 3430 is started.
  • the NAS layer of the UE uses 4G security context 1 to perform integrity protection processing on the tracking area update request message (Tracking area update request); the UE sends the MME to the The tracking area update request message after integrity protection is processed, and a timer 3430 is started.
  • S315b After the UE successfully camps on the 4G communication system, the UE sends a tracking area update request message (Tracking area update request) to the MME in the 4G communication system to realize registration in the 4G communication system.
  • Tracking area update request a tracking area update request message
  • the eNB triggers the RRC SMC process, and uses the locally maintained 4G security context 2 to perform integrity protection processing on the RRC security mode command (RRC Security mode command); the eNB sends the RRC security mode after integrity protection processing to the UE Order.
  • RRC Security mode command RRC Security mode command
  • the 4G security context 2 maintained locally by the eNB is sent to it by the MME.
  • S318b The UE sends a security mode failure message (Security mode failure) to the eNB to notify the eNB that the current RRC SMC process fails.
  • a security mode failure message Security mode failure
  • the MME After the MME receives the attach request message and determines that the attach request message contains the IMSI of the UE, it will reactivate a new set of 4G security contexts locally, and will also instruct the UE to reactivate a set of 4G security contexts. New 4G security context. In this way, the UE and the MME can perform security verification based on the new 4G security context maintained by each.
  • the UE may configure the value of the set threshold independently, or set by the user, or specified by the standard, which is not limited in this application.
  • Subsequent procedures may refer to communication standard protocols, for example, sections 5.4.2, 5.4.3, and 5.5.1 of protocol 24301, which will not be repeated in this example.
  • Embodiment 2 is a diagrammatic representation of Embodiment 1:
  • S401a When the UE resides in the first communication system, the UE performs security verification with the first network device located in the first communication system using the first set of security contexts.
  • the NAS layer in the UE and the first network device maintains the first set of security contexts respectively, and uses the first set of security contexts maintained by them to perform confidentiality protection and integrity on the transmitted messages
  • the NAS layer in the UE and the first network device maintains the first set of security contexts respectively, and uses the first set of security contexts maintained by them to perform confidentiality protection and integrity on the transmitted messages
  • the UE is in the RRC idle state, and when the current network environment meets the inter-system handover condition, the UE's inter-system handover is triggered; the UE starts to perform inter-system handover to switch from the first communication system to the second communication system. During the inter-system handover process, the UE successfully camps on the second communication system. The UE acquires multiple sets of candidate security contexts, so as to select a set of security contexts from the multiple sets of candidate security contexts to perform security verification with the second network device located in the second communication system.
  • the communication system can use the redirection mechanism, blind repeating Orientation mechanism, network search mechanism, reselection mechanism, etc., to realize the inter-system handover of the UE.
  • the UE may trigger an inter-system handover process of switching from the first communication system to the second communication system when determining that the inter-system handover condition is satisfied; or the first network device determines that the system handover is satisfied.
  • a notification message is sent to the UE, instructing the UE to perform an inter-system handover procedure of handover from the first communication system to the second communication system.
  • the UE may calculate the first set of security contexts maintained by itself according to the locally stored multiple versions of the security context mapping algorithm, and generate the set of security contexts. Multiple sets of alternative security contexts.
  • S403a The UE determines a second set of security contexts that pass the security verification test in the multiple sets of candidate security contexts.
  • the second network device may also obtain the third set of security contexts for performing security verification with the UE in two ways.
  • the specific process please refer to Embodiment 1. description, which will not be repeated here.
  • the UE since the UE locally saves multiple versions of the security context mapping algorithm, which may include the set security context mapping algorithm locally saved by the first network device/second network device, that is, multiple sets of alternatives generated by the UE At least one set of alternative security contexts in the security context is consistent with the third set of security contexts maintained by the second network device. Therefore, the UE may select the second set of security contexts that is consistent with the third set of security contexts maintained by the second network device from the multiple sets of alternative security contexts through S403a.
  • the security context mapping algorithm which may include the set security context mapping algorithm locally saved by the first network device/second network device, that is, multiple sets of alternatives generated by the UE At least one set of alternative security contexts in the security context is consistent with the third set of security contexts maintained by the second network device. Therefore, the UE may select the second set of security contexts that is consistent with the third set of security contexts maintained by the second network device from the multiple sets of alternative security contexts through S403a.
  • the UE may perform S403a by the following steps:
  • the UE selects a set of security contexts to be tested from the multiple sets of candidate security contexts, wherein the security context to be tested is any set of candidate security contexts in the multiple sets of candidate security contexts;
  • the UE uses the selected security context to be tested to perform a security verification test with the second network device, and if it is determined that the security verification test passes, then determine that the security context to be tested is the second set of security contexts; otherwise, continue to The multiple sets of candidate security contexts select the next set of security contexts to be tested, until it is determined that the selected security contexts to be tested pass the security verification test; finally, the UE determines that the security context to be tested that has passed the security verification test is the second security context to be tested.
  • Set of security contexts are possible set of security contexts.
  • the selection sequence of the multiple sets of alternative security contexts may be preset or random, which is not limited in this application.
  • the UE may determine that the selected security context to be tested has passed the security verification test under the following circumstances:
  • Case 1 The UE decrypts the encrypted downlink message from the second network device by using the security context to be tested, and the decryption succeeds to obtain the downlink message.
  • the encrypted downlink message is generated by the second network device using the third set of security context to encrypt the downlink message.
  • Case 2 The UE uses the security context to be tested to perform integrity protection verification on the downlink message after integrity protection processing from the second network device, and the integrity protection verification succeeds, and the downlink message is obtained. information.
  • the downlink message after the integrity protection processing is generated by the second network device performing the integrity protection processing on the downlink message by using the third set of security context.
  • Case 3 The UE uses the security context to be tested to perform decryption processing and integrity protection verification on the downlink message after encryption and integrity protection processing from the second network device, and the decryption and integrity protection verification is performed. If the test is successful, the downlink message is obtained.
  • the downlink message after the encryption and integrity protection processing is generated by the second network device using the third set of security context to perform encryption and integrity protection processing on the downlink message.
  • the downlink message involved in the above situation may be, but is not limited to, any of the following: a security mode command (security mode command), a tracking area update accept message (tracking area update accept), an RRC security mode command (security mode command) ), attach accept message (attach accept).
  • a security mode command security mode command
  • tracking area update accept tracking area update accept
  • RRC security mode command security mode command
  • attach accept message attach accept
  • S404a The UE activates the second set of security contexts, so that the second set of security contexts can be used for subsequent security verification with the second network device.
  • S405a The UE uses the second set of security contexts to perform security authentication with the second network device.
  • the UE can be securely connected with the second network device, thereby ensuring that all The UE can be successfully handed over to the second communication system.
  • the embodiments of the present application provide a communication method, in which, during the process of switching from the first communication system to the second communication system, the UE can acquire multiple sets of alternative security contexts; A set of security contexts that pass the security verification test is determined in the set of candidate security contexts; the UE activates the set of security contexts for subsequent security verification with the network device of the second communication system.
  • the UE Since the set of security contexts activated by the UE has passed the security verification test, that is, the set of security contexts is consistent with the security contexts maintained by the network device in the second communication system, the UE uses this set of security contexts to communicate with the second communication system
  • the network device that performs security verification can realize successful security verification, thereby ensuring that the UE can be successfully handed over to the second communication system.
  • the present application also provides a communication example, which will be described in detail below with reference to the flowchart of the communication example shown in FIG. 4B .
  • This example is described by taking the UE switching from the 5G communication system to the 4G communication system as an example.
  • the security context corresponding to the 5G communication system is abbreviated as 5G security context
  • the security context corresponding to the 4G communication system is abbreviated as 4G security context.
  • S401b The UE resides in the 5G communication system and the UE is in the RRC idle state. At this time, the current network environment satisfies the conditions for triggering the inter-system handover from the 5G communication system to the 4G communication system (for example, the signal quality of the 5G communication system is reduced, and the 4G communication system When the signal quality of the UE is relatively high), the inter-system handover of the UE is triggered.
  • the UE After the UE successfully camps on the 4G communication system, the UE sends a tracking area update request message (Tracking area update request) to the MME in the 4G communication system to realize registration in the 4G communication system. At this time, the UE uses the 5G security context to perform integrity protection on the tracking area update request message.
  • Tracking area update request a tracking area update request message
  • the tracking area update request may carry status indication information (UE status), and the status indication information (UE status) is used to instruct the UE to switch from the 5G communication system to the 4G communication system.
  • UE status status indication information
  • S403b The UE uses two versions of the security context mapping algorithm to calculate the 5G security context maintained by the UE to obtain 4G security context 1 and 4G security context 2.
  • the UE uses two versions of the security context mapping algorithm including: the 33501_CR0611r1 protocol of the previous version, and the 33501_CR0611r1 protocol of the refreshed version.
  • S404b After the MME receives the tracking area update request message after the integrity protection processing sent by the UE, it determines that the UE is in the RRC idle state, and is currently in the process of switching the UE from the 5G communication system to the 4G communication system, then according to The identity identifier carried in the area update request message is tracked to find the AMF in the 5G communication system, and the MME sends a context request to the AMF through the N26 interface.
  • the context request may be an integrity-protected tracking area update request message received by the MME.
  • S405b When the context request is an integrity-protected tracking area update request message received by the MME, the AMF uses the 5G security context to perform integrity protection verification on the integrity-protected tracking area update request , after the integrity protection check succeeds, the AMF uses a saved version of the security context mapping algorithm to calculate the 5G security context maintained by the AMF, and obtains 4G security context 1.
  • the security context mapping algorithm used by the AMF may be the 33501_CR0611r1 protocol of the previous version, or the 33501_CR0611r1 protocol of the refreshed version.
  • the 4G security context 1 obtained by the AMF is the same as one of the two sets of 4G security contexts (ie, 4G security context 1) obtained by the UE.
  • S406b The AMF sends the obtained 4G security context 1 to the MME through a context response through the N26 interface.
  • time when the UE executes S403b may be before, after or at the same time as executing S402, which is not limited in this application.
  • the UE can select the 4G security context that passes the security verification test (that is, the same as the 4G security context 1 maintained by the MME) from the two sets of 4G security contexts, but is not limited to the following scenarios 1-3. .
  • Scenario 1 to Scenario 3 are only a few examples of the UE performing the security verification test, which do not limit the security verification test scenarios involved in this example.
  • the security verification test can also pass the UE attachment process, etc. Scenario implementation, since the attachment process is similar to the processes in these examples, it can be referred to each other, and details are not repeated in this example.
  • Scenario 1 SMC process.
  • S407b After the MME acquires the 4G security context 1 from the AMF, it can trigger the SMC process of the NAS layer, select a new set of algorithms (security algorithms), and generate a security mode command (Security mode command), wherein all the The key set identifier (key set identifier) in the security mode command described above is set to an identifier indicating 4G security context 1.
  • the MME uses the locally maintained 4G security context 1 to perform integrity protection processing on the security mode command, and sends the integrity protection processed security mode command to the UE.
  • the UE After receiving the security mode command processed by the integrity protection, the UE replaces the original algorithm with the new algorithm selected by the MME. Since the UE has two sets of 4G security contexts at this time (4G security context 1 and 4G security context 2, the NAS COUNT value in one set of 4G security contexts is 0, and the NAS COUNT value in the other set of 4G security contexts is NR COUNT) . The UE can use one set of 4G security contexts in two sets of 4G security contexts to perform integrity protection verification on the received security mode command after integrity protection processing.
  • S409b The UE performs encryption and integrity protection processing on a security mode complete message (Security mode complete) using the activated 4G security context 1, and sends the encrypted and integrity protection processed security mode complete message to the MME .
  • Scenario 2 The MME sends a tracking area update accept message (Tracking area update accept).
  • S410b The MME uses the 4G security context 1 obtained from the AMF to encrypt and integrity-protect the tracking area update accept message; the MME sends the encrypted and integrity-protected message to the UE Tracking area update accept message.
  • S411b Since the UE has two sets of 4G security contexts (4G security context 1 and 4G security context 2 at this time), the NAS COUNT value in one set of 4G security contexts is 0, and the NAS COUNT value in the other set of 4G security contexts is NR COUNT).
  • the UE can use one set of 4G security contexts in the two sets of 4G security contexts to decrypt and verify the integrity protection of the received tracking area update acceptance message after encryption and integrity protection processing.
  • the decryption and integrity protection verification are successful ( Indicates that the UE selects 4G security context 1), then activates a set of 4G security contexts used this time; if the decryption or integrity protection check fails (indicating that the UE selects 4G security context 2), another set of 4G security contexts is used.
  • the security context that is, the 4G security context 1 performs decryption and integrity protection verification on the received security mode command after encryption and integrity protection processing, until the decryption and integrity protection verification succeed; the UE activates the last used one.
  • Set of 4G security context ie 4G security context 1).
  • S412b The UE uses the activated 4G security context 1 to perform encryption and integrity protection processing on the tracking area update complete message (Tracking area update complete), and sends the tracking area update complete message after encryption and integrity protection processing to the MME message to complete the registration of the UE in the 4G communication system.
  • Scenario 3 The eNB in the 4G communication system triggers the RRC SMC process.
  • the eNB triggers the RRC SMC process, and uses the locally maintained 4G security context 1 to perform integrity protection processing on the RRC security mode command (RRC Security mode command); the eNB sends the RRC security mode after integrity protection processing to the UE Order.
  • RRC Security mode command RRC Security mode command
  • the 4G security context 1 maintained locally by the eNB is sent to it by the MME.
  • S414b Since the UE has two sets of 4G security contexts (4G security context 1 and 4G security context 2 at this time), the NAS COUNT value in one set of 4G security contexts is 0, and the NAS COUNT value in the other set of 4G security contexts is NR COUNT).
  • the UE can use one set of 4G security contexts in two sets of 4G security contexts to perform integrity protection verification on the received RRC security mode command after integrity protection processing.
  • Context 1 activate a set of 4G security contexts used this time; if the integrity protection check fails (indicating that the UE selects 4G security context 2), then use another set of security contexts (ie 4G security context 1) Perform integrity protection verification on the received RRC security mode command after integrity protection processing until the integrity protection verification succeeds; the UE activates the last set of 4G security contexts used (ie, 4G security context 1).
  • S415b The UE performs encryption and integrity protection processing on an RRC security mode complete message (RRC Security mode complete) using the activated 4G security context 1, and sends the encrypted and integrity protection processed RRC security to the MME Mode complete message.
  • RRC Security mode complete an RRC security mode complete message
  • this example does not limit the method in which the UE selects the 4G security context, and the UE may decide which set of 4G security contexts to choose first when performing the security verification test; or the UE may use Randomly select, or set a priority order to select the 4G security context.
  • the UE may preferentially select a 4G security context with a NAS count equal to NR count for the security verification test, or the UE may preferentially select a 4G security context with a NAS count equal to 0 for the security verification test.
  • S501a When the UE resides in the first communication system, the UE performs security verification with the first network device located in the first communication system using the first set of security contexts.
  • the NAS layer in the UE and the first network device maintains the first set of security contexts respectively, and uses the first set of security contexts maintained by them to perform confidentiality protection and integrity on the transmitted messages
  • the NAS layer in the UE and the first network device maintains the first set of security contexts respectively, and uses the first set of security contexts maintained by them to perform confidentiality protection and integrity on the transmitted messages
  • S502a The UE is in the RRC idle state, and when the current network environment satisfies the inter-system handover condition, the UE's inter-system handover is triggered; the UE starts to perform the inter-system handover to switch from the first communication system to the second communication system. During the inter-system handover process, the UE successfully camps on the second communication system.
  • the communication system can use the redirection mechanism or the blind redirection mechanism. , network search mechanism, reselection mechanism, etc., to realize the inter-system handover of UE.
  • the UE may trigger an inter-system handover process of switching from the first communication system to the second communication system when determining that the inter-system handover condition is satisfied; or the first network device determines that the system handover is satisfied.
  • a notification message is sent to the UE, instructing the UE to perform an inter-system handover procedure of handover from the first communication system to the second communication system.
  • the UE triggers the TAU process or the attachment process, and sends a tracking area update request message (tracking area update request) or an attach request message (attach request) to the second core network device in the second communication system.
  • the second core network device receives the tracking area update request message or the attach request message from the UE.
  • the tracking area update request or attach request message may carry status indication information (UE status), and the status indication information may also instruct the UE to switch from the 5G communication system to the 4G communication system.
  • UE status status indication information
  • the status indication information may also instruct the UE to switch from the 5G communication system to the 4G communication system.
  • S504a When the second core network device determines that the UE is in the RRC idle state, it locally activates a new set of security contexts.
  • the second core network device may determine that the UE is in the RRC idle state in various ways.
  • the second core network device may further determine that the UE is switched from the first communication system to the second communication system according to the status indication information (UE status) carried in the tracking area update request or the attach request message.
  • UE status the status indication information
  • the second core network device may also notify the second access network device in the second communication system of the activated new set of security contexts, so that the second access network device The network access device can also use the new set of security contexts to perform security authentication with the UE.
  • the second core network device sends an authentication request message to the UE, and the UE receives the authentication request message from the core device.
  • S506a The UE activates a new set of security contexts according to the authentication request message.
  • both the UE and the second network device activate a new set of security contexts
  • the security contexts maintained by the two are consistent (included in the security contexts maintained by the two)
  • the NAS counts are all initial values (such as 0, to be consistent). Therefore, the UE and the second network device can use the new set of security contexts to perform security verification subsequently, and can ensure that the security verification is successful.
  • S507a The UE and the second network device use a new set of security contexts to perform security verification.
  • the UE and the second network device can be successfully connected with each other, thereby ensuring that the UE can be successfully handed over to the second communication system.
  • the embodiment of the present application provides a communication method, in which, during the process of switching from the first communication system to the second communication system, the UE can trigger the TAU process or the attach process to make the The UE and the core network device in the second communication system activate a new set of security contexts in the TAU procedure or the attach procedure. Since the new set of security contexts activated by the two are consistent, the two subsequently use the new set of security contexts for security verification, which can achieve successful security verification, thereby ensuring that the UE can successfully switch to the second communication system.
  • the present application also provides a communication example, which will be described in detail below with reference to the flowchart of the communication example shown in FIG. 5B .
  • This example is described by taking the UE switching from the 5G communication system to the 4G communication system as an example.
  • the security context corresponding to the 5G communication system is abbreviated as 5G security context
  • the security context corresponding to the 4G communication system is abbreviated as 4G security context.
  • S501b The UE resides in the 5G communication system and the UE is in the RRC idle state. At this time, the current network environment satisfies the conditions for triggering the inter-system handover from the 5G communication system to the 4G communication system (for example, the signal quality of the 5G communication system is degraded, and the 4G communication system When the signal quality of the UE is relatively high), the inter-system handover of the UE is triggered.
  • S502b After the UE successfully camps on the 4G communication system, the UE sends a tracking area update request message (Tracking area update request) to the MME in the 4G communication system to realize registration in the 4G communication system.
  • Tracking area update request a tracking area update request message
  • the UE may use the 5G security context to perform integrity protection processing on the tracking area update request message.
  • S503b After receiving the tracking area update request message sent by the UE, the MME compulsorily triggers an authentication process to activate a new set of 4G security contexts.
  • the MME may also send the new set of 4G security contexts to the eNB, so that the eNB can use the new set of 4G security contexts to perform security authentication with the UE.
  • S504b The MME sends an authentication request message (Authentication Request) to the UE.
  • Authentication Request an authentication request message
  • S505b In the case that the UE does not obtain the 4G security context through the calculation of the security context mapping algorithm, or the UE obtains the 4G security context but the 4G security context is not activated, the UE shall obtain the 4G security context according to the received authentication The request message activates a new set of 4G security contexts.
  • the UE and the MME can perform security verification based on the new 4G security context maintained by each.
  • S506b The UE is authenticated successfully, and sends an authentication response message (Authentication response) to the MME.
  • this implementation is only an example of an MME initiating a mandatory authentication process, and does not constitute a limitation thereto.
  • the MME may also trigger the MME to initiate a forced authentication process through an attach request message, and the specific process may refer to the above steps, which will not be described in detail in this example.
  • Embodiment 4 is a diagrammatic representation of Embodiment 4:
  • S601a When the UE resides in the first communication system, the UE performs security verification with the first network device located in the first communication system using the first set of security contexts.
  • the NAS layer in the UE and the first network device maintains the first set of security contexts respectively, and uses the first set of security contexts maintained by them to perform confidentiality protection and integrity on the transmitted messages
  • the NAS layer in the UE and the first network device maintains the first set of security contexts respectively, and uses the first set of security contexts maintained by them to perform confidentiality protection and integrity on the transmitted messages
  • S602a The UE is in the RRC connected state, and when the current network environment meets the inter-system handover condition, the UE's inter-system handover is triggered; the UE starts to perform the inter-system handover to switch from the first communication system to the second communication system. During the inter-system handover process, the UE successfully camps on the second communication system. The UE acquires the second set of security contexts, so as to perform security verification with the second network device located in the second communication system.
  • the communication system may implement the inter-system handover of the UE through the handover mechanism.
  • the UE may trigger an inter-system handover process of switching from the first communication system to the second communication system when determining that the inter-system handover condition is satisfied; or the first network device determines that the system handover is satisfied.
  • a notification message is sent to the UE, instructing the UE to perform an inter-system handover procedure of handover from the first communication system to the second communication system.
  • the UE obtains the second set of security contexts by calculating the first set of security contexts maintained by itself with a locally saved version of the security context mapping algorithm to generate the second set of security contexts .
  • S603a The second core network device located in the second communication system acquires multiple sets of candidate security contexts, so as to select a set of security contexts from the multiple sets of candidate security contexts to perform security verification with the UE.
  • the second core network device may acquire the multiple sets of alternative security contexts in but not limited to the following two ways:
  • the second core network device receives the multiple sets of candidate security contexts from the first core network device.
  • the multiple sets of candidate security contexts are generated by the first set of security contexts maintained by the first core network device according to multiple versions of security context mapping algorithms, and the first core network device is located in the in the first communication system and included in the first network device.
  • Manner 2 the second core network device receives the first set of security contexts from the first core network device; the second core network device calculates the first set of security contexts according to multiple versions of security context mapping algorithms , and generate the multiple sets of alternative security contexts.
  • the second core network device determines, among the multiple sets of candidate security contexts, a third set of security contexts that have passed the security verification test.
  • the first core network device or the second core network device locally stores multiple versions of the security context mapping algorithm, which may include the set security context mapping algorithm locally stored by the UE, that is, the multiple versions of the security context mapping algorithm obtained by the second core network device. At least one set of alternative security contexts in the set of alternative security contexts is consistent with the second set of security contexts maintained by the UE. Therefore, the second core network device may select a third set of security contexts consistent with the second set of security contexts maintained by the UE from the multiple sets of candidate security contexts through S604a.
  • the second core network device may also perform S604a through the following steps:
  • the second core network device selects a set of security contexts to be tested from the multiple sets of alternative security contexts, wherein the security context to be tested is any set of alternative security contexts in the multiple sets of alternative security contexts context;
  • the second core network device uses the selected security context to be tested to perform a security verification test with the UE, and if it is determined that the security verification test passes, it is determined that the security context to be tested is the third set of security contexts; otherwise, continue Select the next set of security contexts to be tested from the multiple sets of candidate security contexts until it is determined that the selected security contexts to be tested pass the security verification test; finally, the second core network device determines the security contexts to be tested that pass the security verification test for the third set of security contexts.
  • the selection sequence of the multiple sets of alternative security contexts may be preset or random, which is not limited in this application.
  • the second core network device may determine that the selected security context to be tested has passed the security verification test under the following circumstances:
  • Case 1 The second core network device uses the security context to be tested to decrypt the encrypted uplink message from the UE, and the decryption succeeds to obtain the uplink message.
  • Case 2 The second core network device uses the security context to be tested to perform integrity protection verification on the uplink message after integrity protection processing from the UE, and the integrity protection verification succeeds, and obtains the Upstream news.
  • Case 3 The second core network device uses the security context to be tested to perform decryption processing and integrity protection verification on the encrypted and integrity-protected uplink message from the UE, and decrypt and integrity-protect the uplink message. The verification is successful, and the upstream message is obtained.
  • the uplink message involved in the above situation may be, but is not limited to, any of the following: a tracking area update request message (tracking area update request), an attach request message (attach request).
  • the second core network device can activate the third set of security contexts, so that the second set of security contexts can be used for subsequent security verification with the UE.
