WO2019019787A1 - 通信方法、基站和终端设备 - Google Patents

通信方法、基站和终端设备 Download PDF

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Publication number
WO2019019787A1
WO2019019787A1 PCT/CN2018/088311 CN2018088311W WO2019019787A1 WO 2019019787 A1 WO2019019787 A1 WO 2019019787A1 CN 2018088311 W CN2018088311 W CN 2018088311W WO 2019019787 A1 WO2019019787 A1 WO 2019019787A1
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WIPO (PCT)
Prior art keywords
key
base station
terminal device
indication information
target base
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PCT/CN2018/088311
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English (en)
French (fr)
Inventor
胡力
徐小英
王海光
陈璟
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华为技术有限公司
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Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Publication of WO2019019787A1 publication Critical patent/WO2019019787A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W12/00—Security arrangements; Authentication; Protecting privacy or anonymity
    • H04W12/04—Key management, e.g. using generic bootstrapping architecture [GBA]

Definitions

  • the present application relates to the field of communications and, more particularly, to a communication method, a base station, and a terminal device.
  • a terminal device moves from a coverage area of a source base station to a coverage area of a target base station, and establishes a connection with a target base station. At this time, an update is adopted between the terminal device and the target base station. The subsequent access layer key is communicated.
  • the base station adopts a centralized unit (CU) and a distributed unit (DU). That is, the CU and the DU are respectively responsible for the radio access network protocols of different layers. Multiple DUs can be connected in the same CU, and the same DU can cover multiple cells. Therefore, the case where the terminal device moves in each cell is different from the LTE mobile.
  • the security performance and security requirements of the CU and the DU are also different.
  • the present application provides a communication method, a base station, and a terminal device, which can provide a flexible method for updating a key.
  • a communication method includes: a target base station receiving a first request message from a terminal device, where the first request message includes first identifier information, where the first identifier information is used to indicate the terminal The device and the source base station; the target base station sends a second request message to the source base station according to the first request message, where the second request message includes second identifier information, where the second identifier information is used to indicate
  • the terminal device receives the first key and the first indication information from the source base station, where the first indication information is used to indicate that the first key is an updated key or not updated.
  • the second base station sends the second indication information to the terminal device according to the first indication information, where the second indication information is used to indicate the access between the terminal device and the target base station.
  • the layer key is an updated key or a key that is not updated.
  • the first identifier information may use a Resume Identifier (Resume ID) to indicate the terminal device and the source base station.
  • the first identifier information may be a physical cell identifier (PCI) indicating a source base station, and a cell radio temporary identifier (C-RNTI) indicating the terminal device.
  • PCI physical cell identifier
  • C-RNTI cell radio temporary identifier
  • the target base station when the terminal device moves from the cell covered by the source base station to the cell covered by the target base station, the target base station receives the first key and the first indication information sent by the source base station, where the first indication information is used. Indicates whether the first key is the updated key, and the target base station may send the second indication information to the terminal device according to the first indication information sent by the source base station, to indicate update or not update the connection between the terminal device and the target base station.
  • the layer key which provides a flexible way to update the key.
  • the second request message further includes third indication information, where the third indication information is used to request to update the key or not to update the key.
  • the third request message carries the third indication information, where the third indication information is used to request whether to update the key, which saves the number of times of sending signaling, and improves the decision efficiency.
  • the third indication information is used to request that the key is not updated; or, in the target When the trust level of the base station to the source base station is lower than the trust threshold, the third indication information is used to request an update key.
  • the first request message further includes fourth indication information, where the fourth indication information is used to request an update key or request not to update a key; and the fourth indication information is used in the fourth indication information.
  • the third indication information is used to request an update key; or, in a case where the fourth indication information is used to request not to update a key, the third indication information is used for requesting Do not update the key.
  • the fourth indication information is carried in the first request message, and the fourth indication information is used to request whether to update the key, which saves the number of times of sending signaling, and improves the decision efficiency.
  • one or more decision points in the terminal device, the target base station, and the source base station are introduced to determine whether to update the key, and may be coordinated and determined according to real-time status information of each decision point and a preset policy. Whether to update the key provides a flexible way to update the key. In the case where a plurality of decision points are introduced, it is possible to determine whether to update the key by a plurality of decision points, thereby improving the security performance of communication between the terminal device and the target base station.
  • the first indication information is used to indicate that the first key is an unupdated key and the third indication information is used to request an update key
  • the second indication information is used to indicate that the access stratum key between the terminal device and the target base station is an updated key.
  • the method further includes: the target base station receiving a next hop chain counter NCC from the source base station; the target base station generating a second key according to the NCC, the second key An access layer key between the terminal device and the target base station; the target base station sends the NCC to the terminal device.
  • the method further includes: the target base station receiving an NCC from the source base station, and transmitting the NCC to the terminal device.
  • the second indication information is used to indicate the terminal device and the The access stratum key between the target base stations is an unupdated key.
  • the terminal device is in an inactive state
  • the first request message is used to request to restore a radio resource control RRC connection of the terminal device
  • the second indication information is carried in a first response.
  • the first response message is used to indicate that the terminal device remains in an inactive state; or the first response message is used to instruct the terminal device to resume an RRC connection.
  • the terminal device access layer key is updated or not may be updated without restoring the RRC connection of the terminal device.
  • the key simplifies the process of decision key update and saves signaling overhead.
  • the second request message is used to request to acquire a context of the terminal device; the first indication information is carried in a second response message, and the second response message includes the terminal The context of the device, the context of the terminal device containing the first key.
  • a second aspect provides a communication method, including: a source base station receiving a second request message from a target base station, where the second request message includes second identifier information, where the second identifier information is used to indicate a terminal device; The source base station sends the first key and the first indication information to the target base station according to the second request message, where the first indication information is used to indicate that the first key is an updated key or Unupdated key.
  • the source base station may receive the second request message sent by the target base station, and according to the second request message, go to the target.
  • the base station sends the first key and the first indication information, where the first indication information is used to indicate whether the first key is an updated key, so that the target base station determines an access layer key between the terminal device and the target base station, This provides a flexible way to update the key.
  • the first identifier information may use a Resume Identifier (Resume ID) to indicate the terminal device and the source base station.
  • the first identifier information may be a physical cell identifier (PCI) indicating a source base station, and a cell radio temporary identifier (C-RNTI) indicating the terminal device.
  • PCI physical cell identifier
  • C-RNTI cell radio temporary identifier
  • the second request message further includes third indication information
  • the third indication information is used to request an update key
  • the first indication information is used to indicate The first key is an updated key; or, when the trust level of the source base station to the target base station is lower than a trust threshold, the first indication information is used to indicate that the first key is an update After the key.
  • the third indication information is used to request whether to update the key in the second request message, which saves the number of times the signaling is sent, and improves the decision efficiency.
  • one or more decision points in the terminal device, the target base station, and the source base station are introduced to determine whether to update the key, and may be coordinated and determined according to real-time status information of each decision point and a preset policy. Whether to update the key provides a flexible way to update the key. In the case where a plurality of decision points are introduced, it is possible to determine whether to update the key by a plurality of decision points, thereby improving the security performance of communication between the terminal device and the target base station.
  • the method further includes: the source base station sending, to the target base station, a next hop chain counter NCC for generating the first key.
  • the first indication information is used to indicate that the first key is not updated, where the trust level of the source base station is higher than or equal to a trust threshold. Key.
  • the second request message is used to request to acquire a context of the terminal device; the first indication information is carried in a second response message, and the second response message includes the terminal The context of the device, the context of the terminal device containing the first key.
  • the third aspect provides a communication method, including: the terminal device sends a first request message to the target base station, where the first request message includes first identifier information, where the first identifier information is used to indicate the terminal device and a source base station; the terminal device receives the second indication information sent by the target base station, where the second indication information is used to indicate that the access layer key between the target base station and the terminal device is an updated secret Key or unupdated key.
  • the terminal device when the terminal device moves from the cell covered by the source base station to the cell covered by the target base station, the terminal device receives the second indication information sent by the target base station to indicate the connection between the terminal device and the target base station. Whether the inbound key is an updated key provides a flexible way to update the key.
  • the first identifier information may use a Resume Identifier (Resume ID) to indicate the terminal device and the source base station.
  • the first identifier information may be a physical cell identifier (PCI) indicating a source base station, and a cell radio temporary identifier (C-RNTI) indicating the terminal device.
  • PCI physical cell identifier
  • C-RNTI cell radio temporary identifier
  • the first request message includes fourth indication information, where the fourth indication information is used to request an update key or not to update a key.
  • the fourth indication information is used to request an update key, where the number of unupdated keys of the terminal device is greater than or equal to a count threshold, where the terminal device does not
  • the number of update keys is the number of unupdated keys in the time interval between the time when the terminal device last updated the key and the current time; or the number of unupdated keys at the terminal device is less than the count
  • the fourth indication information is used to request that the key is not updated; or, in a case where the first state information of the terminal device is changed, the fourth indication information is used to request an update key, where
  • the first state information includes any one of the following: a tracking area identifier TAI of the terminal device, a radio access network RAN group to which the terminal device currently belongs, and a radio access technology RAT currently used by the terminal device; Or, in a case that the first state information of the terminal device is not changed, the fourth indication information is used to request that the key is not updated.
  • the method further includes: the fourth indication information is used to request an update key, and the second indication information is used to indicate the access between the terminal device and the target base station.
  • the terminal device disconnects the connection with the target base station and reselects the accessed base station.
  • one or more decision points in the terminal device, the target base station, and the source base station are introduced to determine whether to update the key, and may be coordinated and determined according to real-time status information of each decision point and a preset policy. Whether to update the key provides a flexible way to update the key. In the case where a plurality of decision points are introduced, it is possible to determine whether to update the key by a plurality of decision points, thereby improving the security performance of communication between the terminal device and the target base station.
  • the method further includes: the terminal device receives a next hop chain counter NCC sent by the target base station; and the second indication information is used to indicate the terminal device and the target base station
  • the terminal device In the case that the access layer key is an updated key, the terminal device generates a third key according to the NCC, where the third key is between the terminal device and the target base station. Access layer key.
  • the terminal device is in an inactive state
  • the first request message is used to request to restore a radio resource control RRC connection of the terminal device
  • the second indication information is carried in a first response.
  • the first response message is used to indicate that the terminal device remains in an inactive state; or the first response message is used to instruct the terminal device to resume an RRC connection.
  • a fourth aspect provides a communication method, including: receiving, by a target base station, a first request message from a terminal device, where the first request message includes first identifier information, where the first identifier information is used to indicate the terminal device and a source base station, where the source base station and the target base station belong to the same centralized unit CU, the target base station sends second indication information to the terminal device according to the first request message, the second The indication information is used to indicate that the access stratum key between the terminal device and the target base station is an updated key or an unupdated key.
  • the target base station may send the second indication information to the terminal device to indicate whether the access layer key between the terminal device and the target base station is updated.
  • the latter key provides a flexible way to update the key.
  • the first identifier information may use a Resume Identifier (Resume ID) to indicate the terminal device and the source base station.
  • the first identifier information may be a physical cell identifier (PCI) indicating a source base station, and a cell radio temporary identifier (C-RNTI) indicating the terminal device.
  • PCI physical cell identifier
  • C-RNTI cell radio temporary identifier
  • the second indication information is used to indicate The access layer key between the terminal device and the target base station is an updated key; or, in the case that the number of unupdated keys of the terminal device is greater than or equal to a count threshold, the second indication
  • the information is used to indicate that the access layer key between the terminal device and the target base station is an updated key, wherein the number of unupdated keys of the terminal device is the last update of the terminal device. The number of unupdated keys in the time interval from the moment of the key to the current time.
  • the method further includes: Generating, by the target base station, the first key according to a next hop chain counter NCC, where the first key is an access stratum key between the terminal device and the target base station; The terminal device transmits the NCC.
  • the second indication information is used to indicate The access layer key between the terminal device and the target base station is an unupdated key; or, in the case that the number of unupdated keys of the terminal device is less than the count threshold, the second The indication information is used to indicate that the access layer key between the terminal device and the target base station is an unupdated key, wherein the number of unupdated keys of the terminal device is the last update of the terminal device The number of unupdated keys in the time interval from the time of the key to the current time.
  • one or two decision points of the terminal device and the target base station are introduced to determine whether to update the key, and the key may be coordinated according to real-time status information of each decision point and a preset policy. , thus providing a flexible way to update the key.
  • two decision points it is possible to determine whether to update the key by the two decision points, thereby improving the security performance of the communication between the terminal device and the target base station.
  • the introduction of two decision points can balance the decision-making ability of each decision point, or by decentralized decision-making ability, so that each decision point can determine whether to update the key according to their respective states, and can take into account the state of other decision points, thus providing A secure and flexible solution for updating keys.
  • the terminal device is in an inactive state
  • the first request message is used to request to restore a radio resource control RRC connection of the terminal device
  • the second indication information is carried in a first response.
  • the first response message is used to indicate that the terminal device remains in an inactive state; or the first response message is used to instruct the terminal device to resume an RRC connection.
  • a base station for performing the method of any of the above first aspect or any of the possible implementations of the first aspect.
  • the base station comprises means for performing the method of any of the above-described first aspect or any of the possible implementations of the first aspect.
  • a base station is provided, the base station being operative to perform the method in any of the possible implementations of the second aspect or the second aspect.
  • the base station comprises means for performing the method of any of the above-described second or second aspects of the second aspect.
  • a terminal device configured to perform the method in any of the foregoing third aspect or any possible implementation manner of the third aspect.
  • the terminal device comprises means for performing the method in any of the possible implementations of the third aspect or the third aspect described above.
  • a base station for performing the method in any of the possible implementations of the fourth aspect or the fourth aspect above.
  • the base station comprises means for performing the method of any of the above-described fourth or fourth aspects of the fourth aspect.
  • a communication system comprising the base station according to the fifth aspect, the sixth aspect, and the terminal device according to the seventh aspect.
  • the communication system includes the terminal device of the seventh aspect and the base station of the eighth aspect.
  • a base station comprising: a communication interface, a memory, a processor, and a bus system.
  • the communication interface, the memory and the processor are connected by the bus system, the memory is for storing instructions, the processor is configured to execute instructions stored by the memory to control the communication interface to receive signals and/or transmit signals, and When the processor executes the instructions stored by the memory, the execution causes the processor to perform the method of the first aspect or any of the possible implementations of the first aspect.
  • a base station comprising: a communication interface, a memory, a processor, and a bus system.
  • the communication interface, the memory and the processor are connected by the bus system, the memory is for storing instructions, the processor is configured to execute instructions stored by the memory to control the communication interface to receive signals and/or transmit signals, and When the processor executes the instructions stored by the memory, the execution causes the processor to perform the method of any of the possible implementations of the second aspect or the second aspect.
  • a terminal device comprising: a communication interface, a memory, a processor, and a bus system.
  • the communication interface, the memory and the processor are connected by the bus system, the memory is for storing instructions, the processor is configured to execute instructions stored by the memory to control the communication interface to receive signals and/or transmit signals, and
  • the execution causes the processor to perform the method of any of the possible implementations of the third aspect or the third aspect.
  • a base station comprising: a communication interface, a memory, a processor, and a bus system.
  • the communication interface, the memory and the processor are connected by the bus system, the memory is for storing instructions, the processor is configured to execute instructions stored by the memory to control the communication interface to receive signals and/or transmit signals, and When the processor executes the instructions stored by the memory, the execution causes the processor to perform the method of any of the possible implementations of the fourth aspect or the fourth aspect.
  • a fourteenth aspect there is provided a communication system comprising the base station according to the tenth aspect, the eleventh aspect, and the terminal device of the twelfth aspect.
  • the communication system includes the terminal device described in the twelfth aspect and the base station according to the thirteenth aspect.
  • a fifteenth aspect a computer readable medium for storing a computer program, the computer program comprising instructions for performing the method of the first aspect or any of the possible implementations of the first aspect.
  • a computer readable medium for storing a computer program comprising instructions for performing the method of any of the second aspect or any of the possible implementations of the second aspect.
  • a seventeenth aspect a computer readable medium for storing a computer program, the computer program comprising instructions for performing the method of any of the third aspect or any of the possible implementations of the third aspect.
  • a computer readable medium for storing a computer program comprising instructions for performing the method of any of the fourth aspect or any of the possible implementations of the fourth aspect.
  • FIG. 1 is a schematic diagram of an application environment of an embodiment of the present application.
  • FIG. 2 is a schematic diagram of an application environment of an embodiment of the present application.
  • FIG. 3 is a schematic diagram of a communication method according to an embodiment of the present application.
  • FIG. 4 is a schematic diagram of a communication method according to still another embodiment of the present application.
  • FIG. 5 is a schematic diagram of a communication method according to still another embodiment of the present application.
  • FIG. 6 is a schematic diagram of a communication method according to still another embodiment of the present application.
  • FIG. 7 is a schematic diagram of interaction of a communication method according to an embodiment of the present application.
  • FIG. 8 is a schematic diagram of interaction of a communication method according to still another embodiment of the present application.
  • FIG. 9 is a schematic diagram of interaction of a communication method according to still another embodiment of the present application.
  • FIG. 10 is a schematic diagram of interaction of a communication method according to still another embodiment of the present application.
  • FIG. 11 is a schematic diagram of interaction of a communication method according to still another embodiment of the present application.
  • FIG. 12 is a schematic structural diagram of a base station according to an embodiment of the present application.
  • FIG. 13 is a schematic structural diagram of a base station according to still another embodiment of the present application.
  • FIG. 14 is a schematic structural diagram of a terminal device according to still another embodiment of the present application.
  • FIG. 15 is a schematic structural diagram of a base station according to still another embodiment of the present application.
  • FIG. 16 is a schematic structural diagram of a base station according to still another embodiment of the present application.
  • FIG. 17 is a schematic structural diagram of a base station according to still another embodiment of the present application.
  • FIG. 18 is a schematic structural diagram of a terminal device according to still another embodiment of the present application.
  • FIG. 19 is a schematic structural diagram of a base station according to still another embodiment of the present application.
  • FIG. 20 is a schematic structural diagram of a base station according to still another embodiment of the present application.
  • FIG. 21 is a schematic structural diagram of a terminal device according to still another embodiment of the present application.
  • the inactive state is a state of the terminal device, which is different from the Radio Resource Control (RRC) connected (connected) state and the RRC idle state. status.
  • RRC Radio Resource Control
  • part of the bearer resources may be reserved.
  • SRB Signal Resource Bearer
  • DRB Data Resource Bearer
  • the core network, the base station, and the terminal device can all save the context of the terminal device.
  • the base station may allocate an Access Stratum (AS) identifier to the terminal device in an inactive state.
  • the AS identifier may be a Resume Identifier (Resume ID).
  • the Resume ID can be used to find a base station that stores the context of the terminal device.
  • the terminal device in an inactive state can transmit small data between the base station and the base station.
  • Access and Mobility Management Function Used for management of mobile networks, which can be responsible for providing access and mobility support for terminal devices.
  • the function of the AMF may include at least one of the following: registration management, reachability management, mobility management, access authentication, and access authorization.
  • the terminal device involved in the embodiments of the present application may include various handheld devices having wireless communication functions, in-vehicle devices, wearable devices, computing devices, or other processing devices connected to the wireless modem, and various forms.
  • the user equipment User Equipment, UE
  • the mobile station Mobile Station, MS
  • the terminal the terminal device, and the like are not limited in this embodiment of the present application.
  • the base station in this embodiment of the present application may include various forms of macro base stations, micro base stations, relay stations, access points, transceiver nodes, transmission nodes, and the like.
  • the names of devices with base station functionality may vary.
  • an evolved Node B for example, an evolved NodeB, an eNB or an eNodeB
  • 3G 3rd Generation
  • 5G 5th Generation
  • g-node eg, g Node B, gNB
  • NR New Radio
  • An embodiment of the present application provides a flexible key replacement method, which introduces one or more decision points in a terminal device, a target base station, and a source base station to determine whether to update a key, for example, according to each decision point.
  • Real-time status information and preset policies determine whether to update the key.
  • FIG. 1 illustrates a possible application environment of an embodiment of the present application.
  • the target base station in FIG. 1 may be a base station of any one of the foregoing base stations, for example, may be an eNodeB in an LTE network, or a gNB in a 5G system; the source base station may also be any one of the above base stations. Base station.
  • the communication method of the embodiment of the present application is used to provide a secure and flexible key replacement method to improve communication efficiency.
  • FIG. 2 shows another possible application environment of the embodiment of the present application.
  • the base station shown in FIG. 2 may be a base station in 5G.
  • a base station may perform a separation of a central unit (CU) and a distributed unit (DU), or a protocol stack separation.
  • CUs and DUs can handle different protocol layers.
  • the DU can handle the Radio Link Control (RLC) protocol and the following protocols, and the CU can process protocols above the RLC layer.
  • RLC Radio Link Control
  • the CU can handle a Packet Data Convergence Protocol (PDCP) or a Radio Resource Control (RRC) protocol.
  • PDCP Packet Data Convergence Protocol
  • RRC Radio Resource Control
  • the DU can be used to process the Physical Layer (PHY) protocol, the Media Access Control (MAC) protocol, and the RLC protocol.
  • PHY Physical Layer
  • MAC Media Access Control
  • RLC Radio Link Control
  • the same CU may be connected to one or more DUs, and the same DU may include one or more cells.
  • the CU and the DU may be collectively referred to as a gNB.
  • the terminal device when the terminal device moves between cells, there may be a case where the terminal device replaces the cell without replacing the CU.
  • the terminal device in the case where the terminal device moves from the cell 1 to the cell 3, although the DU is replaced, the CU is not replaced.
  • the terminal device moves from the cell 1 to the cell 2
  • neither the DU nor the CU is replaced.
  • the operations performed by the source base station and the target base station in the method of the present application are all performed by the same CU, or the source base station and the target base station belong to the same CU.
  • FIG. 3 is a schematic flowchart of a communication method 300 according to an embodiment of the present application.
  • the method of Figure 3 can be performed by a target base station. It should be noted that if the method 300 is applied to the application environment of FIG. 2, it may be applicable to a case where the target base station and the source base station belong to different CUs. In other words, the terminal device moves from the cell covered by the first CU to the cell covered by the second CU, and the first CU and the second CU are different CUs. As shown in FIG. 3, the illustrated method 300 includes:
  • the target base station receives the first request message from the terminal device, where the first request message includes first identifier information, where the first identifier information is used to indicate the terminal device and the source base station.
  • the first identifier information may be used to indicate the terminal device and the source base station by using the same identifier, or two identifiers may be used to respectively indicate the terminal device and the source base station.
  • a Resume Identifier may be used to indicate the terminal device and the source base station.
  • the physical cell identifier may be used to indicate the source base station, and the cell radio network temporary identifier (Cell Radio temporary) is used.
  • the identifier, C-RNTI indicates the terminal device.
  • the terminal device may be in an inactive state, and the first request message may be used to request to restore an RRC connection of the terminal device.
  • the terminal device moves to the target base station, and transmits a first request message to the target base station.
  • the terminal device may be in an inactive state
  • the first identifier information may be a Resume ID
  • the first request message may be an RRC Connection Resume Request message.
  • the terminal device may be in a connected state, and the first request message may be used to request to re-establish an RRC connection of the terminal device.
  • the terminal device moves to the target base station, and if the terminal device has an abnormal situation, the first request message is sent to the target base station.
  • the terminal device may be in a connected state
  • the first identifier information may be a PCI
  • the first request message may be an RRC Connection Re-establishment Request message.
  • the target base station sends a second request message to the source base station according to the first request message, where the second request message includes second identifier information, where the second identifier information is used to indicate the terminal device. .
  • the target base station may determine the source base station according to the first identifier information, and send a second request message to the source base station.
  • the second identifier information is determined according to the first identifier information, or the first identifier information and the second identifier information may be the same.
  • the first identifier information indicates the terminal device and the source base station by using the same identifier
  • the second identifier information may be the same as the first identifier information.
  • the first identification information and the second identification information may both include a Resume ID.
  • the second identifier information may include an identifier indicating the terminal device.
  • the second identification information may include a C-RNTI to indicate the terminal device.
  • the second request message may be used to request to acquire a context of the terminal device.
  • the second request message may be a Retrieve UE Context Request message.
  • the second request message may be a Radio Link Failure Indication message.
  • the target base station receives the first key and the first indication information from the source base station, where the first indication information is used to indicate that the first key is an updated key or an unupdated secret. key.
  • the first key may be understood as an Access Stratum (AS) key used between the terminal device and the target base station.
  • AS Access Stratum
  • the target base station may determine the first key as an access layer key between the terminal device and the target base station, or may not The first key is determined as an access stratum key between the terminal device and the target base station. For example, as will be exemplified later, in some cases, the target base station may generate a key by itself as a key between the terminal device and the target base station.
  • the first indication information may be carried in a second response message, where the second response message is used to respond to the second request message.
  • the second response message may be a Retrieve UE Context Response message, and the second response message may include the terminal device.
  • Context the context of the terminal device may include the first key.
  • the target base station sends second indication information to the terminal device according to the first indication information, where the second indication information is used to indicate an access layer confidentiality between the terminal device and the target base station.
  • the key is an updated key or an unupdated key.
  • the target base station may directly use the first key as an access layer key between the terminal device and the target base station.
  • the target base station may not use the first key as an access layer key between the terminal device and the target base station according to the first indication information and the preset policy, but generate a key by itself as the access layer. Key.
  • the method 300 further includes: the target base station from the source base station Receiving the NCC, and sending the NCC and the second indication information to the terminal device, where the second indication information is used to indicate that the access layer key between the terminal device and the target base station is an updated key, so that the terminal device is After receiving the second indication information, according to the NCC, a third key is generated as an access layer key.
  • the first key is generated by the source base station according to the NCC, and the third key and the first key may be the same key.
  • the second indication information may be used to indicate the terminal device.
  • the access layer key with the target base station is an unupdated key
  • the terminal device may determine the fourth key as an access layer key between the terminal device and the target base station.
  • the fourth key is an access layer key between the terminal device and the source base station, and in this example, the fourth key and the first key may be the same key.
  • the second indication information may be carried in the first response message, where the first response message may be used to respond to the first request message, where The first response message may be used to indicate that the terminal device remains in an inactive state.
  • the first response message may be an RRC Connection Release message; or the first response message may be used to indicate that the terminal device resumes the RRC connection.
  • the first response message may be an RRC Connection Resume message; or the first response message may be used to indicate that the terminal device re-establishment is complete, for example, the first response message may be an RRC connection re-establishment. (RRC Connection Re-establishment) message.
  • the terminal device access layer key is an update key without restoring the RRC connection of the terminal device, thereby simplifying the decision-making secret The process of key update and saving signaling overhead.
  • the second indication information may indicate, in an explicit or implicit manner, that the access stratum key between the terminal device and the target base station is an updated key or an unupdated key.
  • the second indication information may directly indicate whether the access layer key is an updated key.
  • whether the access layer key is an update key may be indicated by whether the first response message sent by the target base station to the terminal device carries the NCC. If the NCC is carried in the first response message, the target base station indicates that the access layer key is the updated key; if the first response message does not carry the NCC, the target base station indicates that the access layer key is not Updated key.