  • the second core network device may also send the third set of security contexts to the second access network device in the second communication system, so that, The second access network device may further perform security verification with the UE according to the received third set of security contexts.
  • the second network device (including the second core network device and the second access network device) in the second communication system uses the third set of security contexts to perform security authentication with the UE.
  • the UE can be securely connected with the second network device, thereby ensuring that all The UE can be successfully handed over to the second communication system.
  • an embodiment of the present application provides a communication method, in which, during the process of switching the UE from the first communication system to the second communication system, the core network device located in the second communication system can obtain the multiple sets of alternative security contexts; and a set of security contexts that pass the security verification test is determined in the multiple sets of alternative security contexts; the core network device located in the second communication system activates the set of security contexts for subsequent security with the UE verify. Since the set of security contexts activated by the core network device in the second communication system has passed the security verification test, that is, the set of security contexts is consistent with the security context maintained by the UE, therefore, the core network device in the second communication system can use the set of security contexts. The set security context performs security verification with the UE, so that the security verification can be successful, thereby ensuring that the UE can be successfully handed over to the second communication system.
  • the present application also provides a communication example, which will be described in detail below with reference to the flowchart of the communication example shown in FIG. 6B .
  • This example is described by taking the UE switching from the 5G communication system to the 4G communication system as an example.
  • the security context corresponding to the 5G communication system is abbreviated as 5G security context
  • the security context corresponding to the 4G communication system is abbreviated as 4G security context.
  • S601b The UE resides in the 5G communication system and the UE is in the RRC connection state. At this time, the current network environment satisfies the 5G to 4G inter-system event described in Protocol 38.331, triggering the UE to switch from the 5G communication system to the 4G communication system inter-system handover.
  • S602b The UE uses a certain version of the security context mapping algorithm to calculate the 5G security context maintained by the UE to obtain 4G security context 1.
  • the security context mapping algorithm used by the UE may be the 33501_CR0611r1 protocol of the previous version, or the 33501_CR0611r1 protocol of the refreshed version.
  • S603b The AMF in the 5G communication system uses two versions of the security context mapping algorithm to calculate the 5G security context maintained by itself to obtain 4G security context 1 and 4G security context 2.
  • the AMF uses two versions of the security context mapping algorithm, including: the 33501_CR0611r1 protocol of the previous version, and the 33501_CR0611r1 protocol of the refreshed version.
  • the 4G security context 1 obtained by the UE is the same as one set (4G security context 1) of the two sets of 4G security contexts calculated by the AMF.
  • the AMF sends the two sets of security contexts generated by the AMF to the MME in the 4G communication system through the N26 interface.
  • the message can be an existing message, such as a forward relocation request message (Forward relocation request), or a newly defined message.
  • S605b After the UE performs integrity protection processing on the tracking area update request message (Tracking area update request) using the 4G security context 1, the UE sends the tracking area update request after the integrity protection processing to the MME, so as to realize the 4G Registration of communication systems.
  • the MME has two sets of 4G security contexts (4G security context 1 and 4G security context 2, the NAS COUNT value in one set of 4G security contexts is 0, and the NAS COUNT value in the other set of 4G security contexts is NR COUNT ).
  • the MME can use one set of 4G security contexts in two sets of 4G security contexts to perform integrity protection verification on the received tracking area update request message after integrity protection processing.
  • security context 1 activates a set of 4G security contexts used this time; if the integrity protection check fails (indicating that the MME selects 4G security context 2), then use another set of security contexts (that is, 4G security context 1 ) performs integrity protection verification on the received tracking area update request message after integrity protection processing until the integrity protection verification succeeds; the MME activates the last used set of 4G security contexts (ie, 4G security context 1).
  • the MME may further send the 4G security context 1 to the eNB in the 4G communication system.
  • this example does not limit the method in which the MME selects the order of 4G security contexts, and the MME may decide which set of 4G security contexts to choose first when performing the security verification test; or the MME may use Randomly select, or set a priority order to select the 4G security context.
  • the MME may preferentially select a 4G security context with a NAS count equal to NR count for the security verification test, or the MME may preferentially select a 4G security context with a NAS count equal to 0 for the security verification test.
  • Embodiment 5 is a diagrammatic representation of Embodiment 5:
  • S701a When the UE resides in the first communication system, the UE performs security verification with the first network device located in the first communication system using the first set of security contexts.
  • the NAS layer in the UE and the first network device maintains the first set of security contexts respectively, and uses the first set of security contexts maintained by them to perform confidentiality protection and integrity on the transmitted messages
  • the NAS layer in the UE and the first network device maintains the first set of security contexts respectively, and uses the first set of security contexts maintained by them to perform confidentiality protection and integrity on the transmitted messages
  • S702a The UE is in the RRC connected state, and when the current network environment satisfies the inter-system handover condition, the UE's inter-system handover is triggered; the UE starts to perform the inter-system handover to switch from the first communication system to the second communication system. During the inter-system handover process, the UE successfully camps on the second communication system. The UE acquires multiple sets of candidate security contexts, so as to select a set of security contexts from the multiple sets of candidate security contexts to perform security verification with the second network device located in the second communication system.
  • the communication system may implement the inter-system handover of the UE through the handover mechanism.
  • the UE may trigger an inter-system handover process of switching from the first communication system to the second communication system when determining that the inter-system handover condition is satisfied; or the first network device determines that the system handover is satisfied.
  • a notification message is sent to the UE, instructing the UE to perform an inter-system handover procedure of handover from the first communication system to the second communication system.
  • the UE may calculate the first set of security contexts maintained by itself according to the locally stored multiple versions of the security context mapping algorithm, and generate the set of security contexts. Multiple sets of alternative security contexts.
  • the second network device in the second communication system needs to acquire a third set of security contexts for performing security verification with the UE.
  • the second network device may also obtain a third set of security contexts for performing security verification with the UE through the two methods described in the first embodiment.
  • the UE since the UE locally saves multiple versions of the security context mapping algorithm, which may include the set security context mapping algorithm locally saved by the first network device/second network device, that is, multiple sets of alternatives generated by the UE At least one set of alternative security contexts in the security context is consistent with the third set of security contexts maintained by the second network device. Therefore, the UE may select a second set of security contexts consistent with the third set of security contexts maintained by the second network device from the multiple sets of alternative security contexts through subsequent steps, thereby activating the second set of security contexts security context.
  • S703a The UE selects a set of alternative security contexts from the multiple sets of alternative security contexts to perform integrity protection processing on the uplink message, and sends the uplink message after integrity protection processing to the second network device; if not After receiving the response message to the uplink message from the second network device, the UE performs S703a again until receiving the response message to the uplink message from the second network device through S704a.
  • the selection sequence of the multiple sets of alternative security contexts may be preset or random, which is not limited in this application.
  • the uplink message may be, but is not limited to, any of the following: a tracking area update request message (tracking area update request), an attach request message (attach request); the response message may be, but not limited to, any of the following Items: tracking area update accept message (tracking area update accept), attach accept message (attach accept), security mode command (security mode command), RRC security mode command (RRC security mode command).
  • the second network device after receiving the uplink message processed by the integrity protection, the second network device will use the third set of security context maintained locally to perform integrity protection verification on the uplink message processed by the integrity protection. , if the integrity protection check fails, discard the received uplink message after the integrity protection process; if the integrity protection check succeeds, feed back a response message of the uplink message to the UE.
  • the second network device still uses the third set of security contexts to achieve successful integrity protection verification .
  • the NAS count in the alternative security context used by the UE is equal to the NR count, and the NR count value is less than 255; the NAS count value in the third set of security contexts used by the second network device is 0, and the second Network devices may use a third set of security contexts to achieve integrity protection success.
  • the UE sends the lower eight bits of the locally stored uplink NAS count value to the second network device through a tracking area update request message (Tracking area update request), and the second network device receives the The upstream NAS count value is larger than the upstream NAS count value in the locally stored third set of security contexts.
  • the second network device will update the upstream NAS count value in the third set of security contexts to the received NAS count. value. Therefore, the uplink NAS count values contained in the three sets of security contexts in the second network device and the alternative security contexts used by the UE may be the same due to the above process, but the downlink NAS count values contained in the two may be different. .
  • the UE temporarily does not activate the alternate security context used for the last integrity protection processing on the uplink message, but continues to perform security verification on the downlink message to determine the final candidate security context that needs to be activated.
  • the response message of the uplink message is processed by the second network device using the third set of security context for integrity protection, so the UE can also determine that activation is required by the following step S705a alternative security context.
  • the response message of the uplink message is processed by the second network device using the third set of security context for encryption and integrity protection. Therefore, the UE can also perform the following step S706a to determine An alternate security context that needs to be activated.
  • S705a The UE uses one set of the multiple sets of alternative security contexts to perform integrity protection verification on the received response message after integrity protection processing; if the integrity protection verification is successful, directly Activate the alternative security context used this time; if the integrity protection verification fails, use the next set of alternative security contexts to perform integrity protection verification on the received response message after integrity protection processing until the integrity protection verification is completed. Validation succeeded; activate the last set of alternate security contexts used.
  • S706a The UE uses a set of alternative security contexts in the multiple sets of alternative security contexts to decrypt and verify the integrity protection of the received response message after encryption and integrity protection; if the decryption and integrity protection If the verification is successful, the alternative security context used this time is directly activated; if the decryption or integrity protection verification fails, the next set of alternative security contexts are used to decrypt the received response message after encryption and integrity protection. and integrity protection check until decryption and integrity protection check succeed; activate the last set of alternate security contexts used.
  • the selection sequence of the multiple sets of alternative security contexts may be preset or random, which is not limited in this application.
  • the UE may preferentially select the alternative security context used when S703 is executed for the last time.
  • the UE may select an alternative security context (hereinafter referred to as the second set of security contexts) that is consistent with the third set of security contexts used by the second network device from multiple alternative security contexts, and activate the alternate security context.
  • the second set of security contexts an alternative security context that is consistent with the third set of security contexts used by the second network device from multiple alternative security contexts
  • S707a The UE uses the activated second set of security contexts to perform security verification with the second network device.
  • the UE can be securely connected with the second network device, thereby ensuring that all The UE can be successfully handed over to the second communication system.
  • the embodiments of the present application provide a communication method, in which, during the process of switching from the first communication system to the second communication system, the UE can acquire multiple sets of alternative security contexts; A set of security contexts that pass the security verification is determined in the set of candidate security contexts; the UE activates the set of security contexts for subsequent security verification with the network device of the second communication system. Since the set of security contexts activated by the UE has passed the security check, that is, the set of security contexts is consistent with the security context maintained by the network device in the second communication system, the UE uses the set of security contexts to communicate with the second communication system The network device that performs security verification can realize successful security verification, thereby ensuring that the UE can be successfully handed over to the second communication system.
  • the present application further provides a communication example, which will be described in detail below with reference to the flowchart of the communication example shown in FIG. 7B .
  • This example is described by taking the UE switching from the 5G communication system to the 4G communication system as an example.
  • the security context corresponding to the 5G communication system is abbreviated as 5G security context
  • the security context corresponding to the 4G communication system is abbreviated as 4G security context.
  • S701b The UE resides in the 5G communication system and the UE is in the RRC connection state. At this time, the current network environment satisfies the 5G to 4G inter-system event described in Protocol 38.331, triggering the UE to switch from the 5G communication system to the 4G communication system inter-system handover.
  • S702b After the UE successfully camps on the 4G communication system, the UE uses two versions of the security context mapping algorithm to calculate the 5G security context maintained by the UE to obtain 4G security context 1 and 4G security context 2.
  • the UE uses two versions of the security context mapping algorithm including: the 33501_CR0611r1 protocol of the previous version, and the 33501_CR0611r1 protocol of the refreshed version.
  • S703b The AMF in the 5G communication system uses a saved version of the security context mapping algorithm to calculate the 5G security context maintained by the AMF to obtain 4G security context 1.
  • the security context mapping algorithm used by the AMF may be the 33501_CR0611r1 protocol of the previous version, or the 33501_CR0611r1 protocol of the refreshed version.
  • the 4G security context 1 obtained by the AMF is the same as one of the two sets of 4G security contexts (ie, 4G security context 1) obtained by the UE.
  • S704b The AMF sends the obtained 4G security context 1 to the MME in the 4G communication system through a forward relocation request (forward relocation request) through the N26 interface.
  • S705b The UE selects a set of 4G security contexts from the obtained two sets of 4G security contexts to perform integrity protection processing on the Tracking area update request message (Tracking area update request), and sends the integrity protection processing to the MME.
  • the MME uses the locally stored 4G security context 1 to perform integrity protection verification on the received tracking area update request message after integrity protection processing.
  • this example does not limit the method for selecting the order of the 4G security context by the UE in step S705b, and the UE can decide which set of 4G security contexts to choose first; 4G security context is selected in priority order.
  • the UE may preferentially select a 4G security context with a NAS count equal to NR count, or the UE may preferentially select a 4G security context with a NAS count equal to 0.
  • the MME may have two situations: one is that the MME fails to verify the integrity protection using 4G security context 1; the second is that the MME uses the 4G security context integrity protection to verify successfully .
  • the communication system can make the UE reselect the 4G security context through S706b-S708b, so as to ensure that the MME can use the 4G security context integrity protection to check successfully.
  • the MME can directly use the 4G security context integrity protection to verify the success.
  • S706b The MME uses 4G security context 1 to perform integrity protection verification on the received tracking area update request message after integrity protection processing; 2), the MME discards the received tracking area update request message after integrity protection processing.
  • the UE After the T3430 timer expires, the UE starts the T3411 timer according to the 24.301 protocol, and after the T3411 timer expires, the UE re-integrates the tracking area update request message using another set of 4G security contexts protection processing, and send the tracking area update request message after the integrity protection processing to the MME.
  • S708b The MME uses 4G security context 1 to perform integrity protection verification on the re-received tracking area update request message after integrity protection processing, and the integrity protection verification is successful (representing the 4G context 1 selected by the UE this time) .
  • S709b The MME uses 4G security context 1 to perform integrity protection verification on the received tracking area update request message after integrity protection processing; 1, or the selected 4G security context 2 (where the NAS count included in the 4G security context 2 is NR count)).
  • the MME needs to feed back a tracking area update accept message (Tracking area update accept) to the UE.
  • Tracking area update accept a tracking area update accept message
  • the MME may also feed back a security mode command (security mode command) to the UE after the 4G security context 1 integrity protection verification is successful in S708b or S709b, or trigger the eNB to send the UE to the UE.
  • a security mode command security mode command
  • Send RRC security mode command RRC security mode command
  • Scenario 1 The MME performs integrity protection processing on the tracking area update accept message.
  • S710b The MME uses 4G security context 1 to perform integrity protection processing on the tracking area update accept message, and sends the integrity protection processed tracking area update accept message to the UE.
  • the UE may use one set of 4G security contexts in two sets of 4G security contexts to perform integrity protection verification on the received tracking area update accept message after integrity protection processing, if the integrity protection verification is successful (indicating that the UE Select 4G security context 1), activate a set of 4G security contexts used this time; if the integrity protection check fails (indicating that the MME selects 4G security context 2), then use another set of security contexts (ie 4G security context 1) Perform integrity protection verification on the received tracking area update acceptance message after integrity protection processing, until the integrity protection verification succeeds; the UE activates the last set of 4G security contexts used (that is, 4G security contexts). Context 1).
  • Scenario 2 The MME performs encryption and integrity protection on the tracking area update accept message.
  • S712b The MME performs encryption and integrity protection processing on the tracking area update accept message using 4G security context 1, and sends the encrypted and integrity protection processed tracking area update accept message to the UE.
  • the UE may use one set of 4G security contexts in the two sets of 4G security contexts to decrypt and verify the integrity protection of the received tracking area update acceptance message after encryption and integrity protection processing. If the verification succeeds (indicating that the UE selects 4G security context 1), activate a set of 4G security contexts used this time; if the decryption or integrity protection verification fails (indicating that the MME selects 4G security context 2), then Use another set of security contexts (that is, 4G security context 1) to decrypt and integrity-protect the received tracking area update acceptance message after encryption and integrity protection processing, until the decryption and integrity-protection verification are successful; the The UE activates the last used set of 4G security contexts (ie 4G security context 1).
  • S714 The UE uses the activated 4G security context 1 to perform encryption and integrity protection processing on the tracking area update complete message (Tracking area update complete). Subsequently, the UE and the MME may use the 4G security context 1 maintained by them to perform security verification.
  • this example does not limit the method in which the UE selects the 4G security context in step S711b or S713b, and the UE can decide which set of 4G security contexts to choose first; Select, or set the priority order to select the 4G security context.
  • the UE may preferentially select a 4G security context with a NAS count equal to NR count, or the UE may preferentially select a 4G security context with a NAS count equal to 0.
  • the UE preferentially selects the 4G security context used when performing the integrity protection processing on the tracking area update request message for the last time.
  • S302b-S304b may be executed after S305b, S309b or S315b, or S302b-S304b may be executed before S312b.
  • the present application also provides a communication device, the structure of which is shown in FIG. 8 , including a communication unit 801 and a processing unit 802 .
  • the communication apparatus 800 may be applied to the core network device or UE in the communication system shown in FIG. 2 , and may implement the communication methods provided in the above embodiments and examples.
  • the physical representation of the communication device 800 may be a communication device, such as a core device or a UE; or the communication device may be other devices capable of implementing the functions of the communication device, such as a processor or an internal processor of the communication device. Chips, etc.
  • the communication device 800 may be a field-programmable gate array (FPGA), a complex programmable logic device (CPLD), an application specific integrated circuit (application specific integrated circuits, ASIC), or some programmable chips such as System on a chip (SOC).
  • FPGA field-programmable gate array
  • CPLD complex programmable logic device
  • ASIC application specific integrated circuits
  • SOC System on a chip
  • the communication unit 801 is used for receiving and sending data.
  • the communication unit 801 may be implemented through a physical interface, a communication module, a communication interface, and an input/output interface.
  • the communication device 800 may connect a network cable or cable through the communication unit 801, thereby establishing a physical connection with other devices.
  • the communication unit 801 may be implemented by a transceiver, for example, a mobile communication module.
  • the mobile communication module can provide wireless communication solutions including 2G/3G/4G/5G etc. applied to the UE.
  • the mobile communication module may include at least one antenna, at least one filter, a switch, a power amplifier, a low noise amplifier (LNA), and the like.
  • the UE can access the AN device in the communication system through the mobile communication module, and interact with the AN device, thereby realizing the interaction between the UE and the communication system.
  • the communication apparatus 800 is applied to the UE of the embodiment shown in FIG. 3A or FIG. 3B .
  • the specific functions of the processing unit 802 in this embodiment will be introduced below.
  • the processing unit 802 is used for:
  • a first set of security contexts is obtained; wherein, the first set of security contexts are used for the processing unit 802 to perform security verification with the first network device, the first network device is located in the second communication system;
  • the communication unit 801 initiates a registration process to the first network device.
  • processing unit 802 is specifically configured to:
  • the processing unit 802 fails the security authentication with the first network device using the first set of security contexts, including:
  • the processing unit 802 uses the first set of security contexts to decrypt the encrypted downlink message from the first network device, and the decryption fails; or the processing unit 802 uses the first set of security contexts context, perform integrity protection verification on the downlink message after integrity protection processing from the first network device, and the integrity protection verification fails; or the processing unit 802 uses the first set of security contexts to The downlink message after encryption and integrity protection processing from the first network device is subjected to decryption processing and integrity protection verification, and the decryption fails or the integrity protection verification fails; or the processing unit 802 uses the first set of security context, perform integrity protection processing on the uplink message, and send the integrity protection processed uplink message to the first network device, and the terminal device does not receive the uplink message from the first network device response message.
  • the downlink message is any one of the following: a safety mode command, a tracking area update accept message, a radio resource control RRC safety mode command, and an attach accept message;
  • the uplink message is any one of the following: a tracking area update request message and an attach request message.
  • the first network device includes: a core network device or an access network device located in the second communication system.
  • the processing unit 802 when the processing unit 802 initiates a registration process to the first network device in the second communication system through the communication unit 801, the processing unit 802 is specifically configured to:
  • the first set of security contexts includes a non-access stratum count value NAS count.
  • the processing unit 802 when acquiring the first set of security contexts, is specifically configured to:
  • the first communication system is a fifth-generation 5G communication system
  • the second communication system is a fourth-generation 4G communication system.
  • the communication apparatus 800 is applied to the UE of the embodiment shown in FIG. 4A or FIG. 4B .
  • the specific functions of the processing unit 802 in this embodiment will be introduced below.
  • the processing unit 802 is used for:
  • the first set of security contexts are activated, and the first set of security contexts are used to perform security authentication with a first network device located in the second communication system.
  • the processing unit 802 when selecting the first set of security contexts that pass the security verification test from the multiple sets of candidate security contexts, is specifically configured to:
  • An integrity protection check is performed on the downlink message processed by the integrity protection of a network device, and the integrity protection check is successful, and the downlink message is obtained; or the downlink message is obtained by using the security context to be tested;
  • the downlink message after the encryption and integrity protection processing is decrypted and verified by integrity protection, and the decryption and integrity protection verification are successful, and the downlink message is obtained;
  • the downlink message is any one of the following: a security mode command, a tracking area update accept message, a radio resource control RRC security mode Command, Attach Accept message.
  • the first network device includes: a core network device or an access network device located in the second communication system.
  • the first set of security contexts includes a non-access stratum count value NAS count.
  • the processing unit 802 when acquiring multiple sets of candidate security contexts, is specifically configured to:
  • the first communication system is a fifth-generation 5G communication system
  • the second communication system is a fourth-generation 4G communication system.
  • the communication apparatus 800 is applied to the core network device located in the second communication system in the embodiment shown in FIG. 5A or FIG. 5B (for example, the 4G communication in the embodiment shown in FIG. 5B ) MME in the system).
  • the specific functions of the processing unit 802 in this embodiment will be introduced below.
  • the processing unit 802 is used for:
  • the communication unit 801 receives a tracking area update request message or an attach request message from the terminal device;
  • a new set of security contexts is activated; wherein the new set of security contexts is used for the first network device to perform security verification with the terminal device, and the first set of security contexts is used for security verification between the first network device and the terminal device.
  • a network device is located in the second communication system;
  • An authentication request message is sent to the terminal device through the communication unit 801, so that the terminal device activates a new set of security contexts.
  • processing unit 802 is further configured to:
  • the new set of security contexts are sent to the access network device in the second communication system through the communication unit 801 .
  • the new set of security contexts includes a non-access stratum count value NAS count.
  • processing unit 802 is further configured to:
  • the terminal device According to the status indication information UE status carried in the tracking area update request message or the attach request message, it is determined that the terminal device is switched from the first communication system to the second communication system.
  • the first communication system is a fifth-generation 5G communication system
  • the second communication system is a fourth-generation 4G communication system.
  • the communication apparatus 800 is applied to the UE of the embodiment shown in FIG. 5A or FIG. 5B .
  • the specific functions of the processing unit 802 in this embodiment will be introduced below.
  • the processing unit 802 is used for:
  • a new set of security contexts is activated; wherein, the new set of security contexts is used for the processing unit 802 to perform security verification with the first network device, and the first network device is located in the in the second communication system;
  • the processing unit 802 when the processing unit 802 sends a tracking area update request message or an attach request message to the core network device in the second communication system through the communication unit 801, it is specifically configured to:
  • the first set of security contexts is used for the terminal device and the second network device to perform security verification, so the the second network device is located in the first communication system;
  • the new set of security contexts includes a non-access stratum count value NAS count.
  • the tracking area update request message or the attach request message carries status indication information
  • the status indication information UE status is used to instruct the terminal device to switch from the first communication system to the second communication system.
  • the first communication system is a fifth-generation 5G communication system
  • the second communication system is a fourth-generation 4G communication system.
  • the communication apparatus 800 is applied to the first core network device located in the second communication system in the embodiment shown in FIG. 6A or FIG. 6B (for example, in the embodiment shown in FIG. 6B , MME in 4G communication system).
  • the specific functions of the processing unit 802 in this embodiment will be introduced below.
  • the processing unit 802 is used for:
  • the terminal device In the process of switching the terminal device from the first communication system to the second communication system, obtain multiple sets of alternative security contexts; wherein, the first core network device is located in the second communication system;
  • the processing unit 802 when acquiring multiple sets of candidate security contexts, is specifically configured to:
  • the multiple sets of alternative security contexts are the second set of security contexts mapped to the second set of security contexts by the second core network device according to multiple versions of the security context mapping algorithms Calculated and generated, the second set of security contexts is used for security verification between the second core network device and the terminal device, and the second core network device is located in the first communication system;
  • the second set of security contexts of the second core network device; the second set of security contexts are calculated according to the security context mapping algorithms of multiple versions, and the multiple sets of candidate security contexts are generated; wherein, the second set of security contexts For the second core network device to perform security verification with the terminal device, the second core network device is located in the first communication system.