  • the target base station when the terminal device moves from the cell covered by the source base station to the cell covered by the target base station, the target base station receives the first key and the first indication information sent by the source base station, where the first indication information is used. Indicates whether the first key is the updated key, and the target base station may send the second indication information to the terminal device according to the first indication information sent by the source base station, to indicate update or not update the connection between the terminal device and the target base station.
  • the layer key which provides a flexible way to update the key.
  • the second request message further includes third indication information, where the third indication information is used to request to update the key or not to update the key.
  • the third indication information is carried in the second request message, which saves signaling and improves decision efficiency.
  • the target base station may determine the third indication information according to the preset policy; or the target base station may further receive the fourth indication information from the terminal device, where the fourth indication information is used to request to update the key or not to update the key, the target The base station may determine the third indication information according to the fourth indication information.
  • the fourth indication information may be carried in the first request message.
  • the fourth indication information is carried in the first request message, which saves signaling and improves decision efficiency.
  • any one or any combination of the terminal device, the target base station, and the source base station may participate in a process of deciding whether to update an access layer key between the terminal device and the target base station.
  • the source base station may decide whether to update the key; or, the terminal device may decide whether to update the key; or, the target base station and the source base station may jointly decide whether to update the key; or may be jointly performed by the source base station and the terminal device. Whether the decision is to update the key; or, the terminal device and the target base station can jointly decide whether to update the key.
  • the source base station, the target base station, and the terminal device may jointly decide whether to update the key.
  • the target base station may determine the third indication information according to the preset policy.
  • the foregoing preset policy may be a policy that is obtained according to the user subscription information.
  • the target base station may obtain the preset policy from the core network device.
  • the preset policy may also be pre-configured.
  • the foregoing preset policy may be determining third indication information according to a trust level of the target base station to the source base station.
  • the target base station may hold a trust list in which the correspondence between the PCI and the trust level is stored, or an evolved universal mobile communication system Terrestrial Radio Access Network (Evolved Universal Mobile Telecommunications System Terrestrial Radio Access Network, E-UTRAN) Correspondence between E-UTRAN cell global identifier (ECGI) and trust level.
  • E-UTRAN evolved universal mobile communication system Terrestrial Radio Access Network
  • ECGI Evolved Universal Mobile Telecommunications System Terrestrial Radio Access Network
  • the correspondence may be determined by the deployment location of the target base station and the source base station, and may also be determined by the manufacturer or the like of the base station.
  • the trust level of the source base station and the trust threshold may be a value, and the trust level and the trust threshold may be pre-configured in the target base station.
  • the third indication information is used to request not to update the key; or, if the trust level of the target base station to the source base station is lower than the trust threshold, the third indication information Used to request an update key.
  • the target base station can store a trust list of the target base station to the plurality of base stations. If the source base station is located in the trust list, or the trust level of the target base station to the source base station meets a preset condition, or the trust level of the target base station to the source base station is higher than or equal to the trust threshold, the third indication information may be determined to request the update key.
  • the foregoing policy according to the user subscription information may include policy indication information of the target base station for a terminal device or a Packet Data Unit (PDU) session.
  • These policy indication information can be obtained by the target base station from the core network device.
  • the core network device may include at least one of the following: a Policy Control Function (PCF) entity, a Unified Data Management (UDM) entity, a Structured Data Storage Network Function (SDSF) entity, or The Unstructured Data Storage Network Function (UDSF) entity obtains, the policy of the user subscription information acquisition may be used to indicate whether the access layer key used between the target base station and the foregoing terminal device is updated.
  • the key, or the above policy indication information indicates whether the access stratum key used for the PDU session between the target base station and the above-mentioned terminal device is an updated key.
  • the target base station may not participate in the decision of whether to update the key, but receive the fourth indication information from the terminal device, and send the third indication information according to the fourth indication information, or the target base station may also use the fourth indication information. Transparent transmission to the source base station. For example, in a case where the fourth indication information is used to request an update key, the third indication information is used to request an update key; or, in the case where the fourth indication information is used to request not to update a key The third indication information is used to request that the key is not updated.
  • the target base station may determine the third indication information according to the preset policy and the fourth indication information. For example, if the fourth indication information indicates that the key is not to be updated, the target base station may determine whether to update the key according to a preset policy. If the target base station determines the update key according to the preset policy, the third indication information is used. Requesting to update the key; if the target base station determines not to update the key according to the preset policy, the third indication information is used to request not to update the key. For another example, if the fourth indication information indicates an update key, the third indication information may be used to request the update key regardless of the decision made by the target base station according to the preset policy.
  • the terminal device and the target base station as decision points for determining whether to update the key, it is possible to coordinate whether to update the key according to the real-time status information of each decision point, thereby providing a flexible method for updating the key.
  • one or more decision points in the terminal device, the target base station, and the source base station are introduced to determine whether to update the key, and may be coordinated and determined according to real-time status information of each decision point and a preset policy. Whether to update the key provides a flexible way to update the key. In the case where a plurality of decision points are introduced, it is possible to determine whether to update the key by a plurality of decision points, thereby improving the security performance of communication between the terminal device and the target base station.
  • the first indication information is used to indicate that the first key is an unupdated key and the third indication information is used to request an update key
  • the second indication information is used to indicate that the access stratum key between the terminal device and the target base station is an updated key.
  • the foregoing method may be understood as: after receiving the first indication information, the target base station checks whether the first key indicated by the first indication information conforms to the one-way decision principle.
  • the one-way decision principle means that in the case of two or more decision points (for example, a terminal device, a source base station, and a target base station), there may be a one-way decision from never updating the key to updating the key. Process, without the decision process from updating the key to not updating the key. In other words, in the case where there are a plurality of decision points for determining whether to update the key, the key needs to be updated as long as there is one decision point to determine the update key.
  • the target base station is one of the decision point or the decision point
  • the third indication information requests the update key
  • the target base station receives the first key and the first indication information from the source base station, the An indication whether the first key is an updated key. If the first indication information indicates that the first key is an unupdated key, it indicates that the source base station does not determine the first key according to the one-way decision principle, for example, if the security performance of the source base station is attacked, it may be determined. And sending the first key and the first indication information that do not conform to the one-way decision principle.
  • the target base station may determine not to determine the first key as the access stratum key between the terminal device and the target base station, but generate a second key according to the NCC received from the source base station, and The second key is determined as the access layer key.
  • the target base station may send the foregoing NCC and second indication information for generating the second key, where the second indication information is used to indicate an access layer key between the terminal device and the target base station.
  • the terminal device For the updated key, the terminal device generates a third key as the access layer key according to the NCC.
  • the third key and the second key may be the same key.
  • the target base station may generate the second key according to the foregoing NCC and the derived parameters.
  • the foregoing derivative parameter may include at least one of the following: a PCI, an E-UTRA Absolute Radio Frequency Channel Number-Down Link (EARFCN-DL), and an unused target base station. Next Hop (NH) or the access stratum key currently used by the target base station with the terminal device.
  • a PCI a PCI
  • E-UTRA Absolute Radio Frequency Channel Number-Down Link E-UTRA Absolute Radio Frequency Channel Number-Down Link
  • NH Next Hop
  • the access stratum key currently used by the target base station with the terminal device.
  • the target base station may perform longitudinal key derivation; if the NH bound to the NCC is already used, the target base station may perform lateral key derivation. If longitudinal key derivation is performed, the target base station will use NH as the key derivation parameter. If horizontal key derivation is performed, the target base station uses the access layer key currently used by the target base station as a derivative parameter. For the above two derivatives, the derived parameters may also include PCI and/or EARFCN-DL.
  • FIG. 4 is a schematic flowchart of a communication method 400 according to an embodiment of the present application.
  • the method of Figure 4 can be performed by a source base station. It should be noted that the nouns, terms, and step descriptions involved in the embodiment shown in FIG. 4 can be referred to the related description in the embodiment shown in FIG. 3.
  • method 400 includes:
  • the source base station receives a second request message from the target base station, where the second request message includes second identifier information, where the second identifier information is used to indicate the terminal device.
  • the second identifier information may include a Resume ID, or the second identifier information may include a C-RNTI, or the second identifier information may also include other identifiers indicating the terminal device.
  • the second request message may be used to request to acquire a context of the terminal device.
  • the source base station may obtain the context of the terminal device according to the second identifier information.
  • the second request message may be a Retrieve UE Context Request message.
  • the second request message may be a radio link failure indication (Radio Link Failure Indication) message.
  • Radio Link Failure Indication Radio Link Failure Indication
  • the source base station may obtain the context of the terminal device according to the Resume ID, and the context of the terminal device may include an access layer key, an NCC, and the like.
  • the source base station may also acquire the context of the terminal device according to the C-RNTI.
  • the source base station sends a first key and first indication information to the target base station according to the second request message, where the first indication information is used to indicate that the first key is updated. Key or unupdated key.
  • the source base station may receive the second request message sent by the target base station, and according to the second request message, go to the target.
  • the base station sends the first key and the first indication information, where the first indication information is used to indicate whether the first key is an updated key, so that the target base station determines an access layer key between the terminal device and the target base station, This provides a flexible way to update the key.
  • the first indication information is used to indicate The first key is an updated key; or, when the trust level of the source base station to the target base station is lower than a trust threshold, the first indication information is used to indicate that the first key is an update After the key.
  • any one or any combination of the terminal device, the target base station, and the source base station may participate in a process of deciding whether to update an access layer key between the terminal device and the target base station.
  • the source base station may decide whether to update the key; or, the terminal device may decide whether to update the key; or, the target base station and the source base station may jointly decide whether to update the key; or may be jointly performed by the source base station and the terminal device. Whether the decision is to update the key; or, the terminal device and the target base station can jointly decide whether to update the key.
  • the source base station, the target base station, and the terminal device may jointly decide whether to update the key.
  • the source base station may determine and send the first key and the first indication information according to the second request message.
  • the process of determining, by the source base station, the first key and the first indication information is consistent with the one-way decision principle.
  • the one-way decision principle refers to a one-way decision that there is no update key to update key in the case where there are two or more decision points (for example, a terminal device, a source base station, and a target base station). Process, without the decision process from updating the key to not updating the key. In other words, in the case where there are a plurality of decision points for determining whether to update the key, the key needs to be updated as long as there is one decision point to determine the update key.
  • the source base station may participate in the process of deciding whether to update the key, or that the source base station may not participate in the process of deciding whether to update the key.
  • the source base station may determine to update the key or not to update the key according to a preset policy. And determining, according to the decision result, the first key and the first indication information.
  • the source base station may be based on the terminal device or
  • the indication information of the target base station and the preset policy are used to determine the first indication information.
  • the indication information of the target base station may include third indication information.
  • the indication information of the terminal device may include fourth indication information.
  • the source base station determines an update key, and the first indication information is used to indicate that the first key is an updated key; if all decision points indicate no When the key is updated, the source base station determines not to update the key, and the first indication information is used to indicate that the first key is an unupdated key.
  • the source base station may determine the first key and the first indication information according to the third indication information.
  • the source base station When the third indication information requests to update the key, the source base station generates a first key according to the NCC, and determines that the first indication information indicates that the first key is the updated key.
  • the source base station uses the access layer key used by the source base station and the terminal device as the first key, and determines that the first indication information indicates that the first key is the updated secret. key. In other words, the source base station determines the first key and the first indication information according to the indication information of the other decision points, and the source base station itself does not participate in the process of determining the update key.
  • the foregoing preset policy may be: determining whether to update the key according to the trust level of the source base station to the target base station, where the preset policy may be a policy obtained according to the user subscription information, for example, the source base station may acquire the core network device. Pre-defined strategy. Alternatively, the preset policy may also be pre-configured.
  • the preset policy may be determining whether to update the key according to the degree of trust of the source base station to the target base station.
  • the source base station can store a trust list of the source base station to the plurality of base stations. If the target base station is located in the trust list, or the trust level of the source base station to the target base station meets a preset condition or is higher than a preset threshold, the source base station may determine not to update the key.
  • the source base station maintains a trust list in which the correspondence between the PCI and the trust level is stored, or the evolved universal mobile communication system Terrestrial Radio Access Network (E) - UTRAN) Correspondence between E-UTRAN cell global identifier (ECGI) and trust level.
  • the correspondence may be determined by the deployment location of the source base station and the target base station, and may also be determined by the manufacturer of the base station or the like.
  • the trust level of the source base station and the trust threshold may be a value, and the trust level and the trust threshold may be pre-configured in the source base station.
  • the foregoing policy according to the user subscription information may include policy indication information of the source base station for the terminal device or a Packet Data Unit (PDU) session.
  • policy indication information can be obtained by the source base station from the core network device.
  • the core network device may include at least one of the following: a Policy Control Function (PCF) entity, a Unified Data Management (UDM) entity, and a Structured Data Storage Network Function (SDSF) entity.
  • PCF Policy Control Function
  • UDM Unified Data Management
  • SDSF Structured Data Storage Network Function
  • the unstructured data storage network function (UDSF) entity obtains, the policy of the user subscription information acquisition is used to indicate whether the access layer key used between the target base station and the terminal device is updated.
  • the key, or the above policy indication information indicates whether the access stratum key used for the PDU session between the target base station and the above-mentioned terminal device is an updated key.
  • the source base station may generate the first key according to the NCC, and send the first key, the NCC, and the first indication information to the target base station, where the first indication information Used to indicate that the first key is an updated key.
  • the source base station may generate the first key according to the foregoing NCC and the derived parameters.
  • the foregoing derivative parameters may include at least one of the following: a PCI, an E-UTRA Absolute Radio Frequency Channel Number-Down Link (EARFCN-DL), and an unused source base station. Next Hop (NH) or the access stratum key currently used by the source base station with the terminal device.
  • the source base station can perform longitudinal key derivation; if the NH bound to the NCC is already used, the source base station can perform lateral key derivation. If longitudinal key derivation is performed, the source base station will use NH as the key derivation parameter. If horizontal key derivation is performed, the source base station uses the access layer key currently used by the source base station as a derivative parameter. For the above two derivatives, the derived parameters may also include PCI and/or EARFCN-DL.
  • the source base station may send the first key and the first indication information to the target base station, where the first key is used between the source base station and the terminal device. a key, the first indication information is used to indicate that the first key is an unupdated key.
  • one or more decision points in the terminal device, the target base station, and the source base station are introduced to determine whether to update the key, and may be coordinated and determined according to real-time status information of each decision point and a preset policy. Whether to update the key provides a flexible way to update the key. In the case where a plurality of decision points are introduced, it is possible to determine whether to update the key by a plurality of decision points, thereby improving the security performance of communication between the terminal device and the target base station.
  • the method further includes: the source base station sending, to the target base station, an NCC for generating the first key.
  • the first indication information is used to indicate that the first key is not updated. Key.
  • the second request message is used to request to acquire a context of the terminal device; the first indication information is carried in a second response message, and the second response message includes the terminal The context of the device, the context of the terminal device containing the first key.
  • FIG. 5 is a schematic flowchart of a communication method 500 according to an embodiment of the present application.
  • the method of Figure 5 can be performed by a terminal device. It should be noted that the nouns, terms, and step descriptions involved in the embodiment shown in FIG. 5 can be referred to the related description in the embodiment shown in FIG. 3 or FIG. 4.
  • Method 500 includes:
  • the terminal device sends a first request message to the target base station, where the first request message includes first identifier information, where the first identifier information is used to indicate the terminal device and the source base station.
  • the first identifier information may be used to indicate the terminal device and the source base station by using the same identifier, or two identifiers may be used to respectively indicate the terminal device and the source base station.
  • a Resume Identifier may be used to indicate the terminal device and the source base station.
  • the PCI indication source base station and the cell radio temporary identifier may be used to indicate the terminal device.
  • C-RNTI cell radio temporary identifier
  • the terminal device may be in an inactive state, and the first request message may be used to request to restore an RRC connection of the terminal device.
  • the terminal device may move to the target base station if it is in an inactive state, and the terminal device may send a first request message to the target base station if the cell change is perceived.
  • the terminal device may be in an inactive state
  • the first identifier information may be a Resume ID
  • the first request message may be an RRC Connection Resume Request message.
  • the terminal device may be in a connected state, and the first request message may be used to request to re-establish an RRC connection of the terminal device.
  • the terminal device moves to the target base station while in the connected state.
  • the first request message may be sent to the target base station.
  • the terminal device may be in a connected state
  • the first identifier information may be a PCI
  • the first request message may be an RRC Connection Re-establishment Request message.
  • the terminal device receives second indication information that is sent by the target base station, where the second indication information is used to indicate that an access layer key between the target base station and the terminal device is an updated key. Or a key that has not been updated.
  • the first request message is used to request to restore an RRC connection of the terminal device, where the second indication information is carried in the first response message.
  • the first response message is used to indicate that the terminal device remains in an inactive state; or the first response message is used to instruct the terminal device to resume an RRC connection.
  • the second indication information may be carried in the first response message, where the first response message may be used to respond to the first request message, the first The response message may be used to indicate that the terminal device remains in an inactive state.
  • the first response message may be an RRC Connection Release message; or the first response message may be used to instruct the terminal device to resume the RRC connection, for example,
  • the first response message may be an RRC Connection Resume message; or the first response message may be used to indicate that the terminal device re-establishment is complete, for example, the first response message may be an RRC connection re-establishment (RRC) Connection Re-establishment) message.
  • RRC RRC connection re-establishment
  • the terminal device access layer key is an update key without restoring the RRC connection of the terminal device, thereby simplifying the decision-making secret The process of key update and saving signaling overhead.
  • the second indication information may indicate, in an explicit or implicit manner, that the access stratum key between the terminal device and the target base station is an updated key or an unupdated key.
  • the second indication information may directly indicate whether the access layer key is an updated key.
  • whether the access layer key is an update key may be indicated by whether the first response message sent by the target base station to the terminal device carries the NCC. If the NCC is carried in the first response message, the target base station indicates that the access layer key is the updated key; if the first response message does not carry the NCC, the target base station indicates that the access layer key is not Updated key.
  • the terminal device when the terminal device moves from the cell covered by the source base station to the cell covered by the target base station, the terminal device receives the second indication information sent by the target base station to indicate the connection between the terminal device and the target base station. Whether the inbound key is an updated key provides a flexible way to update the key.
  • the first request message includes fourth indication information, where the fourth indication information is used to request to update the key or not to update the key.
  • any one or any combination of the terminal device, the target base station, and the source base station may participate in a process of deciding whether to update an access layer key between the terminal device and the target base station.
  • the source base station may decide whether to update the key; or, the terminal device may decide whether to update the key; or, the target base station and the source base station may jointly decide whether to update the key; or may be jointly performed by the source base station and the terminal device. Whether the decision is to update the key; or, the terminal device and the target base station can jointly decide whether to update the key.
  • the source base station, the target base station, and the terminal device may jointly decide whether to update the key.
  • the terminal device may determine the fourth indication information according to the preset policy.
  • the preset policy may be a policy that is obtained according to the user subscription information.
  • the target base station may obtain the preset policy from the core network device.
  • the preset policy may also be pre-configured.
  • the foregoing preset policy may include determining fourth indication information according to the number of times that the terminal device does not update the key, or the foregoing preset policy may include determining that the fourth indication information is determined according to whether the first state information of the terminal device changes. .
  • the above-mentioned policy acquired according to user subscription information may include policy indication information for a terminal device or a PDU session.
  • These policy indication information can be obtained from the core network device.
  • the core network device may include at least one of the following: a PCF entity, a UDM entity, an SDSF entity, or a UDSF entity, where the user subscription information acquisition policy is used to indicate whether an access stratum key between the target base station and the foregoing terminal device is used.
  • the updated key, or the policy indication information indicates whether the access stratum key used for the PDU session between the target base station and the terminal device is an updated key.
  • the fourth indication information is used to request an update key, where the terminal device is not updated.
  • the number of key times is the number of unupdated keys in the time interval between the time when the terminal device last updated the key and the current time; or the number of unupdated keys in the terminal device is less than the count threshold
  • the fourth indication information is used to request that the key is not updated.
  • the size of the counting threshold may be determined according to an empirical value, which is not limited by the embodiment of the present application.
  • a counter may be set in the terminal device.
  • the terminal device sends the first request message once and receives the second indication information indicating that the key is not updated
  • the counter may be incremented by one, if the terminal device receives the update password. After the second indication of the key, the counter can be reset to zero.
  • the number of times the above unupdated key can be represented by a counter.
  • the fourth indication information may be used to request an update key; when the counter is less than the count threshold, the fourth indication information may be used to request that the key not be updated.
  • the fourth indication information is used to request an update key, where the first state information includes any one of the following The tracking area identity (TAI) of the terminal device, the radio access network (RAN) group to which the terminal device currently belongs, and the radio access technology currently used by the terminal device (Radio) Access technology, RAT); or, in a case where the first state information of the terminal device is not changed, the fourth indication information is used to request that the key is not updated.
  • TAI The tracking area identity
  • RAN radio access network
  • RAT radio access technology currently used by the terminal device
  • the method 500 further includes: the fourth indication information is used to request an update key, and the second indication information is used to indicate an access layer key between the terminal device and the target base station.
  • the terminal device disconnects from the target base station and reselects the base station.
  • the above method may be understood as: after receiving the second indication information, the terminal device checks whether the access layer key indicated by the second indication information conforms to the one-way decision principle.
  • the one-way decision principle refers to the case where there are two or more decision points (for example, a terminal device, a source base station, and a target base station), and there may be no update key to update secret.
  • the one-way decision process of the key without the decision process from updating the key to not updating the key.
  • the key needs to be updated as long as there is one decision point to determine the update key.
  • the terminal device may also check whether the access layer key indicated by the second indication information complies with the one-way decision after receiving the second indication information. in principle. For example, if the fourth indication information requests to update the key. The terminal device may verify whether the second indication information indicates that the access layer key between the terminal device and the target base station is an updated key. If the second indication information indicates that the access layer key is an unupdated key, it indicates that the second indication information does not indicate the access layer key according to the one-way decision principle. For example, in the case that the security performance of the target base station is attacked, the second indication information that does not comply with the one-way decision principle may be determined and sent.
  • the network currently accessed by the terminal device may have security problems, and the terminal device may choose to disconnect from the currently connected target base station and reselect the base station. For example, when the terminal device is in the RRC connected state, the terminal device may disconnect the RRC connection with the target base station, reselect the base station, and establish a new RRC connection with the reselected base station. When the terminal device is in an inactive state, the terminal device may stop the process of restoring the RRC connection with the target base station, reselect the base station, and request the reselected base station to resume the RRC connection.
  • the terminal device may disconnect the RRC connection with the target base station, reselect the base station, and establish a new RRC connection with the reselected base station.
  • the terminal device may stop the process of restoring the RRC connection with the target base station, reselect the base station, and request the reselected base station to resume the RRC connection.
  • one or more decision points in the terminal device, the target base station, and the source base station are introduced to determine whether to update the key, and may be coordinated and determined according to real-time status information of each decision point and a preset policy. Whether to update the key provides a flexible way to update the key. In the case where a plurality of decision points are introduced, it is possible to determine whether to update the key by a plurality of decision points, thereby improving the security performance of communication between the terminal device and the target base station.
  • the method 500 further includes: the terminal device receives an NCC sent by the target base station; and the second indication information is used to indicate that an access layer key between the terminal device and the target base station is In the case of the updated key, the terminal device generates a third key according to the NCC, and the third key is an access layer key between the terminal device and the target base station.
  • the foregoing terminal device may generate the third key according to the foregoing NCC and the derived parameters.
  • the foregoing derivation parameters may include at least one of the following: PCI, evolved universal land-based radio access downlink absolute radio frequency, and NH used by the source base station or access layer confidentiality between the source device and the terminal device currently used by the source base station. key.
  • the foregoing derivation parameters may include at least one of the following: PCI, an evolved universal land-based radio access downlink absolute radio frequency point, and an access stratum key currently used by the NH or the terminal device with the source base station.
  • the terminal device may perform longitudinal key derivation; if the NCC is the same as the NCC stored by the UE, the terminal device may perform horizontal key derivation. If longitudinal key derivation is performed, the terminal device will use NH as the key derivation parameter. If the horizontal key derivation is performed, the terminal device uses the access layer key currently used by the terminal device as a derivative parameter. For the above two derivatives, the derived parameters may also include PCI and/or EARFCN-DL.
  • FIG. 6 is a schematic flowchart of a communication method 600 according to an embodiment of the present application.
  • the method of Figure 6 can be performed by a base station. It should be noted that, if the method of FIG. 6 is applied to the application environment of FIG. 2, it is applicable to the case where the target base station and the source base station belong to the same CU, or the terminal device moves from the first cell covered by the same CU to the same CU. Among the second cells covered. It should be noted that the nouns, terms, and step descriptions involved in the embodiment shown in FIG. 6 can be referred to the related description in the embodiments shown in FIG. 3 to FIG. 5.
  • Method 600 includes:
  • the target base station receives the first request message from the terminal device, where the first request message includes first identifier information, where the first identifier information is used to indicate the terminal device and the source base station.
  • the target base station sends second indication information to the terminal device according to the first request message, where the second indication information is used.
  • the access layer key indicating the terminal device and the target base station is an updated key or an unupdated key.
  • the source base station and the target base station belong to the same CU, and the source base station and the target base station may be the same CU, or the source base station and the target base station may be the same base station.
  • the terminal device moves from a cell covered by the same CU to another cell covered by the same CU.
  • the target base station may determine the source base station according to the first identifier information included in the first request message, and then determine whether the source base station and the target base station belong to the same CU. If the source base station and the target base station belong to the same CU, the target base station and the source base station are the same base station. If the target base station and the source base station belong to the same CU, the target base station may send the terminal device to the terminal device according to the first request message and/or the preset policy. Sending the second indication information to indicate whether the access layer key is an updated key.
  • the first identifier information may be used to indicate the terminal device and the source base station by using the same identifier, or two identifiers may be used to respectively indicate the terminal device and the source base station.
  • a Resume Identifier may be used to indicate the terminal device and the source base station.
  • the physical cell identifier may be used to indicate the source base station, and the cell radio network temporary identifier (Cell Radio temporary) is used.
  • the identifier, C-RNTI indicates the terminal device.
  • the target base station may send the second indication information to the terminal device to indicate whether the access layer key between the terminal device and the target base station is updated.
  • the latter key provides a flexible way to update the key.
  • the first request message further includes fourth indication information
  • the fourth indication information is used to request an update key
  • the second indication information is used to indicate The access stratum key between the terminal device and the target base station is an updated key.
  • any one or combination of the terminal device and the target base station may participate in a process of deciding whether to update an access layer key between the terminal device and the target base station. For example, whether the key is updated by the target base station may be decided; or the terminal device may decide whether to update the key; or, the terminal device and the target base station may jointly decide whether to update the key.
  • the target base station may participate in the process of deciding whether to update the key, or the target base station may not participate in the process of deciding whether to update the key, but determine the second indication information according to the fourth indication information sent by the terminal device.
  • the method may further include: determining, by the target base station, the update key or according to the preset policy. Do not update the key.
  • the foregoing preset policy may be a policy that is obtained according to the user subscription information.
  • the target base station may obtain the preset policy from the core network device.
  • the above preset policy may also be pre-configured.
  • the foregoing preset policy may be determining whether to update the key according to the number of times the terminal device does not update the key in the same CU.
  • the preset policy may also be that the target base station and the source base station do not need to update the key if they belong to the same CU.
  • step 602 may include: the target base station may send the second indication information according to the fourth indication information and the preset policy. For example, if the fourth indication information indicates that the update key and/or the target base station determines the update key according to the preset policy, the target base station generates a new access layer key, and the second indication information is used to indicate the access layer. The key is an updated key; if the fourth indication information indicates that the key is not updated, and the target base station determines not to update the key according to the preset policy, the second indication information is used to indicate that the access layer key is not Updated key.
  • the target base station may determine whether to update the key according to the fourth indication information.
  • the target base station updates the key; when the fourth indication information indicates that the key is not updated, the target base station does not update the key, that is, the target base station itself does not participate in the process of deciding to update the key.
  • one or two decision points of the terminal device and the target base station are introduced to determine whether to update the key, and the key may be coordinated according to real-time status information of each decision point and a preset policy. , thus providing a flexible way to update the key.
  • two decision points it is possible to determine whether to update the key by the two decision points, thereby improving the security performance of the communication between the terminal device and the target base station.
  • the introduction of two decision points can balance the decision-making ability of each decision point, or by decentralized decision-making ability, so that each decision point can determine whether to update the key according to their respective states, and can take into account the state of other decision points, thus providing A secure and flexible solution for updating keys.
  • the second indication information is used to indicate between the terminal device and the target base station, where the number of unupdated keys of the terminal device is greater than or equal to a count threshold.
  • the access layer key is an updated key, wherein the number of unupdated keys of the terminal device is an unupdated time in a time interval between a time when the last update key of the terminal device is updated to a current time. The number of keys.
  • the method 600 further includes The target base station generates the first key according to an NCC, where the first key is an access layer key between the terminal device and the target base station; and the target base station sends the terminal key to the terminal device The NCC.
  • the target base station may generate the second key according to the foregoing NCC and the derived parameters.
  • the foregoing derivative parameter may include at least one of the following: a PCI, an E-UTRA Absolute Radio Frequency Channel Number-Down Link (EARFCN-DL), and an unused target base station. Next Hop (NH) or the access stratum key currently used by the target base station with the terminal device.
  • a PCI a PCI
  • E-UTRA Absolute Radio Frequency Channel Number-Down Link E-UTRA Absolute Radio Frequency Channel Number-Down Link
  • NH Next Hop
  • the access stratum key currently used by the target base station with the terminal device.
  • the target base station may perform longitudinal key derivation; if the NH bound to the NCC is already used, the target base station may perform lateral key derivation. If longitudinal key derivation is performed, the target base station will use NH as the key derivation parameter. If horizontal key derivation is performed, the target base station uses the access layer key currently used by the target base station as a derivative parameter. For the above two derivatives, the derived parameters may also include PCI and/or EARFCN-DL.
  • the second indication information is used to indicate The access layer key between the terminal device and the target base station is an unupdated key; or, in the case that the number of unupdated keys of the terminal device is less than the count threshold, the second The indication information is used to indicate that the access layer key between the terminal device and the target base station is an unupdated key, wherein the number of unupdated keys of the terminal device is the last update of the terminal device The number of unupdated keys in the time interval from the time of the key to the current time.
  • a counter corresponding to the terminal device may be set in the target base station, and each time the target base station sends the second indication information indicating that the first key is an unupdated key to the terminal device, the counter may be incremented by one, if the target base station sends After the second indication indicating that the first key is the updated key, the counter can be reset to zero.
  • the number of times the above unupdated key can be represented by a counter.
  • the second indication information may be used to indicate that the first key is the updated key; when the counter is less than the counting threshold, the second indication information may be used to indicate that the first key is updated Key.
  • the terminal device is in an inactive state
  • the first request message is used to request to restore a radio resource control RRC connection of the terminal device
  • the second indication information is carried in the first response.
  • the first response message is used to indicate that the terminal device remains in an inactive state; or the first response message is used to instruct the terminal device to resume an RRC connection.
  • FIG. 7 is a schematic diagram of a specific embodiment of an embodiment of the present application.
  • Figure 7 shows the communication process in which the source base station determines as a decision point whether to update the key.
  • the steps performed by the source base station may be performed by the CU.
  • the same or similar content as the above in the method 700 will not be repeated here.
  • method 700 includes:
  • the terminal device sends a first request message to the target base station, where the first request message includes first identifier information.
  • the first request message may refer to the related description in the embodiment shown in FIG. 3.
  • the first identifier information may be a Resume ID, or the first identifier information may be a C-RNTI for indicating the terminal device and a PCI for indicating the source base station.
  • the target base station may determine the source base station according to the first identifier information.
  • the terminal device may move from the coverage area of the source base station to the coverage area of the target base station while in an inactive state or a connected state.
  • the first request message may include an RRC Connection Resume Request (RRC Connection Resume Request) message.
  • RRC Connection Resume Request RRC Connection Resume Request
  • the RRC Connection Recovery Request message is used to request to resume the RRC connection.
  • the first request message may include other types of information, which is not limited by the embodiment of the present application.
  • the first request message may further include message authentication code (MAC) information, where the MAC information is used to indicate that the first request message is generated by a legal terminal device.
  • the MAC information may be obtained by the terminal device according to a RRC integrity protection key (for example, krrc-int) derived from a gNB root key (for example, KgNB) and an integrity protection algorithm.
  • the target base station sends a second request message to the source base station, where the second request message includes second identifier information, where the second identifier information is used to indicate the terminal device.
  • the second identifier information and the second request message may be referred to the related description in the embodiment shown in FIG. 3.
  • the second identification information may be a Resume ID.
  • the second identification information may be a C-RNTI of the terminal device.
  • the second request message may be a context request message, where the context request message is used to request to obtain context information corresponding to the terminal device.
  • the context request message further includes the foregoing MAC information.
  • the source base station determines whether to update the key.
  • the source base station may determine whether to update the key according to a preset policy.
  • a preset policy For the content of the above preset policy, reference may be made to the related description in the embodiment shown in FIG.
  • the source base station may determine a context of the locally stored terminal device according to the second identifier information included in the context request message.
  • the source base station may check the MAC according to the security parameter of the context of the terminal device.
  • security parameters in context may include an access stratum key between the source base station and the terminal device, an integrity protection algorithm, and the like.
  • the source base station may derive an RRC integrity protection key according to the access layer key between the source base station and the terminal device, and verify the MAC according to the foregoing RRC integrity protection key and the integrity protection algorithm.
  • step S704 may be performed.
  • the source base station sends the first indication information and the first key to the target base station, where the first indication information is used to indicate that the first key is an updated key or an unupdated key.
  • the related content of the first indication information and the first key may be referred to the related description of the embodiment of FIG. 3.
  • the first indication information may be carried in the second response message, and the second response message is used to respond to the second request message.
  • the second response message may be a context response message, where the context response message includes a context of the terminal device, and the context of the terminal device includes the first key.
  • the first key is the updated key, and the first indication information is used to indicate that the first key is the updated key; when the source is in step S703
  • the first key is a key between the terminal device and the source base station, and the first indication information is used to indicate that the first key is an unupdated key.
  • the first indication information may further include an NCC, and the first indication information may further include an NCC, where the first key is according to the NCC derived key.
  • the retained key command (retain-key) or the modified secret may be set in the first indication information.
  • Key command (change-key) the retain-key instruction or the change-key instruction can also be applied to the second indication information to the fourth indication information.
  • KgNB represents the original key used between the source base station and the terminal device
  • KgNB* represents the new key. It should be noted that KgNB* may be the first key in the embodiment of FIG. 3 to FIG. 5.
  • the target base station sends the second indication information to the terminal device.
  • the second indication information is used to indicate that the access stratum key between the terminal device and the target base station is an updated key or an unupdated key.
  • the target base station may use the first key as an access layer key between the terminal device and the terminal device.
  • the second indication information may indicate, in at least two manners, whether an access layer key between the terminal device and the target base station is replaced.
  • the second indication information may not carry a retain-key. Instead, whether or not the key is replaced is indicated by whether or not to carry the NCC. For example, if the second indication information carries the NCC, the update key is indicated. If the second indication information does not carry the NCC, it indicates that the key is not updated.
  • the second indication information may be carried in the first response message, where the first response message may be used to indicate that the terminal device remains in an inactive state, or the first response message may be used to instruct the terminal device to resume the RRC connection.
  • the first response message may include an RRC Connection Release (RRC Connection Release) message or an RRC Connection Recovery message.
  • the network side may not resume the RRC connection, but send an RRC connection release message. Therefore, the migration of the context is completed in the process that the terminal device is in an inactive state, and the RRC connection does not need to be reestablished, which saves signaling overhead.
  • the terminal device determines an access layer key according to the second indication information.
  • the terminal device derives a new key KgNB* according to the NCC carried by the second indication information.
  • KgNB* is used as an access layer key for communication between the terminal device and the base station.
  • the source base station in a case where the terminal device moves from the source base station coverage area to the target base station coverage area, the source base station is introduced to determine whether to update the access layer key between the target base station and the terminal device, and a type is provided.
  • a flexible way to update keys in a case where the terminal device moves from the source base station coverage area to the target base station coverage area, the source base station is introduced to determine whether to update the access layer key between the target base station and the terminal device, and a type is provided.
  • FIG. 8 shows a communication procedure in which the terminal device determines as a decision point whether to update the key.
  • the steps performed by the source base station may be performed by the CU.
  • the same or similar content as the above in the method 800 will not be repeated here. As shown in FIG. 8, method 800 includes:
  • the terminal device determines fourth indication information, where the fourth indication information is used to request an update key.
  • the terminal device may determine the fourth indication information according to the preset policy.
  • the preset strategy can refer to the embodiment of FIG. 5.
  • the terminal device may move from the coverage area of the source base station to the coverage area of the target base station while in an inactive state or a connected state.
  • the terminal device sends a first request message to the target base station.
  • the first request message includes a first identifier and fourth indication information.
  • the fourth indication information is used to request to update the key or not to update the key.
  • the first request message may refer to the related description in the embodiment shown in FIG. 3.
  • the first identifier information may be a Resume ID, or the first identifier information may be a C-RNTI for indicating the terminal device and a PCI for indicating the source base station.
  • the target base station may determine the source base station according to the first identifier information.
  • the fourth indication information may carry a retain-key instruction or a change-key instruction to indicate whether the request updates the key.
  • the first request message may include an RRC Connection Resume Request (RRC Connection Resume Request) message.
  • RRC Connection Resume Request RRC Connection Resume Request
  • the RRC Connection Recovery Request message is used to request to resume the RRC connection.
  • the first request message may include other types of information, which is not limited by the embodiment of the present application.
  • the first request message may further include MAC information.
  • the target base station and the source base station are gNBs in FIG.
  • the source base station and the target base station may belong to the same CU.
  • the source base station and the target base station are the same base station.
  • the method 800 does not need to execute S803 to S804, but performs S805 next.
  • the target base station sends a second request message to the source base station, where the second request message includes second identifier information and third indication information.
  • the second request message and the second identification information may refer to the related description of the embodiment of FIG. 3.
  • the second identifier information is used to indicate the terminal device.
  • the second identification information may be a Resume ID.
  • the second identification information may be a C-RNTI of the terminal device.
  • the second request message may be a context request message, where the context request message is used to request to acquire context information corresponding to the terminal device.
  • the context request message may further include MAC information.
  • the third indication information is used to request to update the key or not to update the key.
  • the target base station may determine the third indication information according to the fourth indication information. For example, if the fourth indication information requests an update key, the third indication information requests an update key. If the fourth indication information requests not to update the key, the third indication information requests not to update the key.
  • the third indication information may indicate whether to request an update key by carrying retain-key signaling or change-key signaling.
  • the terminal device is introduced as a single decision point to determine whether to request an update key, and thus the target base station does not participate in the process of deciding whether to update the key, but is equivalent to transparent transmission of the fourth. Instructions.
  • a method of using a target base station as a decision point is also introduced, in which case the target base station participates in a decision to determine whether to update the key, and It is not the result of the decision of the transparent transmission terminal equipment.
  • the source base station sends the first indication information and the first key to the target base station, where the first indication information is used to indicate that the first key is an updated key or an unupdated key.
  • the first indication information may be carried in the second response message, and the second response message is used to respond to the second request message.
  • the second response message may be a context response message, where the context response message includes a context of the terminal device, and the context of the terminal device includes the first key.
  • the source base station may determine, according to the third indication information, whether to update the key. For example, when the third indication information requests not to update the key, it is determined not to update the key. If the third indication information requests an update key, it is determined to update the key.
  • the first indication information is used to indicate that the first key is the updated key; when it is determined that the key is not updated, the first The key is a key between the terminal device and the source base station, and the first indication information is used to indicate that the first key is an unupdated key.
  • the first indication information may further include an NCC, and the first indication information may further include an NCC, where the first key is according to the NCC derived key.
  • the retained key command (retain-key) or the modified secret may be set in the first indication information.
  • Key command (change-key) the retain-key instruction or the change-key instruction can also be applied to the second indication information to the fourth indication information.
  • the source base station may determine a context of the locally stored terminal device according to the second identifier information included in the context request message.
  • the source base station may check the MAC according to the security parameter of the context of the terminal device.
  • security parameters in context may include an access stratum key between the source base station and the terminal device, an integrity protection algorithm, and the like.
  • the source base station may derive an RRC integrity protection key according to the access layer key between the source base station and the terminal device, and verify the MAC according to the foregoing RRC integrity protection key and the integrity protection algorithm.
  • step S805 may be performed.
  • the target base station sends the second indication information to the terminal device.
  • the second indication information is used to indicate that the access stratum key between the terminal device and the target base station is an updated key or an unupdated key.
  • the target base station may use the first key as an access layer key between the terminal device and the terminal device.
  • the second indication information may indicate, in at least two manners, whether an access layer key between the terminal device and the target base station is replaced.
  • the second indication information may not carry a retain-key. Instead, whether or not the key is replaced is indicated by whether or not to carry the NCC. For example, if the second indication information carries the NCC, the update key is indicated. If the second indication information does not carry the NCC, it indicates that the key is not updated.
  • the second indication information may be carried in the first response message, where the first response message may be used to indicate that the terminal device remains in an inactive state, or the first response message may be used to instruct the terminal device to resume the RRC connection.
  • the first response message may include an RRC Connection Release (RRC Connection Release) message or an RRC Connection Recovery message.
  • the target base station may determine and send the second indication information according to the first request message.
  • the target base station may determine and send the second indication information according to the first request message.
  • the network side may not resume the RRC connection, but send an RRC connection release message.
  • the migration of the context may be completed in the process that the terminal device is in an inactive state, and the RRC connection does not need to be re-established.
  • the terminal device determines an access layer key according to the second indication information.
  • the terminal device may check whether the content indicated by the second indication information conforms to the one-way decision principle. If the content indicated by the second indication information conforms to the one-way decision principle, the terminal device may disconnect from the target base station and reselect the base station for access. If the second indication information is not degraded, the terminal device may select to retain the original key or generate a new key according to the indication of the second indication information.
  • the foregoing non-compliance with the one-way decision principle may refer to the case where the fourth indication information requests the update of the key, and the second indication information indicates that the access layer key between the terminal device and the target base station is an unupdated key.
  • the embodiment of the present application tends to securely update the key policy process. Therefore, if the terminal device can detect that the second indication information sent by the target base station does not comply with the one-way decision principle, the device may be disconnected from the target base station and reselected. The base station performs access, thereby improving the security of the communication.
  • the terminal device in a case where the terminal device moves from the source base station coverage area to the target base station coverage area, the terminal device is introduced to determine whether to update the access layer key between the target base station and the terminal device, and provides a A flexible way to update keys.
  • FIG. 9 shows a communication procedure in which a target base station and a source base station collectively determine whether to update a key as a decision point.
  • the source base station is the gNB in FIG. 2
  • the steps performed by the source base station may be performed by the CU.
  • the same or similar content as the above in the method 900 will not be repeated here.
  • method 900 includes:
  • the terminal device sends a first request message to the target base station, where the first request message includes first identifier information.
  • the first request message may refer to the related description in the embodiment shown in FIG. 3.
  • the first identifier information may be a Resume ID, or the first identifier information may be a C-RNTI for indicating the terminal device and a PCI for indicating the source base station.
  • the target base station may determine the source base station according to the first identifier information.
  • the terminal device may move from the coverage area of the source base station to the coverage area of the target base station while in an inactive state or a connected state.
  • the first request message may include an RRC Connection Resume Request (RRC Connection Resume Request) message.
  • RRC Connection Resume Request RRC Connection Resume Request
  • the RRC Connection Recovery Request message is used to request to resume the RRC connection.
  • the first request message may include other types of information, which is not limited by the embodiment of the present application.
  • the first request message may further include message authentication code (MAC) information, where the MAC information is used to indicate that the first request message is generated by a legal terminal device.
  • the MAC information may be obtained by the terminal device according to a RRC integrity protection key (for example, krrc-int) derived from a gNB root key (for example, KgNB) and an integrity protection algorithm.
  • the target base station determines third indication information, where the third indication information is used to request to update the key or not to update the key.
  • the target base station may determine the third indication information according to the preset policy.
  • the preset policy can be referred to the related content of the embodiment of FIG. 3.
  • the target base station may determine a source base station, where the source base station stores context information of the terminal device.
  • the target base station sends a second request message to the source base station, where the second request message includes second identifier information and third indication information.
  • the second identifier information and the second request message may be referred to the related description in the embodiment shown in FIG. 3.
  • the second identification information may be a Resume ID.
  • the second identification information may be a C-RNTI of the terminal device.
  • the second request message may be a context request message, where the context request message is used to request to obtain context information corresponding to the terminal device.
  • the context request message further includes the foregoing MAC information.
  • the source base station determines whether to update the key.
  • the source base station may determine whether to update the key according to the third indication information and the preset policy.
  • the third indication information and the preset policy refer to the embodiment of FIG. 4 .
  • the source base station may determine a context of the locally stored terminal device according to the second identifier information included in the context request message.
  • the source base station may check the MAC according to the security parameter of the context of the terminal device.
  • security parameters in context may include an access stratum key between the source base station and the terminal device, an integrity protection algorithm, and the like.
  • the source base station may derive an RRC integrity protection key according to the access layer key between the source base station and the terminal device, and verify the MAC according to the foregoing RRC integrity protection key and the integrity protection algorithm.
  • step S905 may be performed.
  • the source base station sends the first indication information and the first key to the target base station, where the first indication information is used to indicate that the first key is an updated key or an unupdated key.
  • the first indication information may include a retian-key. If the first indication information indicates that the access layer key between the terminal device and the target base station is an updated key, the first indication information may further include an NCC, where the first key is a KgNB derived from the NCC. *.
  • the first indication information may be carried in the second response message, where the second response message may include a context response message, where the context response message includes a context of the terminal device, and the context of the terminal device includes the first secret key.
  • the target base station receives the first key and the first indication information sent by the source base station, and determines the second indication information according to the first indication information.
  • the second indication information is used to indicate that the access stratum key between the terminal device and the target base station is an updated key or an unupdated key.
  • the target base station may check whether the first key indicated by the first indication information conforms to the one-way decision principle, and determine, according to the check result, whether the first key is used as an access layer between the target base station and the terminal device.
  • the target base station may check whether the first key indicated by the first indication information conforms to the one-way decision principle, and determine, according to the check result, whether the first key is used as an access layer between the target base station and the terminal device. Key.
  • a one-way decision principle reference may be made to the related description of the embodiment of FIG.
  • the target base station sends the second indication information to the terminal device.
  • the second indication information is used to indicate that the access stratum key between the terminal device and the target base station is an updated key or an unupdated key.
  • the target base station may use the first key as an access layer key between the terminal device and the terminal device.
  • the second indication information may indicate, in at least two manners, whether an access layer key between the terminal device and the target base station is replaced.
  • the second indication information may not carry a retain-key. Instead, whether or not the key is replaced is indicated by whether or not to carry the NCC. For example, if the second indication information carries the NCC, the update key is indicated. If the second indication information does not carry the NCC, it indicates that the key is not updated.
  • the second indication information may be carried in the first response message, where the first response message may be used to indicate that the terminal device remains in an inactive state, or the first response message may be used to instruct the terminal device to resume the RRC connection.
  • the first response message may include an RRC Connection Release (RRC Connection Release) message or an RRC Connection Recovery message.
  • the network side may not resume the RRC connection, but send an RRC connection release message.
  • the context migration can be completed in the process that the terminal device is in an inactive state, and the RRC connection does not need to be re-established, thereby saving signaling overhead.
  • the terminal device determines an access layer key according to the second indication information.
  • the terminal device derives a new key KgNB* according to the NCC carried by the second indication information.
  • KgNB* is used as an access layer key for communication between the terminal device and the base station.
  • the target base station and the source base station are introduced to determine whether to update the access layer key between the target base station and the terminal device, Coordinating to determine whether to update the key provides a flexible way to update the key.
  • FIG. 10 shows a communication procedure in which a terminal device, a target base station, and a source base station collectively determine whether to update a key as a decision point.
  • the source base station is the gNB in FIG. 2
  • the steps performed by the source base station may be performed by the CU.
  • the same or similar content as above in the method 1000 will not be repeated here.
  • method 1000 includes:
  • the terminal device determines fourth indication information, where the fourth indication information is used to request an update key.
  • the terminal device may determine the fourth indication information according to the preset policy.
  • the preset strategy can refer to the embodiment of FIG. 5.
  • the terminal device may move from the coverage area of the source base station to the coverage area of the target base station while in an inactive state or a connected state.
  • the terminal device sends a first request message to the target base station.
  • the first request message includes a first identifier and fourth indication information.
  • the fourth indication information is used to request to update the key or not to update the key.
  • the first request message may refer to the related description in the embodiment shown in FIG. 3.
  • the first identifier information may be a Resume ID, or the first identifier information may be a C-RNTI for indicating the terminal device and a PCI for indicating the source base station.
  • the target base station may determine the source base station according to the first identifier information.
  • the fourth indication information may carry a retain-key instruction or a change-key instruction to indicate whether the request updates the key.
  • the first request message may include an RRC Connection Resume Request (RRC Connection Resume Request) message.
  • RRC Connection Resume Request RRC Connection Resume Request
  • the RRC Connection Recovery Request message is used to request to resume the RRC connection.
  • the first request message may include other types of information, which is not limited by the embodiment of the present application.
  • the first request message may further include MAC information.
  • the target base station determines third indication information, where the third indication information is used to request to update the key or not to update the key.
  • the target base station may determine the third indication information according to the fourth indication information and the preset policy.
  • the target base station may determine the third indication information according to the fourth indication information and the preset policy.
  • the target base station may determine a source base station, where the source base station stores context information of the terminal device.
  • the target base station and the source base station are gNBs in FIG.
  • the source base station and the target base station may belong to the same CU.
  • the source base station and the target base station are the same base station.
  • the method 1000 does not need to execute S1004 to S1006, but performs S1007 next.
  • the target base station sends a second request message to the source base station, where the second request message includes second identifier information and third indication information.
  • the second identifier information and the second request message may be referred to the related description in the embodiment shown in FIG. 3.
  • the second identification information may be a Resume ID.
  • the second identification information may be a C-RNTI of the terminal device.
  • the second request message may be a context request message, where the context request message is used to request to obtain context information corresponding to the terminal device.
  • the context request message further includes the foregoing MAC information.
  • the terminal device, the target base station, and the source base station are collectively used as the decision point.
  • the target base station participates in the decision to determine whether to update the key, instead of transmitting the terminal device. The result of the decision.
  • the source base station determines whether to update the key.
  • the source base station may determine whether to update the key according to the third indication information and the preset policy.
  • the third indication information and the preset policy refer to the embodiment of FIG. 4 .
  • the source base station may determine a context of the locally stored terminal device according to the second identifier information included in the context request message.
  • the source base station may check the MAC according to the security parameter of the context of the terminal device.
  • security parameters in context may include an access stratum key between the source base station and the terminal device, an integrity protection algorithm, and the like.
  • the source base station may derive an RRC integrity protection key according to the access layer key between the source base station and the terminal device, and verify the MAC according to the foregoing RRC integrity protection key and the integrity protection algorithm.
  • step S1006 may be performed.
  • the source base station sends the first indication information and the first key to the target base station, where the first indication information is used to indicate that the first key is an updated key or an unupdated key.
  • the first indication information may include a retian-key. If the first indication information indicates that the access layer key between the terminal device and the target base station is an updated key, the first indication information may further include an NCC, where the first key is a KgNB derived from the NCC. *.
  • the first indication information may be carried in the second response message, where the second response message may include a context response message, where the context response message includes a context of the terminal device, and the context of the terminal device includes the first secret key.
  • the target base station receives the first key and the first indication information sent by the source base station, and determines the second indication information according to the first indication information.
  • the second indication information is used to indicate that the access stratum key between the terminal device and the target base station is an updated key or an unupdated key.
  • the target base station may check whether the first key indicated by the first indication information conforms to the one-way decision principle, and determine, according to the check result, whether the first key is used as an access layer between the target base station and the terminal device.
  • the target base station may check whether the first key indicated by the first indication information conforms to the one-way decision principle, and determine, according to the check result, whether the first key is used as an access layer between the target base station and the terminal device. Key.
  • a one-way decision principle reference may be made to the related description of the embodiment of FIG.
  • the target base station sends the second indication information to the terminal device.
  • the second indication information is used to indicate that the access stratum key between the terminal device and the target base station is an updated key or an unupdated key.
  • the target base station may use the first key as an access layer key between the terminal device and the terminal device.
  • the second indication information may indicate, in at least two manners, whether an access layer key between the terminal device and the target base station is replaced.
  • the second indication information may not carry a retain-key. Instead, whether or not the key is replaced is indicated by whether or not to carry the NCC. For example, if the second indication information carries the NCC, the update key is indicated. If the second indication information does not carry the NCC, it indicates that the key is not updated.
  • the second indication information may be carried in the first response message, where the first response message may be used to indicate that the terminal device remains in an inactive state, or the first response message may be used to instruct the terminal device to resume the RRC connection.
  • the first response message may include an RRC Connection Release (RRC Connection Release) message or an RRC Connection Recovery message.
  • the network side may not resume the RRC connection but send an RRC connection release message in S1008.
  • the migration of the context can be completed in the process that the terminal device is in an inactive state, and the RRC connection does not need to be re-established, thereby saving signaling overhead.
  • the terminal device determines an access layer key according to the second indication information.
  • the terminal device may check whether the content indicated by the second indication information conforms to the one-way decision principle. If the content indicated by the second indication information conforms to the one-way decision principle, the terminal device may disconnect from the target base station and reselect the base station for access. If the second indication information is not degraded, the terminal device may select to retain the original key or generate a new key according to the indication of the second indication information.