  • the processing unit 802 when determining the first set of security contexts that pass the security verification test in the multiple sets of candidate security contexts, is specifically configured to:
  • the processed uplink message is decrypted and verified for integrity protection, and the decryption and verification of integrity protection are successful to obtain the uplink message;
  • the uplink message is any one of the following: a tracking area update request message and an attach request message.
  • processing unit 802 is further configured to:
  • the first set of security contexts are sent to the access network device in the second communication system through the communication unit 801 .
  • the first set of security contexts includes a non-access stratum count value NAS count.
  • the first communication system is a fifth-generation 5G communication system
  • the second communication system is a fourth-generation 4G communication system.
  • the communication apparatus 800 is applied to the UE of the embodiment shown in FIG. 7A or FIG. 7B .
  • the specific functions of the processing unit 802 in this embodiment will be introduced below.
  • the processing unit 802 is used for:
  • processing unit 802 is further configured to:
  • the response message is processed by the integrity protection of the first network device, after receiving the response message of the uplink message from the first network device through the communication unit 801, in the Select a set of alternative security contexts from the multiple sets of alternative security contexts to perform integrity protection verification on the response message after the integrity protection processing, and activate the alternative security context used this time if the integrity protection verification is successful ; Otherwise, in the multiple sets of alternative security contexts, select the next set of alternative security contexts to perform integrity protection verification on the response message after the integrity protection processing, until the integrity protection verification is successful, activate the last used Alternative security context;
  • the response message is encrypted and integrity protected by the first network device
  • From the multiple sets of alternative security contexts select one set of alternative security contexts to perform decryption processing and integrity protection verification on the response message after encryption and integrity protection processing. If decryption and integrity protection verification are successful, then Activate the alternative security context used this time; otherwise, select the next set of alternative security contexts in the multiple sets of alternative security contexts to decrypt and verify the integrity protection of the response message after encryption and integrity protection processing. Check until decryption and integrity protection check succeed, activate the last used alternative security context.
  • the terminal device is in a connected state of a radio resource control RRC connection
  • the uplink message is any one of the following: a tracking area update request message, an attach request message;
  • the response message is any one of the following: a tracking area update accept message, an attach accept message, a security mode command, and a radio resource control RRC security mode command.
  • the processing unit 802 when acquiring multiple sets of candidate security contexts, is specifically configured to:
  • any set of alternative security contexts includes the non-access stratum count NAS count.
  • the first communication system is a fifth-generation 5G communication system
  • the second communication system is a fourth-generation 4G communication system.
  • each function in each embodiment of the present application Units can be integrated in one processing unit, or they can exist physically alone, or two or more units can be integrated into one unit.
  • the above-mentioned integrated units may be implemented in the form of hardware, or may be implemented in the form of software functional units.
  • the integrated unit if implemented in the form of a software functional unit and sold or used as an independent product, may be stored in a computer-readable storage medium.
  • the technical solutions of the present application can be embodied in the form of software products in essence, or the parts that contribute to the prior art, or all or part of the technical solutions, and the computer software products are stored in a storage medium , including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) or a processor (processor) to execute all or part of the steps of the methods described in the various embodiments of the present application.
  • the aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), magnetic disk or optical disk and other media that can store program codes .
  • the present application also provides a communication device, which can be applied to the core network device or terminal device in the communication system as shown in FIG. 2, and can realize the communication provided by the above embodiments and examples
  • the method has the functions of the communication device shown in FIG. 8 .
  • the communication device 900 includes: a communication module 901 , a processor 902 and a memory 903 . Wherein, the communication module 901, the processor 902 and the memory 903 are connected to each other.
  • the communication module 901 , the processor 902 and the memory 903 are connected to each other through a bus 904 .
  • the bus 904 may be a peripheral component interconnect standard (peripheral component interconnect, PCI) bus or an extended industry standard architecture (extended industry standard architecture, EISA) bus or the like.
  • PCI peripheral component interconnect
  • EISA extended industry standard architecture
  • the bus can be divided into an address bus, a data bus, a control bus, and the like. For ease of presentation, only one thick line is used in FIG. 9, but it does not mean that there is only one bus or one type of bus.
  • the communication module 901 is used for receiving and sending data to realize communication interaction with other devices.
  • the communication module 901 may be implemented through a physical interface, a communication module, a communication interface, and an input/output interface.
  • the communication module 901 may also be implemented by a transceiver.
  • the communication device 900 is applied to the UE of the embodiment shown in FIG. 3A or FIG. 3B .
  • the specific functions of the processor 902 in this embodiment will be introduced below.
  • processor 902 for:
  • a first set of security contexts is obtained; wherein, the first set of security contexts is used for the processor 902 to perform security verification with the first network device, the first network device is located in the second communication system;
  • the processor 902 When the processor 902 fails to perform security verification with the first network device using the first set of security contexts, the processor 902 initiates a registration process to the first network device through the communication module 901 .
  • the communication device 900 is applied to the UE of the embodiment shown in FIG. 4A or FIG. 4B .
  • the specific functions of the processor 902 in this embodiment will be introduced below.
  • the processor 902 is used for:
  • the first set of security contexts are activated, and the first set of security contexts are used to perform security authentication with a first network device located in the second communication system.
  • the communication device 900 is applied to the core network device located in the second communication system in the embodiment shown in FIG. 5A or FIG. 5B (for example, the 4G communication in the embodiment shown in FIG. 5B ) MME in the system).
  • the specific functions of the processor 902 in this embodiment will be introduced below.
  • the processor 902 is used for:
  • a tracking area update request message or an attachment request message from the terminal device is received by the communication module 901;
  • a new set of security contexts is activated; wherein the new set of security contexts is used for the first network device to perform security verification with the terminal device, and the first set of security contexts is used for security verification between the first network device and the terminal device.
  • a network device is located in the second communication system;
  • the communication device 900 is applied to the UE of the embodiment shown in FIG. 5A or FIG. 5B .
  • the specific functions of the processor 902 in this embodiment will be introduced below.
  • processor 902 for:
  • a new set of security contexts is activated; wherein, the new set of security contexts is used for the processing unit 802 to perform security verification with the first network device, and the first network device is located in the in the second communication system;
  • the communication device 900 is applied to the first core network device located in the second communication system in the embodiment shown in FIG. 6A or FIG. 6B (for example, in the embodiment shown in FIG. 6B , MME in 4G communication system).
  • the specific functions of the processor 902 in this embodiment will be introduced below.
  • the processor 902 is used for:
  • the terminal device In the process of switching the terminal device from the first communication system to the second communication system, obtain multiple sets of alternative security contexts; wherein, the first core network device is located in the second communication system;
  • the communication device 900 is applied to the UE of the embodiment shown in FIG. 7A or FIG. 7B .
  • the specific functions of the processor 902 in this embodiment will be introduced below.
  • the processor 902 is used for:
  • this embodiment does not describe the specific functions of the processor 902 in detail.
  • the specific functions of the processor 902 reference may be made to the descriptions in the communication methods provided in the above embodiments and examples, as well as the implementation shown in FIG. 8 .
  • the specific function description of the communication device 800 in the example will not be repeated here.
  • the memory 903 is used to store program instructions and data.
  • the program instructions may include program code, and the program code includes computer operation instructions.
  • the memory 903 may include random access memory (RAM), and may also include non-volatile memory (non-volatile memory), such as at least one disk storage.
  • the processor 902 executes the program instructions stored in the memory 903 and uses the data stored in the memory 903 to implement the above functions, thereby implementing the communication methods provided by the above embodiments.
  • the memory 903 in FIG. 9 of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memory.
  • the non-volatile memory may be a read-only memory (Read-Only Memory, ROM), a programmable read-only memory (Programmable ROM, PROM), an erasable programmable read-only memory (Erasable PROM, EPROM), an electrically programmable read-only memory (Erasable PROM, EPROM). Erase programmable read-only memory (Electrically EPROM, EEPROM) or flash memory.
  • Volatile memory may be Random Access Memory (RAM), which acts as an external cache.
  • RAM Static RAM
  • DRAM Dynamic RAM
  • SDRAM Synchronous DRAM
  • SDRAM double data rate synchronous dynamic random access memory
  • Double Data Rate SDRAM DDR SDRAM
  • enhanced SDRAM ESDRAM
  • synchronous link dynamic random access memory Synchlink DRAM, SLDRAM
  • Direct Rambus RAM Direct Rambus RAM
  • the embodiments of the present application further provide a computer program, which, when the computer program runs on a computer, enables the computer to execute the communication methods provided by the above embodiments.
  • the embodiments of the present application further provide a computer-readable storage medium, where a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a computer, the computer executes the communication provided by the above embodiments. method.
  • the storage medium may be any available medium that the computer can access.