  • the foregoing non-compliance with the one-way decision principle may refer to that, in the case that the fourth indication information requests the update of the key, the second indication information indicates that the access layer key between the terminal device and the target base station is an unupdated key.
  • the embodiment of the present application tends to securely update the key policy process. Therefore, if the terminal device can detect that the second indication information sent by the target base station does not comply with the one-way decision principle, the device may be disconnected from the target base station and reselected. The base station performs access, thereby improving the security of the communication.
  • the access layer key provides a flexible way to update the key.
  • FIG. 11 shows a communication method 1100.
  • Figure 11 illustrates the process by which the target base station can continue to initiate a path switch after performing any of methods 300 through 1000.
  • the target base station can acquire unused ⁇ NH, NCC ⁇ pairs from the AMF for key derivation. In turn, forward security is achieved, that is, the source base station cannot derive the key currently used by the target base station.
  • Method 1100 includes:
  • S1101 Perform any one of method 300 to method 1000.
  • S1102 Perform a path switching process between the target base station and the AMF to notify the AMF link change, and the AMF will carry a new ⁇ NH, NCC ⁇ pair in the reply message.
  • the terminal device determines whether to update the key. Alternatively, the terminal device may determine to update the key again after a period of time after performing any of the methods 300 to 1000.
  • the terminal device sends a first request message to the target base station, where the first request message includes first identifier information, where the first identifier information is used to indicate the terminal device and the source base station, and the first request message may be, for example, an RRC connection recovery request. Message.
  • the first request message may include fourth indication information to indicate whether the terminal device requests to update the key.
  • the target base station generates a new key according to the new ⁇ NH, NCC ⁇ pair to serve as an access layer key between the terminal device and the target base station.
  • the target base station sends a first response message to the terminal device, where the first response message includes the second indication information and the NCC, where the second indication information is used to indicate the update key.
  • the first response message is for responding to the first request message.
  • the first response message may be an RRC Connection Abort message or an RRC Connection Recovery message.
  • the target base station may initiate a path switch process.
  • the target base station can acquire unused ⁇ NH, NCC ⁇ pairs from the AMF for key derivation.
  • forward security is achieved, that is, the source base station cannot derive the key currently used by the target base station, thereby improving communication security.
  • FIG. 12 is a schematic block diagram of a base station 1200 according to an embodiment of the present application. It should be understood that the base station 1200 can perform the various steps performed by the target base station in the methods of FIGS. 1 through 11, and to avoid repetition, it will not be described in detail herein.
  • the base station 1200 can include various types of base stations, such as gNBs, NR base stations, macro base stations, micro base stations, and the like.
  • the base station 1200 includes:
  • the receiving unit 1210 is configured to receive, by the terminal device, a first request message, where the first request message includes first identifier information, where the first identifier information is used to indicate the terminal device and the source base station;
  • the sending unit 1220 is configured to send, according to the first request message, a second request message to the source base station, where the second request message includes second identifier information, where the second identifier information is used to indicate the terminal device ;
  • the receiving unit 1210 is further configured to receive, by the source base station, a first key and first indication information, where the first indication information is used to indicate that the first key is an updated key or not updated. Key
  • the sending unit 1220 is further configured to send the second indication information to the terminal device according to the first indication information, where the second indication information is used to indicate the access between the terminal device and the target base station.
  • the layer key is an updated key or a key that is not updated.
  • FIG. 13 is a schematic block diagram of a base station 1300 according to an embodiment of the present application. It should be understood that the base station 1300 can perform the various steps performed by the source base station in the methods of FIGS. 1 through 11, and in order to avoid repetition, it will not be described in detail herein.
  • the base station 1300 can include various types of base stations, such as gNBs, NR base stations, macro base stations, micro base stations, and the like.
  • the base station 1300 includes:
  • the receiving unit 1310 is configured to receive a second request message from the target base station, where the second request message includes second identifier information, where the second identifier information is used to indicate the terminal device;
  • the sending unit 1320 is configured to send, according to the second request message, the first key and the first indication information to the target base station, where the first indication information is used to indicate that the first key is updated Key or unupdated key.
  • FIG. 14 is a schematic block diagram of a terminal device 1400 according to an embodiment of the present application. It should be understood that the terminal device 1400 can perform the various steps performed by the terminal device in the methods of FIGS. 1 through 11, and in order to avoid repetition, it will not be described in detail herein.
  • the terminal device 1400 may include various types of base stations, such as gNBs, NR base stations, macro base stations, micro base stations, and the like.
  • the terminal device 1400 includes:
  • the sending unit 1410 is configured to send a first request message to the target base station, where the first request message includes first identifier information, where the first identifier information is used to indicate the terminal device and the source base station;
  • the receiving unit 1420 is configured to receive second indication information that is sent by the target base station, where the second indication information is used to indicate that an access layer key between the target base station and the terminal device is an updated key. Or a key that has not been updated.
  • FIG. 15 is a schematic block diagram of a base station 1500 according to an embodiment of the present application. It should be understood that the base station 1500 can perform the various steps performed by the target base station in the method of FIG. 6, and to avoid repetition, it will not be described in detail herein.
  • the base station 1500 can include various types of base stations, such as gNBs, NR base stations, macro base stations, micro base stations, and the like.
  • the base station 1500 includes:
  • the receiving unit 1510 is configured to receive, by the terminal device, a first request message, where the first request message includes first identifier information, where the first identifier information is used to indicate the terminal device and the source base station;
  • the sending unit 1520 is configured to: when the source base station and the target base station belong to the same CU, the target base station sends second indication information to the terminal device according to the first request message, where the second The indication information is used to indicate that the access stratum key between the terminal device and the target base station is an updated key or an unupdated key.
  • the base station shown in FIG. 15 may be a chip or a circuit.
  • a chip or circuit that can be placed in a base station.
  • the base station 1500 corresponds to the source base stations in FIGS. 1 through 11. Further, the above communication interface 1510 can also be interchanged with the transceiver.
  • the transceiver includes a receiver and a transmitter. Still further, the base station 1500 can also include a bus system.
  • the processor 1530, the memory 1520, the receiver and the transmitter are connected by a bus system, and the processor 1530 is configured to execute instructions stored by the memory 1520 to control the receiver to receive signals and control the transmitter to send signals to complete the communication of the present application.
  • the receiver and the transmitter may be the same or different physical entities. When they are the same physical entity, they can be collectively referred to as transceivers.
  • the memory 1520 can be integrated in the processor 1530 or can be disposed separately from the processor 1530.
  • the functions of the receiver and the transmitter can be implemented by using a transceiver circuit or a transceiver chip.
  • the processor 1530 can be implemented by a dedicated processing chip, a processing circuit, a processor, or a general purpose chip.
  • a base station provided by an embodiment of the present application may be implemented by using a general-purpose computer.
  • Program code to implement processor 1530, receiver and transmitter functions is stored in a memory that implements the functions of processor 1530, receiver, and transmitter by executing code in memory.
  • FIG. 16 is a schematic block diagram of a base station 1600 according to an embodiment of the present application. It should be understood that the base station 1600 can perform the various steps performed by the target base station in the methods of FIGS. 1 through 11, and to avoid repetition, it will not be described in detail herein.
  • Base station 1600 can include various types of base stations, such as gNBs, NR base stations, macro base stations, micro base stations, and the like.
  • the base station 1600 includes:
  • a memory 1620 for storing instructions
  • the processor 1630 is respectively connected to the memory 1620 and the communication interface 1610, and is configured to execute the instruction stored by the memory 1620 to perform the following steps when the instruction is executed:
  • the communication interface 1610 Receiving, by the communication interface 1610, a first request message, where the first request message includes first identifier information, where the first identifier information is used to indicate the terminal device and the source base station;
  • the second indication information Transmitting, according to the first indication information, the second indication information to the terminal device by using the communication interface 1610, where the second indication information is used to indicate an access layer confidentiality between the terminal device and the target base station.
  • the key is an updated key or an unupdated key.
  • the base station shown in FIG. 16 may be a chip or a circuit.
  • a chip or circuit that can be placed in a base station.
  • the base station 1600 corresponds to the source base station in FIGS. 1 through 11.
  • the above communication interface 1610 can also be interchanged with the transceiver.
  • the transceiver includes a receiver and a transmitter.
  • the base station 1600 can also include a bus system.
  • the processor 1630, the memory 1620, the receiver and the transmitter are connected by a bus system, and the processor 1630 is configured to execute instructions stored by the memory 1620 to control the receiver to receive signals and control the transmitter to send signals to complete the communication of the present application.
  • the receiver and the transmitter may be the same or different physical entities. When they are the same physical entity, they can be collectively referred to as transceivers.
  • the memory 1620 can be integrated in the processor 1630 or can be disposed separately from the processor 1630.
  • the functions of the receiver and the transmitter can be implemented by using a transceiver circuit or a transceiver chip.
  • the processor 1630 can be implemented by a dedicated processing chip, a processing circuit, a processor, or a general purpose chip.
  • a base station provided by an embodiment of the present application may be implemented by using a general-purpose computer.
  • Program code to implement processor 1630, receiver and transmitter functions is stored in a memory that implements the functions of processor 1630, receiver, and transmitter by executing code in memory.
  • FIG. 17 is a schematic block diagram of a base station 1700 according to an embodiment of the present application. It should be understood that the base station 1700 can perform the various steps performed by the source base station in the methods of FIGS. 1 through 11, and to avoid repetition, it will not be described in detail herein.
  • the base station 1700 can include various types of base stations, such as gNBs, NR base stations, macro base stations, micro base stations, and the like.
  • the base station 1700 includes:
  • a memory 1720 for storing instructions
  • the processor 1730 is connected to the memory 1720 and the communication interface 1710, respectively, for executing the instructions stored by the memory 1720 to perform the following steps when the instructions are executed:
  • the device shown in FIG. 17 may be a chip or a circuit.
  • a chip or circuit that can be placed in a base station.
  • the base station 1700 corresponds to the source base stations in FIGS. 1 through 11.
  • the above communication interface 1710 can also be interchanged with the transceiver.
  • the transceiver includes a receiver and a transmitter.
  • the base station 1700 can also include a bus system.
  • the processor 1730, the memory 1720, the receiver and the transmitter are connected by a bus system, and the processor 1730 is configured to execute the instruction stored by the memory 1720 to control the receiver to receive the signal, and control the transmitter to send the signal to complete the communication of the present application.
  • the receiver and the transmitter may be the same or different physical entities. When they are the same physical entity, they can be collectively referred to as transceivers.
  • the memory 1720 can be integrated in the processor 1730 or can be disposed separately from the processor 1730.
  • the functions of the receiver and the transmitter can be implemented by using a transceiver circuit or a transceiver chip.
  • the processor 1730 can be implemented by a dedicated processing chip, a processing circuit, a processor, or a general purpose chip.
  • a base station provided by an embodiment of the present application may be implemented by using a general-purpose computer.
  • Program code to implement processor 1730, receiver and transmitter functions is stored in a memory that implements the functions of processor 1730, receiver, and transmitter by executing code in memory.
  • FIG. 18 is a schematic block diagram of a terminal device 1800 according to an embodiment of the present application. It should be understood that the terminal device 1800 can perform the various steps performed by the terminal device in the methods of FIGS. 1 through 11, and in order to avoid repetition, it will not be described in detail herein.
  • the terminal device 1800 may include various types of base stations, such as gNBs, NR base stations, macro base stations, micro base stations, and the like.
  • the terminal device 1800 includes:
  • a memory 1820 for storing instructions
  • the processor 1830 is connected to the memory 1820 and the communication interface 1810, respectively, for executing the instructions stored by the memory 1820 to perform the following steps when executing the instructions:
  • Second indication information that is sent by the target base station, where the second indication information is used to indicate that an access layer key between the target base station and the terminal device is an updated key. Or a key that has not been updated.
  • the terminal device shown in FIG. 18 may be a chip or a circuit.
  • a chip or circuit that can be placed in the terminal device.
  • the terminal device 1800 corresponds to the terminal device in FIGS. 1 to 11.
  • the above communication interface 1810 can also be interchanged with the transceiver.
  • the transceiver includes a receiver and a transmitter.
  • the terminal device 1800 can also include a bus system.
  • the processor 1830, the memory 1820, the receiver and the transmitter are connected by a bus system, and the processor 1830 is configured to execute instructions stored by the memory 1820 to control the receiver to receive signals and control the transmitter to send signals to complete the communication of the present application.
  • the receiver and the transmitter may be the same or different physical entities. When they are the same physical entity, they can be collectively referred to as transceivers.
  • the memory 1820 can be integrated in the processor 1830 or can be disposed separately from the processor 1830.
  • the functions of the receiver and the transmitter can be implemented by using a transceiver circuit or a transceiver chip.
  • the processor 1830 can be implemented by a dedicated processing chip, a processing circuit, a processor, or a general purpose chip.
  • the terminal device provided by the embodiment of the present application may be implemented by using a general-purpose computer.
  • Program code to implement processor 1830, receiver and transmitter functions is stored in a memory that implements the functions of processor 1830, receiver, and transmitter by executing code of the memory.
  • FIG. 19 is a schematic block diagram of a base station 1900 according to an embodiment of the present application. It should be understood that the base station 1900 can perform the various steps performed by the target base station in the method of FIG. 6, and to avoid repetition, it will not be described in detail herein.
  • the base station 1900 can include various types of base stations, such as gNBs, NR base stations, macro base stations, micro base stations, and the like.
  • the base station 1900 includes:
  • the processor 1930 is connected to the memory 1920 and the communication interface 1910, respectively, for executing the instructions stored by the memory 1920 to perform the following steps when executing the instructions:
  • the second indication information is sent to the terminal device by using the communication interface 1910, where the second indication information is used.
  • the access layer key indicating the terminal device and the target base station is an updated key or an unupdated key.
  • the base station shown in FIG. 19 may be a chip or a circuit.
  • a chip or circuit that can be placed in a base station.
  • the base station 1900 corresponds to the source base station in FIGS. 1 through 11. Further, the above communication interface 1910 can also be interchanged with the transceiver.
  • the transceiver includes a receiver and a transmitter. Still further, the base station 1900 can also include a bus system.
  • the processor 1930, the memory 1920, the receiver and the transmitter are connected by a bus system, and the processor 1930 is configured to execute instructions stored in the memory 1920 to control the receiver to receive signals, and control the transmitter to send signals to complete the communication of the present application.
  • the receiver and the transmitter may be the same or different physical entities. When they are the same physical entity, they can be collectively referred to as transceivers.
  • the memory 1920 may be integrated in the processor 1930 or may be provided separately from the processor 1930.
  • the functions of the receiver and the transmitter can be implemented by using a transceiver circuit or a transceiver chip.
  • the processor 1930 can be implemented by a dedicated processing chip, a processing circuit, a processor, or a general purpose chip.
  • a base station provided by an embodiment of the present application may be implemented by using a general-purpose computer.
  • Program code to implement processor 1930, receiver and transmitter functions is stored in a memory that implements the functions of processor 1930, receiver, and transmitter by executing code in memory.
  • FIG. 20 is a schematic structural diagram of a base station 2000 according to an embodiment of the present application.
  • the base station 2000 can be the base station shown in Figures 1 through 11.
  • base station 2000 can be a source base station or a target base station.
  • the base station 2000 can include one or more radio frequency units, such as a remote radio unit (RRU) 2001 and one or more baseband units (BBUs) (also referred to as digital units, DUs). 2002.
  • RRU 2001 may be referred to as a transceiver unit, a transceiver, a transceiver circuit, or a transceiver, etc., which may include at least one antenna 2011 and a radio frequency unit 2012.
  • the RRU2001 part is mainly used for transmitting and receiving radio frequency signals and converting radio frequency signals and baseband signals, for example, for transmitting the signaling messages described in the foregoing embodiments to the terminal device.
  • the BBU2002 part is mainly used for performing baseband processing, controlling a base station, and the like.
  • the RRU 2001 and the BBU 2002 may be physically disposed together or physically separated, that is, distributed base stations.
  • the BBU 2002 is a control center of a base station, and may also be referred to as a processing unit, and is mainly used to perform baseband processing functions such as channel coding, multiplexing, modulation, spread spectrum, and the like.
  • the BBU processing unit
  • the BBU can be used to control the base station to perform an operation procedure about the base station in the foregoing method embodiment.
  • the BBU 2002 may be composed of one or more boards, and multiple boards may jointly support a single access standard radio access network (such as an LTE network), or may separately support different access technologies. Access Network.
  • the BBU 2002 also includes a memory 2021 and a processor 2022.
  • the memory 2021 is used to store necessary instructions and data.
  • the memory 2021 stores preset information, a codebook, and the like in the above embodiment.
  • the processor 2022 is configured to control the base station to perform necessary actions, for example, to control the base station to perform an operation procedure about the base station in the foregoing method embodiment.
  • the memory 2021 and the processor 2022 can serve one or more boards. That is, the memory and processor can be individually set on each board. It is also possible that multiple boards share the same memory and processor. In addition, the necessary circuits can be set on each board.
  • FIG. 21 is a schematic structural diagram of a terminal device 2100 according to an embodiment of the present application.
  • the terminal device 2100 can be adapted for use in the application environment described in FIGS. 1 through 11.
  • FIG. 21 shows only the main components of the terminal device 2100.
  • the terminal device 2100 includes a processor, a memory, a control circuit, an antenna, and an input and output device.
  • the processor is mainly used for processing the communication protocol and the communication data, and controlling the entire terminal device, executing the software program, and processing the data of the software program, for example, for supporting the terminal device 2100 to perform the terminal device action described in the above communication method 200.
  • the memory is mainly used to store software programs and data, such as data used in the above communication process.
  • the control circuit is mainly used for converting baseband signals and radio frequency signals and processing radio frequency signals.
  • the control circuit together with the antenna can also be called a transceiver, and is mainly used for transmitting and receiving RF signals in the form of electromagnetic waves.
  • Input and output devices such as a touch screen, a display screen, and a keyboard light are mainly used to receive data input by a user and output data to a user.
  • the processor can read the software program in the storage unit, interpret and execute the data of the software program.
  • the processor performs baseband processing on the data to be sent, and then outputs the baseband signal to the radio frequency circuit.
  • the radio frequency circuit performs radio frequency processing on the baseband signal, and then transmits the radio frequency signal to the outside through the antenna in the form of electromagnetic waves.
  • the RF circuit receives the RF signal through the antenna, converts the RF signal into a baseband signal, and outputs the baseband signal to the processor, which converts the baseband signal into data and processes the data.
  • the disclosed systems, devices, and methods may be implemented in other manners.
  • the device embodiments described above are merely illustrative.
  • the division of the unit is only a logical function division.
  • there may be another division manner for example, multiple units or components may be combined or Can be integrated into another system, or some features can be ignored or not executed.
  • the mutual coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interface, device or unit, and may be in an electrical, mechanical or other form.
  • the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of the embodiment.
  • each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.
  • the functions may be stored in a computer readable storage medium if implemented in the form of a software functional unit and sold or used as a standalone product.
  • the technical solution of the present application which is essential or contributes to the prior art, or a part of the technical solution, may be embodied in the form of a software product, which is stored in a storage medium, including
  • the instructions are used to cause a computer device (which may be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present application.
  • the foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, and the like, which can store program codes. medium.

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Abstract

本申请提供了一种通信方法、基站和终端设备。该通信方法包括：目标基站从终端设备接收第一请求消息，第一请求消息包括第一标识信息，第一标识信息用于指示终端设备和源基站；目标基站根据第一请求消息，向源基站发送第二请求消息，第二请求消息包括第二标识信息，第二标识信息用于指示终端设备；目标基站从源基站接收第一密钥和第一指示信息，其中，第一指示信息用于指示第一密钥是更新后的密钥或未更新的密钥；目标基站根据第一指示信息，向终端设备发送第二指示信息，第二指示信息用于指示终端设备与目标基站之间的接入层密钥是更新后的密钥或未更新的密钥。本申请能够提供一种灵活的更换密钥的方法。

Description

通信方法、基站和终端设备
本申请要求于2017年7月27日提交中国专利局、申请号为201710625322.9、申请名称为“通信方法、基站和终端设备”中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及通信领域，并且更具体地，涉及通信方法、基站和终端设备。
背景技术
随着通信技术的发展，不同的通信系统的无线接入网的安全性能以及对安全性的要求各不相同。例如，在长期演进系统(Long Term Evolution,LTE)系统中，终端设备从源基站的覆盖区域移动到目标基站的覆盖区域，与目标基站建立连接，此时，终端设备和目标基站之间采用更新后的接入层密钥进行通信。而在第五代(the fifth generation,5G)移动通信技术中，基站采用了集中式单元(Central Unit,CU)和分布式单元(distributed unit,DU)分离的部署方式。即CU和DU分别负责不同层的无线接入网协议。同一CU下可以连接多个DU，同一DU可以覆盖多个小区。因此，终端设备在各小区移动的情况与LTE移动不同。与LTE系统相比，CU和DU的安全性能以及对安全性的要求也不同。
因此，如何灵活地更新终端设备和目标基站之间的接入层密钥是业界亟待解决的问题。
发明内容
本申请提供一种通信方法、基站和终端设备，能够提供一种灵活的更新密钥的方法。
第一方面，提供了一种通信方法，该方法包括：目标基站从终端设备接收第一请求消息，所述第一请求消息包括第一标识信息，所述第一标识信息用于指示所述终端设备和源基站；所述目标基站根据所述第一请求消息，向所述源基站发送第二请求消息，所述第二请求消息包括第二标识信息，所述第二标识信息用于指示所述终端设备；所述目标基站从所述源基站接收第一密钥和第一指示信息，其中，所述第一指示信息用于指示所述第一密钥是更新后的密钥或未更新的密钥；所述目标基站根据所述第一指示信息，向所述终端设备发送第二指示信息，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥或未更新的密钥。
例如，所述第一标识信息可以采用恢复标识(Resume Identifier,Resume ID)来指示终端设备和源基站。或者，第一标识信息也可以采用物理小区标识(Physical cell identifier,PCI)指示源基站、小区无线网络临时标识(Cell Radio temporary identifier,C-RNTI)指示终端设备。
在本申请实施例中，在终端设备从源基站覆盖的小区移动至目标基站覆盖的小区的情 况下，目标基站接收源基站发送的第一密钥和第一指示信息，第一指示信息用于指示第一密钥是否是更新后的密钥，目标基站可以根据源基站发送的第一指示信息，向终端设备发送第二指示信息，以指示更新或者不更新终端设备与目标基站之间的接入层密钥，从而提供了一种灵活的更新密钥的方法。
在一种可能的实现方式中，所述第二请求消息还包括第三指示信息，所述第三指示信息用于请求更新密钥或不更新密钥。
在本申请实施例中，在第二请求消息中携带第三指示信息，第三指示信息用于请求是否更新密钥，节省了发送信令的次数，提高了决策效率。
在一种可能的实现方式中，在所述目标基站对所述源基站的信任等级高于信任阈值的情况下，所述第三指示信息用于请求不更新密钥；或，在所述目标基站对所述源基站的信任等级低于所述信任阈值的情况下，所述第三指示信息用于请求更新密钥。
在一种可能的实现方式中，所述第一请求消息还包括第四指示信息，所述第四指示信息用于请求更新密钥或请求不更新密钥；在所述第四指示信息用于请求更新密钥的情况下，所述第三指示信息用于请求更新密钥；或，在所述第四指示信息用于请求不更新密钥的情况下，所述第三指示信息用于请求不更新密钥。
在本申请实施例中，在第一请求消息中携带第四指示信息，第四指示信息用于请求是否更新密钥，节省了发送信令的次数，提高了决策效率。
在本申请实施例中，引入了终端设备、目标基站和源基站中的一个或多个决策点，以确定是否更新密钥，可以根据各决策点的实时状态信息以及预设的策略，协调确定是否更新密钥，从而提供了一种灵活的更新密钥的方法。在引入多个决策点的情况下，可以由多个决策点确定是否更新密钥，从而提高了终端设备与目标基站通信的安全性能。并且引入多个决策点可以平衡每个决策点的决策能力，或者说通过分散决策能力，使得各决策点能够根据各自的状态确定是否更新密钥，并且能够兼顾其他决策点的状态，从而提供了一种安全、灵活的更新密钥的方案。
在一种可能的实现方式中，在所述第一指示信息用于指示所述第一密钥是未更新的密钥以及所述第三指示信息用于请求更新密钥的情况下，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥。
在一种可能的实现方式中，还包括：所述目标基站从所述源基站接收下一跳链计数器NCC；所述目标基站根据所述NCC，生成第二密钥，所述第二密钥为所述终端设备与所述目标基站之间的接入层密钥；所述目标基站向所述终端设备发送所述NCC。
在一种可能的实现方式中，在所述第一指示信息用于指示所述第一密钥是更新后的密钥的情况下，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥；所述方法还包括：所述目标基站从所述源基站接收NCC，并向所述终端设备发送所述NCC。
在一种可能的实现方式中，在所述第一指示信息用于指示所述第一密钥是未更新的密钥的情况下，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是未更新的密钥。
在一种可能的实现方式中，所述终端设备处于未激活态，所述第一请求消息用于请求恢复所述终端设备的无线资源控制RRC连接；所述第二指示信息携带在第一响应消息中， 所述第一响应消息用于指示所述终端设备保持未激活态；或，所述第一响应消息用于指示所述终端设备恢复RRC连接。
在本申请实施例中，在第一响应消息用于指示终端设备保持未激活态的情况下，可以在无需恢复终端设备的RRC连接的情况下，指示终端设备接入层密钥是否为更新密钥，从而简化了决策密钥更新的过程，并节约了信令开销。
在一种可能的实现方式中，所述第二请求消息用于请求获取所述终端设备的上下文；所述第一指示信息携带在第二响应消息中，所述第二响应消息包含所述终端设备的上下文，所述终端设备的上下文包含所述第一密钥。
第二方面，提供了一种通信方法，包括：源基站从目标基站接收第二请求消息，所述第二请求消息包含第二标识信息，所述第二标识信息用于指示终端设备；所述源基站根据所述第二请求消息，向所述目标基站发送第一密钥和第一指示信息，其中，所述第一指示信息用于指示所述第一密钥是更新后的密钥或未更新的密钥。
在本申请实施例中，在终端设备从源基站覆盖的小区移动至目标基站覆盖的小区的情况下，源基站可以接收目标基站发送的第二请求消息，并根据该第二请求消息，向目标基站发送第一密钥和第一指示信息，第一指示信息用于指示第一密钥是否是更新后的密钥，以便于目标基站确定终端设备与目标基站之间的接入层密钥，从而提供了一种灵活的更新密钥的方法。
例如，所述第一标识信息可以采用恢复标识(Resume Identifier,Resume ID)来指示终端设备和源基站。或者，第一标识信息也可以采用物理小区标识(Physical cell identifier,PCI)指示源基站、小区无线网络临时标识(Cell Radio temporary identifier,C-RNTI)指示终端设备。
在一种可能的实现方式中，在所述第二请求消息还包含第三指示信息，且所述第三指示信息用于请求更新密钥的情况下，所述第一指示信息用于指示所述第一密钥为更新后的密钥；或，在所述源基站对所述目标基站的信任等级低于信任阈值的情况下，第一指示信息用于指示所述第一密钥为更新后的密钥。
在本申请实施例中，通过在第二请求消息中携带第三指示信息，第三指示信息用于请求是否更新密钥，节省了发送信令的次数，提高了决策效率。
在本申请实施例中，引入了终端设备、目标基站和源基站中的一个或多个决策点，以确定是否更新密钥，可以根据各决策点的实时状态信息以及预设的策略，协调确定是否更新密钥，从而提供了一种灵活的更新密钥的方法。在引入多个决策点的情况下，可以由多个决策点确定是否更新密钥，从而提高了终端设备与目标基站通信的安全性能。并且引入多个决策点可以平衡每个决策点的决策能力，或者说通过分散决策能力，使得各决策点能够根据各自的状态确定是否更新密钥，并且能够兼顾其他决策点的状态，从而提供了一种安全、灵活的更新密钥的方案。
在一种可能的实现方式中，还包括：所述源基站向所述目标基站发送用于生成所述第一密钥的下一跳链计数器NCC。
在一种可能的实现方式中，在所述源基站对所述目标基站的信任等级高于或等于信任阈值的情况下，所述第一指示信息用于指示所述第一密钥为未更新的密钥。
在一种可能的实现方式中，所述第二请求消息用于请求获取所述终端设备的上下文； 所述第一指示信息携带在第二响应消息中，所述第二响应消息包含所述终端设备的上下文，所述终端设备的上下文包含所述第一密钥。
第三方面，提供了一种通信方法，包括：终端设备向目标基站发送第一请求消息，所述第一请求消息包含第一标识信息，所述第一标识信息用于指示所述终端设备以及源基站；所述终端设备接收所述目标基站发送的第二指示信息，所述第二指示信息用于指示所述目标基站与所述终端设备之间的接入层密钥是更新后的密钥或未更新的密钥。
在本申请实施例中，在终端设备从源基站覆盖的小区移动到目标基站覆盖的小区的情况下，终端设备接收目标基站发送的第二指示信息，以指示终端设备与目标基站之间的接入层密钥是否是更新后的密钥，从而提供了一种灵活的更新密钥的方法。
例如，所述第一标识信息可以采用恢复标识(Resume Identifier,Resume ID)来指示终端设备和源基站。或者，第一标识信息也可以采用物理小区标识(Physical cell identifier,PCI)指示源基站、小区无线网络临时标识(Cell Radio temporary identifier,C-RNTI)指示终端设备。
在一种可能的实现方式中，所述第一请求消息包含第四指示信息，所述第四指示信息用于请求更新密钥或不更新密钥。
在一种可能的实现方式中，在所述终端设备的未更新密钥次数大于或等于计数阈值的情况下，所述第四指示信息用于请求更新密钥，其中，所述终端设备的未更新密钥次数为所述终端设备的上一次更新密钥的时刻至当前时刻之间的时间区间内的未更新密钥次数；或，在所述终端设备的未更新密钥次数小于所述计数阈值的情况下，所述第四指示信息用于请求不更新密钥；或，在所述终端设备的第一状态信息改变的情况下，所述第四指示信息用于请求更新密钥，其中，所述第一状态信息包含以下任意一项：所述终端设备的跟踪区标识TAI、所述终端设备当前所属的无线接入网RAN组和所述终端设备当前使用的无线接入技术RAT；或，在所述终端设备的第一状态信息未改变的情况下，所述第四指示信息用于请求不更新密钥。
在一种可能的实现方式中，还包括：在所述第四指示信息用于请求更新密钥，且所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是未更新的密钥的情况下，所述终端设备断开与所述目标基站之间的连接，并重新选择接入的基站。
在本申请实施例中，引入了终端设备、目标基站和源基站中的一个或多个决策点，以确定是否更新密钥，可以根据各决策点的实时状态信息以及预设的策略，协调确定是否更新密钥，从而提供了一种灵活的更新密钥的方法。在引入多个决策点的情况下，可以由多个决策点确定是否更新密钥，从而提高了终端设备与目标基站通信的安全性能。并且引入多个决策点可以平衡每个决策点的决策能力，或者说通过分散决策能力，使得各决策点能够根据各自的状态确定是否更新密钥，并且能够兼顾其他决策点的状态，从而提供了一种安全、灵活的更新密钥的方案。
在一种可能的实现方式中，还包括：所述终端设备接收所述目标基站发送的下一跳链计数器NCC；在所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥为更新后的密钥的情况下，所述终端设备根据所述NCC，生成第三密钥，所述第三密钥为所述终端设备与所述目标基站之间的接入层密钥。
在一种可能的实现方式中，所述终端设备处于未激活态，所述第一请求消息用于请求 恢复所述终端设备的无线资源控制RRC连接，所述第二指示信息携带在第一响应消息中；其中，所述第一响应消息用于指示所述终端设备保持未激活态；或，所述第一响应消息用于指示所述终端设备恢复RRC连接。
第四方面，提供了一种通信方法，包括：目标基站从终端设备接收第一请求消息，所述第一请求消息包括第一标识信息，所述第一标识信息用于指示所述终端设备和源基站；在所述源基站与所述目标基站属于同一集中式单元CU的情况下，所述目标基站根据所述第一请求消息，向所述终端设备发送第二指示信息，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥或未更新的密钥。
在本申请实施例中，在目标基站与源基站属于同一CU的情况下，目标基站可以向终端设备发送第二指示信息，以指示终端设备与目标基站之间的接入层密钥是否为更新后的密钥，从而提供了一种灵活的更新密钥的方法。
例如，所述第一标识信息可以采用恢复标识(Resume Identifier,Resume ID)来指示终端设备和源基站。或者，第一标识信息也可以采用物理小区标识(Physical cell identifier,PCI)指示源基站、小区无线网络临时标识(Cell Radio temporary identifier,C-RNTI)指示终端设备。
在一种可能的实现方式中，在所述第一请求消息还包括第四指示信息，且所述第四指示信息用于请求更新密钥的情况下，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥；或，在所述终端设备的未更新密钥次数大于或等于计数阈值的情况下，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥为更新后的密钥，其中，所述终端设备的未更新密钥次数为所述终端设备的上一次更新密钥的时刻至当前时刻之间的时间区间内的未更新密钥次数。
在一种可能的实现方式中，在所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥的情况下，还包括：所述目标基站根据下一跳链计数器NCC生成所述第一密钥，所述第一密钥为所述终端设备与所述目标基站之间的接入层密钥；所述目标基站向所述终端设备发送所述NCC。
在一种可能的实现方式中，在所述第一请求消息还包括第四指示信息，且所述第四指示信息用于请求不更新密钥的情况下，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是未更新的密钥；或，在所述终端设备的未更新密钥次数小于所述计数阈值的情况下，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥为未更新的密钥，其中，所述终端设备的未更新密钥次数为所述终端设备的上一次更新密钥的时刻至当前时刻之间的时间区间内的未更新密钥次数。
在本申请实施例中，引入了终端设备和目标基站的一个或两个决策点，以确定是否更新密钥，可以根据各决策点的实时状态信息以及预设的策略，协调确定是否更新密钥，从而提供了一种灵活的更新密钥的方法。在引入两个决策点的情况下，可以由两个决策点确定是否更新密钥，从而提高了终端设备与目标基站通信的安全性能。并且引入两个决策点可以平衡每个决策点的决策能力，或者说通过分散决策能力，使得各决策点能够根据各自的状态确定是否更新密钥，并且能够兼顾其他决策点的状态，从而提供了一种安全、灵活的更新密钥的方案。
在一种可能的实现方式中，所述终端设备处于未激活态，所述第一请求消息用于请求 恢复所述终端设备的无线资源控制RRC连接，所述第二指示信息携带在第一响应消息中，所述第一响应消息用于指示所述终端设备保持未激活态；或，所述第一响应消息用于指示所述终端设备恢复RRC连接。
第五方面，提供了一种基站，该基站用于执行上述第一方面或第一方面的任意可能的实现方式中的方法。具体地，该基站包括用于执行上述第一方面或第一方面的任意可能的实现方式中的方法的单元。
第六方面，提供了一种基站，该基站用于执行上述第二方面或第二方面的任意可能的实现方式中的方法。具体地，该基站包括用于执行上述第二方面或第二方面的任意可能的实现方式中的方法的单元。
第七方面，提供了一种终端设备，该终端设备用于执行上述第三方面或第三方面的任意可能的实现方式中的方法。具体地，该终端设备包括用于执行上述第三方面或第三方面的任意可能的实现方式中的方法的单元。
第八方面，提供了一种基站，该基站用于执行上述第四方面或第四方面的任意可能的实现方式中的方法。具体地，该基站包括用于执行上述第四方面或第四方面的任意可能的实现方式中的方法的单元。
第九方面，提供了一种通信系统，该通信系统包括上述第五方面、第六方面所述的基站以及第七方面所述的终端设备。或者，该通信系统包括上述第七方面所述的终端设备和第八方面所述的基站。
第十方面，提供了一种基站，该基站包括：通信接口、存储器、处理器和总线系统。其中，该通信接口、该存储器和该处理器通过该总线系统相连，该存储器用于存储指令，该处理器用于执行该存储器存储的指令，以控制该通信接口接收信号和/或发送信号，并且当该处理器执行该存储器存储的指令时，该执行使得该处理器执行第一方面或第一方面的任意可能的实现方式中的方法。
第十一方面，提供了一种基站，该基站包括：通信接口、存储器、处理器和总线系统。其中，该通信接口、该存储器和该处理器通过该总线系统相连，该存储器用于存储指令，该处理器用于执行该存储器存储的指令，以控制该通信接口接收信号和/或发送信号，并且当该处理器执行该存储器存储的指令时，该执行使得该处理器执行第二方面或第二方面的任意可能的实现方式中的方法。
第十二方面，提供了一种终端设备，该终端设备包括：通信接口、存储器、处理器和总线系统。其中，该通信接口、该存储器和该处理器通过该总线系统相连，该存储器用于存储指令，该处理器用于执行该存储器存储的指令，以控制该通信接口接收信号和/或发送信号，并且当该处理器执行该存储器存储的指令时，该执行使得该处理器执行第三方面或第三方面的任意可能的实现方式中的方法。
第十三方面，提供了一种基站，该基站包括：通信接口、存储器、处理器和总线系统。其中，该通信接口、该存储器和该处理器通过该总线系统相连，该存储器用于存储指令，该处理器用于执行该存储器存储的指令，以控制该通信接口接收信号和/或发送信号，并且当该处理器执行该存储器存储的指令时，该执行使得该处理器执行第四方面或第四方面的任意可能的实现方式中的方法。
第十四方面，提供了一种通信系统，该通信系统包括上述第十方面、第十一方面所述 的基站以及第十二方面所述的终端设备。或者，该通信系统包括上述第十二方面所述的终端设备和第十三方面所述的基站。
第十五方面，提供了一种计算机可读介质，用于存储计算机程序，该计算机程序包括用于执行第一方面或第一方面的任意可能的实现方式中的方法的指令。
第十六方面，提供了一种计算机可读介质，用于存储计算机程序，该计算机程序包括用于执行第二方面或第二方面的任意可能的实现方式中的方法的指令。
第十七方面，提供了一种计算机可读介质，用于存储计算机程序，该计算机程序包括用于执行第三方面或第三方面的任意可能的实现方式中的方法的指令。
第十八方面，提供了一种计算机可读介质，用于存储计算机程序，该计算机程序包括用于执行第四方面或第四方面的任意可能的实现方式中的方法的指令。
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图1是本申请实施例的应用环境的示意图。
图2是本申请实施例的应用环境的示意图。
图3是本申请实施例的通信方法的示意图。
图4是本申请又一实施例的通信方法的示意图。
图5是本申请又一实施例的通信方法的示意图。
图6是本申请又一实施例的通信方法的示意图。
图7是本申请实施例的通信方法的交互示意图。
图8是本申请又一实施例的通信方法的交互示意图。
图9是本申请又一实施例的通信方法的交互示意图。
图10是本申请又一实施例的通信方法的交互示意图。
图11是本申请又一实施例的通信方法的交互示意图。
图12是本申请实施例的基站的结构示意图。
图13是本申请又一实施例的基站的结构示意图。
图14是本申请又一实施例的终端设备的结构示意图。
图15是本申请又一实施例的基站的结构示意图。
图16是本申请又一实施例的基站的结构示意图。
图17是本申请又一实施例的基站的结构示意图。
图18是本申请又一实施例的终端设备的结构示意图。
图19是本申请又一实施例的基站的结构示意图。
图20是本申请又一实施例的基站的结构示意图。
图21是本申请又一实施例的终端设备的结构示意图。
具体实施方式
为了便于理解，首先介绍本申请实施例中出现的一些术语。
未激活(inactive)态：未激活态是终端设备的一种状态，它是区别于无线资源控制(Radio Resource Control,RRC)连接(connected)态和RRC空闲(idle)态之外的另一种状态。在终端设备处于未激活态的情况下，可以保留部分承载资源，例如，可以保留信令资 源承载(Signal Resource Bearer,SRB)，并且可以释放全部或部分数据资源承载(Data Resource Bearer,DRB)。其中，核心网、基站和终端设备都可以保存终端设备的上下文。基站可以为处于未激活态的终端设备分配接入层(Access Stratum,AS)标识。例如，该AS标识可以是恢复标识(Resume Identifier,Resume ID)。可选地，Resume ID可以用于寻找储存终端设备的上下文的基站。可选地，处于未激活态的终端设备可以和基站之间传输小数据。
接入与移动管理功能(Access and Mobility Management Function,AMF)：用于移动网络的管理，可以负责对终端设备提供接入和移动性支持。可选地，AMF的功能可以包含以下至少一项：注册管理、可达性管理、移动性管理、接入认证、接入授权等功能。
需要说明的是，本申请实施例中涉及到的终端设备可以包括各种具有无线通信功能的手持设备、车载设备、可穿戴设备、计算设备或连接到无线调制解调器的其它处理设备，以及各种形式的用户设备(User Equipment，UE)，移动台(Mobile Station，MS)，终端(terminal)，终端设备(terminal device)等等，本申请实施例对此不作限定。
在本申请实施例中的基站可包括各种形式的宏基站，微基站，中继站，接入点，收发节点，传输节点等等。在采用不同的无线接入技术的系统中，具有基站功能的设备的名称可能会有所不同。例如，在LTE网络中，称为演进的节点B(例如，evolved NodeB，eNB或eNodeB)，在第三代(3rd Generation，3G)网络中，称为节点B(Node B)等等。在第五代(5th Generation，5G)网络中，可以称为g节点(例如，g Node B,gNB)，或者无线(New Radio,NR)基站。
在本申请实施例提供一种灵活的密钥更换方法，其引入了终端设备、目标基站和源基站中的一个或多个决策点，以确定是否更新密钥，例如，可以根据各决策点的实时状态信息以及预设的策略，确定是否更新密钥。
本申请实施例的通信方法可以应用于多种无线接入网架构中。图1示出了一种本申请实施例的可能的应用环境。如图1所示，终端设备从源基站覆盖的小区移动到目标基站覆盖的小区时，终端设备可以感知到发生了小区更换。图1中的目标基站可以是上述基站中的任一种类型的基站，例如，可以是LTE网络中的eNodeB，或者是5G系统中的gNB；源基站也可以是上述基站中的任一种类型的基站。在这种情况下，本申请实施例的通信方法用于提供一种安全、灵活的密钥更换方法，以提高通信效率。
图2示出了本申请实施例的另一种可能的应用环境。图2所示的基站可以是5G中的基站。具体地，在5G系统中，基站可以进行集中式单元(Central Unit,CU)和分布式单元(distributed unit,DU)分离，或者说协议栈分离。换句话说，CU和DU可以处理不同的协议层。CU和DU之间可以存在通信连接，以互相传递相关协议层的信息。例如，作为一种可能的方案，DU可以处理无线链路层控制(Radio Link Control，RLC)协议及以下的协议，CU可以处理RLC层以上的协议。例如，CU可以处理分组数据汇聚协议(Packet Data Convergence Protocol,PDCP)或无线资源控制(Radio Resource Control,RRC)协议。DU可以用于处理物理层(Physical Layer,PHY)协议、媒体接入控制层(Media Access Control，MAC)协议和RLC协议。同一个CU可以与一个或多个DU连接，同一个DU可以包括一个或多个小区。可选地，CU和DU可以合称为gNB。
可选地，在图2中，当终端设备在小区之间移动时，有可能存在终端设备更换了小区， 却没有更换CU的情况。例如，终端设备从小区1移动到小区3的情况下，虽然更换了DU，却并没有更换CU。或者，终端设备从小区1移动到小区2的情况下，既没有更换DU，也没有更换CU。在这种情况下，可以理解为本申请方法中的源基站与目标基站所执行的操作都由同一CU执行，或者说，源基站与目标基站属于同一CU。
图3是本申请实施例的通信方法300的示意性流程图。图3的方法可以由目标基站执行。需要说明的是，若方法300应用于图2的应用环境中，其可以适用于目标基站与源基站属于不同CU的情况。或者说，终端设备从第一CU覆盖的小区移动到第二CU覆盖的小区，第一CU与第二CU为不同的CU。如图3所示，所示方法300包括：
S301、目标基站从终端设备接收第一请求消息，所述第一请求消息包括第一标识信息，所述第一标识信息用于指示所述终端设备和源基站。
可选地，所述第一标识信息可以采用同一标识指示所述终端设备和源基站，也可以采用两个标识分别指示所述终端设备和源基站。
例如，若所述第一标识信息采用同一标识指示所述终端设备和源基站，可以采用恢复标识(Resume Identifier,Resume ID)来指示终端设备和源基站。
例如，若所述第一标识信息采用两个标识分别指示所述终端设备和源基站，则可以采用物理小区标识(Physical cell identifier,PCI)指示源基站，采用小区无线网络临时标识(Cell Radio temporary identifier,C-RNTI)指示终端设备。
可选地，所述终端设备可以处于未激活态，所述第一请求消息可以用于请求恢复所述终端设备的RRC连接。例如，在终端设备处于未激活态的情况下，终端设备移动至目标基站，向目标基站发送第一请求消息。
例如，所述终端设备可以处于未激活态，所述第一标识信息可以是Resume ID，所述第一请求消息可以是RRC连接恢复请求(RRC Connection Resume Request)消息。
可选地，所述终端设备可以处于连接态，所述第一请求消息可以用于请求重建立所述终端设备的RRC连接。例如，在终端设备处于连接态的情况下，终端设备移动至目标基站，若终端设备发生异常情况，则向目标基站发送第一请求消息。
可选地，所述终端设备可以处于连接态，所述第一标识信息可以为PCI，所述第一请求消息可以是RRC连接重建立请求(RRC Connection Re-establishment Request)消息。
S302、所述目标基站根据所述第一请求消息，向所述源基站发送第二请求消息，所述第二请求消息包括第二标识信息，所述第二标识信息用于指示所述终端设备。
可选地，所述目标基站可以根据所述第一标识信息，确定所述源基站，并向源基站发送第二请求消息。
可选地，所述第二标识信息是根据所述第一标识信息确定的，或者，所述第一标识信息和所述第二标识信息可以相同。例如，当所述第一标识信息采用同一标识指示终端设备与源基站时，所述第二标识信息可以与所述第一标识信息相同。例如，第一标识信息和第二标识信息可以都包括Resume ID。又例如，若所述第一标识信息分别采用两个标识信息指示终端设备与源基站时，所述第二标识信息可以包括指示终端设备的标识。例如，所述第二标识信息可以包括C-RNTI，以指示终端设备。
可选地，所述第二请求消息可以用于请求获取所述终端设备的上下文。例如，所述第二请求消息可以是恢复终端设备上下文请求(Retrieve UE Context Request)消息。
可选地，当第一请求消息用于请求重建立所述终端设备的RRC连接时，该第二请求消息可以是无线链路失败指示(Radio Link Failure Indication)消息。
S303、所述目标基站从所述源基站接收第一密钥和第一指示信息，其中，所述第一指示信息用于指示所述第一密钥是更新后的密钥或未更新的密钥。
可选地，所述第一密钥可以理解为用于终端设备与目标基站之间的接入层(Access Stratum,AS)密钥。