  • computer readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage media or other magnetic storage devices, or be capable of carrying or storing instructions or data structures in the form of desired program code and any other medium that can be accessed by a computer.
  • the embodiments of the present application further provide a chip, where the chip is used to read a computer program stored in a memory and implement the communication methods provided by the above embodiments.
  • the embodiments of the present application provide a chip system, where the chip system includes a processor for supporting a computer device to implement the functions involved in the service equipment, forwarding equipment, or site equipment in the above embodiments.
  • the chip system further includes a memory for storing necessary programs and data of the computer device.
  • the chip system may be composed of chips, or may include chips and other discrete devices.
  • the embodiments of the present application provide a communication method, apparatus, and device.
  • the method it can be ensured that the terminal device and the network device in the destination communication system use the same security context when the UE performs the inter-system handover process. , therefore, the subsequent two use the security context to perform security verification, which can achieve successful security verification, thereby ensuring that the terminal device can be successfully switched to the destination communication system.
  • the embodiments of the present application may be provided as a method, a system, or a computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.
  • computer-usable storage media including, but not limited to, disk storage, CD-ROM, optical storage, etc.
  • These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory result in an article of manufacture comprising instruction means, the instructions
  • the apparatus implements the functions specified in the flow or flow of the flowcharts and/or the block or blocks of the block diagrams.

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Abstract

本申请公开了一种通信方法、装置及设备，通过该方法，能够保证在UE进行异系统切换过程中，终端设备与目的通信系统中的网络设备使用相同的安全上下文，因此，后续二者使用该安全上下文进行安全验证，可以实现安全验证成功，从而保证终端设备可以成功切换到目的通信系统。

Description

一种通信方法、装置及设备 技术领域
本申请涉及通信技术领域，尤其涉及一种通信方法、装置及设备。
背景技术
终端设备在通信系统中驻留时，终端设备的非接入层(non access stratum，NAS)与该通信系统内的核心网的NAS层均会维护一套安全上下文(security context)。所述安全上下文中包含NAS计数值(count)。
在终端设备需要进行异系统切换从第一通信系统切换到第二通信系统的场景中，终端设备和核心网需要对第一通信系统中的第一套安全上下文进行映射，生成第二通信系统中的第二套安全上下文，并且只有在终端设备和第二通信系统根据所述第二套安全上下文进行安全对接成功后，终端设备才能切换到第二通信系统，通过第二通信系统实现终端设备的业务传输。其中，第一通信系统和第二通信系统为不同制式的通信系统，例如第一通信系统为5G通信系统，第二通信系统为4G通信系统。
目前安全上下文的映射协议版本有多种，不同协议版本对第一套安全上下文中的NAS count进行映射得到的第二套安全上下文中的NAS count可能会出现不同的情况。因此，若终端设备和核心网两侧使用不同的映射协议版本对第一套安全上下文进行映射，就可能会造成终端设备的NAS层维护的第二套安全上下文与核心网的NAS层维护的第二套安全上下文中包含的NAS count不一致的问题。由于NAS count是加解密、完整性保护(简称完保)、解完整性保护的输入参数之一，若终端设备和核心网的各自维护的第二套安全上下文中NAS count不一致，会导致终端设备和核心网安全对接失败，进而导致终端设备无法成功切换到第二通信系统，第二通信系统无法为终端设备提供传输服务，严重影响终端设备的业务。
发明内容
本申请提供一种通信方法、装置及设备，用以解决在进行异系统切换过程中，由于终端设备与核心网使用的安全上下文映射协议版本不一致，导致终端设备无法成功进行通信系统切换的问题。
第一方面，本申请实施例提供了一种通信方法，该方法包括以下步骤：
终端设备在从第一通信系统切换到第二通信系统的过程中，获取第一套安全上下文；其中，所述第一套安全上下文用于所述终端设备与第一网络设备进行安全验证，所述第一网络设备位于所述第二通信系统中；当所述终端设备使用所述第一套安全上下文与所述第一网络设备安全验证失败时，所述终端设备向所述第一网络设备发起注册流程。
在该方法中，终端设备在从第一通信系统切换到第二通信系统的过程中，获取用于与第二通信系统中的网络设备进行安全验证的安全上下文；当所述UE使用该安全上下文与第二通信系统中的网络设备安全验证失败时，则向第二通信系统中的网络设备发起注册流程，以使所述UE和所述第二通信系统中的网络设备均能够在注册流程中激活新的一套安全上下文。由于二者激活的新的一套安全上下文一致，因此，后续二者使用该新的一套安 全上下文进行安全验证，可以实现安全验证成功，从而保证所述UE可以成功切换到所述第二通信系统。
在一种可能的设计中，当所述终端设备使用所述第一套安全上下文与所述第一网络设备安全验证失败的次数大于或等于设定阈值时，所述终端设备向所述第一网络设备发起注册流程。
通过该设计，可以避免在由于其他原因导致少量次数的安全验证失败的情况下，所述终端设备发起注册流程造成的信令开销和时延。
在一种可能的设计中，所述终端设备使用所述第一套安全上下文与所述第一网络设备安全验证失败，包括以下几种情况：
情况一：所述终端设备使用所述第一套安全上下文，对来自所述第一网络设备的加密处理后的下行消息进行解密处理，且解密失败；
情况二：所述终端设备使用所述第一套安全上下文，对来自所述第一网络设备的完整性保护处理后的下行消息进行完整性保护校验，且完整性保护校验失败；
情况三：所述终端设备使用所述第一套安全上下文，对来自所述第一网络设备的加密和完整性保护处理后的下行消息进行解密处理和完整性保护校验，且解密失败或完整性保护校验失败；
情况四：所述终端设备使用所述第一套安全上下文，对上行消息进行完整性保护处理，并向所述第一网络设备发送完整性保护处理后的上行消息，且所述终端设备未接收来自所述第一网络设备的所述上行消息的响应消息。
通过该设计，所述终端设备可以多种情况下，确定使用所述第一套安全上下文安全验证失败。
在一种可能的设计中，所述下行消息为以下任一项：安全模式命令、跟踪区域更新接受消息、无线资源控制RRC安全模式命令、附着接受消息；所述上行消息为以下任一项：跟踪区域更新请求消息、附着请求消息。
在一种可能的设计中，所述第一网络设备包括：位于所述第二通信系统中的核心网设备或接入网设备。
在一种可能的设计中，所述终端设备向所述第二通信系统中的第一网络设备发起注册流程，包括：
所述终端设备向所述第一网络设备发送附着请求消息或注册请求消息，所述附着请求消息或注册请求消息中包含所述终端设备的国际移动用户识别码IMSI。
在一种可能的设计中，所述第一套安全上下文中包含非接入层计数值NAS count。
在一种可能的设计中，所述终端设备获取所述第一套安全上下文，包括：
所述终端设备根据设定安全上下文映射算法，对第二套安全上下文进行计算，生成所述第一套安全上下文；其中，所述第二套安全上下文用于所述终端设备与第二网络设备进行安全验证，所述第二网络设备位于所述第一通信系统中。
在一种可能的设计中，所述第一通信系统为第五代5G通信系统，所述第二通信系统为第四代4G通信系统。
第二方面，本申请实施例提供了一种通信方法，该方法包括以下步骤：
终端设备在从第一通信系统切换到第二通信系统的过程中，获取多套备选安全上下文；所述终端设备在所述多套备选安全上下文中确定通过安全验证测试的第一套安全上下文； 所述终端设备激活所述第一套安全上下文，并使用所述第一套安全上下文与第一网络设备进行安全验证，所述第一网络设备位于所述第二通信系统中。
在该方法中，终端设备在从第一通信系统切换到第二通信系统的过程中，可以获取多套备选安全上下文；并在多套备选安全上下文中确定通过安全验证测试的一套安全上下文；所述UE激活该套安全上下文，用于后续与第二通信系统的网络设备进行安全验证。由于终端设备激活的该套安全上下文是通过安全验证测试的，即该套安全上下文与第二通信系统中的网络设备维护的安全上下文一致，因此，所述终端设备使用该套安全上下文与第二通信系统的网络设备进行安全验证，可以实现安全验证成功，从而保证所述终端设备可以成功切换到所述第二通信系统。
在一种可能的设计中，所述终端设备可以通过以下步骤，在所述多套备选安全上下文中选择通过安全验证测试的第一套安全上下文：
所述终端设备在所述多套备选安全上下文中选择一套待测试安全上下文，其中，所述待测试安全上下文为所述多套备选安全上下文中的任一套备选安全上下文；
所述终端设备使用所述待测试安全上下文，对来自所述第一网络设备的加密处理后的下行消息进行解密处理，且解密成功得到所述下行消息；或者所述终端设备使用所述待测试安全上下文，对来自所述第一网络设备的完整性保护处理后的下行消息进行完整性保护校验，且完整性保护校验成功，得到所述下行消息；或者所述终端设备使用所述待测试安全上下文，对来自所述第一网络设备的加密和完整性保护处理后的下行消息进行解密处理和完整性保护校验，且解密和完整性保护校验成功，得到所述下行消息；
所述终端设备确定所述待测试安全上下文为所述第一套安全上下文。
通过以上步骤，所述终端设备可以确定通过安全验证测试的所述第一套安全上下文。
在一种可能的设计中，当所述终端设备处于无线资源控制RRC连接的空闲态时，所述下行消息为以下任一项：安全模式命令、跟踪区域更新接受消息、无线资源控制RRC安全模式命令、附着接受消息。
在一种可能的设计中，所述第一网络设备包括：位于所述第二通信系统中的核心网设备或接入网设备。
在一种可能的设计中，所述第一套安全上下文中包含非接入层计数值NAS count。
在一种可能的设计中，所述终端设备获取多套备选安全上下文，包括：
所述终端设备分别根据多个版本的安全上下文映射算法，对第二套安全上下文进行计算，生成所述多套备选安全上下文；其中，所述第二套安全上下文用于所述终端设备与第二网络设备进行安全验证，所述第二网络设备位于所述第一通信系统中。
在一种可能的设计中，所述第一通信系统为第五代5G通信系统，所述第二通信系统为第四代4G通信系统。
第三方面，本申请实施例提供了一种通信方法，该方法包括以下步骤：
在终端设备从第一通信系统切换到第二通信系统的过程中，位于第二通信系统中的核心网设备接收到来自所述终端设备的跟踪区域更新请求消息或附着请求消息；所述核心网设备确定所述终端设备的RRC连接为空闲态时，激活新的一套安全上下文；其中，所述新的一套安全上下文用于第一网络设备与所述终端设备进行安全验证，所述第一网络设备位于所述第二通信系统中；所述核心网设备向终端设备发送鉴权请求消息，以使所述终端设备激活新的一套安全上下文。
在该方法中，终端设备在从第一通信系统切换到第二通信系统的过程中，可以通过触发TAU流程或附着流程，使所述终端设备和第二通信系统中的核心网设备在该TAU流程或附着流程中激活新的一套安全上下文。由于二者激活的新的一套安全上下文一致，因此，后续二者使用该新的一套安全上下文进行安全验证，可以实现安全验证成功，从而保证所述终端设备可以成功切换到所述第二通信系统。
在一种可能的设计中，所述核心网设备还可以向所述第二通信系统中的接入网设备发送所述新的一套安全上下文，以使所述接入网设备可以使用所述新的一套安全上下文与所述终端设备进行安全验证。
在一种可能的设计中，所述新的一套安全上下文中包含非接入层计数值NAS count。
在一种可能的设计中，所述核心网设备还可以根据所述跟踪区域更新请求消息或所述附着请求消息中携带的状态指示信息UE status，确定所述终端设备从所述第一通信系统切换到所述第二通信系统。
在一种可能的设计中，所述第一通信系统为第五代5G通信系统，所述第二通信系统为第四代4G通信系统。
第四方面，本申请实施例提供了一种通信方法，该方法包括以下步骤：
终端设备在从第一通信系统切换到第二通信系统的过程中，向所述第二通信系统中的核心网设备发送跟踪区域更新请求消息或附着请求消息；所述终端设备接收来自所述核心网设备的鉴权请求消息；所述终端设备根据所述鉴权请求消息，激活新的一套安全上下文；其中，所述新的一套安全上下文用于所述终端设备与第一网络设备进行安全验证，所述第一网络设备位于所述第二通信系统中；所述终端设备使用所述新的一套安全上下文与所述第一网络设备进行安全验证。
在该方法中，终端设备在从第一通信系统切换到第二通信系统的过程中，可以通过触发TAU流程或附着流程，使所述终端设备和第二通信系统中的核心网设备在该TAU流程或附着流程中激活新的一套安全上下文。由于二者激活的新的一套安全上下文一致，因此，后续二者使用该新的一套安全上下文进行安全验证，可以实现安全验证成功，从而保证所述终端设备可以成功切换到所述第二通信系统。
在一种可能的设计中，所述终端设备向所述第二通信系统中的核心网设备发送跟踪区域更新请求消息或附着请求消息，包括：
所述终端设备使用第一套安全上下文，对所述跟踪区域更新请求消息或所述附着请求消息进行完整性保护处理；所述第一套安全上下文用于所述终端设备与第二网络设备进行安全验证，所述第二网络设备位于所述第一通信系统中；
所述终端设备向所述核心网设备发送完整性保护处理后的所述跟踪区域更新请求消息或所述附着请求消息。
在一种可能的设计中，所述新的一套安全上下文中包含非接入层计数值NAS count。
在一种可能的设计中，所述跟踪区域更新请求消息或所述附着请求消息中携带有状态指示信息，所述状态指示信息UE status用于指示所述终端设备从所述第一通信系统切换到所述第二通信系统。
在一种可能的设计中，所述第一通信系统为第五代5G通信系统，所述第二通信系统为第四代4G通信系统。
第五方面，本申请实施例提供了一种通信方法，该方法包括以下步骤：
在终端设备从第一通信系统切换到第二通信系统的过程中，第一核心网设备获取多套备选安全上下文；其中，所述第一核心网设备位于所述第二通信系统；所述第一核心网设备在所述多套备选安全上下文中确定通过安全验证测试的第一套安全上下文；所述第一核心网设备激活所述第一套安全上下文，并使用所述第一套安全上下文与所述终端设备进行安全验证。
在该方法中，在终端设备从第一通信系统切换到第二通信系统的过程中，位于第二通信系统中的核心网设备可以获取多套备选安全上下文；并在多套备选安全上下文中确定通过安全验证测试的一套安全上下文；位于第二通信系统中的核心网设备激活该套安全上下文，用于后续与终端设备进行安全验证。由于第二通信系统中的核心网设备激活的该套安全上下文是通过安全验证测试的，即该套安全上下文与终端设备维护的安全上下文一致，因此，第二通信系统中的核心网设备可以使用该套安全上下文与终端设备进行安全验证，可以实现安全验证成功，从而保证所述终端设备可以成功切换到所述第二通信系统。
在一种可能的设计中，第一核心网设备可以通过以下方式获取多套备选安全上下文：
方式一：所述第一核心网设备接收来自第二核心网设备的所述多套备选安全上下文；其中，所述多套备选安全上下文为所述第二核心网设备根据多个版本的安全上下文映射算法对第二套安全上下文进行计算生成的，所述第二套安全上下文用于所述第二核心网设备与所述终端设备进行安全验证，所述第二核心网设备位于所述第一通信系统中；
方式二：所述第一核心网设备接收来自第二核心网设备的第二套安全上下文；所述第一核心网设备根据多个版本的安全上下文映射算法对所述第二套安全上下文进行计算，生成所述多套备选安全上下文；其中，所述第二套安全上下文用于所述第二核心网设备与所述终端设备进行安全验证，所述第二核心网设备位于所述第一通信系统中。
在一种可能的设计中，所述第一核心网设备可以通过以下步骤，在所述多套备选安全上下文中确定通过安全验证测试的第一套安全上下文：
所述第一核心网设备在所述多套备选安全上下文中选择一套待测试安全上下文，其中，所述待测试安全上下文为所述多套备选安全上下文中的任一套备选安全上下文；
所述第一核心网设备使用所述待测试安全上下文，对来自所述终端设备的加密处理后的上行消息进行解密处理，且解密成功得到所述上行消息；或者所述第一核心网设备使用所述待测试安全上下文，对来自所述终端设备的完整性保护处理后的上行消息进行完整性保护校验，且完整性保护校验成功，得到所述上行消息；或者
所述第一核心网设备使用所述待测试安全上下文，对来自所述终端设备的加密和完整性保护处理后的上行消息进行解密处理和完整性保护校验，且解密和完整性保护校验成功，得到所述上行消息；
所述第一核心网设备确定所述待测试安全上下文为所述第一套安全上下文。
通过该设计，所述第一核心网设备可以确定通过安全验证测试的第一套安全上下文。
在一种可能的设计中，当所述终端设备处于无线资源控制RRC连接的连接态时，所述上行消息为以下任一项：跟踪区域更新请求消息、附着请求消息。
在一种可能的设计中，所述第一核心网设备还可以向所述第二通信系统中的接入网设备发送所述第一套安全上下文，以使所述接入网设备可以使用所述第一套安全上下文与所述终端设备进行安全验证。
在一种可能的设计中，所述第一套安全上下文中包含非接入层计数值NAS count。
在一种可能的设计中，所述第一通信系统为第五代5G通信系统，所述第二通信系统为第四代4G通信系统。
第六方面，本申请实施例提供了一种通信方法，该方法包括以下步骤：
终端设备在从第一通信系统切换到第二通信系统的过程中，获取多套备选安全上下文；
所述终端设备在所述多套备选安全上下文中选择一套备选安全上下文对上行消息进行完整性保护处理，并将完整性保护处理后的上行消息发送给第一网络设备，所述第一网络设备位于所述第二通信系统中；在所述终端设备未接收到来自所述第一网络设备的所述上行消息的响应消息时，所述终端设备在所述多套备选安全上下文中选择下一套备选安全上下文对所述上行消息进行完整性保护处理，直至接收到来自所述第一网络设备的所述上行消息的响应消息。
通过该方法，所述终端设备可以在使用一套备选安全上下文对上行消息进行完整性保护处理后，未接收到该上行消息的响应消息，则尝试使用下一套备选安全上下文对该上行消息进行完整性保护处理，直至接收到该上行消息的响应消息，以便该上行消息可以安全成功传输到第一网络设备。
在一种可能的设计中，在所述响应消息为所述第一网络设备完整性保护处理后的情况下，所述终端设备还可以在所述多套备选安全上下文中选择一套备选安全上下文对完整性保护处理后的所述响应消息进行完整性保护校验，若完整性保护校验成功，则激活本次使用的备选安全上下文；否则所述终端设备在所述多套备选安全上下文中选择下一套备选安全上下文对完整性保护处理后的所述响应消息进行完整性保护校验，直至完整性保护校验成功，所述终端设备激活最后使用的备选安全上下文；
在所述响应消息为所述第一网络设备加密和完整性保护处理后的情况下，所述终端设备还可以在所述多套备选安全上下文中选择一套备选安全上下文对加密和完整性保护处理后的所述响应消息进行解密处理和完整性保护校验，若解密和完整性保护校验成功，则激活本次使用的备选安全上下文；否则所述终端设备在所述多套备选安全上下文中选择下一套备选安全上下文对加密和完整性保护处理后的所述响应消息进行解密处理和完整性保护校验，直至解密和完整性保护校验成功，所述终端设备激活最后使用的备选安全上下文。
在该方法中，终端设备在从第一通信系统切换到第二通信系统的过程中，可以获取多套备选安全上下文；并在多套备选安全上下文中确定通过安全校验的一套安全上下文；所述终端设备激活该套安全上下文，用于后续与第二通信系统的网络设备进行安全验证。由于终端设备激活的该套安全上下文是通过安全校验的，即该套安全上下文与第二通信系统中的网络设备维护的安全上下文一致，因此，所述终端设备使用该套安全上下文与第二通信系统的网络设备进行安全验证，可以实现安全验证成功，从而保证所述终端设备可以成功切换到所述第二通信系统。
在一种可能的设计中，所述终端设备处于无线资源控制RRC连接的连接态，所述上行消息为以下任一项：跟踪区域更新请求消息、附着请求消息；所述响应消息为以下任一项：跟踪区域更新接受消息、附着接受消息、安全模式命令、无线资源控制RRC安全模式命令。
在一种可能的设计中，所述终端设备获取多套备选安全上下文，包括：
所述终端设备分别根据多个版本的安全上下文映射算法，对第一套安全上下文进行计 算，生成所述多套备选安全上下文；其中，所述第一套安全上下文用于所述终端设备与第二网络设备进行安全验证，所述第二网络设备位于所述第一通信系统中。
在一种可能的设计中，任一套备选安全上下文中包含非接入层计数值NAS count。
在一种可能的设计中，所述第一通信系统为第五代5G通信系统，所述第二通信系统为第四代4G通信系统。
第七方面，本申请实施例提供了一种通信装置，包括用于执行以上任一方面中各个步骤的单元。
第八方面，本申请实施例提供了一种通信设备，包括至少一个处理元件和至少一个存储元件，其中该至少一个存储元件用于存储程序和数据，该至少一个处理元件用于读取并执行存储元件存储的程序和数据，以使得本申请以上任一方面提供的方法被实现。
第九方面，本申请实施例还提供了一种计算机程序，当所述计算机程序在计算机上运行时，使得所述计算机执行上述任一方面提供的方法。
第十方面，本申请实施例还提供了一种计算机可读存储介质，所述计算机可读存储介质中存储有计算机程序，当所述计算机程序被计算机执行时，使得所述计算机执行上述任一方面提供的方法。
第十一方面，本申请实施例还提供了一种芯片，所述芯片用于读取存储器中存储的计算机程序，执行上述任一方面提供的方法。
第十二方面，本申请实施例还提供了一种芯片系统，该芯片系统包括处理器，用于支持计算机装置实现上述任一方面提供的方法。在一种可能的设计中，所述芯片系统还包括存储器，所述存储器用于保存该计算机装置必要的程序和数据。该芯片系统可以由芯片构成，也可以包含芯片和其他分立器件。
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图1A为本申请实施例提供的一种机密性保护过程示意图；
图1B为本申请实施例提供的一种完整性保护过程示意图；
图2为本申请实施例提供的一种通信系统的架构图；
图3A为本申请实施例提供的一种通信方法的流程图；
图3B为本申请实施例提供的一种通信实例的流程图；
图4A为本申请实施例提供的一种通信方法的流程图；
图4B为本申请实施例提供的一种通信实例的流程图；
图5A为本申请实施例提供的一种通信方法的流程图；
图5B为本申请实施例提供的一种通信实例的流程图；
图6A为本申请实施例提供的一种通信方法的流程图；
图6B为本申请实施例提供的一种通信实例的流程图；
图7A为本申请实施例提供的一种通信方法的流程图；
图7B为本申请实施例提供的一种通信实例的流程图；
图8为本申请实施例提供的一种通信装置的结构图；
图9为本申请实施例提供的一种通信设备的结构图。
具体实施方式
本申请提供一种通信方法、装置及设备，用以解决在进行异系统切换过程中，由于终端设备与核心网使用的安全上下文映射协议版本不一致，导致终端设备无法成功完成通信系统切换的问题。其中，方法和设备是基于同一技术构思的，由于方法及设备解决问题的原理相似，因此设备与方法的实施可以相互参见，重复之处不再赘述。
以下，对本申请中的部分用于进行解释说明，以便本领域技术人员理解。
1)、终端设备，是一种向用户提供语音和/或数据连通性的设备。终端设备又可以称为用户设备(user equipment，UE)、移动台(mobile station，MS)、移动终端(mobile terminal，MT)等。在本申请实施例和实例中，仅以终端设备为例UE为例进行说明。
例如，终端设备可以为具有无线连接功能的手持式设备、车载设备等。目前，一些终端设备的举例为：手机(mobile phone)、平板电脑、笔记本电脑、掌上电脑、移动互联网设备(mobile internet device，MID)、智能销售终端(point of sale，POS)、可穿戴设备，虚拟现实(virtual reality，VR)设备、增强现实(augmented reality，AR)设备、工业控制(industrial control)中的无线终端、无人驾驶(self driving)中的无线终端、远程手术(remote medical surgery)中的无线终端、智能电网(smart grid)中的无线终端、运输安全(transportation safety)中的无线终端、智慧城市(smart city)中的无线终端、智慧家庭(smart home)中的无线终端、各类智能仪表(智能水表、智能电表、智能燃气表)等。
2)、通信系统，用于在终端设备请求业务时，采用第三代合作伙伴计划(the 3rd generation partnership project，3GPP)接入技术将终端设备接入数据网络，并实现终端设备和数据网络之间用户面数据的传输以实现相应的业务。除非另外说明，否则在以下本申请实施例中涉及到通信系统均为3GPP通信系统。
其中，通信系统分为接入网(access network，AN)和核心网(core network，CN)。接入网用于通过3GPP接入技术将终端设备汇接到核心网中。核心网用于将终端设备接入到不同的数据网络。另外，按照逻辑功能划分，核心网又可以分为控制面和用户面。
还需说明的是，本申请不限定通信系统的制式，可以为第三代(3 rd generation，3G)通信系统、第四代(4 th generation，4G)通信系统(即长期演进(long term evolution，LTE)通信系统)、第五代(5 th generation，5G)通信系统(即新无线(new radio，NR)通信系统)，或者未来的通信系统，或者基于任一代通信系统演进的通信系统。