需要说明的是，目标基站在接收到第一密钥和第一指示信息之后，可以将所述第一密钥确定为终端设备与目标基站之间的接入层密钥，也可以不将所述第一密钥确定为终端设备与目标基站之间的接入层密钥。例如，后文中将会举例说明，在某些情况下，目标基站可以自己生成密钥，以作为终端设备与目标基站之间的密钥。
可选地，第一指示信息可以携带在第二响应消息中，该第二响应消息用于响应第二请求消息。例如，在第二请求消息用于请求获取终端设备的上下文的情况下，该第二响应消息可以是恢复终端设备上下文响应(Retrieve UE Context Response)消息，所述第二响应消息可以包含终端设备的上下文，该终端设备的上下文可以包含该第一密钥。
S304、所述目标基站根据所述第一指示信息，向所述终端设备发送第二指示信息，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥或未更新的密钥。
可选地，目标基站在接收第一密钥和第一指示信息之后，可以直接将第一密钥作为终端设备与目标基站之间的接入层密钥。或者，目标基站也可以根据第一指示信息和预设策略，不将第一密钥作为终端设备与目标基站之间的接入层密钥，而是自己生成密钥，以作为该接入层密钥。
例如，若第一指示信息用于指示第一密钥为更新后的密钥，且目标基站将该第一密钥确定为该接入层密钥，则方法300还包括：目标基站从源基站接收NCC，并向终端设备发送该NCC以及第二指示信息，该第二指示信息可以用于指示终端设备与目标基站之间的接入层密钥为更新后的密钥，以便于终端设备在接收到第二指示信息之后，根据该NCC，生成第三密钥以作为接入层密钥。在这个示例中，第一密钥是源基站根据NCC生成的，第三密钥与第一密钥可以为相同的密钥。
例如，若第一指示信息用于指示第一密钥为未更新的密钥，且目标基站将该第一密钥确定为该接入层密钥，则第二指示信息可以用于指示终端设备与目标基站之间的接入层密钥为未更新的密钥，终端设备在接收到第二指示信息之后，可以将第四密钥确定为终端设备与目标基站之间的接入层密钥，其中，第四密钥为终端设备与源基站之间的接入层密钥，在这个示例中，第四密钥与第一密钥可以为相同的密钥。
可选地，在第一请求消息用于请求恢复终端设备的RRC连接的情况下，第二指示信息可以携带在第一响应消息中，该第一响应消息可以用于响应第一请求消息，该第一响应消息可以用于指示终端设备保持未激活态，例如，该第一响应消息可以是RRC连接释放(RRC Connection Release)消息；或，该第一响应消息可以用于指示终端设备恢复RRC连接，例如，该第一响应消息可以是RRC连接恢复(RRC Connection Resume)消息；或，该第一响应消息可以用于指示终端设备重建立完成，例如，该第一响应消息可以是RRC连接重建立(RRC Connection Re-establishment)消息。
在第一响应消息用于指示终端设备保持未激活态的情况下，可以在无需恢复终端设备的RRC连接的情况下，指示终端设备接入层密钥是否为更新密钥，从而简化了决策密钥更新的过程，并节约了信令开销。
可选地，第二指示信息可以采用明示或暗示的方式指示终端设备与目标基站之间的接入层密钥是更新后的密钥或未更新的密钥。其中，在明示的方式中，第二指示信息可以直接指示该接入层密钥是否为更新后的密钥。在暗示的方式中，可以通过目标基站向终端设备发送的第一响应消息中是否携带NCC来指示该接入层密钥是否为更新密钥。在第一响应消息中携带NCC，则表示目标基站指示该接入层密钥为更新后的密钥；若第一响应消息中不携带NCC，则表示目标基站指示该接入层密钥是未更新的密钥。
在本申请实施例中，在终端设备从源基站覆盖的小区移动至目标基站覆盖的小区的情况下，目标基站接收源基站发送的第一密钥和第一指示信息，第一指示信息用于指示第一密钥是否是更新后的密钥，目标基站可以根据源基站发送的第一指示信息，向终端设备发送第二指示信息，以指示更新或者不更新终端设备与目标基站之间的接入层密钥，从而提供了一种灵活的更新密钥的方法。
可选地，在方法300中，第二请求消息还包括第三指示信息，第三指示信息用于请求更新密钥或不更新密钥。
上述将第三指示信息携带在第二请求消息中，节省了信令，提高了决策效率。
可选地，目标基站可以根据预设的策略确定第三指示信息；或者，目标基站还可以从终端设备接收第四指示信息，第四指示信息用于请求更新密钥或不更新密钥，目标基站可以根据第四指示信息确定第三指示信息。
可选地，第四指示信息可以携带在第一请求消息之中。
上述将第四指示信息携带在第一请求消息中，节省了信令，提高了决策效率。
可选地，在本申请实施例中，终端设备、目标基站和源基站中的任意一个或任意组合都可以参与决策是否更新终端设备与目标基站之间的接入层密钥的过程。例如，可以由源基站决策是否更新密钥；或者，可以由终端设备决策是否更新密钥；或者，可以由目标基站和源基站共同决策是否更新密钥；或者，可以由源基站和终端设备共同决策是否更新密钥；或者，可以由终端设备和目标基站共同决策是否更新密钥。或者，可以由源基站、目标基站、终端设备共同决策是否更新密钥。
例如，在目标基站作为决策点或决策点之一的情况下，目标基站可以根据预设的策略确定第三指示信息。
其中，上述预设的策略可以是根据用户签约信息获取的策略，例如，目标基站可以从核心网设备获取该预设的策略。或者，该预设的策略也可以是预配置的。可选地，上述预设的策略可以是根据目标基站对源基站的信任等级确定第三指示信息。
示例性地，目标基站可以保存有一个信任列表，该信任列表中存储有PCI与信任等级的对应关系，或演进的通用移动通信系统陆地无线接入网(Evolved Universal Mobile Telecommunications System Terrestrial Radio Access Network,E-UTRAN)小区全球标识(E-UTRAN cell global identifier,ECGI)与信任等级的对应关系。该对应关系可以由目标基站和源基站的部署位置确定，还可由上述基站的制造商等确定。
示例性地，目标基站对源基站的信任等级和上述信任阈值均可以为一个数值，上述信 任等级和上述信任阈值可以均是预先配置在目标基站中的。
例如，若目标基站对源基站的信任等级高于或等于信任阈值，第三指示信息用于请求不更新密钥；或，若目标基站对源基站的信任等级低于信任阈值，第三指示信息用于请求更新密钥。例如，目标基站可以储存目标基站对多个基站的信任列表。若源基站位于信任列表中，或目标基站对源基站的信任等级符合预设条件，或目标基站对源基站的信任等级高于或等于信任阈值，则可以确定第三指示信息请求更新密钥。
示例性地，上述根据用户签约信息获取的策略可包括目标基站针对终端设备或者分组数据单元(Packet Data Unit，PDU)会话的策略指示信息。这些策略指示信息可以由目标基站从核心网设备获得。核心网设备可以包括以下至少一项：策略控制功能(Policy Control Function，PCF)实体、统一数据管理(Unified Data Management，UDM)实体、结构数据存储网络功能(Structured Data Storage network function，SDSF)实体或者无结构数据存储网络功能(Unstructured Data Storage network function，UDSF)实体获得，该用户签约信息获取的策略可以用于指示用于目标基站与上述终端设备之间的接入层密钥是否为更新后的密钥，或者上述策略指示信息指示对目标基站与上述终端设备之间的PDU会话使用的接入层密钥是否为更新后的密钥。
可选地，目标基站可以不参与是否更新密钥的决策，而是从终端设备接收第四指示信息，并根据第四指示信息发送第三指示信息，或者，目标基站也可以将第四指示信息透传给源基站。例如，在所述第四指示信息用于请求更新密钥的情况下，所述第三指示信息用于请求更新密钥；或，在所述第四指示信息用于请求不更新密钥的情况下，所述第三指示信息用于请求不更新密钥。
可选地，在决策点包括终端设备和目标基站的情况下，目标基站可以根据预设的策略以及第四指示信息，确定第三指示信息。例如，若第四指示信息指示不更新密钥，则目标基站可以根据预设的策略，确定是否更新密钥，若目标基站根据预设的策略，确定更新密钥，则第三指示信息用于请求更新密钥；若目标基站根据预设的策略，确定不更新密钥，则第三指示信息用于请求不更新密钥。又例如，若第四指示信息指示更新密钥，则无论目标基站根据预设的策略做出何种决策，第三指示信息都可以用于请求更新密钥。
通过引入终端设备和目标基站作为确定是否更新密钥的决策点，可以根据各决策点的实时状态信息，协调确定是否更新密钥，从而提供了一种灵活的更新密钥的方法。
在本申请实施例中，引入了终端设备、目标基站和源基站中的一个或多个决策点，以确定是否更新密钥，可以根据各决策点的实时状态信息以及预设的策略，协调确定是否更新密钥，从而提供了一种灵活的更新密钥的方法。在引入多个决策点的情况下，可以由多个决策点确定是否更新密钥，从而提高了终端设备与目标基站通信的安全性能。并且引入多个决策点可以平衡每个决策点的决策能力，或者说通过分散决策能力，使得各决策点能够根据各自的状态确定是否更新密钥，并且能够兼顾其他决策点的状态，从而提供了一种安全、灵活的更新密钥的方案。
可选地，在方法300中，在所述第一指示信息用于指示所述第一密钥是未更新的密钥以及所述第三指示信息用于请求更新密钥的情况下，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥。
其中，上述方法可以理解为目标基站在接收所述第一指示信息之后，检验第一指示信 息指示的第一密钥是否符合单向决策原则。
其中，该单向决策原则是指在两个或两个以上的决策点(例如，终端设备、源基站和目标基站)的情况下，可以存在从不更新密钥到更新密钥的单向决策过程，而不存在从更新密钥到不更新密钥的决策过程。换句话说，存在多个用于确定是否更新密钥的决策点的情况下，只要存在一个决策点确定更新密钥，则需要更新密钥。
例如，在目标基站为决策点或决策点之一，当第三指示信息请求更新密钥时，在上述S304部分，目标基站从源基站接收第一密钥和第一指示信息之后，可以检验第一指示信息是否指示第一密钥为更新后的密钥。若第一指示信息指示第一密钥是未更新的密钥，则表示源基站未按照单向决策原则确定第一密钥，比如，在源基站的安全性能受到攻击的情况下，可能会确定并发送不符合单向决策原则的第一密钥和第一指示信息。在这种情况下，目标基站可以确定不将第一密钥确定为终端设备与目标基站之间的接入层密钥，而是根据从源基站接收的NCC生成第二密钥，并将第二密钥确定为接入层密钥。并且，在S304部分中，目标基站可以向终端设备发送上述用于生成第二密钥的NCC和第二指示信息，第二指示信息用于指示终端设备与目标基站之间的接入层密钥为更新后的密钥，终端设备根据所述NCC，生成第三密钥，以作为接入层密钥。在这个示例中，第三密钥与第二密钥可以是相同的密钥。
作为具体示例，上述目标基站可以根据上述NCC和衍生参数，生成上述第二密钥。
其中，上述衍生参数可以包括以下至少一项：PCI、演进型通用陆基无线接入下行绝对无线频点(E-UTRA Absolute Radio Frequency Channel Number-Down Link,EARFCN-DL)以及目标基站未使用的下一跳(Next Hop,NH)或者目标基站当前使用的与终端设备之间的接入层密钥。
作为一个示例，若与NCC绑定的NH未使用，则目标基站可以进行纵向密钥衍生；若与NCC绑定的NH已使用，则目标基站可以进行横向密钥衍生。若进行纵向密钥衍生，目标基站将使用NH作为密钥衍生参数。若进行横向密钥衍生，目标基站使用目标基站当前使用的接入层密钥作为衍生参数。对于上述两种衍生方式，衍生参数还可以包含PCI和/或EARFCN-DL。
图4是本申请实施例的通信方法400的示意性流程图。图4的方法可以由源基站执行。需要指出的是，图4所示实施例中涉及的名词、术语以及步骤说明，均可以参见图3所示实施例中的相关描述。图4所示，方法400包括：
S401、源基站从目标基站接收第二请求消息，所述第二请求消息包含第二标识信息，所述第二标识信息用于指示终端设备。
例如，上述第二标识信息可以包括Resume ID，或者，上述第二标识信息可以包括C-RNTI，或者，上述第二标识信息也可以包括其他指示终端设备的标识。
可选地，所述第二请求消息可以用于请求获取所述终端设备的上下文。可选地，源基站可以根据第二标识信息，获取所述终端设备的上下文。例如，所述第二请求消息可以是恢复终端设备上下文请求(Retrieve UE Context Request)消息。
可选地，所述第二请求消息可以是无线链路失败指示(Radio Link Failure Indication)消息。
作为一个具体示例，源基站可以根据Resume ID，获取终端设备的上下文，终端设备 的上下文可以包括接入层密钥，NCC等。或者，源基站也可以根据C-RNTI，获取所述终端设备的上下文。
S402、所述源基站根据所述第二请求消息，向所述目标基站发送第一密钥和第一指示信息，其中，所述第一指示信息用于指示所述第一密钥是更新后的密钥或未更新的密钥。
在本申请实施例中，在终端设备从源基站覆盖的小区移动至目标基站覆盖的小区的情况下，源基站可以接收目标基站发送的第二请求消息，并根据该第二请求消息，向目标基站发送第一密钥和第一指示信息，第一指示信息用于指示第一密钥是否是更新后的密钥，以便于目标基站确定终端设备与目标基站之间的接入层密钥，从而提供了一种灵活的更新密钥的方法。
可选地，在方法400中，在所述第二请求消息还包含第三指示信息，且所述第三指示信息用于请求更新密钥的情况下，所述第一指示信息用于指示所述第一密钥为更新后的密钥；或，在所述源基站对所述目标基站的信任等级低于信任阈值的情况下，第一指示信息用于指示所述第一密钥为更新后的密钥。
上述通过在第二请求消息中携带第三指示信息，节省了信令，提高了决策效率。
其中，上述第三指示信息可以参见图3的例子中的相关描述，此处不再赘述。
可选地，在本申请实施例中，终端设备、目标基站和源基站中的任意一个或任意组合都可以参与决策是否更新终端设备与目标基站之间的接入层密钥的过程。例如，可以由源基站决策是否更新密钥；或者，可以由终端设备决策是否更新密钥；或者，可以由目标基站和源基站共同决策是否更新密钥；或者，可以由源基站和终端设备共同决策是否更新密钥；或者，可以由终端设备和目标基站共同决策是否更新密钥。或者，可以由源基站、目标基站、终端设备共同决策是否更新密钥。
可选地，在S402部分，源基站接收到第二请求消息之后，可以根据第二请求消息，确定并发送第一密钥和第一指示信息。其中，源基站确定第一密钥和第一指示信息的过程需符合单向决策原则。
其中，该单向决策原则是指存在两个或两个以上的决策点(例如，终端设备、源基站和目标基站)的情况下，可以存在从不更新密钥到更新密钥的单向决策过程，而不存在从更新密钥到不更新密钥的决策过程。换句话说，存在多个用于确定是否更新密钥的决策点的情况下，只要存在一个决策点确定更新密钥，则需要更新密钥。
应理解，源基站可以参与决策是否更新密钥的过程，或者，源基站可以不参与决策是否更新密钥的过程。
作为一个示例，在源基站作为单独决策点的情况下，源基站可以根据预设的策略确定更新密钥或不更新密钥。并根据决策结果，确定并发送上述第一密钥和第一指示信息。
作为另一个示例，在源基站作为决策点之一的情况下，或者说，除源基站之外，决策点还包括终端设备和目标基站中的至少一个的情况下，源基站可以根据终端设备或目标基站的指示信息以及上述预设的策略，确定第一指示信息。例如，目标基站的指示信息可以包括第三指示信息。终端设备的指示信息可以包括第四指示信息。例如，若包括源基站在内的任一决策点指示更新密钥，则源基站确定更新密钥，第一指示信息用于指示第一密钥是更新后的密钥；若所有决策点指示不更新密钥，则源基站确定不更新密钥，第一指示信息用于指示第一密钥是未更新的密钥。
作为再一个示例，在源基站不作为决策点，而是终端设备或目标基站作为决策点的情况下，源基站可以根据第三指示信息确定第一密钥和第一指示信息。当第三指示信息请求更新密钥时，源基站根据NCC生成第一密钥，并确定第一指示信息指示第一密钥是更新后的密钥。当第三指示信息请求不更新密钥时，源基站将源基站与终端设备之前使用的接入层密钥作为第一密钥，并确定第一指示信息指示第一密钥是更新后的密钥。换句话说，源基站根据其他决策点的指示信息确定第一密钥和第一指示信息，源基站本身不参与决策更新密钥的过程。
其中，上述预设的策略可以是根据源基站对目标基站的信任等级确定是否更新密钥，上述预设的策略可以是根据用户签约信息获取的策略，例如，源基站可以从核心网设备获取该预设的策略。或者，该预设的策略也可以是预配置的。
可选地，该预设的策略可以是根据源基站对目标基站的信任程度确定是否更新密钥。例如，源基站可以储存源基站对多个基站的信任列表。若目标基站位于信任列表中，或源基站对目标基站的信任等级符合预设条件或高于预设阈值，则源基站可以确定不更新密钥。
示例性地，源基站保存有一个信任列表，该信任列表中存储有PCI与信任等级的对应关系，或演进的通用移动通信系统陆地无线接入网(Evolved Universal Mobile Telecommunications System Terrestrial Radio Access Network,E-UTRAN)小区全球标识(E-UTRAN cell global identifier,ECGI)与信任等级的对应关系。该对应关系可以由源基站和目标基站的部署位置确定，还可由上述基站的制造商等确定。
示例性地，源基站对目标基站的信任等级和上述信任阈值均可以为一个数值，上述信任等级和上述信任阈值可以均是预先配置在源基站中的。
示例性地，上述根据用户签约信息获取的策略可包括源基站针对终端设备或者分组数据单元(Packet Data Unit，PDU)会话的策略指示信息。这些策略指示信息可以由源基站从核心网设备获取。该核心网设备可以包括以下至少一项：策略控制功能(Policy Control Function，PCF)实体、统一数据管理(Unified Data Management，UDM)实体、结构数据存储网络功能(Structured Data Storage network function，SDSF)实体或者无结构数据存储网络功能(Unstructured Data Storage network function，UDSF)实体获得，该用户签约信息获取的策略用于指示用于目标基站与上述终端设备之间的接入层密钥是否为更新后的密钥，或者上述策略指示信息指示对目标基站与上述终端设备之间的PDU会话使用的接入层密钥是否为更新后的密钥。
可选地，在S402部分，若源基站确定更新密钥，则源基站可以根据NCC生成第一密钥，并且向目标基站发送第一密钥、NCC以及第一指示信息，该第一指示信息用于指示第一密钥是更新后的密钥。
作为具体示例，上述源基站可以根据上述NCC和衍生参数，生成上述第一密钥。
其中，上述衍生参数可以包括以下至少一项：PCI、演进型通用陆基无线接入下行绝对无线频点(E-UTRA Absolute Radio Frequency Channel Number-Down Link,EARFCN-DL)以及源基站未使用的下一跳(Next Hop,NH)或者源基站当前使用的与终端设备之间的接入层密钥。
作为一个示例，若与NCC绑定的NH未使用，则源基站可以进行纵向密钥衍生；若 与NCC绑定的NH已使用，则源基站可以进行横向密钥衍生。若进行纵向密钥衍生，源基站将使用NH作为密钥衍生参数。若进行横向密钥衍生，源基站使用源基站当前使用的接入层密钥作为衍生参数。对于上述两种衍生方式，衍生参数还可以包含PCI和/或EARFCN-DL。
可选地，在S402部分，若源基站确定不更新密钥，则源基站可以向目标基站发送第一密钥和第一指示信息，该第一密钥为源基站与终端设备之间使用的密钥，该第一指示信息用于指示第一密钥是未更新的密钥。
在本申请实施例中，引入了终端设备、目标基站和源基站中的一个或多个决策点，以确定是否更新密钥，可以根据各决策点的实时状态信息以及预设的策略，协调确定是否更新密钥，从而提供了一种灵活的更新密钥的方法。在引入多个决策点的情况下，可以由多个决策点确定是否更新密钥，从而提高了终端设备与目标基站通信的安全性能。并且引入多个决策点可以平衡每个决策点的决策能力，或者说通过分散决策能力，使得各决策点能够根据各自的状态确定是否更新密钥，并且能够兼顾其他决策点的状态，从而提供了一种安全、灵活的更新密钥的方案。
可选地，在方法400中，还包括：所述源基站向所述目标基站发送用于生成所述第一密钥的NCC。
可选地，在方法400中，在所述源基站对所述目标基站的信任等级高于或等于信任阈值的情况下，所述第一指示信息用于指示所述第一密钥为未更新的密钥。
可选地，在方法400中，所述第二请求消息用于请求获取所述终端设备的上下文；所述第一指示信息携带在第二响应消息中，所述第二响应消息包含所述终端设备的上下文，所述终端设备的上下文包含所述第一密钥。
图5是本申请实施例的通信方法500的示意性流程图。图5的方法可以由终端设备执行。需要指出的是，图5所示实施例中涉及的名词、术语以及步骤说明，均可以参见图3或图4所示实施例中的相关描述。方法500包括:
S501、终端设备向目标基站发送第一请求消息，所述第一请求消息包含第一标识信息，所述第一标识信息用于指示所述终端设备以及源基站。
可选地，所述第一标识信息可以采用同一标识指示所述终端设备和源基站，也可以采用两个标识分别指示所述终端设备和源基站。
例如，若所述第一标识信息采用同一标识指示所述终端设备和源基站，可以采用恢复标识(Resume Identifier,Resume ID)来指示终端设备和源基站。
例如，若所述第一标识信息采用两个标识分别指示所述终端设备和源基站，则可以采用PCI指示源基站、小区无线网络临时标识(Cell Radio temporary identifier,C-RNTI)指示终端设备。
可选地，所述终端设备可以处于未激活态，所述第一请求消息可以用于请求恢复所述终端设备的RRC连接。例如，终端设备可以在处于未激活态的情况下，移动至目标基站，终端设备在感知到小区变化的情况下，可以向目标基站发送第一请求消息。
例如，所述终端设备可以处于未激活态，所述第一标识信息可以是Resume ID，所述第一请求消息可以是RRC连接恢复请求(RRC Connection Resume Request)消息。
可选地，所述终端设备可以处于连接态，所述第一请求消息可以用于请求重建立所述 终端设备的RRC连接。例如，终端设备在处于连接态的情况下，移动至目标基站。当终端设备发生异常情况时，可以向目标基站发送第一请求消息。
可选地，所述终端设备可以处于连接态，所述第一标识信息可以为PCI，所述第一请求消息可以是RRC连接重建立请求(RRC Connection Re-establishment Request)消息。
S502、所述终端设备接收所述目标基站发送的第二指示信息，所述第二指示信息用于指示所述目标基站与所述终端设备之间的接入层密钥是更新后的密钥或未更新的密钥。
可选地，在方法500中，当所述终端设备处于未激活态，所述第一请求消息用于请求恢复所述终端设备的RRC连接，所述第二指示信息携带在第一响应消息中；其中，所述第一响应消息用于指示所述终端设备保持未激活态；或，所述第一响应消息用于指示所述终端设备恢复RRC连接。
例如，在第一请求消息用于请求恢复终端设备的RRC连接的情况下，第二指示信息可以携带在第一响应消息中，该第一响应消息可以用于响应第一请求消息，该第一响应消息可以用于指示终端设备保持未激活态，例如，该第一响应消息可以是RRC连接释放(RRC Connection Release)消息；或，该第一响应消息可以用于指示终端设备恢复RRC连接，例如，该第一响应消息可以是RRC连接恢复(RRC Connection Resume)消息；或，该第一响应消息可以用于指示终端设备重建立完成，例如，该第一响应消息可以是RRC连接重建立(RRC Connection Re-establishment)消息。
在第一响应消息用于指示终端设备保持未激活态的情况下，可以在无需恢复终端设备的RRC连接的情况下，指示终端设备接入层密钥是否为更新密钥，从而简化了决策密钥更新的过程，并节约了信令开销。
可选地，第二指示信息可以采用明示或暗示的方式指示终端设备与目标基站之间的接入层密钥是更新后的密钥或未更新的密钥。其中，在明示的方式中，第二指示信息可以直接指示该接入层密钥是否为更新后的密钥。在暗示的方式中，可以通过目标基站向终端设备发送的第一响应消息中是否携带NCC来指示该接入层密钥是否为更新密钥。在第一响应消息中携带NCC，则表示目标基站指示该接入层密钥为更新后的密钥；若第一响应消息中不携带NCC，则表示目标基站指示该接入层密钥是未更新的密钥。
在本申请实施例中，在终端设备从源基站覆盖的小区移动到目标基站覆盖的小区的情况下，终端设备接收目标基站发送的第二指示信息，以指示终端设备与目标基站之间的接入层密钥是否是更新后的密钥，从而提供了一种灵活的更新密钥的方法。
可选地，在方法500中，所述第一请求消息包含第四指示信息，所述第四指示信息用于请求更新密钥或不更新密钥。
可选地，在本申请实施例中，终端设备、目标基站和源基站中的任意一个或任意组合都可以参与决策是否更新终端设备与目标基站之间的接入层密钥的过程。例如，可以由源基站决策是否更新密钥；或者，可以由终端设备决策是否更新密钥；或者，可以由目标基站和源基站共同决策是否更新密钥；或者，可以由源基站和终端设备共同决策是否更新密钥；或者，可以由终端设备和目标基站共同决策是否更新密钥。或者，可以由源基站、目标基站、终端设备共同决策是否更新密钥。
例如，在终端设备作为决策点或决策点之一的情况下，终端设备可以根据预设的策略确定第四指示信息。其中，该预设的策略可以是根据用户签约信息获取的策略，例如，目 标基站可以从核心网设备获取该预设的策略。或者，该预设的策略也可以是预配置的。
可选地，上述预设的策略可以包括根据终端设备的未更新密钥次数确定第四指示信息，或者，上述预设的策略可以包括根据终端设备的第一状态信息是否改变确定第四指示信息。
示例性地，上述根据用户签约信息获取的策略可包括针对终端设备或PDU会话的策略指示信息。这些策略指示信息可以从核心网设备获得。核心网设备可以包括以下至少一项：PCF实体、UDM实体、SDSF实体或者UDSF实体获得，该用户签约信息获取的策略用于指示用于目标基站与上述终端设备之间的接入层密钥是否为更新后的密钥，或者上述策略指示信息指示对目标基站与上述终端设备之间的PDU会话使用的接入层密钥是否为更新后的密钥。
例如，在方法500中，在所述终端设备的未更新密钥次数大于或等于计数阈值的情况下，所述第四指示信息用于请求更新密钥，其中，所述终端设备的未更新密钥次数为所述终端设备的上一次更新密钥的时刻至当前时刻之间的时间区间内的未更新密钥次数；或，在所述终端设备的未更新密钥次数小于所述计数阈值的情况下，所述第四指示信息用于请求不更新密钥。其中，计数阈值的大小可以根据经验值确定，本申请实施例对此不作限定。
作为一个示例，终端设备中可以设置计数器，在终端设备每发送一次第一请求消息，并接收到指示不更新密钥的第二指示信息时，可以将计数器加一，若终端设备接收到更新密钥的第二指示信息之后，可以将计数器归零。上述未更新密钥的次数可以用计数器表示。当计数器大于或等于计数阈值时，第四指示信息可以用于请求更新密钥；当计数器小于计数阈值时，第四指示信息可以用于请求不更新密钥。
可选地，在方法500中，在所述终端设备的第一状态信息改变的情况下，所述第四指示信息用于请求更新密钥，其中，所述第一状态信息包含以下任意一项：所述终端设备的跟踪区标识(Tracking Area identity,TAI)、所述终端设备当前所属的无线接入网(Radio access network,RAN)组和所述终端设备当前使用的无线接入技术(Radio access technology,RAT)；或，在所述终端设备的第一状态信息未改变的情况下，所述第四指示信息用于请求不更新密钥。
可选地，方法500还包括：在所述第四指示信息用于请求更新密钥，且所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是未更新的密钥的情况下，所述终端设备断开与所述目标基站之间的连接，并重新选择基站。其中，上述方法可以理解为终端设备在接收所述第二指示信息之后，检验第二指示信息指示的接入层密钥是否符合单向决策原则。
在本申请实施例中，该单向决策原则是指存在两个或两个以上的决策点(例如，终端设备、源基站和目标基站)的情况下，可以存在从不更新密钥到更新密钥的单向决策过程，而不存在从更新密钥到不更新密钥的决策过程。换句话说，存在多个用于确定是否更新密钥的决策点的情况下，只要存在一个决策点确定更新密钥，则需要更新密钥。
例如，若终端设备作为确定是否更新密钥的决策点或决策点之一，则终端设备在接收第二指示信息之后，也可以检验第二指示信息指示的接入层密钥是否遵守单向决策原则。例如，若第四指示信息请求更新密钥。终端设备可以验证第二指示信息是否指示终端设备与目标基站之间的接入层密钥为更新后的密钥。若第二指示信息指示该接入层密钥为未更 新的密钥，则表示第二指示信息未根据单向决策原则进行指示接入层密钥。比如，在目标基站的安全性能受到攻击的情况下，可能会确定并发送不符合单向决策原则的第二指示信息。因此，终端设备当前接入的网络可能存在安全性的问题，终端设备可以选择与当前连接的目标基站断开，并重新选择基站。例如，当终端设备处于RRC连接态的情况下，终端设备可以断开与目标基站之间的RRC连接，重新选择基站，并与重新选择的基站建立新的RRC连接。当终端设备处于未激活态的情况下，终端设备可以停止与目标基站之间的恢复RRC连接的进程，重新选择基站，并向重新选择的基站请求恢复RRC连接。
例如，当终端设备处于RRC连接态的情况下，终端设备可以断开与目标基站之间的RRC连接，重新选择基站，并与重新选择的基站建立新的RRC连接。当终端设备处于未激活态的情况下，终端设备可以停止与目标基站之间的恢复RRC连接的进程，重新选择基站，并向重新选择的基站请求恢复RRC连接。
在本申请实施例中，引入了终端设备、目标基站和源基站中的一个或多个决策点，以确定是否更新密钥，可以根据各决策点的实时状态信息以及预设的策略，协调确定是否更新密钥，从而提供了一种灵活的更新密钥的方法。在引入多个决策点的情况下，可以由多个决策点确定是否更新密钥，从而提高了终端设备与目标基站通信的安全性能。并且引入多个决策点可以平衡每个决策点的决策能力，或者说通过分散决策能力，使得各决策点能够根据各自的状态确定是否更新密钥，并且能够兼顾其他决策点的状态，从而提供了一种安全、灵活的更新密钥的方案。
可选地，方法500还包括：所述终端设备接收所述目标基站发送的NCC；在所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥为更新后的密钥的情况下，所述终端设备根据所述NCC，生成第三密钥，所述第三密钥为所述终端设备与所述目标基站之间的接入层密钥。
作为具体示例，上述终端设备可以根据上述NCC和衍生参数，生成上述第三密钥。
其中，上述衍生参数可以包括以下至少一项：PCI、演进型通用陆基无线接入下行绝对无线频点以及源基站未使用的NH或者源基站当前使用的与终端设备之间的接入层密钥。
其中，上述衍生参数可以包括以下至少一项：PCI、演进型通用陆基无线接入下行绝对无线频点以及NH或者终端设备当前使用的与源基站之间的接入层密钥。
作为一个示例，若上述NCC与UE存储的NCC不同，则终端设备可以进行纵向密钥衍生；若上述NCC与UE存储的NCC相同，则终端设备可以进行横向密钥衍生。若进行纵向密钥衍生，终端设备将使用NH作为密钥衍生参数。若进行横向密钥衍生，终端设备使用终端设备当前使用的接入层密钥作为衍生参数。对于上述两种衍生方式，衍生参数还可以包含PCI和/或EARFCN-DL。
图6是本申请实施例的通信方法600的示意性流程图。图6的方法可以由基站执行。需要说明的是，若图6的方法应用于图2的应用环境中，其适用于目标基站与源基站属于相同CU的情况，或者说，终端设备从同一CU覆盖的第一小区移动到同一CU覆盖的第二小区之中。需要指出的是，图6所示实施例中涉及的名词、术语以及步骤说明，均可以参见图3至图5所示实施例中的相关描述。方法600包括：
S601、目标基站从终端设备接收第一请求消息，所述第一请求消息包括第一标识信息， 所述第一标识信息用于指示所述终端设备和源基站。
S602、在所述源基站与所述目标基站属于同一CU的情况下，所述目标基站根据所述第一请求消息，向所述终端设备发送第二指示信息，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥或未更新的密钥。
可选地，在本申请实施例中，上述源基站与目标基站属于同一CU，可以指上述源基站和目标基站为同一个CU，或者，可以理解为源基站和目标基站为同一基站。终端设备从同一CU覆盖的小区移动到同一CU覆盖的另一小区。
在S602中，目标基站在接收到第一请求消息之后，可以根据第一请求消息包括的第一标识信息，确定源基站，然后判断源基站与目标基站是否属于同一CU。若源基站与目标基站属于同一CU，相当目标基站与源基站为同一基站，若目标基站与源基站属于同一CU,则目标基站可以根据第一请求消息和/或预设的策略，向终端设备发送第二指示信息，以指示该接入层密钥是否为更新后的密钥。
可选地，所述第一标识信息可以采用同一标识指示所述终端设备和源基站，也可以采用两个标识分别指示所述终端设备和源基站。
例如，若所述第一标识信息采用同一标识指示所述终端设备和源基站，可以采用恢复标识(Resume Identifier,Resume ID)来指示终端设备和源基站。
例如，若所述第一标识信息采用两个标识分别指示所述终端设备和源基站，则可以采用物理小区标识(Physical cell identifier,PCI)指示源基站，采用小区无线网络临时标识(Cell Radio temporary identifier,C-RNTI)指示终端设备。
在本申请实施例中，在目标基站与源基站属于同一CU的情况下，目标基站可以向终端设备发送第二指示信息，以指示终端设备与目标基站之间的接入层密钥是否为更新后的密钥，从而提供了一种灵活的更新密钥的方法。
可选地，在方法600中，在所述第一请求消息还包括第四指示信息，且所述第四指示信息用于请求更新密钥的情况下，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥。
可选地，在本申请实施例中，终端设备和目标基站中的任意一个或组合都可以参与决策是否更新终端设备与目标基站之间的接入层密钥的过程。例如，可以由目标基站决策是否更新密钥；或者，可以由终端设备决策是否更新密钥；或者，可以由终端设备和目标基站共同决策是否更新密钥。
可选地，在两个决策点(例如，终端设备和目标基站)确定是否更新密钥的情况下，可以存在从不更新密钥到更新密钥的单向决策过程，而不存在从更新密钥到不更新密钥的决策过程。换句话说，存在两个决策点的情况下，只要存在一个决策点确定更新密钥，则需要更新密钥。
应理解，目标基站可以参与决策是否更新密钥的过程，或者，目标基站也可以不参与决策是否更新密钥的过程，而是根据终端设备发送的第四指示信息，确定第二指示信息。
作为一个示例，在以目标基站作为单独决策点的情况下，在步骤602中向所述终端设备发送第二指示信息之前，上述方法还可以包括：目标基站根据预设的策略确定更新密钥或不更新密钥。
其中，上述预设的策略可以是根据用户签约信息获取的策略，例如，目标基站可以从 核心网设备获取该预设的策略。或者，上述预设的策略也可以是预配置的。可选地，上述预设的策略可以是根据终端设备在同一CU中未更新密钥的次数确定是否更新密钥。可选地，该预设的策略也可以是目标基站和源基站属于同一CU的情况下无需更新密钥。
作为另一个示例，在目标基站和终端设备都作为决策点的情况下，步骤602可以包括：目标基站可以根据第四指示信息以及上述预设的策略，发送第二指示信息。例如，若第四指示信息指示更新密钥和/或目标基站根据预设的策略确定更新密钥，则目标基站生成新的接入层密钥，且第二指示信息用于指示该接入层密钥是更新后的密钥；若第四指示信息指示不更新密钥，且目标基站根据预设的策略确定不更新密钥，则第二指示信息用于指示该接入层密钥是未更新的密钥。
作为再一个示例，在目标基站不作为决策点，而是终端设备作为决策点的情况下，目标基站可以根据第四指示信息，确定是否更新密钥。当第四指示信息指示更新密钥时，目标基站更新密钥；当第四指示信息指示不更新密钥时，目标基站不更新密钥，即目标基站本身不参与决策更新密钥的过程。
在本申请实施例中，引入了终端设备和目标基站的一个或两个决策点，以确定是否更新密钥，可以根据各决策点的实时状态信息以及预设的策略，协调确定是否更新密钥，从而提供了一种灵活的更新密钥的方法。在引入两个决策点的情况下，可以由两个决策点确定是否更新密钥，从而提高了终端设备与目标基站通信的安全性能。并且引入两个决策点可以平衡每个决策点的决策能力，或者说通过分散决策能力，使得各决策点能够根据各自的状态确定是否更新密钥，并且能够兼顾其他决策点的状态，从而提供了一种安全、灵活的更新密钥的方案。
可选地，在方法600中，在所述终端设备的未更新密钥次数大于或等于计数阈值的情况下，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥为更新后的密钥，其中，所述终端设备的未更新密钥次数为所述终端设备的上一次更新密钥的时刻至当前时刻之间的时间区间内的未更新密钥次数。
可选地，在方法600中，在所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥的情况下，方法600还包括：所述目标基站根据NCC生成所述第一密钥，所述第一密钥为所述终端设备与所述目标基站之间的接入层密钥；所述目标基站向所述终端设备发送所述NCC。
作为具体示例，上述目标基站可以根据上述NCC和衍生参数，生成上述第二密钥。
其中，上述衍生参数可以包括以下至少一项：PCI、演进型通用陆基无线接入下行绝对无线频点(E-UTRA Absolute Radio Frequency Channel Number-Down Link,EARFCN-DL)以及目标基站未使用的下一跳(Next Hop,NH)或者目标基站当前使用的与终端设备之间的接入层密钥。
作为一个示例，若与NCC绑定的NH未使用，则目标基站可以进行纵向密钥衍生；若与NCC绑定的NH已使用，则目标基站可以进行横向密钥衍生。若进行纵向密钥衍生，目标基站将使用NH作为密钥衍生参数。若进行横向密钥衍生，目标基站使用目标基站当前使用的接入层密钥作为衍生参数。对于上述两种衍生方式，衍生参数还可以包含PCI和/或EARFCN-DL。
可选地，在方法600中，在所述第一请求消息还包括第四指示信息，且所述第四指示 信息用于请求不更新密钥的情况下，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是未更新的密钥；或，在所述终端设备的未更新密钥次数小于所述计数阈值的情况下，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥为未更新的密钥，其中，所述终端设备的未更新密钥次数为所述终端设备的上一次更新密钥的时刻至当前时刻之间的时间区间内的未更新密钥次数。
作为一个示例，目标基站中可以设置终端设备对应的计数器，目标基站每次向终端设备发送指示第一密钥为未更新密钥的第二指示信息时，可以将计数器加一，若目标基站发送指示第一密钥为更新后的密钥的第二指示信息之后，可以将计数器归零。上述未更新密钥的次数可以用计数器表示。当计数器大于或等于计数阈值时，第二指示信息可以用于指示第一密钥为更新后的密钥；当计数器小于计数阈值时，第二指示信息可以用于指示第一密钥为更新后的密钥。
可选地，在方法600中，所述终端设备处于未激活态，所述第一请求消息用于请求恢复所述终端设备的无线资源控制RRC连接，所述第二指示信息携带在第一响应消息中，所述第一响应消息用于指示所述终端设备保持未激活态；或，所述第一响应消息用于指示所述终端设备恢复RRC连接。
图7是本申请实施例的具体实施例的示意图。图7示出了源基站作为决策点确定是否更新密钥的通信过程。可选地，当源基站是图2中的gNB的情况下，源基站所执行的步骤可以由CU执行。方法700中与上文相同或相似的内容，此处不再赘述。如图7所示，方法700包括：
S701、终端设备向目标基站发送第一请求消息，所述第一请求消息包括第一标识信息。
其中，所述第一标识信息，第一请求消息可以参见图3所示实施例中的相关描述。
例如，该第一标识信息可以是Resume ID，或者，第一标识信息可以是用于指示终端设备的C-RNTI和用于指示源基站的PCI。可选地，目标基站可以根据第一标识信息确定源基站。
可选地，终端设备可以在处于未激活态或连接态的情况下从源基站的覆盖区域移动到目标基站的覆盖区域。
可选地，所述第一请求消息可以包括RRC连接恢复请求(RRC Connection Resume Request)消息。该RRC连接恢复请求消息用于请求恢复RRC连接。或者，第一请求消息可以包括其他类型的信息，本申请实施例对此不作限定。
可选地，所述第一请求消息还可以包括消息校验码(Message Authentication Code,MAC)信息，所述MAC信息用于指示所述第一请求消息为合法的终端设备生成。其中，MAC信息可以由终端设备根据gNB的根密钥(例如，KgNB)衍生出的RRC完整性保护密钥(例如，krrc-int)和完整性保护算法得到。
S702、目标基站向源基站发送第二请求消息，该第二请求消息包括第二标识信息，第二标识信息用于指示终端设备。
其中，所述第二标识信息，第二请求消息可以参见图3所示实施例中的相关描述。
例如，第二标识信息可以是Resume ID。或者，第二标识信息可以终端设备的C-RNTI。
可选地，第二请求消息可以是上下文请求消息，所述上下文请求消息用于请求获取所述终端设备对应的上下文信息。可选地，所述上下文请求消息还包括上述MAC信息。
S703、源基站在接收第二请求消息之后，确定是否更新密钥。
其中，源基站可以根据预设的策略确定是否更新密钥。关于上述预设的策略的内容可以参考图4所示实施例中的相关描述。
可选地，若第二请求消息为上下文请求消息，则所述源基站可以根据所述上下文请求消息包括的第二标识信息，确定本地存储的终端设备的上下文。
可选地，若第二请求消息包括MAC消息，则所述源基站可以根据所述终端设备的上下文的安全参数校验MAC。例如，上下文中的安全参数可以包括源基站与终端设备之间的接入层密钥、完整性保护算法等。
具体地，源基站可以根据上述源基站与终端设备之间的接入层密钥衍生出RRC完整性保护密钥，并根据上述RRC完整性保护密钥和上述完整性保护算法校验上述MAC。
可选地，源基站在校验MAC成功后，可以执行步骤S704。
S704、源基站向目标基站发送第一指示信息和第一密钥，所述第一指示信息用于指示第一密钥是更新后的密钥或未更新的密钥。
其中，第一指示信息和第一密钥的相关内容可以参见图3的实施例的相关描述。
可选地，第一指示信息可以承载于第二响应消息中，第二响应消息用于响应第二请求消息。若第二请求消息为上下文请求消息，则该第二响应消息可以为上下文响应消息，该上下文响应消息包括所述终端设备的上下文，该终端设备的上下文包括该第一密钥。
可选地，当步骤S703中源基站确定更新密钥时，第一密钥为更新后的密钥，第一指示信息用于指示第一密钥是更新后的密钥；当步骤S703中源基站确定不更新密钥时，第一密钥为终端设备与源基站之间的密钥，第一指示信息用于指示第一密钥是未更新的密钥。
若该第一指示信息用于指示第一密钥为更新后的密钥，所述第一指示信息还可以包括NCC，所述第一指示信息还可以包括NCC，该第一密钥为根据该NCC衍生的密钥。其中，源基站衍生第一密钥的具体方法可以参见图4的实施例。
可选地，关于具体指示终端设备与目标基站之间的接入层密钥是否为更新后的密钥的方式，可以在第一指示信息中设置保留密钥指令(retain-key)或修改密钥指令(change-key)。相应地，retain-key指令或change-key指令也可以应用于第二指示信息至第四指示信息中。
例如，当设置retain-key＝真(true)或，change-key＝假(false)时，表示不更新密钥，或表示密钥是未更新的密钥；当设置retain-key＝true，或change-key＝true时，表示更新密钥或表示密钥是更新后的密钥。
可选地，若S703中，源基站确定不更新密钥，则还可以在第一指示信息中指示KgNB*＝KgNB。其中，KgNB表示源基站与终端设备之间使用的原密钥，KgNB*表示新密钥。需要说明的是，KgNB*可以是图3至图5的实施例中的第一密钥。
S705、目标基站向终端设备发送第二指示信息。
其中，第二指示信息用于指示终端设备与目标基站之间的接入层密钥是更新后的密钥或未更新的密钥。
可选地，目标基站可以将该第一密钥作为与终端设备之间的接入层密钥。
可选地，第二指示信息可以采用至少两种方式指示是否更换了终端设备与目标基站之间的接入层密钥。
在第一种方式中，第二指示信息可以携带retain-key，若retain-key＝true，第二指示信息还携带有NCC；若retain-key＝false，则第二指示信息无需携带NCC。
在第二种方式中，第二指示信息可以不携带retain-key。而是通过是否携带NCC指示是否更换了密钥。例如，若第二指示信息中携带NCC，则指示更新密钥。若第二指示信息不携带NCC，则指示未更新密钥。
可选地，第二指示信息可以承载于第一响应消息中，该第一响应消息可以用于指示终端设备保持未激活态，或，该第一响应消息可以用于指示终端设备恢复RRC连接。例如，第一响应消息可以包括RRC连接释放(RRC Connection Release)消息或RRC连接恢复消息。
需要说明的是，在S701中，虽然第一请求消息可以承载于RRC连接恢复请求中，但是在S705中网络侧可以不恢复RRC连接，而是发送RRC连接释放消息。从而在终端设备处于未激活态的过程中完成上下文的迁移，无需重新建立RRC连接，节约了信令开销。
S706、终端设备根据第二指示信息，确定接入层密钥。
例如，若第二指示信息指示更新密钥，则终端设备根据第二指示信息携带的NCC衍生新的密钥KgNB*。并将KgNB*作为终端设备与基站之间通信的接入层密钥。
当第二指示信息指示不更新密钥，则终端设备令KgNB*＝KgNB。
在本申请实施例中，在终端设备从源基站覆盖区域移动到目标基站覆盖区域的情况下，引入了源基站确定是否更新目标基站与终端设备之间的接入层密钥，提供了一种灵活的更新密钥的方法。
图8示出了终端设备作为决策点确定是否更新密钥的通信过程。可选地，当源基站是图2中的gNB的情况下，源基站所执行的步骤可以由CU执行。方法800中与上文相同或相似的内容，此处不再赘述。如图8所示，方法800包括：
S801、终端设备确定第四指示信息，第四指示信息用于请求更新密钥。
其中，终端设备可以根据预设的策略确定第四指示信息。该预设的策略可以参考图5的实施例。
可选地，终端设备可以在处于未激活态或连接态的情况下从源基站的覆盖区域移动到目标基站的覆盖区域。
S802、终端设备向目标基站发送第一请求消息。第一请求消息包括第一标识和第四指示信息。第四指示信息用于请求更新密钥或不更新密钥。
其中，所述第一标识信息，第一请求消息可以参见图3所示实施例中的相关描述。
例如，该第一标识信息可以是Resume ID，或者，第一标识信息可以是用于指示终端设备的C-RNTI和用于指示源基站的PCI。可选地，目标基站可以根据第一标识信息确定源基站。
可选地，如图7的示例所描述的，第四指示信息可以携带retain-key指令或change-key指令以指示请求是否更新密钥。
可选地，所述第一请求消息可以包括RRC连接恢复请求(RRC Connection Resume Request)消息。该RRC连接恢复请求消息用于请求恢复RRC连接。或者，第一请求消息可以包括其他类型的信息，本申请实施例对此不作限定。
可选地，所述第一请求消息还可以包括MAC信息。
可选地，若目标基站和源基站为图2中的gNB。在一种可能的情况下，源基站和目标基站可以属于同一CU。或者说，源基站和目标基站为同一基站。此时，方法800无需执行S803至S804，而是在接下来执行S805。具体过程可以参见图6的实施例。
S803、目标基站向源基站发送第二请求消息，该第二请求消息包括第二标识信息和第三指示信息。
其中，第二请求消息和第二标识信息可以参考图3的实施例的相关描述。
其中，第二标识信息用于指示终端设备。例如，第二标识信息可以是Resume ID。或者，第二标识信息可以终端设备的C-RNTI。
例如，第二请求消息可以是上下文请求消息，所述上下文请求消息用于请求获取所述终端设备对应的上下文信息。
可选地，所述上下文请求消息还可以包括MAC信息。
其中，所述第三指示信息用于请求更新密钥或不更新密钥。目标基站可以根据第四指示信息，确定第三指示信息。例如，若第四指示信息请求更新密钥，则第三指示信息请求更新密钥。若第四指示信息请求不更新密钥，则第三指示信息请求不更新密钥。
例如，所述第三指示信息可以通过携带retain-key信令或change-key信令，指示是否请求更新密钥。
应注意的是，图8的例子中，引入了终端设备作为单决策点，以确定是否请求更新密钥，因而目标基站并不参与决策是否更新密钥的过程，而是相当于透传第四指示信息。在本申请实施例的其他例子中(例如，图9和图10的例子)还引入了目标基站作为决策点的方法，在这种情况下，目标基站参与了确定是否更新密钥的决策，而并非透传终端设备的决策结果。
S804、源基站向目标基站发送第一指示信息和第一密钥，所述第一指示信息用于指示第一密钥是更新后的密钥或未更新的密钥。
可选地，第一指示信息可以承载于第二响应消息中，第二响应消息用于响应第二请求消息。若第二请求消息为上下文请求消息，则该第二响应消息可以为上下文响应消息，该上下文响应消息包括所述终端设备的上下文，该终端设备的上下文包括该第一密钥。
其中，源基站可以根据第三指示信息，确定是否更新密钥。例如，当第三指示信息请求不更新密钥时，确定不更新密钥。若第三指示信息请求更新密钥，则确定更新密钥。
可选地，在确定更新密钥时，第一密钥为更新后的密钥，第一指示信息用于指示第一密钥是更新后的密钥；在确定不更新密钥时，第一密钥为终端设备与源基站之间的密钥，第一指示信息用于指示第一密钥是未更新的密钥。
若该第一指示信息用于指示第一密钥为更新后的密钥，所述第一指示信息还可以包括NCC，所述第一指示信息还可以包括NCC，该第一密钥为根据该NCC衍生的密钥。其中，源基站衍生第一密钥的具体方法可以参见图4的实施例。
可选地，关于具体指示终端设备与目标基站之间的接入层密钥是否为更新后的密钥的方式，可以在第一指示信息中设置保留密钥指令(retain-key)或修改密钥指令(change-key)。相应地，retain-key指令或change-key指令也可以应用于第二指示信息至第四指示信息中。
例如，当设置retain-key＝真(true)或，change-key＝假(false)时，表示不更新密钥，或表示密钥是未更新的密钥；当设置retain-key＝true，或change-key＝true时，表示更新密 钥或表示密钥是更新后的密钥。
可选地，若第二请求消息为上下文请求消息，则所述源基站可以根据所述上下文请求消息包括的第二标识信息，确定本地存储的终端设备的上下文。
可选地，若第二请求消息包括MAC消息，则所述源基站可以根据所述终端设备的上下文的安全参数校验MAC。例如，上下文中的安全参数可以包括源基站与终端设备之间的接入层密钥、完整性保护算法等。
具体地，源基站可以根据上述源基站与终端设备之间的接入层密钥衍生出RRC完整性保护密钥，并根据上述RRC完整性保护密钥和上述完整性保护算法校验上述MAC。
可选地，源基站在校验MAC成功后，可以执行步骤S805。
S805、目标基站向终端设备发送第二指示信息。
其中，第二指示信息用于指示终端设备与目标基站之间的接入层密钥是更新后的密钥或未更新的密钥。
可选地，目标基站可以将该第一密钥作为与终端设备之间的接入层密钥。
可选地，第二指示信息可以采用至少两种方式指示是否更换了终端设备与目标基站之间的接入层密钥。
在第一种方式中，第二指示信息可以携带retain-key，若retain-key＝true，第二指示信息还携带有NCC；若retain-key＝false，则第二指示信息无需携带NCC。
在第二种方式中，第二指示信息可以不携带retain-key。而是通过是否携带NCC指示是否更换了密钥。例如，若第二指示信息中携带NCC，则指示更新密钥。若第二指示信息不携带NCC，则指示未更新密钥。
可选地，第二指示信息可以承载于第一响应消息中，该第一响应消息可以用于指示终端设备保持未激活态，或，该第一响应消息可以用于指示终端设备恢复RRC连接。例如，第一响应消息可以包括RRC连接释放(RRC Connection Release)消息或RRC连接恢复消息。
可选地，若在S802中，目标基站与源基站属于同一CU，则在S805中，目标基站可以根据第一请求消息，确定并发送第二指示信息。具体过程可以参考图6的实施例。
需要说明的是，在S802中，虽然第一请求消息可以承载于RRC连接恢复请求中，但是在S805中网络侧可以不恢复RRC连接，而是发送RRC连接释放消息。在本申请实施例中，可以在终端设备处于未激活态的过程中完成上下文的迁移，无需重新建立RRC连接。
S806、终端设备根据第二指示信息，确定接入层密钥。
可选地，终端设备接收第二指示信息。若第二指示信息指示不更新密钥，则终端设备令KgNB*＝KgNB。若第二指示信息指示更新密钥，则终端设备根据第二指示信息携带的NCC衍生新的密钥KgNB*。
可选地，终端设备在接收到第二指示信息之后，可以检验第二指示信息指示的内容是否符合单向决策原则。若第二指示信息指示的内容是否符合单向决策原则，则终端设备可以与目标基站断开，并重新选择基站进行接入。若第二指示信息未被降级，则终端设备可以根据第二指示信息的指示选择保留原密钥或生成新的密钥。
其中，上述不符合单向决策原则可以指在第四指示信息请求更新密钥的情况下，第二 指示信息却指示终端设备与目标基站之间的接入层密钥为未更新的密钥。本申请实施例倾向于安全的更新密钥策略过程，因此，若终端设备可以检测到目标基站发送的第二指示信息不符合单向决策原则的情况下，可以与目标基站断开，并重新选择基站进行接入，从而提高了通信的安全性。
在本申请实施例中，在终端设备从源基站覆盖区域移动到目标基站覆盖区域的情况下，引入了终端设备确定是否更新目标基站与终端设备之间的接入层密钥，提供了一种灵活的更新密钥的方法。
图9示出了目标基站和源基站共同作为决策点确定是否更新密钥的通信过程。可选地，当源基站是图2中的gNB的情况下，源基站所执行的步骤可以由CU执行。方法900中与上文相同或相似的内容，此处不再赘述。如图9所示，方法900包括：
S901、终端设备向目标基站发送第一请求消息，所述第一请求消息包括第一标识信息。
其中，所述第一标识信息，第一请求消息可以参见图3所示实施例中的相关描述。
例如，该第一标识信息可以是Resume ID，或者，第一标识信息可以是用于指示终端设备的C-RNTI和用于指示源基站的PCI。可选地，目标基站可以根据第一标识信息确定源基站。
可选地，终端设备可以在处于未激活态或连接态的情况下从源基站的覆盖区域移动到目标基站的覆盖区域。
可选地，所述第一请求消息可以包括RRC连接恢复请求(RRC Connection Resume Request)消息。该RRC连接恢复请求消息用于请求恢复RRC连接。或者，第一请求消息可以包括其他类型的信息，本申请实施例对此不作限定。
可选地，所述第一请求消息还可以包括消息校验码(Message Authentication Code,MAC)信息，所述MAC信息用于指示所述第一请求消息为合法的终端设备生成。其中，MAC信息可以由终端设备根据gNB的根密钥(例如，KgNB)衍生出的RRC完整性保护密钥(例如，krrc-int)和完整性保护算法得到。
S902、目标基站确定第三指示信息，第三指示信息用于请求更新密钥或不更新密钥。
可选地，目标基站可以根据预设的策略，确定第三指示信息。该预设的策略可以参见图3的实施例的相关内容。
可选地，目标基站可以确定源基站，所述源基站存储有终端设备的上下文信息。
S903、目标基站向源基站发送第二请求消息，该第二请求消息包括第二标识信息和第三指示信息。
其中，所述第二标识信息，第二请求消息可以参见图3所示实施例中的相关描述。
例如，第二标识信息可以是Resume ID。或者，第二标识信息可以终端设备的C-RNTI。
可选地，第二请求消息可以是上下文请求消息，所述上下文请求消息用于请求获取所述终端设备对应的上下文信息。可选地，所述上下文请求消息还包括上述MAC信息。
S904、源基站确定是否更新密钥。
其中，源基站可以根据第三指示信息和预设的策略确定是否更新密钥，关于第三指示信息和预设的策略可以参见图4的实施例。
可选地，若第二请求消息为上下文请求消息，则所述源基站可以根据所述上下文请求消息包括的第二标识信息，确定本地存储的终端设备的上下文。
可选地，若第二请求消息包括MAC消息，则所述源基站可以根据所述终端设备的上下文的安全参数校验MAC。例如，上下文中的安全参数可以包括源基站与终端设备之间的接入层密钥、完整性保护算法等。
具体地，源基站可以根据上述源基站与终端设备之间的接入层密钥衍生出RRC完整性保护密钥，并根据上述RRC完整性保护密钥和上述完整性保护算法校验上述MAC。
可选地，源基站在校验MAC成功后，可以执行步骤S905。
S905、源基站向目标基站发送第一指示信息和第一密钥，所述第一指示信息用于指示第一密钥是更新后的密钥或未更新的密钥。
可选地，该第一指示信息可以包括retian-key。若该第一指示信息指示终端设备与目标基站之间的接入层密钥为更新后的密钥，所述第一指示信息还可以包括NCC，该第一密钥为根据该NCC衍生的KgNB*。
可选地，第一指示信息可以承载于第二响应消息中，该第二响应消息可以包括上下文响应消息，该上下文响应消息包括所述终端设备的上下文，该终端设备的上下文包括该第一密钥。
S906、目标基站接收源基站发送的第一密钥和第一指示信息，并根据第一指示信息，确定第二指示信息。第二指示信息用于指示终端设备与目标基站之间的接入层密钥是更新后的密钥或未更新的密钥。
其中，目标基站根据第一指示信息，确定第二指示信息的过程可以参见图3的实施例的相关描述。
可选地，目标基站可以校验第一指示信息指示的第一密钥是否符合单向决策原则，并根据校验结果确定是否将第一密钥作为目标基站和终端设备之间的接入层密钥。关于单向决策原则可以参见图3的实施例的相关描述。
S907、目标基站向终端设备发送第二指示信息。
其中，第二指示信息用于指示终端设备与目标基站之间的接入层密钥是更新后的密钥或未更新的密钥。
可选地，目标基站可以将该第一密钥作为与终端设备之间的接入层密钥。
可选地，第二指示信息可以采用至少两种方式指示是否更换了终端设备与目标基站之间的接入层密钥。
在第一种方式中，第二指示信息可以携带retain-key，若retain-key＝true，第二指示信息还携带有NCC；若retain-key＝false，则第二指示信息无需携带NCC。
在第二种方式中，第二指示信息可以不携带retain-key。而是通过是否携带NCC指示是否更换了密钥。例如，若第二指示信息中携带NCC，则指示更新密钥。若第二指示信息不携带NCC，则指示未更新密钥。
可选地，第二指示信息可以承载于第一响应消息中，该第一响应消息可以用于指示终端设备保持未激活态，或，该第一响应消息可以用于指示终端设备恢复RRC连接。例如，第一响应消息可以包括RRC连接释放(RRC Connection Release)消息或RRC连接恢复消息。