例如，在4G通信系统中，接入网还可以称为演进的通用移动通信系统(universal mobile telecommunications system，UMTS)陆地无线接入网(evolved-UMTS terrestrial radio access network，E-UTRAN)，核心网还可以称为演进的分组核心网(evolved packet core，EPC)。
又例如，在5G通信系统中，接入网还可以称为5G无线接入网(NG-无线接入网(radio access network，RAN)，即NG-RAN)，核心网还可以称为5G核心网(5G core，5GC)。
3)、网络设备，为位于通信系统中的网元。所述网络设备可以为接入网中的接入网设备(AN设备)，或者为核心网中的核心网设备。本申请对此不作限定。
4)、AN设备，是通信系统中将终端设备接入到无线网络的设备。所述接入网设备作为无线接入网中的节点，又可以称为基站，还可以称为无线接入网(radio access network，RAN)节点(或设备)。
目前，一些AN设备的举例为：gNB、传输接收点(transmission reception point，TRP)、演进型节点B(evolved Node B，eNB)、无线网络控制器(radio network controller，RNC)、 节点B(Node B，NB)、接入点(access point，AP)基站控制器(base station controller，BSC)、基站收发台(base transceiver station，BTS)、家庭基站(例如，home evolved NodeB，或home Node B，HNB)，或基带单元(base band unit，BBU)，企业LTE离散窄带聚合(Enterprise LTE Discrete Spectrum Aggregation，eLTE-DSA)基站等。
另外，在一种网络结构中，所述AN设备可以包括集中单元(centralized unit，CU)节点和分布单元(distributed unit，DU)节点。这种结构将长期演进(long term evolution，LTE)系统中eNB的协议层拆分开，部分协议层的功能放在CU集中控制，剩下部分或全部协议层的功能分布在DU中，由CU集中控制DU。
示例性的，在4G通信系统中，所述AN设备称为eNB；在5G通信系统中，所述AN设备可以称为gNB。
5)、核心网设备，位于核心网中的网元，用于实现核心网的功能，例如负责根据终端设备通过接入网发送的呼叫请求或业务请求将所述终端设备接续到不同的数据网络上，以及计费、移动性管理、会话管理等业务。由于本申请实施例提供的方法是在终端设备进行异系统切换的场景中，因此，本申请涉及的核心网设备为核心网中负责终端设备的移动性管理功能的网元。
由于移动性管理功能为核心网中控制面功能，因此，在核心网拆分为控制面和用户面的通信系统中，负责移动性管理功能的核心网设备又可以称为控制面网元或控制面设备。
示例性的，在4G移动通信系统中，负责移动性管理功能的核心网设备可以称为移动管理实体(mobility management entity，MME)；在5G移动通信系统中，负责移动性管理功能的核心网设备可以称为接入与移动性管理功能(Access and Mobility Management Function，AMF)网元，简称为AMF。
还需要说明的是，本申请对负责移动性管理功能的核心网设备的名称并不限定，其还可以实现其他功能或与其他功能网元进行融合，并且还可以称为其他名称。
6)、安全验证，又称为安全对接、安全校验等，用于实现接收方和发送方的机密性保护和/或完整性保护。
7)、异系统切换，为将UE从一种制式的通信系统切换到另外一种制式的通信系统。其中，在本申请实施例中，UE可以通过多种切换机制实现所述异系统切换，例如：切换(handover)机制、重定向机制、盲重定向机制、搜网机制、重选机制等。
其中，切换机制为UE处于RRC连接态时执行的，其它机制为UE处于RRC空闲态时执行的。
8)、“和/或”，描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。字符“/”一般表示前后关联对象是一种“或”的关系。
需要说明的是，本申请中所涉及的多个，是指两个或两个以上。至少一个，是指一个或一个以上。
另外，需要理解的是，在本申请的描述中，“第一”、“第二”等词汇，仅用于区分描述的目的，而不能理解为指示或暗示相对重要性，也不能理解为指示或暗示顺序。
需要注意的是，本申请实施例涉及的附着(attach)流程、跟踪区域更新(tracking area update，TAU)流程、安全模式命令(security mode command，SMC)流程、鉴权(authentication)流程可以为通信标准中规定的标准流程，例如通信标准24.301规定的流程。另外上述流程 中涉及的消息以及定时器等也可以参考该通信标准中的定义。
本申请实施例涉及的无线资源控制(radio resource control，RRC)SMC流程、也可以为通信标准中规定的标准流程，例如通信标准36.331规定的流程。另外，该流程中涉及的消息也可以参考该通信标准中的定义。
在对本申请实施例进行具体说明之前，先对UE和核心网的NAS层维护的一套安全上下文进行说明。
UE和通信系统中的网络设备(以下以核心网设备为例)通过一套安全上下文进行安全对接，实现信令的传输安全。所述安全验证包含机密性保护(即加密、解密)和完整性保护(即完保、解完保/完整性保护校验)。例如，在3GPP协议TS33.401中规定了安全上下文中的NAS count是加解密、完保和解完保的参数之一。
具体的，UE可以根据维护的安全上下文对上行消息进行加密和/或完保处理，而核心网设备可以根据维护的安全上下文对接收的加密和/或完保处理后的上行消息进行解密和/或解完保处理，得到该上行消息。
核心网设备可以根据维护的安全上下文对下行消息进行加密和/或完保处理，而终端设备可以根据维护的安全上下文对接收的加密和/或完保处理后的下行消息进行解密和/或解完保处理，得到该下行消息。
为了保证UE和核心网设备之间能够成功安全对接(接收方能够根据维护的安全上下文成功对发送方发送的消息解密或解完保)，二者维护的安全上下文需要对应，即UE和核心网设备二者维护的安全上下文中的NAS count相同。
图1A为接收方和发送方利用NAS count对消息进行机密性保护的过程。参阅图1A中所示，密码算法(即如图中的加解密算法，例如EPS加密算法(EPS encryption algorithm，EEA)等)的输入参数包含：128比特(bit)的机密性密钥(key)、一个32bit的计数值(即NAS count，其本质为消息序列号)、一个5bit的承载标识(即bearer)、一个1bit的传输方向指示(即direction)以及所需密钥流块的长度(即length)。其中，方向指示取值为0时指示上行方向，方向指示取值为1时，指示下行方向。
图1B为接收方和发送方利用NAS count对消息进行完整性保护的过程。参阅图1B中所示，完整性算法(例如EPS完整性算法(EPS integrity algorithm，EIA)等)的输入参数包含：128bit的完整性密钥(key)、一个32bit的计数值(即NAS count，其本质为消息序列号)、一个5bit的承载标识(即bearer)、一个1bit的传输方向指示和待传输的消息本身(即message)。其中，方向指示取值为0时指示上行方向，方向指示取值为1时，指示下行方向。发送方可以根据图中的完整性算法，基于待传输的消息和一系列其他参数，生成校验码(即MAC-I/NAS-MAC)，然后将该消息和校验码同时发送给接收方。接收方根据相同的完整性算法，基于接收的消息以及本地一系列其他参数，生成待验证校验码(XMAC-I/XNAS-MAC)；然后所述接收方对接收的校验码和生成的待验证校验码进行完比对，若二者相同，则说明该消息为完整未被篡改，该消息的完整性验证成功，所述接收方解完保成功；若二者不同，则说明该消息可能被篡改，该消息的完整性验证失败，所述接收方解完保失败。
通过以上对图1A和图1B所示的机密性保护和完整性保护的过程可知，安全上下文中的NAS count作为加解密、完保和解完保的参数之一，发送方和接收方维护的NAS count 值必须相同，才能保证安全对接成功。
需要注意的是，每套安全上下文中包含上行安全上下文和下行安全上下文。上行安全上下文和下行安全上下文均由NAS count，以及一些其他参数组成。
例如，在上行方向上，UE可以利用上行安全上下文对上行消息(例如上行信令)进行加密和/或完保处理，并将加密和/或完保处理后的上行消息发送给核心网设备；相应的，核心网设备可以利用上行安全上下文对接收的加密和/或完保处理后的上行消息进行解密和/或解完保处理，以得到所述上行消息。
又例如，在下行方向上，核心网设备可以利用下行安全上下文对下行消息(例如下行信令)进行加密和/或完保处理，并将加密和/或完保处理后的下行消息发送给UE；相应的，UE可以利用下行安全上下文对接收的加密和/或完保处理后的下行消息进行解密和/或解完保处理，以得到所述下行消息。
通过以上描述可知，终端设备在通信系统中驻留时，终端设备与该通信系统的网络设备只有维护的安全上下文相同，才能实现二者的安全对接，从而通信系统才能为该终端设备提供服务，否则二者无法传输消息，导致终端设备接入失败。
在终端设备需要进行异系统切换的场景中，终端设备和核心网需要对第一通信系统中的第一套安全上下文进行映射，生成第二通信系统中的第二套安全上下文，并且只有在终端设备和第二通信系统根据所述第二套安全上下文进行安全对接成功后，终端设备才能切换到第二通信系统，通过第二通信系统实现终端设备的业务传输。其中，第一通信系统和第二通信系统为不同制式的通信系统，例如第一通信系统为5G通信系统，第二通信系统为4G通信系统。
目前安全上下文的映射协议版本有多种，不同协议版本对第一套安全上下文中的NAS count进行映射得到的第二套安全上下文中的NAS count可能会出现不同的情况。因此，若终端设备和核心网两侧使用不同的映射协议版本对第一套安全上下文进行映射，就可能会造成终端设备的NAS层维护的第二套安全上下文与核心网的NAS层维护的第二套安全上下文中包含的NAS count不一致的问题。由于NAS count是加解密、完保(即完整性保护)、解完保的输入参数之一，若终端设备和核心网的各自维护的第二套安全上下文中NAS count不一致，会导致终端设备和核心网安全对接失败，进而导致终端设备无法成功切换到第二通信系统，第二通信系统无法为终端设备提供传输服务，严重影响终端设备的业务。
示例性的，一种安全上下文映射协议为3GPP协议33501_CR0611r1，用于实现将5G通信系统对应的安全上下文映射为4G通信系统对应的安全上下文。为了便于描述，在后续描述和实例中，将5G通信系统对应的安全上下文简称为5G安全上下文，将4G通信系统对应的安全上下文简称为4G安全上下文。
目前，在该协议具有两个版本，在先版本和刷新版本。下面以这两个版本的协议为例进行说明。
在使用最先的版本对5G安全上下文进行映射时，5G安全上下文中的NAS count(简称为NR count)会映射为初始值0，即生成的4G安全上下文中的NAS count(简称为LTE count)为0。
在使用刷新版本对5G安全上下文进行映射时，5G安全上下文中的NAS count(即NR  count)不发生变化，即生成的4G安全上下文中的NAS count(即LTE count)等于NR count。
下面结合附图，对本申请实施例进行具体说明。
图2示出了本申请实施例提供的通信方法适用的一种通信架构。
其中，本通信架构中兼容有多种不同制式的通信系统。图2仅以5G通信系统和4G通信系统为例进行说明。
需要说明的是本申请不对本申请提供方法所使用的通信架构造成限定，该架构中还可以至少包含以下任意两种通信系统：5G通信系统、4G通信系统、未来的新一代通信系统、全球移动通讯(Global System of Mobile communication，GSM)系统、码分多址(Code Division Multiple Access，CDMA)系统、宽带码分多址(Wideband Code Division Multiple Access，WCDMA)系统、通用分组无线业务(General Packet Radio Service，GPRS)、先进的长期演进(Advanced long term evolution，LTE-A)系统、通用移动通信系统(Universal Mobile Telecommunication System，UMTS)、以及第三代合作伙伴计划(The 3rd Generation Partnership Project，3GPP)相关的蜂窝系统，以及基于以上通信系统演进的通信系统。
总之，本申请实施例描述的通信架构是为了更加清楚的说明本申请实施例的技术方案，并不构成对于本申请实施例提供的技术方案的限定，本领域普通技术人员可知，随着通信技术的发展、网络架构的演变，本申请实施例提供的技术方案对于类似的技术问题和场景，同样适用。
在图2所示的通信架构中，在满足异系统切换条件的情况下，UE可以通过异系统切换，从一个通信系统切换到另一个通信系统。
如图2中所示，该通信架构中，4G通信系统中包含两部分：接入网和核心网。其中，所述接入网即为图中所示的E-UTRAN，所述核心网中包含以下网元：移动性管理功能(mobility management entity，MME)、服务网元(serving gateway，SGW)、分组数据网关(packet data network gateway，PGW)、策略与计费规则功能(policy and charging rules function，PCRF)网元(简称为PCRF)、归属用户服务器(home subscriber server，HSS)等。
其中，按照逻辑功能划分，所述PGW还可以分为：PGW控制面(PGW-control，PGW-C)网元(简称为PGW-C)和PGW用户面(PGW-user，PGW-U)(简称为PGW-U)。
5G通信系统中也包含两部分：接入网和核心网。其中，所述接入网即为图中所示的NG-RAN，AMF网元(简称为AMF)、用户面功能(user plane function，UPF)网元(简称为UPF)、会话管理功能(session management function，SMF)网元(简称为SMF)、策略与计费功能(policy and charge function，PCF)网元(简称为PCF)、统一数据管理(unified data management，UDM)网元(简称为UDM)等。
需要说明的是，在图2所示的兼容4G通信系统和5G通信系统的通信架构中，如图所示，SMF和PGW-C可以融合在同一网元中，也可以分开设置在不同的设备中，同样地，UPF和PGW-U、HSS和UDM、以及PCF和PCRF网元亦是如此，在本申请实施例中对其组成方式并不做具体限定。
在4G通信系统中的两个网络设备之间可以通过相应的接口实现通信，具体可以参考图2所示。以及5G通信系统中的两个网络设备之间也可以通过相应的接口实现通信，具体可以参考图2所示。需要说明的是，为了实现UE在5G通信系统和4G通信系统之间异 系统切换，5G通信系统中的AMF和4G通信系统中的MME之间也能够通过接口N26进行通信，以实现信令以及安全上下文的传输，保证UE的无缝切换。
需要理解的是，4G通信系统或5G通信系统中的以上各网元既可以是在专用硬件上实现的网络元件，也可以是在专用硬件上运行的软件实例，或者是在虚拟化平台(例如云平台)上虚拟化功能的实例。此外，本申请实施例并不限定通信系统中各个网元的分布形式，可选的，以上各个网元可以分别部署在不同的物理设备中，或者多个网元融合在同一物理设备中。
另外，本申请实施例也不对通信系统中各网元的名称进行限定，例如，在不同制式的通信系统中，各网元可以有其它名称；又例如，当多个网元融合在同一物理设备中时，该物理设备也可以有其他名称。
通过以上对安全上下文的描述可知，在UE进行异系统切换过程中，由于UE和核心网设备使用的安全上下文映射算法不一致，可能会导致二者维护的安全上下文不一致(二者维护的安全上下文中的包含的NAS count不一致)，最终导致UE无法成功切换到新通信系统。为了解决上述问题，本申请实施例提供了通信方法，该方法可以应用于如图2所示的通信系统中。
为了便于说明，本申请以下实施例将UE进行异系统切换的源通信系统称为第一通信系统，将UE进行异系统切换的目的通信系统称为第二通信系统。进一步的，为了便于区分和说明不同通信系统中的网络设备，将位于第一通信系统中的网络设备称为第一网络设备，将位于第二通信系统中的网络设备称为第二网络设备。其中，所述第一网络设备可以包含位于所述第一通信系统中的第一核心网设备和第一AN设备，所述第二网络设备可以包含位于所述第二通信系统中的第二核心网设备和第二AN设备。
需要说明的是，本申请各个实施例不限定所述第一通信系统和所述第二通信系统的制式。示例性的，所述第一通信系统可以为5G通信系统，所述第二通信系统可以为4G通信系统；或者所述第一通信系统可以为4G通信系统，所述第二通信系统可以为5G通信系统；又或者所述第一通信系统可以为6G通信系统，所述第二通信系统可以为5G通信系统等。
实施例一：
下面参阅图3A所示的通信方法流程图，对本实施例提供的通信方法进行详细说明。
S301a：UE驻留在第一通信系统时，所述UE与位于第一通信系统中的第一网络设备使用第一套安全上下文进行安全验证。
具体的，所述UE和所述第一网络设备中的NAS层分别维护所述第一套安全上下文，并使用各自维护的所述第一套安全上下文，对传输的消息进行机密性保护和完整性保护，具体过程可以参考以上对图1A和图1B的具体描述，此处不再赘述。
S302a：在当前网络环境满足异系统切换条件时，触发UE的异系统切换；UE启动执行异系统切换，从第一通信系统切换到第二通信系统。在进行异系统切换过程中，所述UE成功驻留到第二通信系统。所述UE获取第二套安全上下文，以便使用所述第二套安全上下文与位于第二通信系统中的第二网络设备进行安全验证。
示例性的，在UE当前网络环境中第一通信系统的信号质量降低，而第二通信系统的信号质量较高时，通信系统可以通过切换机制、重定向机制、盲重定向机制、搜网机制、 重选机制等，实现UE的异系统切换。
可选的，所述UE可以在确定满足异系统切换条件时，触发从所述第一通信系统切换到所述第二通信系统的异系统切换流程；或者所述第一网络设备确定满足系统切换条件时，向所述UE发送通知消息，指示所述UE执行从所述第一通信系统切换到所述第二通信系统的异系统切换流程。以上具体过程可以参考目前的通信协议，此处不再详细赘述。
可选的，所述UE在获取所述第二套安全上下文时，可以根据本地保存的设定安全上下文映射算法，对自身维护的所述第一套安全上下文进行计算，生成所述第二套安全上下文。
S303a：所述UE使用所述第二套安全上下文与所述第二网络设备进行安全验证。
需要说明的是，为了实现与所述UE进行安全验证，在S303a之前，所述第二网络设备还可以通过以下两种方式，获取第三套安全上下文：
方式一：在所述UE执行异系统切换过程中，所述第一网络设备根据本地保存的设定安全上下文映射算法，对自身维护的所述第一套安全上下文进行计算，生成所述第三套安全上下文。所述第一网络设备可以通过接口N26向所述第二网络设备发送所述第三套安全上下文。
需要说明的是，当所述UE本地保存的设定安全上下文映射算法与所述第一网络设备本地保存的设定安全上下文映射算法相同时，所述UE生成的第二套安全上下文与所述第一网络设备生成的第三套安全上下文相同。当所述UE本地保存的设定安全上下文映射算法与所述第一网络设备本地保存的设定安全上下文映射算法不同时，所述UE生成的第二套安全上下文与所述第一网络设备生成的第三套安全上下文可能不同。
方式二：在所述UE执行异系统切换过程中，所述第一网络设备将本地维护的第一套安全上下文发送给所述第二网络设备。所述第二网络设备根据本地保存的设定安全上下文映射算法，对接收的所述第一套安全上下文进行计算，生成所述第三套安全上下文。所述第一网络设备可以通过接口N26向所述第二网络设备发送所述第一套安全上下文。
与方式一类似的，当所述UE本地保存的设定安全上下文映射算法与所述第二网络设备本地保存的设定安全上下文映射算法相同时，所述UE生成的第二套安全上下文与所述第二网络设备生成的第三套安全上下文相同。当所述UE本地保存的设定安全上下文映射算法与所述第二网络设备本地保存的设定安全上下文映射算法不同时，所述UE生成的第二套安全上下文与所述第二网络设备生成的第三套安全上下文可能不同。
综上，当所述UE生成的第二套安全上下文与所述第二网络设备获取的第三安全上下文相同时，所述UE使用所述第二套安全上下文与所述第二网络设备进行安全验证，可以安全验证成功，即所述UE与所述第二网络设备安全对接成功，从而保证所述UE可以成功切换到所述第二通信系统。
相反的，而当所述UE生成的第二套安全上下文与所述第二网络设备获取的第三安全上下文不同时，所述UE使用所述第二套安全上下文与所述第二网络设备进行安全验证，会导致安全验证失败，即所述UE与所述第二网络设备安全对接失败，进而导致所述UE无法成功切换到所述第二通信系统。
S304a：当所述UE生成的第二套安全上下文与所述第二网络设备获取的第三安全上下文不同，所述UE使用所述第二套安全上下文与所述第二网络设备安全验证失败时，所述UE向所述第二网络设备发起注册流程，以使所述UE和所述第二网络设备可以同时激活新 的一套安全上下文。
在一种实施方式中，当所述UE使用所述第二套安全上下文与所述第二网络设备安全验证失败的次数大于或等于设定阈值时，所述UE向所述第二网络设备发起注册流程。这样可以避免在由于其他原因导致少量次数的安全验证失败的情况下，所述UE发起注册流程造成的信令开销和时延。
其中，所述设定阈值的取值可以根据实际应用或具体场景具体设定，本申请实施例对此不作限定，示例性的，所述设定阈值可以为2、3、4等。
在一种实施方式中，所述UE使用所述第二套安全上下文与所述第二网络设备安全验证失败，可以但不限于包含以下情况：
情况一：所述UE使用所述第二套安全上下文，对来自所述第二网络设备的加密处理后的下行消息进行解密处理，且解密失败。
情况二：所述UE使用所述第二套安全上下文，对来自所述第二网络设备的完整性保护处理后的下行消息进行完整性保护校验，且完整性保护校验失败。
情况三：所述UE使用所述第二套安全上下文，对来自所述第二网络设备的加密和完整性保护处理后的下行消息进行解密处理和完整性保护校验，且解密失败或完整性保护校验失败。
情况四：所述UE使用所述第二套安全上下文，对上行消息进行完整性保护处理，并向所述第二网络设备发送完整性保护处理后的上行消息，且所述UE未接收来自所述第二网络设备的所述上行消息的响应消息。
示例性的，在以上情况中涉及的所述下行消息可以但不限于为以下任一项：安全模式命令(security mode command)、跟踪区域更新接受消息(tracking area update accept)、RRC安全模式命令(security mode command)、附着接受消息(attach accept)；在以上情况中涉及的所述上行消息可以但不限于为以下任一项：跟踪区域更新请求消息(tracking area update request)、附着请求消息(attach request)。
在一种实施方式中，所述UE向所述第二网络设备发起注册流程，可以但不限于包括以下步骤：
所述UE删除所述第二套安全上下文，以及释放所述UE的RRC连接；
所述UE向所述第二网络设备发送附着请求消息(attach request)，所述附着请求消息中包含所述UE的国际移动用户识别码(international mobile subscriber identification number，IMSI)。
这样，所述第二网络设备接收到所述UE在注册流程中发送的附着请求消息后，当确定所述附着请求消息中包含所述UE的IMSI，则会在本地激活新的一套安全上下文，并指示所述UE激活新的一套安全上下文。
由于UE和第二网络设备均激活新的一套安全上下文，因此，二者维护的安全上下文一致(二者维护的安全上下文中的包含的NAS count均为初始值(例如0)，保持一致)。因此，后续所述UE和所述第二网络设备可以使用该新的一套安全上下文进行安全验证，且能够保证安全验证成功。
S305a：所述UE与所述第二网络设备使用新的一套安全上下文进行安全验证。
通过S305a，所述UE与所述第二网络设备可以安全对接成功，从而保证所述UE可以成功切换到所述第二通信系统。
综上所述，本申请实施例提供了一种通信方法，在该方法中，UE在从第一通信系统切换到第二通信系统的过程中，获取用于与第二通信系统中的网络设备进行安全验证的安全上下文；当所述UE使用该安全上下文与第二通信系统中的网络设备安全验证失败时，则向第二通信系统中的网络设备发起注册流程，以使所述UE和所述第二通信系统中的网络设备均能够在注册流程中激活新的一套安全上下文。由于二者激活的新的一套安全上下文一致，因此，后续二者使用该新的一套安全上下文进行安全验证，可以实现安全验证成功，从而保证所述UE可以成功切换到所述第二通信系统。
基于图3A所示的实施例，本申请还提供了一种通信实例，下面参阅图3B所示的通信实例的流程图，对该实例进行详细说明。本实例以所述UE从5G通信系统切换到4G通信系统为例进行说明。并且为了便于说明，本实例将5G通信系统对应的安全上下文简称为5G安全上下文，将4G通信系统对应的安全上下文简称为4G安全上下文。
S301b：UE驻留在5G通信系统，此时当前网络环境满足触发5G通信系统到4G通信系统的异系统切换条件(例如5G通信系统的信号质量降低，而4G通信系统的信号质量较高)时，触发UE的异系统切换。
S302b：所述UE使用安全上下文映射算法1对所述UE维护的5G安全上下文进行计算，得到4G安全上下文1。
其中，所述UE使用的安全上下文映射算法1可以为在先版本的33501_CR0611r1协议，或者为刷新版本的33501_CR0611r1协议。其中，在使用最先的版本对5G安全上下文进行映射时，5G安全上下文中的NAS count(简称为NR count)会映射为初始值0，即生成的4G安全上下文1中的NAS count(简称为LTE count)为0。
在使用刷版本对5G安全上下文进行映射时，5G安全上下文中的NAS count(即NR count)不发生变化，即生成的4G安全上下文1中的NAS count(即LTE count)等于NR count。
S303b：5G通信系统中的AMF使用安全上下文映射算法2对所述AMF维护的5G安全上下文进行计算，得到4G安全上下文2。
所述AMF使用的安全上下文映射算法2也可以为在先版本的33501_CR0611r1协议，或者为刷新版本的33501_CR0611r1协议。
在本申请实施例中，仅以所述UE和所述AMF使用的安全上下文映射算法不同为例，即所述UE计算得到的4G安全上下文1和所述AMF得到的计算得到的4G安全上下文2不同。
S304b：所述AMF通过接口N26向4G通信系统中的MME发送计算得到的所述4G安全上下文2。
所述UE使用生成的4G安全上下文1与4G通信系统中的网络设备进行安全验证失败，由于UE使用的4G安全上下文1与4G通信系统中的网络设备使用的4G安全上下文2不同，因此会发生安全验证失败的情况。下面按照场景1-场景4，对安全验证失败进行具体说明。需要说明的是，场景1-场景4仅为安全验证失败的几个示例，其并不对本实例中的涉及的安全验证失败的场景构成限定，另外UE附着流程失败等场景也适用于本实例，由于附着流程与这些示例流程类似，可以相互参考，本实例不再赘述。
场景1：SMC流程失败。
S305b：所述UE成功驻留到4G通信系统后，UE向4G通信系统中的MME发送跟踪 区域更新请求消息(Tracking area update request)以实现在4G通信系统的注册。
S306b：所述MME选择触发NAS层的SMC流程，选用一套新的算法，生成安全模式命令(Security mode command)，其中，所述安全模式命令中的密钥设置标识(key set identifier)设置为指示4G安全上下文2的标识符。所述MME使用本地维护的4G安全上下文2对所述安全模式命令进行完整性保护处理，向所述UE发送完整性保护处理后的所述安全模式命令。
S307b：由于所述UE与所述MME分别维护的4G安全上下文不一致(分别维护的4G安全上下文中的NAS count不一致)，因此，所述UE使用本地维护的4G安全上下文1对接收的完整性保护处理后的所述安全模式命令进行完整性保护校验，会发生完整性保护校验失败(即SMC流程失败)。
S308b：按照协议24.301的规定，所述UE向所述MME安全模式拒绝消息(Security mode reject)，通知所述MME本次的SMC流程失败。
场景2：UE解密、解完保失败。
S309b：所述UE成功驻留4G通信系统后，UE向4G通信系统中的MME发送跟踪区域更新请求消息(Tracking area update request)以实现在4G通信系统的注册。
S310b：所述MME生成跟踪区域更新接受消息(Tracking area update accept)，并使用本地维护的4G安全上下文2对所述跟踪区域更新接受消息进行加密和完整性保护处理；所述MME向所述UE发送加密和完整性保护处理后的跟踪区域更新接受消息。
S311b：由于所述UE与所述MME分别维护的4G安全上下文不一致(分别维护的4G安全上下文中的NAS count不一致)，因此，所述UE使用本地维护的4G安全上下文1对接收的加密和完整性保护处理后的跟踪区域更新接受消息进行解密和完整性保护校验，会发生解密失败或完整性保护校验失败，此时所述UE会将接收的加密和完整性保护处理后的跟踪区域更新接受消息丢弃。
需要说明的是，按照24.301协议，所述MME可以在接收到跟踪区域更新请求消息后，自主选择执行上述场景一还是执行场景二。
场景3：连接态MME解完保失败。
S312b：所述UE处于RRC连接态时，按照协议24.301，UE的NAS层使用4G安全上下文1对跟踪区域更新请求消息(Tracking area update request)进行完整性保护处理；所述UE向所述MME发送完整性保护处理后的所述跟踪区域更新请求消息，并启动3430定时器。
S313b：由于所述UE与所述MME分别维护的4G安全上下文不一致(分别维护的4G安全上下文中的NAS count不一致)，因此，所述MME使用本地维护的4G安全上下文2对接收的完整性保护处理的跟踪区域更新请求进行完整性保护校验，且完整性保护校验失败，此时，所述MME会将接收的完整性保护处理的跟踪区域更新请求丢弃。
S314b：所述UE在未接收网络侧对跟踪区域更新请求的响应消息时，所述T3430定时器持续计时，直至所述T3430定时器超时。
场景4：RRC SMC流程失败。
S315b：所述UE成功驻留到4G通信系统后，UE向4G通信系统中的MME发送跟踪区域更新请求消息(Tracking area update request)以实现在4G通信系统的注册。
S316b：eNB触发RRC SMC流程，使用本地维护的4G安全上下文2对RRC安全模 式命令(RRC Security mode command)进行完整性保护处理；所述eNB向所述UE发送完整性保护处理后的RRC安全模式命令。
其中，所述eNB本地维护的4G安全上下文2为所述MME向其发送的。
S317b：由于所述UE与所述eNB分别维护的4G安全上下文不一致(分别维护的4G安全上下文中的NAS count不一致)，因此，所述UE使用本地维护的4G安全上下文1对接收的完整性保护处理后的RRC安全模式命令进行完整性保护校验，会发生完整性保护校验失败(即RRC SMC流程失败)。
S318b：所述UE向所述eNB发送安全模式失败消息(Security mode failure)，以通知所述eNB本次的RRC SMC流程失败。
S319b：所述UE确定使用本地维护的4G安全上下文1与4G通信系统中的网络设备(MME、eNB)安全对接失败次数大于或等于设定阈值时，所述UE本地维护的4G安全上下文、网络分配的身份标识清除，成为一张白卡(即从未在网络注册过的卡)，释放RRC连接，并使用自身的IMSI重新进行注册，即所述UE向所述MME发送附着请求消息，其中，所述附着请求消息中包含的所述UE的IMSI(即EPS移动身份(EPS mobile identity)为所述UE的IMSI)。所述MME接收到所述附着请求消息后，确定所述附着请求消息中包含所述UE的IMSI，则会在本地重新激活一套新的4G安全上下文，也会指示所述UE重新激活一套新的4G安全上下文。这样，所述UE和所述MME可以基于各自维护的新的4G安全上下文进行安全验证。
其中，所述UE可以自主配置所述设定阈值的取值，或者为用户设定的，或者为标准规定的，本申请对此不做限定。
后续流程可以参考通信标准协议，例如，协议24301的5.4.2、5.4.3以及5.5.1章节，本实例不再赘述。
实施例二：
下面参阅图4A所示的通信方法流程图，对本实施例提供的通信方法进行详细说明。
S401a：UE驻留在第一通信系统时，所述UE与位于第一通信系统中的第一网络设备使用第一套安全上下文进行安全验证。
具体的，所述UE和所述第一网络设备中的NAS层分别维护所述第一套安全上下文，并使用各自维护的所述第一套安全上下文，对传输的消息进行机密性保护和完整性保护，具体过程可以参考以上对图1A和图1B的具体描述，此处不再赘述。
S402a：UE处于RRC空闲态，在当前网络环境满足异系统切换条件时，触发UE的异系统切换；UE启动执行异系统切换，从第一通信系统切换到第二通信系统。在进行异系统切换过程中，所述UE成功驻留到第二通信系统。所述UE获取多套备选安全上下文，以便在多套备选安全上下文中选择一套安全上下文与位于第二通信系统中的第二网络设备进行安全验证。
示例性的，在UE当前网络环境中第一通信系统的信号质量降低，而第二通信系统的信号质量较高时，由于UE处于RRC空闲态，因此，通信系统可以通过重定向机制、盲重定向机制、搜网机制、重选机制等，实现UE的异系统切换。
可选的，所述UE可以在确定满足异系统切换条件时，触发从所述第一通信系统切换到所述第二通信系统的异系统切换流程；或者所述第一网络设备确定满足系统切换条件时， 向所述UE发送通知消息，指示所述UE执行从所述第一通信系统切换到所述第二通信系统的异系统切换流程。以上具体过程可以参考目前的通信协议，此处不再详细赘述。
可选的，所述UE在获取所述多套备选安全上下文时，可以根据本地保存的多个版本的安全上下文映射算法，对自身维护的所述第一套安全上下文进行计算，生成所述多套备选安全上下文。
S403a：所述UE在所述多套备选安全上下文中确定通过安全验证测试的第二套安全上下文。
同实施例一中的描述，在S403a之前，所述第二网络设备也可以通过两种方式，获取用于与所述UE进行安全验证的第三套安全上下文，具体过程可以参考实施例一中的描述，此处不再赘述。
需要说明的是，由于所述UE本地保存多个版本的安全上下文映射算法，其中可以包含第一网络设备/第二网络设备本地保存的设定安全上下文映射算法，即UE生成的多套备选安全上下文中存在至少一套备选安全上下文与所述第二网络设备维护的第三套安全上下文一致。因此，所述UE可以通过S403a，在所述多套备选安全上下文中选择出与所述第二网络设备维护的第三套安全上下文一致的所述第二套安全上下文。
在一种实施方式中，所述UE可以通过以下步骤执行S403a：
所述UE在所述多套备选安全上下文中选择一套待测试安全上下文，其中，所述待测试安全上下文为所述多套备选安全上下文中的任一套备选安全上下文；
若所述UE使用选择的该待测试安全上下文与所述第二网络设备进行安全验证测试，若确定安全验证测试通过，则确定该待测试安全上下文为所述第二套安全上下文；否则继续在所述多套备选安全上下文选择下一套待测试安全上下文，直至确定选择的待测试安全上下文通过安全验证测试；最后，所述UE确定通过安全验证测试的待测试安全上下文为所述第二套安全上下文。
可选的，所述多套备选安全上下文的选择顺序可以为预设的，或者随机的，本申请对此不作限定。
具体的，所述UE可以在以下情况下，确定选择的待测试安全上下文通过安全验证测试：
情况一：所述UE使用所述待测试安全上下文，对来自所述第二网络设备的加密处理后的下行消息进行解密处理，且解密成功得到所述下行消息。其中，该加密处理后的下行消息为所述第二网络设备使用第三套安全上下文对该下行消息进行加密生成的。
情况二：所述UE使用所述待测试安全上下文，对来自所述第二网络设备的完整性保护处理后的下行消息进行完整性保护校验，且完整性保护校验成功，得到所述下行消息。其中，该完整性保护处理后的下行消息为所述第二网络设备使用第三套安全上下文对该下行消息进行完整性保护处理生成的。
情况三：所述UE使用所述待测试安全上下文，对来自所述第二网络设备的加密和完整性保护处理后的下行消息进行解密处理和完整性保护校验，且解密和完整性保护校验成功，得到所述下行消息。其中，该加密和完整性保护处理后的下行消息为所述第二网络设备使用第三套安全上下文对该下行消息进行加密和完整性保护处理生成的。
示例性的，以上情况中涉及的下行消息可以但不限于为以下任一项：安全模式命令(security mode command)、跟踪区域更新接受消息(tracking area update accept)、RRC安 全模式命令(security mode command)、附着接受消息(attach accept)。
S404a：所述UE激活第二套安全上下文，以便后续可以使用所述第二套安全上下文与所述第二网络设备进行安全验证。
S405a：所述UE使用所述第二套安全上下文与所述第二网络设备进行安全验证。
由于所述UE使用的所述第二套安全上下文与所述第二网络设备使用的第三套安全上下文一致，因此，所述UE可以与所述第二网络设备可以安全对接成功，从而保证所述UE可以成功切换到所述第二通信系统。
综上所述，本申请实施例提供了一种通信方法，在该方法中，UE在从第一通信系统切换到第二通信系统的过程中，可以获取多套备选安全上下文；并在多套备选安全上下文中确定通过安全验证测试的一套安全上下文；所述UE激活该套安全上下文，用于后续与第二通信系统的网络设备进行安全验证。由于UE激活的该套安全上下文是通过安全验证测试的，即该套安全上下文与第二通信系统中的网络设备维护的安全上下文一致，因此，所述UE使用该套安全上下文与第二通信系统的网络设备进行安全验证，可以实现安全验证成功，从而保证所述UE可以成功切换到所述第二通信系统。
基于图4A所示的实施例，本申请还提供了一种通信实例，下面参阅图4B所示的通信实例的流程图，对该实例进行详细说明。本实例以所述UE从5G通信系统切换到4G通信系统为例进行说明。并且为了便于说明，本实例将5G通信系统对应的安全上下文简称为5G安全上下文，将4G通信系统对应的安全上下文简称为4G安全上下文。
S401b：UE驻留在5G通信系统，且UE处于RRC空闲态，此时当前网络环境满足触发5G通信系统到4G通信系统的异系统切换条件(例如5G通信系统的信号质量降低，而4G通信系统的信号质量较高)时，触发UE的异系统切换。
S402b：所述UE成功驻留到4G通信系统后，UE向4G通信系统中的MME发送跟踪区域更新请求消息(Tracking area update request)以实现在4G通信系统的注册。此时UE使用5G安全上下文对所述跟踪区域更新请求消息进行完整性保护。
其中，所述跟踪区域更新请求中可以携带状态指示信息(UE status)，所述状态指示信息(UE status)用于指示所述UE从5G通信系统切换到4G通信系统。
S403b：所述UE使用两个版本的安全上下文映射算法，对所述UE维护的5G安全上下文进行计算，得到4G安全上下文1和4G安全上下文2。
其中，所述UE使用两个版本的安全上下文映射算法包含：为在先版本的33501_CR0611r1协议，和刷新版本的33501_CR0611r1协议。
S404b：所述MME收到UE发送的完整性保护处理后的跟踪区域更新请求消息后，确定所述UE处于RRC空闲态，且当前处于UE从5G通信系统切换到4G通信系统的过程，则根据跟踪区域更新请求消息中携带的身份标识，找到所述5G通信系统中的AMF，所述MME通过N26接口向所述AMF发送上下文请求。
可选的，所述上下文请求可以为所述MME接收的完整性保护处理后的跟踪区域更新请求消息。
S405b：在所述上下文请求为所述MME接收的完整性保护处理后的跟踪区域更新请求消息时，所述AMF使用5G安全上下文对完整性保护处理后的跟踪区域更新请求进行完整性保护校验，在完整性保护校验成功后，所述AMF使用保存的一个版本的安全上下文映 射算法对所述AMF维护的5G安全上下文进行计算，得到4G安全上下文1。
其中，所述AMF使用的安全上下文映射算法可以为在先版本的33501_CR0611r1协议，或者为刷新版本的33501_CR0611r1协议。
通过以上描述可知，所述AMF得到的4G安全上下文1与所述UE得到的两套4G安全上下文中的一套(即4G安全上下文1)相同。
S406b：所述AMF通过N26接口将得到的4G安全上下文1通过上下文响应发送给所述MME。
需要说明的是，所述UE执行S403b的时间可以在执行S402之前、之后或同时，本申请对此不作限定。
在本实例中，所述UE可以但不限于通过以下场景1-场景3，在两套4G安全上下文中，选择出通过安全验证测试的4G安全上下文(即与MME维护的4G安全上下文1相同)。需要说明的是，场景1-场景3仅为UE进行安全验证测试的几个示例，其并不对本实例中涉及的安全验证测试的场景构成限定，例如，安全验证测试还可以通过UE附着流程等场景实现，由于附着流程与这些示例中的流程类似，可以相互参考，本实例不再赘述。
下面按照场景1-场景3，对UE进行安全验证测试过程进行具体说明。
场景1：SMC流程。
S407b：所述MME从所述AMF获取所述4G安全上下文1之后，可以触发NAS层的SMC流程，选择一套新的算法(安全算法)，生成安全模式命令(Security mode command)，其中，所述安全模式命令中的密钥设置标识(key set identifier)设置为指示4G安全上下文1的标识符。所述MME使用本地维护的4G安全上下文1对所述安全模式命令进行完整性保护处理，向所述UE发送完整性保护处理后的所述安全模式命令。
S408b：所述UE收到完整性保护处理后的安全模式命令后，使用所述MME选择的新的算法替换原有的算法。由于此时UE有两套4G安全上下文(4G安全上下文1和4G安全上下文2，其中一套4G安全上下文中的NAS COUNT值是0，另一套4G安全上下文中的NAS COUNT值是NR COUNT)。UE可以在两套4G安全上下文中使用一套4G安全上下文对接收的完整性保护处理后的安全模式命令进行完整性保护校验，若完整性保护校验成功(表示UE选择的是4G安全上下文1)，则激活本次使用的一套4G安全上下文；若完整性保护校验失败(表示UE选择的是4G安全上下文2)，则再使用另一套安全上下文(即4G安全上下文1)对接收的完整性保护处理后的安全模式命令进行完整性保护校验，直至完整性保护校验成功；所述UE激活最后使用的一套4G安全上下文(即4G安全上下文1)。
S409b：所述UE使用激活的4G安全上下文1对安全模式完成消息(Security mode complete)进行加密和完整性保护处理，并向所述MME发送加密和完整性保护处理后的所述安全模式完成消息。
后续流程可参考通信标准协议，例如协议24.301第5.5章节，本实例不再赘述。
场景2：MME下发跟踪区域更新接受消息(Tracking area update accept)。
S410b：所述MME使用从所述AMF获取的所述4G安全上下文1对跟踪区域更新接受消息进行加密和完整性保护处理；所述MME向所述UE发送加密和完整性保护处理后的所述跟踪区域更新接受消息。
S411b：由于此时UE有两套4G安全上下文(4G安全上下文1和4G安全上下文2， 其中一套4G安全上下文中的NAS COUNT值是0，另一套4G安全上下文中的NAS COUNT值是NR COUNT)。UE可以在两套4G安全上下文中使用一套4G安全上下文对接收的加密和完整性保护处理后的跟踪区域更新接受消息进行解密和完整性保护校验，若解密和完整性保护校验成功(表示UE选择的是4G安全上下文1)，则激活本次使用的一套4G安全上下文；若解密或完整性保护校验失败(表示UE选择的是4G安全上下文2)，则再使用另一套安全上下文(即4G安全上下文1)对接收的加密和完整性保护处理后的安全模式命令进行解密和完整性保护校验，直至解密和完整性保护校验成功；所述UE激活最后使用的一套4G安全上下文(即4G安全上下文1)。
S412b：所述UE使用激活的4G安全上下文1对跟踪区域更新完成消息(Tracking area update complete)进行加密与完整性保护处理，并向所述MME发送加密和完整性保护处理后的跟踪区域更新完成消息，以完成所述UE在4G通信系统中的注册。
场景3：4G通信系统中的eNB触发RRC SMC流程。
S413b：eNB触发RRC SMC流程，使用本地维护的4G安全上下文1对RRC安全模式命令(RRC Security mode command)进行完整性保护处理；所述eNB向所述UE发送完整性保护处理后的RRC安全模式命令。
其中，所述eNB本地维护的4G安全上下文1为所述MME向其发送的。
S414b：由于此时UE有两套4G安全上下文(4G安全上下文1和4G安全上下文2，其中一套4G安全上下文中的NAS COUNT值是0，另一套4G安全上下文中的NAS COUNT值是NR COUNT)。UE可以在两套4G安全上下文中使用一套4G安全上下文对接收的完整性保护处理后的RRC安全模式命令进行完整性保护校验，若完整性保护校验成功(表示UE选择的是4G安全上下文1)，则激活本次使用的一套4G安全上下文；若完整性保护校验失败(表示UE选择的是4G安全上下文2)，则再使用另一套安全上下文(即4G安全上下文1)对接收的完整性保护处理后的RRC安全模式命令进行完整性保护校验，直至完整性保护校验成功；所述UE激活最后使用的一套4G安全上下文(即4G安全上下文1)。
需要说明的是，4G安全上下文对RRC的安全影响可参照33.401协议A3中的规定，此处不再详细描述。
S415b：所述UE使用激活的4G安全上下文1对RRC安全模式完成消息(RRC Security mode complete)进行加密和完整性保护处理，并向所述MME发送加密和完整性保护处理后的所述RRC安全模式完成消息。
后续流程可参考通信标准协议，例如协议24.301第5.5章节，本实例不再赘述。
需要说明的是，本实例不对所述UE选择4G安全上下文的顺序的方法进行限制，所述UE在进行安全校验测试时，可以自行决定优先选择哪套4G安全上下文；或者所述UE可以采用随机选择，或者设定优先顺序选择4G安全上下文。示例性的，所述UE可以优先选择NAS count等于NR count的4G安全上下文进行安全验证测试，或者所述UE可以优先选择NAS count等于0的4G安全上下文进行安全验证测试。
实施例三：
下面参阅图5A所示的通信方法流程图，对本申请实施例提供的通信方法进行详细说明。
S501a：UE驻留在第一通信系统时，所述UE与位于第一通信系统中的第一网络设备使用第一套安全上下文进行安全验证。
具体的，所述UE和所述第一网络设备中的NAS层分别维护所述第一套安全上下文，并使用各自维护的所述第一套安全上下文，对传输的消息进行机密性保护和完整性保护，具体过程可以参考以上对图1A和图1B的具体描述，此处不再赘述。
S502a：所述UE处于RRC空闲态，在当前网络环境满足异系统切换条件时，触发UE的异系统切换；UE启动执行异系统切换，从第一通信系统切换到第二通信系统。在进行异系统切换过程中，所述UE成功驻留到第二通信系统。
示例性的，在UE当前网络环境中第一通信系统的信号质量降低，而第二通信系统的信号质量较高时，由于UE处于RRC空闲态，通信系统可以通过重定向机制、盲重定向机制、搜网机制、重选机制等，实现UE的异系统切换。
可选的，所述UE可以在确定满足异系统切换条件时，触发从所述第一通信系统切换到所述第二通信系统的异系统切换流程；或者所述第一网络设备确定满足系统切换条件时，向所述UE发送通知消息，指示所述UE执行从所述第一通信系统切换到所述第二通信系统的异系统切换流程。以上具体过程可以参考目前的通信协议，此处不再详细赘述。
S503a：所述UE触发TAU流程或附着流程，向第二通信系统中的第二核心网设备发送跟踪区域更新请求消息(tracking area update request)或附着请求消息(attach request)。所述第二核心网设备接收来自所述UE的所述跟踪区域更新请求消息或附着请求消息。
可选的，所述跟踪区域更新请求或附着请求消息中可以携带状态指示信息(UE status)，所述状态指示信息还可以指示所述UE从5G通信系统切换到4G通信系统。
S504a：所述第二核心网设备确定所述UE处于RRC空闲态时，在本地激活新的一套安全上下文。
可选的，所述第二核心网设备可以通过多种方式确定所述UE处于RRC空闲态。另外，所述第二核心网设备还可以根据所述跟踪区域更新请求或附着请求消息中携带的状态指示信息(UE status)，确定所述UE从第一通信系统切换到第二通信系统。
另外，所述第二核心网设备在S504a之后，还可以将所述激活的新的一套安全上下文通知给所述第二通信系统中的第二接入网设备，以使所述第二接入网设备也可以使用该新的一套安全上下文与所述UE进行安全验证。
S505a：所述第二核心网设备向所述UE发送鉴权请求消息，所述UE接收来自所述核心设备的鉴权请求消息。
S506a：所述UE根据所述鉴权请求消息激活新的一套安全上下文。
由于UE和第二网络设备(包含第二核心网设备和第二接入网设备)均激活新的一套安全上下文，因此，二者维护的安全上下文一致(二者维护的安全上下文中的包含的NAS count均为初始值(例如0)，保持一致)。因此，后续所述UE和所述第二网络设备可以使用该新的一套安全上下文进行安全验证，且能够保证安全验证成功。
S507a：所述UE与所述第二网络设备使用新的一套安全上下文进行安全验证。
通过S507a，所述UE与所述第二网络设备可以安全对接成功，从而保证所述UE可以成功切换到所述第二通信系统。
综上所述，本申请实施例提供了一种通信方法，在该方法中，UE在从第一通信系统切换到第二通信系统的过程中，可以通过触发TAU流程或附着流程，使所述UE和第二通 信系统中的核心网设备在该TAU流程或附着流程中激活新的一套安全上下文。由于二者激活的新的一套安全上下文一致，因此，后续二者使用该新的一套安全上下文进行安全验证，可以实现安全验证成功，从而保证所述UE可以成功切换到所述第二通信系统。
基于图5A所示的实施例，本申请还提供了一种通信实例，下面参阅图5B所示的通信实例的流程图，对该实例进行详细说明。本实例以所述UE从5G通信系统切换到4G通信系统为例进行说明。并且为了便于说明，本实例将5G通信系统对应的安全上下文简称为5G安全上下文，将4G通信系统对应的安全上下文简称为4G安全上下文。
S501b：UE驻留在5G通信系统，且UE处于RRC空闲态，此时当前网络环境满足触发5G通信系统到4G通信系统的异系统切换条件(例如5G通信系统的信号质量降低，而4G通信系统的信号质量较高)时，触发UE的异系统切换。
S502b：所述UE成功驻留到4G通信系统后，所述UE向4G通信系统中的MME发送跟踪区域更新请求消息(Tracking area update request)以实现在4G通信系统的注册。
可选的，此时UE可以使用5G安全上下文对所述跟踪区域更新请求消息进行完整性保护处理。
S503b：所述MME在接收到所述UE发送的跟踪区域更新请求消息之后，强制触发鉴权流程，激活新的一套4G安全上下文。
另外，所述MME还可以将所述新的一套4G安全上下文发送给所述eNB，以使所述eNB可以使用该新的一套4G安全上下文与所述UE进行安全验证。
S504b：所述MME向所述UE发送鉴权请求消息(Authentication Request)。
S505b：在所述UE未通过安全上下文映射算法计算获取4G安全上下文的情况下，或所述UE在获取4G安全上下文，但该4G安全上下文未激活的情况下，所述UE根据接收的鉴权请求消息激活新的一套4G安全上下文。
这样，所述UE和所述MME可以基于各自维护的新的4G安全上下文进行安全验证。
S506b：所述UE鉴权成功，向所述MME发送鉴权响应消息(Authentication response)。
后续流程可以参考通信标准协议，例如协议24301第5.5章节，本实例不再赘述。
另外还需要说明的是，本实施仅为MME发起强制鉴权流程的一个示例，并不对其构成限定。例如，所述MME还可以通过附着请求消息，触发所述MME发起强制鉴权流程，具体过程可以参考以上步骤，本实例对此不再详细赘述。
实施例四：
下面参阅图6A所示的通信方法流程图，对本实施例提供的通信方法进行详细说明。
S601a：UE驻留在第一通信系统时，所述UE与位于第一通信系统中的第一网络设备使用第一套安全上下文进行安全验证。
具体的，所述UE和所述第一网络设备中的NAS层分别维护所述第一套安全上下文，并使用各自维护的所述第一套安全上下文，对传输的消息进行机密性保护和完整性保护，具体过程可以参考以上对图1A和图1B的具体描述，此处不再赘述。
S602a：UE处于RRC连接态，在当前网络环境满足异系统切换条件时，触发UE的异系统切换；UE启动执行异系统切换，从第一通信系统切换到第二通信系统。在进行异系统切换过程中，所述UE成功驻留到第二通信系统。所述UE获取第二套安全上下文，以 便与位于第二通信系统中的第二网络设备进行安全验证。
示例性的，在当前网络环境满足协议38.331描述的异系统切换事件时，通信系统可以通过切换机制，实现UE的异系统切换。
可选的，所述UE可以在确定满足异系统切换条件时，触发从所述第一通信系统切换到所述第二通信系统的异系统切换流程；或者所述第一网络设备确定满足系统切换条件时，向所述UE发送通知消息，指示所述UE执行从所述第一通信系统切换到所述第二通信系统的异系统切换流程。以上具体过程可以参考目前的通信协议，此处不再详细赘述。
其中，所述UE中获取所述第二套安全上下文是，可以跟本地保存的某个版本的安全上下文映射算法，对自身维护的第一套安全上下文进行计算，生成所述第二套安全上下文。
S603a：位于第二通信系统中的第二核心网设备获取多套备选安全上下文，以便在所述多套备选安全上下文中选择一套安全上下文与UE进行安全验证。
可选的，所述第二核心网设备可以但不限于通过以下两种方式获取所述多套备选安全上下文：
方式一：所述第二核心网设备接收来自第一核心网设备的所述多套备选安全上下文。其中，所述多套备选安全上下文为所述第一核心网设备根据多个版本的安全上下文映射算法对其维护的第一套安全上下文进行计算生成的，所述第一核心网设备位于所述第一通信系统中，且包含在第一网络设备中。
方式二：所述第二核心网设备接收来自第一核心网设备的第一套安全上下文；所述第二核心网设备根据多个版本的安全上下文映射算法对所述第一套安全上下文进行计算，生成所述多套备选安全上下文。
S604a：所述第二核心网设备在所述多套备选安全上下文中确定通过安全验证测试的第三套安全上下文。
由于所述第一核心网设备或所述第二核心网设备本地保存多个版本的安全上下文映射算法，其中可以包含UE本地保存的设定安全上下文映射算法，即第二核心网设备获取的多套备选安全上下文中存在至少一套备选安全上下文与所述UE维护的第二套安全上下文一致。因此，所述第二核心网设备可以通过S604a，在所述多套备选安全上下文中选择出与所述UE维护的第二套安全上下文一致的第三套安全上下文。
与实施例二中的S403a类似的，所述第二核心网设备可以也通过以下步骤执行S604a：
所述第二核心网设备在所述多套备选安全上下文中选择一套待测试安全上下文，其中，所述待测试安全上下文为所述多套备选安全上下文中的任一套备选安全上下文；
若所述第二核心网设备使用选择的该待测试安全上下文与所述UE进行安全验证测试，若确定安全验证测试通过，则确定该待测试安全上下文为所述第三套安全上下文；否则继续在所述多套备选安全上下文选择下一套待测试安全上下文，直至确定选择的待测试安全上下文通过安全验证测试；最后，所述第二核心网设备确定通过安全验证测试的待测试安全上下文为所述第三套安全上下文。
可选的，所述多套备选安全上下文的选择顺序可以为预设的，或者随机的，本申请对此不作限定。
具体的，所述第二核心网设备可以在以下情况下，确定选择的待测试安全上下文通过安全验证测试：
情况一：所述第二核心网设备使用所述待测试安全上下文，对来自所述UE的加密处 理后的上行消息进行解密处理，且解密成功得到所述上行消息。
情况二：所述第二核心网设备使用所述待测试安全上下文，对来自所述UE的完整性保护处理后的上行消息进行完整性保护校验，且完整性保护校验成功，得到所述上行消息。
情况三：所述第二核心网设备使用所述待测试安全上下文，对来自所述UE的加密和完整性保护处理后的上行消息进行解密处理和完整性保护校验，且解密和完整性保护校验成功，得到所述上行消息。
示例性的，以上情况中涉及的上行消息可以但不限于为以下任一项：跟踪区域更新请求消息(tracking area update request)、附着请求消息(attach request)。
S605a：所述第二核心网设备可以激活所述第三套安全上下文，以便后续可以使用所述第二套安全上下文与所述UE进行安全验证。
可选的，所述第二核心网设备在激活所述第三套安全上下文之后，还可以向所述第二通信系统中的第二接入网设备发送所述第三套安全上下文，这样，所述第二接入网设备还可以根据接收的所述第三套安全上下文与所述UE进行安全验证。
S606a：第二通信系统中的第二网络设备(包含所述第二核心网设备和第二接入网设备)使用所述第三套安全上下文与所述UE进行安全验证。
由于所述UE使用的所述第二套安全上下文与所述第二网络设备使用的第三套安全上下文一致，因此，所述UE可以与所述第二网络设备可以安全对接成功，从而保证所述UE可以成功切换到所述第二通信系统。
综上所述，本申请实施例提供了一种通信方法，在该方法中，在UE从第一通信系统切换到第二通信系统的过程中，位于第二通信系统中的核心网设备可以获取多套备选安全上下文；并在多套备选安全上下文中确定通过安全验证测试的一套安全上下文；位于第二通信系统中的核心网设备激活该套安全上下文，用于后续与UE进行安全验证。由于第二通信系统中的核心网设备激活的该套安全上下文是通过安全验证测试的，即该套安全上下文与UE维护的安全上下文一致，因此，第二通信系统中的核心网设备可以使用该套安全上下文与UE进行安全验证，可以实现安全验证成功，从而保证所述UE可以成功切换到所述第二通信系统。
基于图6A所示的实施例中，本申请还提供了一种通信实例，下面参阅图6B所示的通信实例的流程图，对该实例进行详细说明。本实例以所述UE从5G通信系统切换到4G通信系统为例进行说明。并且为了便于说明，本实例将5G通信系统对应的安全上下文简称为5G安全上下文，将4G通信系统对应的安全上下文简称为4G安全上下文。
S601b：UE驻留在5G通信系统，且UE处于RRC连接态，此时当前网络环境满足协议38.331描述的5G到4G异系统的事件，触发UE从5G通信系统到4G通信系统的异系统切换。
S602b：所述UE使用某个版本的安全上下文映射算法，对所述UE维护的5G安全上下文进行计算，得到4G安全上下文1。
其中，所述UE使用的安全上下文映射算法可以为在先版本的33501_CR0611r1协议，或者为刷新版本的33501_CR0611r1协议。
S603b：5G通信系统中的AMF使用两个版本的安全上下文映射算法，对自身维护的5G安全上下文进行计算，得到4G安全上下文1和4G安全上下文2。
其中，所述AMF使用两个版本的安全上下文映射算法包含：为在先版本的33501_CR0611r1协议，和刷新版本的33501_CR0611r1协议。
通过以上描述可知，所述UE得到的4G安全上下文1与所述AMF计算得到的两套4G安全上下文中的一套(4G安全上下文1)相同。
S604b：所述AMF通过N26接口，生成的两套安全上下文发送给4G通信系统中的MME。
需要说明的是，本实例对所述AMF向所述MME发送两套安全上下文的消息的不作限定。该消息可以为现有的消息，例如前向重定位请求消息(Forward relocation request)，也可以为新定义的消息。
S605b：所述UE使用4G安全上下文1对跟踪区域更新请求消息(Tracking area update request)进行完整性保护处理后，将完整性保护处理后的跟踪区域更新请求发送给所述MME，以实现在4G通信系统的注册。
S606b：此时MME有两套4G安全上下文(4G安全上下文1和4G安全上下文2，其中一套4G安全上下文中的NAS COUNT值是0，另一套4G安全上下文中的NAS COUNT值是NR COUNT)。MME可以在两套4G安全上下文中使用一套4G安全上下文对接收的完整性保护处理后的跟踪区域更新请求消息进行完整性保护校验，若完整性保护校验成功(表示MME选择的是4G安全上下文1)，则激活本次使用的一套4G安全上下文；若完整性保护校验失败(表示MME选择的是4G安全上下文2)，则再使用另一套安全上下文(即4G安全上下文1)对接收的完整性保护处理后的跟踪区域更新请求消息进行完整性保护校验，直至完整性保护校验成功；所述MME激活最后使用的一套4G安全上下文(即4G安全上下文1)。
可选的，所述MME在激活所述4G安全上下文1之后，还可以将所述4G安全上下文1发送给4G通信系统中的eNB。
后续流程可参考通信标准协议，例如协议24.301，本实例不再赘述。
需要说明的是，本实例不对所述MME选择4G安全上下文的顺序的方法进行限制，所述MME在进行安全校验测试时，可以自行决定优先选择哪套4G安全上下文；或者所述MME可以采用随机选择，或者设定优先顺序选择4G安全上下文。示例性的，所述MME可以优先选择NAS count等于NR count的4G安全上下文进行安全验证测试，或者所述MME可以优先选择NAS count等于0的4G安全上下文进行安全验证测试。
实施例五：
下面参阅图7A所示的通信方法流程图，对本申请实施例提供的通信方法进行详细说明。
S701a：UE驻留在第一通信系统时，所述UE与位于第一通信系统中的第一网络设备使用第一套安全上下文进行安全验证。
具体的，所述UE和所述第一网络设备中的NAS层分别维护所述第一套安全上下文，并使用各自维护的所述第一套安全上下文，对传输的消息进行机密性保护和完整性保护，具体过程可以参考以上对图1A和图1B的具体描述，此处不再赘述。
S702a：UE处于RRC连接态，在当前网络环境满足异系统切换条件时，触发UE的异系统切换；UE启动执行异系统切换，从第一通信系统切换到第二通信系统。在进行异系 统切换过程中，所述UE成功驻留到第二通信系统。所述UE获取多套备选安全上下文，以便在多套备选安全上下文中选择一套安全上下文与位于第二通信系统中的第二网络设备进行安全验证。
示例性的，在当前网络环境满足协议38.331描述的异系统切换事件时，通信系统可以通过切换机制，实现UE的异系统切换。
可选的，所述UE可以在确定满足异系统切换条件时，触发从所述第一通信系统切换到所述第二通信系统的异系统切换流程；或者所述第一网络设备确定满足系统切换条件时，向所述UE发送通知消息，指示所述UE执行从所述第一通信系统切换到所述第二通信系统的异系统切换流程。以上具体过程可以参考目前的通信协议，此处不再详细赘述。
可选的，所述UE在获取所述多套备选安全上下文时，可以根据本地保存的多个版本的安全上下文映射算法，对自身维护的所述第一套安全上下文进行计算，生成所述多套备选安全上下文。
在S703a之前，所述第二通信系统中的第二网络设备需要获取第三套安全上下文，用于与所述UE进行安全验证。可选的，所述第二网络设备也可以通过实施例一中记载的两种方式，获取用于与所述UE进行安全验证的第三套安全上下文，具体过程可以参考实施例一种的描述，此次不再赘述。
需要说明的是，由于所述UE本地保存多个版本的安全上下文映射算法，其中可以包含第一网络设备/第二网络设备本地保存的设定安全上下文映射算法，即UE生成的多套备选安全上下文中存在至少一套备选安全上下文与所述第二网络设备维护的第三套安全上下文一致。因此，所述UE可以通过后续步骤，在所述多套备选安全上下文中选择出与所述第二网络设备维护的第三套安全上下文一致的第二套安全上下文，从而激活该第二套安全上下文。
S703a：所述UE在多套备选安全上下文中选择一套备选安全上下文对上行消息进行完整性保护处理，并将完整性保护处理后的上行消息发送给所述第二网络设备；若未接收到来自所述第二网络设备的所述上行消息的响应消息，则所述UE重新执行S703a，直至通过S704a接收到来自所述第二网络设备的所述上行消息的响应消息。
其中，在本步骤中，所述多套备选安全上下文的选择顺序可以为预设的，或者随机的，本申请对此不作限定。
示例性的，所述上行消息可以但不限于为以下任一项：跟踪区域更新请求消息(tracking area update request)、附着请求消息(attach request)；所述响应消息可以但不限于为以下任一项：跟踪区域更新接受消息(tracking area update accept)、附着接受消息(attach accept)、安全模式命令(security mode command)、RRC安全模式命令(RRC security mode command)。
需要说明的是，所述第二网络设备接收到该完整性保护处理后的上行消息后，会使用本地维护的第三套安全上下文对该完整性保护处理后的上行消息进行完整性保护校验，若完整性保护校验失败，则丢弃接收的该完整性保护处理后的上行消息；若完整性保护校验成功，则向所述UE反馈所述上行消息的响应消息。
在一些情况下，虽然第二网络设备维护的第三套安全上下文与所述UE选择的备选安全上下文不同，但是所述第二网络设备依然使用第三套安全上下文实现完整性保护校验成功。
例如，UE使用的备选安全上下文中NAS count等于NR count，并且NR count值小于 255；所述第二网络设备使用的第三套安全上下文中NAS count取值为0，此时所述第二网络设备可能使用第三套安全上下文实现完整性保护成功。因为根据24.301协议，UE将本地存储的上行NAS count值的低八位通过跟踪区域更新请求消息(Tracking area update request)发送给所述第二网络设备，而所述第二网络设备在接收到的上行NAS count值比本地存储的第三套安全上下文中上行NAS count值大，按照24301协议，所述第二网络设备会将第三套安全上下文中的上行NAS count值更新为接收到的NAS count值。因此，在所述第二网络设备中的三套安全上下文、UE使用的备选安全上下文中的包含的上行NAS count值可能会因此上述流程导致相同，但是二者包含的下行NAS count值可能不同。
通过以上描述可知，在某些场景中，可能会出现虽然所述UE的上行消息安全验证成功，但是所述UE的下行消息会安全验证失败，这也会最终导致所述UE无法成功切换到所述第二通信系统。
因此，为了保证所述UE的上行消息和下行消息均能够安全验证成功。在S704a之后，所述UE暂时不激活最后一次对上行消息进行完整性保护处理所使用的备选安全上下文，而是继续通过对下行消息进行安全验证，确定最终需要激活的备选安全上下文。
在第一种实施方式中，所述上行消息的响应消息为所述第二网络设备使用第三套安全上下文进行完整性保护处理后的，因此所述UE还可以通过以下步骤S705a，确定需要激活的备选安全上下文。
在第二种实施方式中，所述上行消息的响应消息为所述第二网络设备使用第三套安全上下文进行加密和完整性保护处理后的，因此所述UE还可以通过以下步骤S706a，确定需要激活的备选安全上下文。
S705a：所述UE使用所述多套备选安全上下文中的一套备选安全上下文对接收的完整性保护处理后的响应消息进行完整性保护校验；若完整性保护校验成功，则直接激活本次使用的备选安全上下文；若完整性保护校验失败，再使用下一套备选安全上下文对接收的完整性保护处理后的响应消息进行完整性保护校验，直至完整性保护校验成功；激活最后使用的一套备选安全上下文。
S706a：所述UE使用所述多套备选安全上下文中的一套备选安全上下文对接收的加密和完整性保护处理后的响应消息进行解密和完整性保护校验；若解密和完整性保护校验成功，则直接激活本次使用的备选安全上下文；若解密或完整性保护校验失败，再使用下一套备选安全上下文对接收的加密和完整性保护处理后的响应消息进行解密和完整性保护校验，直至解密和完整性保护校验成功；激活最后使用的一套备选安全上下文。
其中，在S705a或S706a中，所述多套备选安全上下文的选择顺序可以为预设的，或者随机的，本申请对此不作限定。可选的，所述UE可以优先选择在最后一次执行S703时使用的备选安全上下文。
通过S705a或S705b，所述UE可以在多个备选安全上下文中选择出与所述第二网络设备使用的第三套安全上下文一致的备选安全上下文(以下称为第二套安全上下文)，并激活该备选安全上下文。
S707a：所述UE使用激活的第二套安全上下文与所述第二网络设备进行安全验证。
由于所述UE使用的所述第二套安全上下文与所述第二网络设备使用的第三套安全上下文一致，因此，所述UE可以与所述第二网络设备可以安全对接成功，从而保证所述UE可以成功切换到所述第二通信系统。
综上所述，本申请实施例提供了一种通信方法，在该方法中，UE在从第一通信系统切换到第二通信系统的过程中，可以获取多套备选安全上下文；并在多套备选安全上下文中确定通过安全校验的一套安全上下文；所述UE激活该套安全上下文，用于后续与第二通信系统的网络设备进行安全验证。由于UE激活的该套安全上下文是通过安全校验的，即该套安全上下文与第二通信系统中的网络设备维护的安全上下文一致，因此，所述UE使用该套安全上下文与第二通信系统的网络设备进行安全验证，可以实现安全验证成功，从而保证所述UE可以成功切换到所述第二通信系统。
基于图7A所示的实施例，本申请还提供了一种通信实例，下面参阅图7B所示的通信实例的流程图，对该实例进行详细说明。本实例以所述UE从5G通信系统切换到4G通信系统为例进行说明。并且为了便于说明，本实例将5G通信系统对应的安全上下文简称为5G安全上下文，将4G通信系统对应的安全上下文简称为4G安全上下文。
S701b：UE驻留在5G通信系统，且UE处于RRC连接态，此时当前网络环境满足协议38.331描述的5G到4G异系统的事件，触发UE从5G通信系统到4G通信系统的异系统切换。
S702b：所述UE成功驻留到4G通信系统后，所述UE使用两个版本的安全上下文映射算法，对所述UE维护的5G安全上下文进行计算，得到4G安全上下文1和4G安全上下文2。
其中，所述UE使用两个版本的安全上下文映射算法包含：为在先版本的33501_CR0611r1协议，和刷新版本的33501_CR0611r1协议。
S703b：5G通信系统中的AMF使用保存的一个版本的安全上下文映射算法对所述AMF维护的5G安全上下文进行计算，得到4G安全上下文1。
其中，所述AMF使用的安全上下文映射算法可以为在先版本的33501_CR0611r1协议，或者为刷新版本的33501_CR0611r1协议。
通过以上描述可知，所述AMF得到的4G安全上下文1与所述UE得到的两套4G安全上下文中的一套(即4G安全上下文1)相同。
S704b：所述AMF通过N26接口将得到的4G安全上下文1通过前向重定位请求(forward relocation request)发送给4G通信系统中的MME。
S705b：所述UE在得到的两套4G安全上下文中选择一套4G安全上下文对跟踪区域更新请求消息(Tracking area update request)进行完整性保护处理，在向所述MME发送完整性保护处理后的跟踪区域更新请求消息时，按照24.301协议启动T3430定时器。所述MME使用本地保存的4G安全上下文1对接收的完整性保护处理后的跟踪区域更新请求消息进行完整性保护校验。
可选的，本实例不对在步骤S705b中所述UE选择4G安全上下文的顺序的方法进行限制，所述UE可以自行决定优先选择哪套4G安全上下文；或者所述UE可以采用随机选择，或者设定优先顺序选择4G安全上下文。示例性的，所述UE可以优先选择NAS count等于NR count的4G安全上下文，或者所述UE可以优先选择NAS count等于0的4G安全上下文。
在本实例中，所述MME可能会出现两种情况，一种是所述MME使用4G安全上下文1完整性保护校验失败；第二种是所述MME使用4G安全上下文完整性保护校验成功。 其中，在情况1中通信系统可以通过S706b-S708b，使UE重新选择4G安全上下文，以保证所述MME可以使用4G安全上下文完整性保护校验成功。在情况2中，所述MME可以直接使用4G安全上下文完整性保护校验成功。
情况1：所述MME完整性保护校验先失败后成功。
S706b：所述MME使用4G安全上下文1对接收的完整性保护处理后的跟踪区域更新请求消息进行完整性保护校验；在完整性保护校验失败(表示所述UE本次选择的4G安全上下文2)时，所述MME将接收的完整性保护处理后的跟踪区域更新请求消息丢弃。
S707b：在所述T3430定时器超时后，所述UE按照24.301协议启动T3411定时器，并且在T3411定时器超时后，所述UE使用另一套4G安全上下文重新对跟踪区域更新请求消息进行完整性保护处理，并将完整性保护处理后的跟踪区域更新请求消息发送给所述MME。
S708b：所述MME使用4G安全上下文1对重新接收的完整性保护处理后的跟踪区域更新请求消息进行完整性保护校验，且完整性保护校验成功(表示UE本次选择的4G上下文1)。
情况2：所述MME完整性保护校验直接成功。
S709b：所述MME使用4G安全上下文1对接收的完整性保护处理后的跟踪区域更新请求消息进行完整性保护校验；在完整性保护校验成功(表示所述UE本次选择的4G安全上下文1，或者选择的4G安全上下文2(其中4G安全上下文2包含的NAS count为NR count))。
在S708b或S709b之后，所述MME使用4G安全上下文1完整性保护校验成功之后，所述MME需要向所述UE反馈跟踪区域更新接受消息(Tracking area update accept)。
根据所述MME对跟踪区域更新接受消息所执行的安全保护方式的不同，本实例分为两种场景分别进行描述。还需要说明的是，所述MME还可以在S708b或S709b中使用4G安全上下文1完整性保护校验成功之后，向所述UE反馈安全模式命令(security mode command)，或者触发eNB向所述UE发送RRC安全模式命令(RRC security mode command)。具体过程可以参考跟踪区域更新接受消息的处理过程，此处不再赘述。
场景1：MME对跟踪区域更新接受消息进行完整性保护处理。
S710b：所述MME使用4G安全上下文1对跟踪区域更新接受消息进行完整性保护处理，并将完整性保护处理后的跟踪区域更新接受消息发送给所述UE。
S711b：所述UE可以在两套4G安全上下文中使用一套4G安全上下文对接收的完整性保护处理后的跟踪区域更新接受消息进行完整性保护校验，若完整性保护校验成功(表示UE选择的是4G安全上下文1)，则激活本次使用的一套4G安全上下文；若完整性保护校验失败(表示MME选择的是4G安全上下文2)，则再使用另一套安全上下文(即4G安全上下文1)对接收的完整性保护处理后的跟踪区域更新接受消息进行完整性保护校验，直至完整性保护校验成功；所述UE激活最后使用的一套4G安全上下文(即4G安全上下文1)。
场景2：MME对跟踪区域更新接受消息进加密和完整性保护处理。
S712b：所述MME使用4G安全上下文1对跟踪区域更新接受消息进行加密和完整性保护处理，并将加密和完整性保护处理后的跟踪区域更新接受消息发送给所述UE。
S713b：所述UE可以在两套4G安全上下文中使用一套4G安全上下文对接收的加密 和完整性保护处理后的跟踪区域更新接受消息进行解密和完整性保护校验，若解密和完整性保护校验成功(表示UE选择的是4G安全上下文1)，则激活本次使用的一套4G安全上下文；若解密或完整性保护校验失败(表示MME选择的是4G安全上下文2)，则再使用另一套安全上下文(即4G安全上下文1)对接收的加密和完整性保护处理后的跟踪区域更新接受消息进行解密和完整性保护校验，直至解密和完整性保护校验成功；所述UE激活最后使用的一套4G安全上下文(即4G安全上下文1)。
S714：所述UE使用激活的4G安全上下文1对跟踪区域更新完整消息(Tracking area update complete)进行加密和完整性保护处理。后续所述UE和所述MME可以使用各自维护的4G安全上下文1进行安全验证。
还需要说明的是，本实例不对所述UE在步骤S711b或S713b中选择4G安全上下文的顺序的方法进行限制，所述UE可以自行决定优先选择哪套4G安全上下文；或者所述UE可以采用随机选择，或者设定优先顺序选择4G安全上下文。示例性的，所述UE可以优先选择NAS count等于NR count的4G安全上下文，或者所述UE可以优先选择NAS count等于0的4G安全上下文。再例如，所述UE优先选择最后一次对跟踪区域更新请求消息进行完整性保护处理时使用的4G安全上下文。
还需要说明的是，在以上实施例或实例的描述和对应的附图不对步骤之间的前后顺序进行限定，在以上实施例或实例的基础上进行步骤先后顺序的调整，或者增加额外的步骤，或减少一些步骤也属于本申请实施例提供的通信方法。以图3B所示的实例为例，S302b-S304b可以在S305b、S309b或S315b之后执行，或者S302b-S304b可以在S312b之前执行。
基于相同的技术构思，本申请还提供了一种通信装置，该装置的结构如图8所示，包括通信单元801和处理单元802。所述通信装置800可以应用于图2所示的通信系统中的核心网设备，或UE，并可以实现以上实施例以及实例提供的通信方法。可选的，所述通信装置800的物理表现形式可以为一种通信设备，例如核心设备或UE；或者所述通信装置可以能够实现通信设备的功能的其他装置，例如通信设备内部的处理器或芯片等，具体的，该通信装置800可以为现场可编程门阵列(field-programmable gate array，FPGA)、复杂可编程逻辑器件(complex programmable logic device，CPLD)、专用集成电路(application specific intergrated circuits，ASIC)，或片上系统(System on a chip，SOC)等一些可编程的芯片。
下面对所述装置800中的各个单元的功能进行介绍。
所述通信单元801，用于接收和发送数据。
当所述通信装置800应用于核心网设备时，所述通信单元801可以通过物理接口、通信模块、通信接口、输入输出接口实现。所述通信装置800可以通过该通信单.801元连接网线或电缆，进而与其他设备建立物理连接。
当所述通信装置800应用于UE时，所述通信单元801可以通过收发器实现，例如，移动通信模块。
移动通信模块可以提供应用在所述UE上的包括2G/3G/4G/5G等无线通信的解决方案。移动通信模块可以包括至少一个天线、至少一个滤波器，开关，功率放大器，低噪声放大器(low noise amplifier，LNA)等。所述UE可以通过所述移动通信模块接入通信系统中的 AN设备，并与该AN设备进行交互，从而实现UE与通信系统的交互。
在一种实施方式中，所述通信装置800应用于图3A或图3B所示的实施例的UE。下面对该实施方式中的所述处理单元802的具体功能进行介绍。
处理单元802，用于：
在终端设备从第一通信系统切换到第二通信系统的过程中，获取第一套安全上下文；其中，所述第一套安全上下文用于所述处理单元802与第一网络设备进行安全验证，所述第一网络设备位于所述第二通信系统中；
当所述处理单元802使用所述第一套安全上下文与所述第一网络设备安全验证失败时，通过所述通信单元801向所述第一网络设备发起注册流程。
在一种可能的设计中，所述处理单元802，具体用于：
当所述处理单元802使用所述第一套安全上下文与所述第一网络设备安全验证失败的次数大于或等于设定阈值时，通过所述通信单元801向所述第一网络设备发起注册流程。
在一种可能的设计中，所述处理单元802使用所述第一套安全上下文与所述第一网络设备安全验证失败，包括：
所述处理单元802使用所述第一套安全上下文，对来自所述第一网络设备的加密处理后的下行消息进行解密处理，且解密失败；或者所述处理单元802使用所述第一套安全上下文，对来自所述第一网络设备的完整性保护处理后的下行消息进行完整性保护校验，且完整性保护校验失败；或者所述处理单元802使用所述第一套安全上下文，对来自所述第一网络设备的加密和完整性保护处理后的下行消息进行解密处理和完整性保护校验，且解密失败或完整性保护校验失败；或者所述处理单元802使用所述第一套安全上下文，对上行消息进行完整性保护处理，并向所述第一网络设备发送完整性保护处理后的上行消息，且所述终端设备未接收来自所述第一网络设备的所述上行消息的响应消息。
在一种可能的设计中，所述下行消息为以下任一项：安全模式命令、跟踪区域更新接受消息、无线资源控制RRC安全模式命令、附着接受消息；
所述上行消息为以下任一项：跟踪区域更新请求消息、附着请求消息。
在一种可能的设计中，所述第一网络设备包括：位于所述第二通信系统中的核心网设备或接入网设备。
在一种可能的设计中，所述处理单元802，在通过所述通信单元801向所述第二通信系统中的第一网络设备发起注册流程时，具体用于：
向所述第一网络设备发送附着请求消息或注册请求消息，所述附着请求消息或注册请求消息中包含所述终端设备的国际移动用户识别码IMSI。
在一种可能的设计中，所述第一套安全上下文中包含非接入层计数值NAS count。
在一种可能的设计中，所述处理单元802，在获取所述第一套安全上下文时，具体用于：
根据设定安全上下文映射算法，对第二套安全上下文进行计算，生成所述第一套安全上下文；其中，所述第二套安全上下文用于所述处理单元802与第二网络设备进行安全验证，所述第二网络设备位于所述第一通信系统中。
在一种可能的设计中，所述第一通信系统为第五代5G通信系统，所述第二通信系统为第四代4G通信系统。
在另一种实施方式中，所述通信装置800应用于图4A或图4B所示的实施例的UE。下面对该实施方式中的所述处理单元802的具体功能进行介绍。
所述处理单元802，用于：
在终端设备从第一通信系统切换到第二通信系统的过程中，获取多套备选安全上下文；
在所述多套备选安全上下文中确定通过安全验证测试的第一套安全上下文；
激活所述第一套安全上下文，并使用所述第一套安全上下文与第一网络设备进行安全验证，所述第一网络设备位于所述第二通信系统中。
在一种可能的设计中，所述处理单元802，在所述多套备选安全上下文中选择通过安全验证测试的第一套安全上下文时，具体用于：
在所述多套备选安全上下文中选择一套待测试安全上下文，其中，所述待测试安全上下文为所述多套备选安全上下文中的任一套备选安全上下文；
使用所述待测试安全上下文，对来自所述第一网络设备的加密处理后的下行消息进行解密处理，且解密成功得到所述下行消息；或者使用所述待测试安全上下文，对来自所述第一网络设备的完整性保护处理后的下行消息进行完整性保护校验，且完整性保护校验成功，得到所述下行消息；或者使用所述待测试安全上下文，对来自所述第一网络设备的加密和完整性保护处理后的下行消息进行解密处理和完整性保护校验，且解密和完整性保护校验成功，得到所述下行消息；
确定所述待测试安全上下文为所述第一套安全上下文。
在一种可能的设计中，当所述终端设备处于无线资源控制RRC连接的空闲态时，所述下行消息为以下任一项：安全模式命令、跟踪区域更新接受消息、无线资源控制RRC安全模式命令、附着接受消息。
在一种可能的设计中，所述第一网络设备包括：位于所述第二通信系统中的核心网设备或接入网设备。
在一种可能的设计中，所述第一套安全上下文中包含非接入层计数值NAS count。
在一种可能的设计中，所述处理单元802，在获取多套备选安全上下文时，具体用于：
分别根据多个版本的安全上下文映射算法，对第二套安全上下文进行计算，生成所述多套备选安全上下文；其中，所述第二套安全上下文用于所述终端设备与第二网络设备进行安全验证，所述第二网络设备位于所述第一通信系统中。
在一种可能的设计中，所述第一通信系统为第五代5G通信系统，所述第二通信系统为第四代4G通信系统。
在另一种实施方式中，所述通信装置800应用于图5A或图5B所示的实施例的位于第二通信系统中的核心网设备(例如，图5B所示的实施例中的4G通信系统中的MME)。下面对该实施方式中的所述处理单元802的具体功能进行介绍。
所述处理单元802，用于：
在终端设备从第一通信系统切换到第二通信系统的过程中，通过所述通信单元801接收到来自所述终端设备的跟踪区域更新请求消息或附着请求消息；
确定所述终端设备的RRC连接为空闲态时，激活新的一套安全上下文；其中，所述新的一套安全上下文用于第一网络设备与所述终端设备进行安全验证，所述第一网络设备位于所述第二通信系统中；
通过所述通信单元801向所述终端设备发送鉴权请求消息，以使所述终端设备激活新的一套安全上下文。
在一种可能的设计中，所述处理单元802，还用于：
通过所述通信单元801向所述第二通信系统中的接入网设备发送所述新的一套安全上下文。
在一种可能的设计中，所述新的一套安全上下文中包含非接入层计数值NAS count。
在一种可能的设计中，所述处理单元802，还用于：
根据所述跟踪区域更新请求消息或所述附着请求消息中携带的状态指示信息UE status，确定所述终端设备从所述第一通信系统切换到所述第二通信系统。
在一种可能的设计中，所述第一通信系统为第五代5G通信系统，所述第二通信系统为第四代4G通信系统。
在另一种实施方式中，所述通信装置800应用于图5A或图5B所示的实施例的UE。下面对该实施方式中的所述处理单元802的具体功能进行介绍。
处理单元802，用于：
在所述终端设备从第一通信系统切换到第二通信系统的过程中，通过所述通信单元801向所述第二通信系统中的核心网设备发送跟踪区域更新请求消息或附着请求消息；
通过所述通信单元801接收来自所述核心网设备的鉴权请求消息；
根据所述鉴权请求消息，激活新的一套安全上下文；其中，所述新的一套安全上下文用于所述处理单元802与第一网络设备进行安全验证，所述第一网络设备位于所述第二通信系统中；
使用所述新的一套安全上下文与所述第一网络设备进行安全验证。
在一种可能的设计中，所述处理单元802，在通过所述通信单元801向所述第二通信系统中的核心网设备发送跟踪区域更新请求消息或附着请求消息时，具体用于：
使用第一套安全上下文，对所述跟踪区域更新请求消息或所述附着请求消息进行完整性保护处理；所述第一套安全上下文用于所述终端设备与第二网络设备进行安全验证，所述第二网络设备位于所述第一通信系统中；
通过所述通信单元801向所述核心网设备发送完整性保护处理后的所述跟踪区域更新请求消息或所述附着请求消息。
在一种可能的设计中，所述新的一套安全上下文中包含非接入层计数值NAS count。
在一种可能的设计中，所述跟踪区域更新请求消息或所述附着请求消息中携带有状态指示信息，所述状态指示信息UE status用于指示所述终端设备从第一通信系统切换到第二通信系统。
在一种可能的设计中，所述第一通信系统为第五代5G通信系统，所述第二通信系统为第四代4G通信系统。
在另一种实施方式中，所述通信装置800应用于图6A或图6B所示的实施例的位于第二通信系统中的第一核心网设备(例如，图6B所示的实施例中的4G通信系统中的MME)。下面对该实施方式中的所述处理单元802的具体功能进行介绍。
所述处理单元802，用于：
在终端设备从第一通信系统切换到第二通信系统的过程中，获取多套备选安全上下文；其中，所述第一核心网设备位于所述第二通信系统；
在所述多套备选安全上下文中确定通过安全验证测试的第一套安全上下文；
激活所述第一套安全上下文，并使用所述第一套安全上下文与所述终端设备进行安全验证。
在一种可能的设计中，所述处理单元802，在获取多套备选安全上下文时，具体用于：
接收来自第二核心网设备的所述多套备选安全上下文；其中，所述多套备选安全上下文为所述第二核心网设备根据多个版本的安全上下文映射算法对第二套安全上下文进行计算生成的，所述第二套安全上下文用于所述第二核心网设备与所述终端设备进行安全验证，所述第二核心网设备位于所述第一通信系统中；或者接收来自第二核心网设备的第二套安全上下文；根据多个版本的安全上下文映射算法对所述第二套安全上下文进行计算，生成所述多套备选安全上下文；其中，所述第二套安全上下文用于所述第二核心网设备与所述终端设备进行安全验证，所述第二核心网设备位于所述第一通信系统中。
在一种可能的设计中，所述处理单元802，在所述多套备选安全上下文中确定通过安全验证测试的第一套安全上下文时，具体用于：
在所述多套备选安全上下文中选择一套待测试安全上下文，其中，所述待测试安全上下文为所述多套备选安全上下文中的任一套备选安全上下文；
使用所述待测试安全上下文，对来自所述终端设备的加密处理后的上行消息进行解密处理，且解密成功得到所述上行消息；或者使用所述待测试安全上下文，对来自所述终端设备的完整性保护处理后的上行消息进行完整性保护校验，且完整性保护校验成功，得到所述上行消息；或者使用所述待测试安全上下文，对来自所述终端设备的加密和完整性保护处理后的上行消息进行解密处理和完整性保护校验，且解密和完整性保护校验成功，得到所述上行消息；
确定所述待测试安全上下文为所述第一套安全上下文。
在一种可能的设计中，当所述终端设备处于无线资源控制RRC连接的连接态时，所述上行消息为以下任一项：跟踪区域更新请求消息、附着请求消息。
在一种可能的设计中，所述处理单元802，还用于：
通过所述通信单元801向所述第二通信系统中的接入网设备发送所述第一套安全上下文。
在一种可能的设计中，所述第一套安全上下文中包含非接入层计数值NAS count。
在一种可能的设计中，所述第一通信系统为第五代5G通信系统，所述第二通信系统为第四代4G通信系统。
在另一种实施方式中，所述通信装置800应用于图7A或图7B所示的实施例的UE。下面对该实施方式中的所述处理单元802的具体功能进行介绍。
所述处理单元802，用于：
在终端设备从第一通信系统切换到第二通信系统的过程中，获取多套备选安全上下文；
在所述多套备选安全上下文中选择一套备选安全上下文对上行消息进行完整性保护处理，并将完整性保护处理后的上行消息发送给第一网络设备，所述第一网络设备位于所述第二通信系统中；
在未通过所述通信单元801接收到来自所述第一网络设备的所述上行消息的响应消息时，在所述多套备选安全上下文中选择下一套备选安全上下文对所述上行消息进行完整性保护处理，直至通过所述通信单元801接收到来自所述第一网络设备的所述上行消息的响应消息。
在一种可能的设计中，所述处理单元802，还用于：
在所述响应消息为所述第一网络设备完整性保护处理后的情况下，在通过所述通信单元801接收到来自所述第一网络设备的所述上行消息的响应消息之后，在所述多套备选安全上下文中选择一套备选安全上下文对完整性保护处理后的所述响应消息进行完整性保护校验，若完整性保护校验成功，则激活本次使用的备选安全上下文；否则在所述多套备选安全上下文中选择下一套备选安全上下文对完整性保护处理后的所述响应消息进行完整性保护校验，直至完整性保护校验成功，激活最后使用的备选安全上下文；
在所述响应消息为所述第一网络设备加密和完整性保护处理后的情况下，在通过所述通信单元801接收到来自所述第一网络设备的所述上行消息的响应消息之后，在所述多套备选安全上下文中选择一套备选安全上下文对加密和完整性保护处理后的所述响应消息进行解密处理和完整性保护校验，若解密和完整性保护校验成功，则激活本次使用的备选安全上下文；否则在所述多套备选安全上下文中选择下一套备选安全上下文对加密和完整性保护处理后的所述响应消息进行解密处理和完整性保护校验，直至解密和完整性保护校验成功，激活最后使用的备选安全上下文。
在一种可能的设计中，所述终端设备处于无线资源控制RRC连接的连接态，所述上行消息为以下任一项：跟踪区域更新请求消息、附着请求消息；
所述响应消息为以下任一项：跟踪区域更新接受消息、附着接受消息、安全模式命令、无线资源控制RRC安全模式命令。
在一种可能的设计中，所述处理单元802，在获取多套备选安全上下文时，具体用于：
分别根据多个版本的安全上下文映射算法，对第一套安全上下文进行计算，生成所述多套备选安全上下文；其中，所述第一套安全上下文用于所述终端设备与第二网络设备进行安全验证，所述第二网络设备位于所述第一通信系统中。
在一种可能的设计中，任一套备选安全上下文中包含非接入层计数值NAS count。
在一种可能的设计中，所述第一通信系统为第五代5G通信系统，所述第二通信系统为第四代4G通信系统。
需要说明的是，本申请以上实施例中对模块的划分是示意性的，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，另外，在本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是单独物理存在，也可以两个或两个以上单元集成在一个单元中。上述集成的单元既可以采用硬件的形式实现，也可以采用软件功能单元的形式实现。
所述集成的单元如果以软件功能单元的形式实现并作为独立的产品销售或使用时，可以存储在一个计算机可读取存储介质中。基于这样的理解，本申请的技术方案本质上或者说对现有技术做出贡献的部分或者该技术方案的全部或部分可以以软件产品的形式体现出来，该计算机软件产品存储在一个存储介质中，包括若干指令用以使得一台计算机设备(可以是个人计算机，服务器，或者网络设备等)或处理器(processor)执行本申请各个 实施例所述方法的全部或部分步骤。而前述的存储介质包括：U盘、移动硬盘、只读存储器(Read-Only Memory，ROM)、随机存取存储器(Random Access Memory，RAM)、磁碟或者光盘等各种可以存储程序代码的介质。
基于相同的技术构思，本申请还提供了一种通信设备，所述通信设备可以应用于如图2所示的通信系统中的核心网设备或终端设备，可以实现以上实施例以及实例提供的通信方法，具有图8所示的通信装置的功能。参阅图9所示，所述通信设备900包括：通信模块901、处理器902以及存储器903。其中，所述通信模块901、所述处理器902以及所述存储器903之间相互连接。
可选的，所述通信模块901、所述处理器902以及所述存储器903之间通过总线904相互连接。所述总线904可以是外设部件互连标准(peripheral component interconnect，PCI)总线或扩展工业标准结构(extended industry standard architecture，EISA)总线等。所述总线可以分为地址总线、数据总线、控制总线等。为便于表示，图9中仅用一条粗线表示，但并不表示仅有一根总线或一种类型的总线。
所述通信模块901，用于接收和发送数据，实现与其他设备之间的通信交互。例如，当所述通信设备900应用于核心网设备时，所述通信模块901可以通过物理接口、通信模块、通信接口、输入输出接口实现。又例如，当所述通信设备900应用于终端设备时，所述通信模块901还可以通过收发器实现。
在一种实施方式中，所述通信设备900应用于图3A或图3B所示的实施例的UE。下面对该实施方式中的所述处理器902的具体功能进行介绍。
处理器902，用于：
在终端设备从第一通信系统切换到第二通信系统的过程中，获取第一套安全上下文；其中，所述第一套安全上下文用于所述处理器902与第一网络设备进行安全验证，所述第一网络设备位于所述第二通信系统中；
当所述处理器902使用所述第一套安全上下文与所述第一网络设备安全验证失败时，通过所述通信模块901向所述第一网络设备发起注册流程。
在另一种实施方式中，所述通信设备900应用于图4A或图4B所示的实施例的UE。下面对该实施方式中的所述处理器902的具体功能进行介绍。
所述处理器902，用于：
在终端设备从第一通信系统切换到第二通信系统的过程中，获取多套备选安全上下文；
在所述多套备选安全上下文中确定通过安全验证测试的第一套安全上下文；
激活所述第一套安全上下文，并使用所述第一套安全上下文与第一网络设备进行安全验证，所述第一网络设备位于所述第二通信系统中。
在另一种实施方式中，所述通信设备900应用于图5A或图5B所示的实施例的位于第二通信系统中的核心网设备(例如，图5B所示的实施例中的4G通信系统中的MME)。下面对该实施方式中的所述处理器902的具体功能进行介绍。
所述处理器902，用于：
在终端设备从第一通信系统切换到第二通信系统的过程中，通过所述通信模块901接 收到来自所述终端设备的跟踪区域更新请求消息或附着请求消息；
确定所述终端设备的RRC连接为空闲态时，激活新的一套安全上下文；其中，所述新的一套安全上下文用于第一网络设备与所述终端设备进行安全验证，所述第一网络设备位于所述第二通信系统中；
通过所述通信模块901向所述终端设备发送鉴权请求消息，以使所述终端设备激活新的一套安全上下文。
在另一种实施方式中，所述通信设备900应用于图5A或图5B所示的实施例的UE。下面对该实施方式中的所述处理器902的具体功能进行介绍。
处理器902，用于：
在所述终端设备从第一通信系统切换到第二通信系统的过程中，通过所述通信模块901向所述第二通信系统中的核心网设备发送跟踪区域更新请求消息或附着请求消息；
通过所述通信模块901接收来自所述核心网设备的鉴权请求消息；
根据所述鉴权请求消息，激活新的一套安全上下文；其中，所述新的一套安全上下文用于所述处理单元802与第一网络设备进行安全验证，所述第一网络设备位于所述第二通信系统中；
使用所述新的一套安全上下文与所述第一网络设备进行安全验证。
在另一种实施方式中，所述通信设备900应用于图6A或图6B所示的实施例的位于第二通信系统中的第一核心网设备(例如，图6B所示的实施例中的4G通信系统中的MME)。下面对该实施方式中的所述处理器902的具体功能进行介绍。
所述处理器902，用于：
在终端设备从第一通信系统切换到第二通信系统的过程中，获取多套备选安全上下文；其中，所述第一核心网设备位于所述第二通信系统；
在所述多套备选安全上下文中确定通过安全验证测试的第一套安全上下文；
激活所述第一套安全上下文，并使用所述第一套安全上下文与所述终端设备进行安全验证。
在另一种实施方式中，所述通信设备900应用于图7A或图7B所示的实施例的UE。下面对该实施方式中的所述处理器902的具体功能进行介绍。
所述处理器902，用于：
在终端设备从第一通信系统切换到第二通信系统的过程中，获取多套备选安全上下文；
在所述多套备选安全上下文中选择一套备选安全上下文对上行消息进行完整性保护处理，并将完整性保护处理后的上行消息发送给第一网络设备，所述第一网络设备位于所述第二通信系统中；
在未通过所述通信模块901接收到来自所述第一网络设备的所述上行消息的响应消息时，在所述多套备选安全上下文中选择下一套备选安全上下文对所述上行消息进行完整性保护处理，直至通过所述通信模块901接收到来自所述第一网络设备的所述上行消息的响应消息。
需要说明的是，本实施例不对所述处理器902的具体功能进行详细描述，所述处理器 902的具体功能可以参考以上实施例以及实例提供的通信方法中的描述，以及图8所示实施例中对所述通信装置800的具体功能描述，此处不再赘述。
所述存储器903，用于存放程序指令和数据等。具体地，程序指令可以包括程序代码，该程序代码包括计算机操作指令。存储器903可能包含随机存取存储器(random access memory，RAM)，也可能还包括非易失性存储器(non-volatile memory)，例如至少一个磁盘存储器。处理器902执行存储器903所存放的程序指令，并使用所述存储器903中存储的数据，实现上述功能，从而实现上述实施例提供的通信方法。
可以理解，本申请图9中的存储器903可以是易失性存储器或非易失性存储器，或可包括易失性和非易失性存储器两者。其中，非易失性存储器可以是只读存储器(Read-Only Memory，ROM)、可编程只读存储器(Programmable ROM，PROM)、可擦除可编程只读存储器(Erasable PROM，EPROM)、电可擦除可编程只读存储器(Electrically EPROM，EEPROM)或闪存。易失性存储器可以是随机存取存储器(Random Access Memory，RAM)，其用作外部高速缓存。通过示例性但不是限制性说明，许多形式的RAM可用，例如静态随机存取存储器(Static RAM，SRAM)、动态随机存取存储器(Dynamic RAM，DRAM)、同步动态随机存取存储器(Synchronous DRAM，SDRAM)、双倍数据速率同步动态随机存取存储器(Double Data Rate SDRAM，DDR SDRAM)、增强型同步动态随机存取存储器(Enhanced SDRAM，ESDRAM)、同步连接动态随机存取存储器(Synchlink DRAM，SLDRAM)和直接内存总线随机存取存储器(Direct Rambus RAM，DR RAM)。应注意，本文描述的系统和方法的存储器旨在包括但不限于这些和任意其它适合类型的存储器。
基于以上实施例，本申请实施例还提供了一种计算机程序，当所述计算机程序在计算机上运行时，使得所述计算机执行以上实施例提供的通信方法。
基于以上实施例，本申请实施例还提供了一种计算机可读存储介质，该计算机可读存储介质中存储有计算机程序，所述计算机程序被计算机执行时，使得计算机执行以上实施例提供的通信方法。
其中，存储介质可以是计算机能够存取的任何可用介质。以此为例但不限于：计算机可读介质可以包括RAM、ROM、EEPROM、CD-ROM或其他光盘存储、磁盘存储介质或者其他磁存储设备、或者能够用于携带或存储具有指令或数据结构形式的期望的程序代码并能够由计算机存取的任何其他介质。
基于以上实施例，本申请实施例还提供了一种芯片，所述芯片用于读取存储器中存储的计算机程序，实现以上实施例提供的通信方法。
基于以上实施例，本申请实施例提供了一种芯片系统，该芯片系统包括处理器，用于支持计算机装置实现以上实施例中业务设备、转发设备或站点设备所涉及的功能。在一种可能的设计中，所述芯片系统还包括存储器，所述存储器用于保存该计算机装置必要的程序和数据。该芯片系统，可以由芯片构成，也可以包含芯片和其他分立器件。
综上所述，本申请实施例提供了一种通信方法、装置及设备，通过该方法，能够保证在UE进行异系统切换过程中，终端设备与目的通信系统中的网络设备使用相同的安全上下文，因此，后续二者使用该安全上下文进行安全验证，可以实现安全验证成功，从而保证终端设备可以成功切换到目的通信系统。
本领域内的技术人员应明白，本申请的实施例可提供为方法、系统、或计算机程序产 品。因此，本申请可采用完全硬件实施例、完全软件实施例、或结合软件和硬件方面的实施例的形式。而且，本申请可采用在一个或多个其中包含有计算机可用程序代码的计算机可用存储介质(包括但不限于磁盘存储器、CD-ROM、光学存储器等)上实施的计算机程序产品的形式。
本申请是参照根据本申请的方法、设备(系统)、和计算机程序产品的流程图和/或方框图来描述的。应理解可由计算机程序指令实现流程图和/或方框图中的每一流程和/或方框、以及流程图和/或方框图中的流程和/或方框的结合。可提供这些计算机程序指令到通用计算机、专用计算机、嵌入式处理机或其他可编程数据处理设备的处理器以产生一个机器，使得通过计算机或其他可编程数据处理设备的处理器执行的指令产生用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的装置。
这些计算机程序指令也可存储在能引导计算机或其他可编程数据处理设备以特定方式工作的计算机可读存储器中，使得存储在该计算机可读存储器中的指令产生包括指令装置的制造品，该指令装置实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能。
这些计算机程序指令也可装载到计算机或其他可编程数据处理设备上，使得在计算机或其他可编程设备上执行一系列操作步骤以产生计算机实现的处理，从而在计算机或其他可编程设备上执行的指令提供用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的步骤。
显然，本领域的技术人员可以对本申请进行各种改动和变型而不脱离本申请的保护范围。这样，倘若本申请的这些修改和变型属于本申请权利要求及其等同技术的范围之内，则本申请也意图包含这些改动和变型在内。

Claims (32)

  1. 一种通信方法，其特征在于，包括：
    终端设备在从第一通信系统切换到第二通信系统的过程中，获取第一套安全上下文；其中，所述第一套安全上下文用于所述终端设备与第一网络设备进行安全验证，所述第一网络设备位于所述第二通信系统中；
    当所述终端设备使用所述第一套安全上下文与所述第一网络设备安全验证失败时，所述终端设备向所述第一网络设备发起注册流程。
  2. 如权利要求1所述的方法，其特征在于，当所述终端设备使用所述第一套安全上下文与所述第一网络设备安全验证失败时，所述终端设备向所述第二通信系统中的第一网络设备发起注册流程，包括：
    当所述终端设备使用所述第一套安全上下文与所述第一网络设备安全验证失败的次数大于或等于设定阈值时，所述终端设备向所述第一网络设备发起注册流程。
  3. 如权利要求1或2所述的方法，其特征在于，所述终端设备使用所述第一套安全上下文与所述第一网络设备安全验证失败，包括：
    所述终端设备使用所述第一套安全上下文，对来自所述第一网络设备的加密处理后的下行消息进行解密处理，且解密失败；或者
    所述终端设备使用所述第一套安全上下文，对来自所述第一网络设备的完整性保护处理后的下行消息进行完整性保护校验，且完整性保护校验失败；或者
    所述终端设备使用所述第一套安全上下文，对来自所述第一网络设备的加密和完整性保护处理后的下行消息进行解密处理和完整性保护校验，且解密失败或完整性保护校验失败；或者
    所述终端设备使用所述第一套安全上下文，对上行消息进行完整性保护处理，并向所述第一网络设备发送完整性保护处理后的上行消息，且所述终端设备未接收来自所述第一网络设备的所述上行消息的响应消息。
  4. 如权利要求3所述的方法，其特征在于，所述下行消息为以下任一项：安全模式命令、跟踪区域更新接受消息、无线资源控制RRC安全模式命令、附着接受消息；
    所述上行消息为以下任一项：跟踪区域更新请求消息、附着请求消息。
  5. 如权利要求1-4任一项所述的方法，其特征在于，所述第一网络设备包括：位于所述第二通信系统中的核心网设备或接入网设备。
  6. 如权利要求1-5任一项所述的方法，其特征在于，所述终端设备向所述第二通信系统中的第一网络设备发起注册流程，包括：
    所述终端设备向所述第一网络设备发送附着请求消息或注册请求消息，所述附着请求消息或注册请求消息中包含所述终端设备的国际移动用户识别码IMSI。
  7. 如权利要求1-6任一项所述的方法，其特征在于，所述第一套安全上下文中包含非接入层计数值NAS count。
  8. 如权利要求1-7任一项所述的方法，其特征在于，所述终端设备获取所述第一套安全上下文，包括：
    所述终端设备根据设定安全上下文映射算法，对第二套安全上下文进行计算，生成所述第一套安全上下文；其中，所述第二套安全上下文用于所述终端设备与第二网络设备进 行安全验证，所述第二网络设备位于所述第一通信系统中。
  9. 如权利要求1-8任一项所述的方法，其特征在于，所述第一通信系统为第五代5G通信系统，所述第二通信系统为第四代4G通信系统。
  10. 一种通信方法，其特征在于，包括：
    终端设备在从第一通信系统切换到第二通信系统的过程中，向所述第二通信系统中的核心网设备发送跟踪区域更新请求消息或附着请求消息；
    所述终端设备接收来自所述核心网设备的鉴权请求消息；
    所述终端设备根据所述鉴权请求消息，激活新的一套安全上下文；其中，所述新的一套安全上下文用于所述终端设备与第一网络设备进行安全验证，所述第一网络设备位于所述第二通信系统中；
    所述终端设备使用所述新的一套安全上下文与所述第一网络设备进行安全验证。
  11. 如权利要求10所述的方法，其特征在于，所述终端设备向所述第二通信系统中的核心网设备发送跟踪区域更新请求消息或附着请求消息，包括：
    所述终端设备使用第一套安全上下文，对所述跟踪区域更新请求消息或所述附着请求消息进行完整性保护处理；所述第一套安全上下文用于所述终端设备与第二网络设备进行安全验证，所述第二网络设备位于所述第一通信系统中；
    所述终端设备向所述核心网设备发送完整性保护处理后的所述跟踪区域更新请求消息或所述附着请求消息。
  12. 如权利要求10或11所述的方法，其特征在于，所述新的一套安全上下文中包含非接入层计数值NAS count。
  13. 如权利要求10-12任一项所述的方法，其特征在于，所述跟踪区域更新请求消息或所述附着请求消息中携带有状态指示信息，所述状态指示信息UE status用于指示所述终端设备从第一通信系统切换到第二通信系统。
  14. 如权利要求10-13任一项所述的方法，其特征在于，所述第一通信系统为第五代5G通信系统，所述第二通信系统为第四代4G通信系统。
  15. 一种通信装置，应用于终端设备其特征在于，包括：
    通信单元，用于接收和发送数据；
    处理单元，用于：
    在终端设备从第一通信系统切换到第二通信系统的过程中，获取第一套安全上下文；其中，所述第一套安全上下文用于所述处理单元与第一网络设备进行安全验证，所述第一网络设备位于所述第二通信系统中；
    当所述处理单元使用所述第一套安全上下文与所述第一网络设备安全验证失败时，通过所述通信单元向所述第一网络设备发起注册流程。
  16. 如权利要求15所述的装置，其特征在于，所述处理单元，具体用于：
    当所述处理单元使用所述第一套安全上下文与所述第一网络设备安全验证失败的次数大于或等于设定阈值时，通过所述通信单元向所述第一网络设备发起注册流程。
  17. 如权利要求15或16所述的装置，其特征在于，所述处理单元使用所述第一套安全上下文与所述第一网络设备安全验证失败，包括：
    所述处理单元使用所述第一套安全上下文，对来自所述第一网络设备的加密处理后的下行消息进行解密处理，且解密失败；或者
    所述处理单元使用所述第一套安全上下文，对来自所述第一网络设备的完整性保护处理后的下行消息进行完整性保护校验，且完整性保护校验失败；或者
    所述处理单元使用所述第一套安全上下文，对来自所述第一网络设备的加密和完整性保护处理后的下行消息进行解密处理和完整性保护校验，且解密失败或完整性保护校验失败；或者
    所述处理单元使用所述第一套安全上下文，对上行消息进行完整性保护处理，并向所述第一网络设备发送完整性保护处理后的上行消息，且所述终端设备未接收来自所述第一网络设备的所述上行消息的响应消息。
  18. 如权利要求17所述的装置，其特征在于，所述下行消息为以下任一项：安全模式命令、跟踪区域更新接受消息、无线资源控制RRC安全模式命令、附着接受消息；
    所述上行消息为以下任一项：跟踪区域更新请求消息、附着请求消息。
  19. 如权利要求15-18任一项所述的装置，其特征在于，所述第一网络设备包括：位于所述第二通信系统中的核心网设备或接入网设备。
  20. 如权利要求15-19任一项所述的装置，其特征在于，所述处理单元，在通过所述通信单元向所述第二通信系统中的第一网络设备发起注册流程时，具体用于：
    向所述第一网络设备发送附着请求消息或注册请求消息，所述附着请求消息或注册请求消息中包含所述终端设备的国际移动用户识别码IMSI。
  21. 如权利要求15-20任一项所述的装置，其特征在于，所述第一套安全上下文中包含非接入层计数值NAS count。
  22. 如权利要求15-21任一项所述的装置，其特征在于，所述处理单元，在获取所述第一套安全上下文时，具体用于：
    根据设定安全上下文映射算法，对第二套安全上下文进行计算，生成所述第一套安全上下文；其中，所述第二套安全上下文用于所述处理单元与第二网络设备进行安全验证，所述第二网络设备位于所述第一通信系统中。
  23. 如权利要求15-22任一项所述的装置，其特征在于，所述第一通信系统为第五代5G通信系统，所述第二通信系统为第四代4G通信系统。
  24. 一种通信装置，应用于终端设备，其特征在于，包括：
    通信单元，用于接收和发送数据；
    处理单元，用于：
    在所述终端设备从第一通信系统切换到第二通信系统的过程中，通过所述通信单元向所述第二通信系统中的核心网设备发送跟踪区域更新请求消息或附着请求消息；
    通过所述通信单元接收来自所述核心网设备的鉴权请求消息；
    根据所述鉴权请求消息，激活新的一套安全上下文；其中，所述新的一套安全上下文用于所述处理单元与第一网络设备进行安全验证，所述第一网络设备位于所述第二通信系统中；
    使用所述新的一套安全上下文与所述第一网络设备进行安全验证。
  25. 如权利要求24所述的装置，其特征在于，所述处理单元，在通过所述通信单元向所述第二通信系统中的核心网设备发送跟踪区域更新请求消息或附着请求消息时，具体用于：
    使用第一套安全上下文，对所述跟踪区域更新请求消息或所述附着请求消息进行完整 性保护处理；所述第一套安全上下文用于所述终端设备与第二网络设备进行安全验证，所述第二网络设备位于所述第一通信系统中；
    通过所述通信单元向所述核心网设备发送完整性保护处理后的所述跟踪区域更新请求消息或所述附着请求消息。
  26. 如权利要求24或25所述的装置，其特征在于，所述新的一套安全上下文中包含非接入层计数值NAS count。
  27. 如权利要求24-26任一项所述的装置，其特征在于，所述跟踪区域更新请求消息或所述附着请求消息中携带有状态指示信息，所述状态指示信息UE status用于指示所述终端设备从第一通信系统切换到第二通信系统。
  28. 如权利要求24-27任一项所述的装置，其特征在于，所述第一通信系统为第五代5G通信系统，所述第二通信系统为第四代4G通信系统。
  29. 一种通信设备，其特征在于，包括：
    通信模块，用于接收和发送数据；
    处理器，用于通过所述通信模块，实现权利要求1-14任一项所述的方法。
  30. 一种计算机可读存储介质，其特征在于，所述计算机可读存储介质中存储有计算机程序，当所述计算机程序在计算机上运行时，使得计算机执行权利要求1-14任一项所述的方法。
  31. 一种计算机程序产品，其特征在于，当所述计算机程序产品在计算机上运行时，使得所述计算机执行权利要求1-14任一项所述的方法。
  32. 一种芯片，其特征在于，所述芯片与存储器耦合，所述芯片读取存储器中存储的计算机程序，执行权利要求1-14任一项所述的方法。
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