需要说明的是，在S901中，虽然第一请求消息可以承载于RRC连接恢复请求中，但是在S907中网络侧可以不恢复RRC连接，而是发送RRC连接释放消息。可以在终端设 备处于未激活态的过程中完成上下文的迁移，无需重新建立RRC连接，从而节约了信令开销。
S908、终端设备根据第二指示信息，确定接入层密钥。
例如，若第二指示信息指示更新密钥，则终端设备根据第二指示信息携带的NCC衍生新的密钥KgNB*。并将KgNB*作为终端设备与基站之间通信的接入层密钥。
当第二指示信息指示不更新密钥，则终端设备令KgNB*＝KgNB。
在本申请实施例中，在终端设备从源基站覆盖区域移动到目标基站覆盖区域的情况下，引入了目标基站和源基站确定是否更新目标基站与终端设备之间的接入层密钥，以协调确定是否更新密钥，提供了一种灵活的更新密钥的方法。
图10示出了终端设备、目标基站和源基站共同作为决策点确定是否更新密钥的通信过程。可选地，当源基站是图2中的gNB的情况下，源基站所执行的步骤可以由CU执行。方法1000中与上文相同或相似的内容，此处不再赘述。如图10所示，方法1000包括：
S1001、终端设备确定第四指示信息，第四指示信息用于请求更新密钥。
其中，终端设备可以根据预设的策略确定第四指示信息。该预设的策略可以参考图5的实施例。
可选地，终端设备可以在处于未激活态或连接态的情况下从源基站的覆盖区域移动到目标基站的覆盖区域。
S1002、终端设备向目标基站发送第一请求消息。第一请求消息包括第一标识和第四指示信息。第四指示信息用于请求更新密钥或不更新密钥。
其中，所述第一标识信息，第一请求消息可以参见图3所示实施例中的相关描述。
例如，该第一标识信息可以是Resume ID，或者，第一标识信息可以是用于指示终端设备的C-RNTI和用于指示源基站的PCI。可选地，目标基站可以根据第一标识信息确定源基站。
可选地，如图7的示例所描述的，第四指示信息可以携带retain-key指令或change-key指令以指示请求是否更新密钥。
可选地，所述第一请求消息可以包括RRC连接恢复请求(RRC Connection Resume Request)消息。该RRC连接恢复请求消息用于请求恢复RRC连接。或者，第一请求消息可以包括其他类型的信息，本申请实施例对此不作限定。
可选地，所述第一请求消息还可以包括MAC信息。
S1003、目标基站确定第三指示信息，第三指示信息用于请求更新密钥或不更新密钥。
可选地，目标基站可以根据第四指示信息和预设的策略确定第三指示信息，具体过程可以参见图3的实施例的相关描述。
可选地，目标基站可以确定源基站，所述源基站存储有终端设备的上下文信息。
可选地，若目标基站和源基站为图2中的gNB。在一种可能的情况下，源基站和目标基站可以属于同一CU。或者说，源基站和目标基站为同一基站。此时，方法1000无需执行S1004至S1006，而是在接下来执行S1007。具体过程可以参见图6的实施例。
S1004、目标基站向源基站发送第二请求消息，该第二请求消息包括第二标识信息和第三指示信息。
其中，所述第二标识信息，第二请求消息可以参见图3所示实施例中的相关描述。
例如，第二标识信息可以是Resume ID。或者，第二标识信息可以终端设备的C-RNTI。
可选地，第二请求消息可以是上下文请求消息，所述上下文请求消息用于请求获取所述终端设备对应的上下文信息。可选地，所述上下文请求消息还包括上述MAC信息。
应注意的是，图10的例子中，引入了终端设备、目标基站和源基站共同作为决策点，在这种情况下，目标基站参与了确定是否更新密钥的决策，而并非透传终端设备的决策结果。
S1005、源基站确定是否更新密钥。
其中，源基站可以根据第三指示信息和预设的策略确定是否更新密钥，关于第三指示信息和预设的策略可以参见图4的实施例。
可选地，若第二请求消息为上下文请求消息，则所述源基站可以根据所述上下文请求消息包括的第二标识信息，确定本地存储的终端设备的上下文。
可选地，若第二请求消息包括MAC消息，则所述源基站可以根据所述终端设备的上下文的安全参数校验MAC。例如，上下文中的安全参数可以包括源基站与终端设备之间的接入层密钥、完整性保护算法等。
具体地，源基站可以根据上述源基站与终端设备之间的接入层密钥衍生出RRC完整性保护密钥，并根据上述RRC完整性保护密钥和上述完整性保护算法校验上述MAC。
可选地，源基站在校验MAC成功后，可以执行步骤S1006。
S1006、源基站向目标基站发送第一指示信息和第一密钥，所述第一指示信息用于指示第一密钥是更新后的密钥或未更新的密钥。
可选地，该第一指示信息可以包括retian-key。若该第一指示信息指示终端设备与目标基站之间的接入层密钥为更新后的密钥，所述第一指示信息还可以包括NCC，该第一密钥为根据该NCC衍生的KgNB*。
可选地，第一指示信息可以承载于第二响应消息中，该第二响应消息可以包括上下文响应消息，该上下文响应消息包括所述终端设备的上下文，该终端设备的上下文包括该第一密钥。
S1007、目标基站接收源基站发送的第一密钥和第一指示信息，并根据第一指示信息，确定第二指示信息。第二指示信息用于指示终端设备与目标基站之间的接入层密钥是更新后的密钥或未更新的密钥。
其中，目标基站根据第一指示信息，确定第二指示信息的过程可以参见图3的实施例的相关描述。
可选地，目标基站可以校验第一指示信息指示的第一密钥是否符合单向决策原则，并根据校验结果确定是否将第一密钥作为目标基站和终端设备之间的接入层密钥。关于单向决策原则可以参见图3的实施例的相关描述。
S1008、目标基站向终端设备发送第二指示信息。
其中，第二指示信息用于指示终端设备与目标基站之间的接入层密钥是更新后的密钥或未更新的密钥。
可选地，目标基站可以将该第一密钥作为与终端设备之间的接入层密钥。
可选地，第二指示信息可以采用至少两种方式指示是否更换了终端设备与目标基站之 间的接入层密钥。
在第一种方式中，第二指示信息可以携带retain-key，若retain-key＝true，第二指示信息还携带有NCC；若retain-key＝false，则第二指示信息无需携带NCC。
在第二种方式中，第二指示信息可以不携带retain-key。而是通过是否携带NCC指示是否更换了密钥。例如，若第二指示信息中携带NCC，则指示更新密钥。若第二指示信息不携带NCC，则指示未更新密钥。
可选地，第二指示信息可以承载于第一响应消息中，该第一响应消息可以用于指示终端设备保持未激活态，或，该第一响应消息可以用于指示终端设备恢复RRC连接。例如，第一响应消息可以包括RRC连接释放(RRC Connection Release)消息或RRC连接恢复消息。
需要说明的是，在S1002中，虽然第一请求消息可以承载于RRC连接恢复请求中，但是在S1008中网络侧可以不恢复RRC连接，而是发送RRC连接释放消息。可以在终端设备处于未激活态的过程中完成上下文的迁移，无需重新建立RRC连接，从而节约了信令开销。
S1009、终端设备根据第二指示信息，确定接入层密钥。
可选地，终端设备接收第二指示信息。若第二指示信息指示不更新密钥，则终端设备令KgNB*＝KgNB。若第二指示信息指示更新密钥，则终端设备根据第二指示信息携带的NCC衍生新的密钥KgNB*。
可选地，终端设备在接收到第二指示信息之后，可以检验第二指示信息指示的内容是否符合单向决策原则。若第二指示信息指示的内容是否符合单向决策原则，则终端设备可以与目标基站断开，并重新选择基站进行接入。若第二指示信息未被降级，则终端设备可以根据第二指示信息的指示选择保留原密钥或生成新的密钥。
其中，上述不符合单向决策原则可以指在第四指示信息请求更新密钥的情况下，第二指示信息却指示终端设备与目标基站之间的接入层密钥为未更新的密钥。本申请实施例倾向于安全的更新密钥策略过程，因此，若终端设备可以检测到目标基站发送的第二指示信息不符合单向决策原则的情况下，可以与目标基站断开，并重新选择基站进行接入，从而提高了通信的安全性。
在本申请实施例中，在终端设备从源基站覆盖区域移动到目标基站覆盖区域的情况下，引入了终端设备、目标基站和源基站三个决策点确定是否更新目标基站与终端设备之间的接入层密钥，提供了一种灵活的更新密钥的方法。
图11示出了通信方法1100。图11示出了在执行完方法300至方法1000中的任一方法之后，目标基站可以继续发起路径切换(path switch)的过程。目标基站可以从AMF获取未使用的{NH,NCC}对，进行密钥衍生。进而实现前向安全，即源基站无法推演出目标基站当前使用的密钥。方法1100包括：
S1101、执行方法300至方法1000中的任一方法。
S1102、目标基站和AMF之间执行路径切换的过程，以通知AMF链路改变，AMF会在回复消息中携带新的{NH,NCC}对。
S1103、终端设备确定是否更新密钥。可选地，终端设备可以在执行方法300至1000中的任一方法后的一段时间后，确定再次更新密钥。
S1104、终端设备再次向目标基站发送第一请求消息，该第一请求消息包括第一标识信息，第一标识信息用于指示终端设备和源基站，该第一请求消息例如可以是RRC连接恢复请求消息。可选地，第一请求消息可以包括第四指示信息，以指示终端设备是否请求更新密钥。
S1105、目标基站根据新的{NH,NCC}对，生成新的密钥，以作为终端设备与目标基站之间的接入层密钥。
S1106、目标基站向终端设备发送第一响应消息，该第一响应消息中包括第二指示信息和该NCC，该第二指示信息用于指示更新密钥。该第一响应消息用于响应第一请求消息。该第一响应消息可以是RRC连接中止消息，或RRC连接恢复消息。
S1107、UE接收该第一响应消息后，根据NCC，衍生新密钥。
在本申请实施例中，在终端设备从源基站覆盖的小区移动至目标基站覆盖的小区之后，目标基站可以发起路径切换(path switch)的过程。目标基站可以从AMF获取未使用的{NH,NCC}对，进行密钥衍生。进而实现前向安全，即源基站无法推演出目标基站当前使用的密钥，从而提高了通信安全。
上文结合图1至图11，介绍了本申请实施例的通信方法，接下来将结合图12至图19，介绍本申请实施例的装置。
图12是本申请实施例的基站1200的示意性框图。应理解，基站1200能够执行图1至图11的方法中由目标基站执行的各个步骤，为了避免重复，此处不再详述。基站1200可以包括各种类型的基站，例如gNB、NR基站、宏基站、微基站等。基站1200包括：
接收单元1210，用于从终端设备接收第一请求消息，所述第一请求消息包括第一标识信息，所述第一标识信息用于指示所述终端设备和源基站；
发送单元1220，用于根据所述第一请求消息，向所述源基站发送第二请求消息，所述第二请求消息包括第二标识信息，所述第二标识信息用于指示所述终端设备；
所述接收单元1210还用于从所述源基站接收第一密钥和第一指示信息，其中，所述第一指示信息用于指示所述第一密钥是更新后的密钥或未更新的密钥；
所述发送单元1220还用于根据所述第一指示信息，向所述终端设备发送第二指示信息，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥或未更新的密钥。
图13是本申请实施例的基站1300的示意性框图。应理解，基站1300能够执行图1至图11的方法中由源基站执行的各个步骤，为了避免重复，此处不再详述。基站1300可以包括各种类型的基站，例如gNB、NR基站、宏基站、微基站等。基站1300包括：
接收单元1310，用于从目标基站接收第二请求消息，所述第二请求消息包含第二标识信息，所述第二标识信息用于指示终端设备；
发送单元1320，用于根据所述第二请求消息，向所述目标基站发送第一密钥和第一指示信息，其中，所述第一指示信息用于指示所述第一密钥是更新后的密钥或未更新的密钥。
图14是本申请实施例的终端设备1400的示意性框图。应理解，终端设备1400能够执行图1至图11的方法中由终端设备执行的各个步骤，为了避免重复，此处不再详述。终端设备1400可以包括各种类型的基站，例如gNB、NR基站、宏基站、微基站等。终 端设备1400包括：
发送单元1410，用于向目标基站发送第一请求消息，所述第一请求消息包含第一标识信息，所述第一标识信息用于指示所述终端设备以及源基站；
接收单元1420，用于接收所述目标基站发送的第二指示信息，所述第二指示信息用于指示所述目标基站与所述终端设备之间的接入层密钥是更新后的密钥或未更新的密钥。
图15是本申请实施例的基站1500的示意性框图。应理解，基站1500能够执行图6的方法中由目标基站执行的各个步骤，为了避免重复，此处不再详述。基站1500可以包括各种类型的基站，例如gNB、NR基站、宏基站、微基站等。基站1500包括：
接收单元1510，用于从终端设备接收第一请求消息，所述第一请求消息包括第一标识信息，所述第一标识信息用于指示所述终端设备和源基站；
发送单元1520，用于在所述源基站与所述目标基站属于同一CU的情况下，所述目标基站根据所述第一请求消息，向所述终端设备发送第二指示信息，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥或未更新的密钥。
应理解，图15所示的基站可以是为芯片或电路。例如可设置在基站内的芯片或电路。该基站1500对应于图1至图11中的源基站。进一步地，上述通信接口1510也可以与收发器互换。收发器包括接收器和发送器。再进一步地，该基站1500还可以包括总线系统。
其中，处理器1530、存储器1520、接收器和发送器通过总线系统相连，处理器1530用于执行该存储器1520存储的指令，以控制接收器接收信号，并控制发送器发送信号，完成本申请通信方法中基站的步骤。其中，接收器和发送器可以为相同或不同的物理实体。为相同的物理实体时，可以统称为收发器。所述存储器1520可以集成在所述处理器1530中，也可以与所述处理器1530分开设置。
作为一种实现方式，接收器和发送器的功能可以考虑通过收发电路或者收发专用芯片实现。处理器1530可以考虑通过专用处理芯片、处理电路、处理器或者通用芯片实现。
作为另一种实现方式，可以考虑使用通用计算机的方式来实现本申请实施例提供的基站。即将实现处理器1530，接收器和发送器功能的程序代码存储在存储器中，通用处理器通过执行存储器中的代码来实现处理器1530、接收器和发送器的功能。
图15的基站1500所涉及的与本申请实施例提供的技术方案相关的概念，解释和详细说明及其他步骤请参见前述方法或其他实施例中关于这些内容的描述，此处不作赘述。
图16是本申请实施例的基站1600的示意性框图。应理解，基站1600能够执行图1至图11的方法中由目标基站执行的各个步骤，为了避免重复，此处不再详述。基站1600可以包括各种类型的基站，例如gNB、NR基站、宏基站、微基站等。基站1600包括：
通信接口1610，
存储器1620，用于存储指令，
处理器1630，与所述存储器1620和所述通信接口1610分别相连，用于执行所述存储器1620存储的所述指令，以在执行所述指令时执行如下步骤：
通过所述通信接口1610从终端设备接收第一请求消息，所述第一请求消息包括第一标识信息，所述第一标识信息用于指示所述终端设备和源基站；
根据所述第一请求消息，通过所述通信接口1610向所述源基站发送第二请求消息，所述第二请求消息包括第二标识信息，所述第二标识信息用于指示所述终端设备；
通过所述通信接口1610从所述源基站接收第一密钥和第一指示信息，其中，所述第一指示信息用于指示所述第一密钥是更新后的密钥或未更新的密钥；
根据所述第一指示信息，通过所述通信接口1610向所述终端设备发送第二指示信息，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥或未更新的密钥。
应理解，图16所示的基站可以是为芯片或电路。例如可设置在基站内的芯片或电路。该基站1600对应于图1至图11中的源基站。进一步地，上述通信接口1610也可以与收发器互换。收发器包括接收器和发送器。再进一步地，该基站1600还可以包括总线系统。
其中，处理器1630、存储器1620、接收器和发送器通过总线系统相连，处理器1630用于执行该存储器1620存储的指令，以控制接收器接收信号，并控制发送器发送信号，完成本申请通信方法中基站的步骤。其中，接收器和发送器可以为相同或不同的物理实体。为相同的物理实体时，可以统称为收发器。所述存储器1620可以集成在所述处理器1630中，也可以与所述处理器1630分开设置。
作为一种实现方式，接收器和发送器的功能可以考虑通过收发电路或者收发专用芯片实现。处理器1630可以考虑通过专用处理芯片、处理电路、处理器或者通用芯片实现。
作为另一种实现方式，可以考虑使用通用计算机的方式来实现本申请实施例提供的基站。即将实现处理器1630，接收器和发送器功能的程序代码存储在存储器中，通用处理器通过执行存储器中的代码来实现处理器1630、接收器和发送器的功能。
图16的基站1600所涉及的与本申请实施例提供的技术方案相关的概念，解释和详细说明及其他步骤请参见前述方法或其他实施例中关于这些内容的描述，此处不作赘述。
图17是本申请实施例的基站1700的示意性框图。应理解，基站1700能够执行图1至图11的方法中由源基站执行的各个步骤，为了避免重复，此处不再详述。基站1700可以包括各种类型的基站，例如gNB、NR基站、宏基站、微基站等。基站1700包括：
通信接口1710，
存储器1720，用于存储指令，
处理器1730，与所述存储器1720和所述通信接口1710分别相连，用于执行所述存储器1720存储的所述指令，以在执行所述指令时执行如下步骤：
通过所述通信接口1710从目标基站接收第二请求消息，所述第二请求消息包含第二标识信息，所述第二标识信息用于指示终端设备；
根据所述第二请求消息，通过所述通信接口1710向所述目标基站发送第一密钥和第一指示信息，其中，所述第一指示信息用于指示所述第一密钥是更新后的密钥或未更新的密钥。
应理解，图17所示的装置可以是为芯片或电路。例如可设置在基站内的芯片或电路。该基站1700对应于图1至图11中的源基站。进一步地，上述通信接口1710也可以与收发器互换。收发器包括接收器和发送器。再进一步地，该基站1700还可以包括总线系统。
其中，处理器1730、存储器1720、接收器和发送器通过总线系统相连，处理器1730用于执行该存储器1720存储的指令，以控制接收器接收信号，并控制发送器发送信号，完成本申请通信方法中基站的步骤。其中，接收器和发送器可以为相同或不同的物理实体。为相同的物理实体时，可以统称为收发器。所述存储器1720可以集成在所述处理器1730 中，也可以与所述处理器1730分开设置。
作为一种实现方式，接收器和发送器的功能可以考虑通过收发电路或者收发专用芯片实现。处理器1730可以考虑通过专用处理芯片、处理电路、处理器或者通用芯片实现。
作为另一种实现方式，可以考虑使用通用计算机的方式来实现本申请实施例提供的基站。即将实现处理器1730，接收器和发送器功能的程序代码存储在存储器中，通用处理器通过执行存储器中的代码来实现处理器1730、接收器和发送器的功能。
图17的基站1700所涉及的与本申请实施例提供的技术方案相关的概念，解释和详细说明及其他步骤请参见前述方法或其他实施例中关于这些内容的描述，此处不作赘述。
图18是本申请实施例的终端设备1800的示意性框图。应理解，终端设备1800能够执行图1至图11的方法中由终端设备执行的各个步骤，为了避免重复，此处不再详述。终端设备1800可以包括各种类型的基站，例如gNB、NR基站、宏基站、微基站等。终端设备1800包括：
通信接口1810，
存储器1820，用于存储指令，
处理器1830，与所述存储器1820和所述通信接口1810分别相连，用于执行所述存储器1820存储的所述指令，以在执行所述指令时执行如下步骤：
通过所述通信接口1810向目标基站发送第一请求消息，所述第一请求消息包含第一标识信息，所述第一标识信息用于指示所述终端设备以及源基站；
通过所述通信接口1810接收所述目标基站发送的第二指示信息，所述第二指示信息用于指示所述目标基站与所述终端设备之间的接入层密钥是更新后的密钥或未更新的密钥。
应理解，图18所示的终端设备可以为芯片或电路。例如可设置在终端设备内的芯片或电路。该终端设备1800对应于图1至图11中的终端设备。进一步地，上述通信接口1810也可以与收发器互换。收发器包括接收器和发送器。再进一步地，该终端设备1800还可以包括总线系统。
其中，处理器1830、存储器1820、接收器和发送器通过总线系统相连，处理器1830用于执行该存储器1820存储的指令，以控制接收器接收信号，并控制发送器发送信号，完成本申请通信方法中终端设备的步骤。其中，接收器和发送器可以为相同或不同的物理实体。为相同的物理实体时，可以统称为收发器。所述存储器1820可以集成在所述处理器1830中，也可以与所述处理器1830分开设置。
作为一种实现方式，接收器和发送器的功能可以考虑通过收发电路或者收发专用芯片实现。处理器1830可以考虑通过专用处理芯片、处理电路、处理器或者通用芯片实现。
作为另一种实现方式，可以考虑使用通用计算机的方式来实现本申请实施例提供的终端设备。即将实现处理器1830，接收器和发送器功能的程序代码存储在存储器中，通用处理器通过执行存储器的代码来实现处理器1830、接收器和发送器的功能。
图18的终端设备1800所涉及的与本申请实施例提供的技术方案相关的概念，解释和详细说明及其他步骤请参见前述方法或其他实施例中关于这些内容的描述，此处不作赘述。
图19是本申请实施例的基站1900的示意性框图。应理解，基站1900能够执行图6 的方法中由目标基站执行的各个步骤，为了避免重复，此处不再详述。基站1900可以包括各种类型的基站，例如gNB、NR基站、宏基站、微基站等。基站1900包括：
通信接口1910，
存储器1920，用于存储指令，
处理器1930，与所述存储器1920和所述通信接口1910分别相连，用于执行所述存储器1920存储的所述指令，以在执行所述指令时执行如下步骤：
通过所述通信接口1910从终端设备接收第一请求消息，所述第一请求消息包括第一标识信息，所述第一标识信息用于指示所述终端设备和源基站；
在所述源基站与所述目标基站属于同一CU的情况下，根据所述第一请求消息，通过所述通信接口1910向所述终端设备发送第二指示信息，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥或未更新的密钥。
应理解，图19所示的基站可以是为芯片或电路。例如可设置在基站内的芯片或电路。该基站1900对应于图1至图11中的源基站。进一步地，上述通信接口1910也可以与收发器互换。收发器包括接收器和发送器。再进一步地，该基站1900还可以包括总线系统。
其中，处理器1930、存储器1920、接收器和发送器通过总线系统相连，处理器1930用于执行该存储器1920存储的指令，以控制接收器接收信号，并控制发送器发送信号，完成本申请通信方法中基站的步骤。其中，接收器和发送器可以为相同或不同的物理实体。为相同的物理实体时，可以统称为收发器。所述存储器1920可以集成在所述处理器1930中，也可以与所述处理器1930分开设置。
作为一种实现方式，接收器和发送器的功能可以考虑通过收发电路或者收发专用芯片实现。处理器1930可以考虑通过专用处理芯片、处理电路、处理器或者通用芯片实现。
作为另一种实现方式，可以考虑使用通用计算机的方式来实现本申请实施例提供的基站。即将实现处理器1930，接收器和发送器功能的程序代码存储在存储器中，通用处理器通过执行存储器中的代码来实现处理器1930、接收器和发送器的功能。
图19的基站1900所涉及的与本申请实施例提供的技术方案相关的概念，解释和详细说明及其他步骤请参见前述方法或其他实施例中关于这些内容的描述，此处不作赘述。
图20是本申请实施例提供的一种基站2000的结构示意图。该基站2000可以是图1至图11中所示的基站。例如，基站2000可以是源基站或目标基站。基站2000可以包括一个或多个射频单元，如远端射频单元(remote radio unit,RRU)2001和一个或多个基带单元(based bandunit,BBU)(也可称为数字单元，digital unit，DU)2002。所述RRU2001可以称为收发单元、收发机、收发电路、或者收发器等等，其可以包括至少一个天线2011和射频单元2012。所述RRU2001部分主要用于射频信号的收发以及射频信号与基带信号的转换，例如用于向终端设备发送上述实施例中所述的信令消息。所述BBU2002部分主要用于进行基带处理，对基站进行控制等。所述RRU2001与BBU2002可以是物理上设置在一起，也可以物理上分离设置的，即分布式基站。
所述BBU2002为基站的控制中心，也可以称为处理单元，主要用于完成基带处理功能，如信道编码，复用，调制，扩频等等。例如所述BBU(处理单元)可以用于控制基站执行上述方法实施例中关于基站的操作流程。
在一个示例中，所述BBU2002可以由一个或多个单板构成，多个单板可以共同支持 单一接入制式的无线接入网(如LTE网)，也可以分别支持不同接入制式的无线接入网。所述BBU2002还包括存储器2021和处理器2022。所述存储器2021用以存储必要的指令和数据。例如存储器2021存储上述实施例中的预设信息、码本等。所述处理器2022用于控制基站进行必要的动作，例如用于控制基站执行上述方法实施例中关于基站的操作流程。所述存储器2021和处理器2022可以服务于一个或多个单板。也就是说，可以每个单板上单独设置存储器和处理器。也可以是多个单板共用相同的存储器和处理器。此外每个单板上还可以设置有必要的电路。
图21是本申请实施例提供的一种终端设备2100的结构示意图。该终端设备2100可适用于图1至图11所描述的应用环境中。为了便于说明，图21仅示出了终端设备2100的主要部件。如图21所示，终端设备2100包括处理器、存储器、控制电路、天线以及输入输出装置。处理器主要用于对通信协议以及通信数据进行处理，以及对整个终端设备进行控制，执行软件程序，处理软件程序的数据，例如用于支持终端设备2100执行上述通信方法200所描述的终端设备动作。存储器主要用于存储软件程序和数据，例如存储上述通信过程中使用的数据。控制电路主要用于基带信号与射频信号的转换以及对射频信号的处理。控制电路和天线一起也可以叫做收发器，主要用于收发电磁波形式的射频信号。输入输出装置，例如触摸屏、显示屏，键盘灯主要用于接收用户输入的数据以及对用户输出数据。
当终端设备2100开机后，处理器可以读取存储单元中的软件程序，解释并执行软件程序的数据。当需要通过天线发送数据时，处理器对待发送的数据进行基带处理后，输出基带信号至射频电路，射频电路将基带信号进行射频处理后将射频信号通过天线以电磁波的形式向外发送。当有数据发送到终端设备时，射频电路通过天线接收到射频信号，将射频信号转换为基带信号，并将基带信号输出至处理器，处理器将基带信号转换为数据并对该数据进行处理。
本领域普通技术人员可以意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，能够以电子硬件、或者计算机软件和电子硬件的结合来实现。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，上述描述的系统、装置和单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。
在本申请所提供的几个实施例中，应该理解到，所揭露的系统、装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，所述单元的划分，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，例如多个单元或组件可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或单元的间接耦合或通信连接，可以是电性，机械或其它的形式。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
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，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。
所述功能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)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。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (42)

  1. 一种通信方法，其特征在于，包括：
    目标基站从终端设备接收第一请求消息，所述第一请求消息包括第一标识信息，所述第一标识信息用于指示所述终端设备和源基站；
    所述目标基站根据所述第一请求消息，向所述源基站发送第二请求消息，所述第二请求消息包括第二标识信息，所述第二标识信息用于指示所述终端设备；
    所述目标基站从所述源基站接收第一密钥和第一指示信息，其中，所述第一指示信息用于指示所述第一密钥是更新后的密钥或未更新的密钥；
    所述目标基站根据所述第一指示信息，向所述终端设备发送第二指示信息，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥或未更新的密钥。
  2. 如权利要求1所述的方法，其特征在于，所述第二请求消息还包括第三指示信息，所述第三指示信息用于请求更新密钥或不更新密钥。
  3. 如权利要求2所述的方法，其特征在于：
    在所述目标基站对所述源基站的信任等级高于信任阈值的情况下，所述第三指示信息用于请求不更新密钥；或，
    在所述目标基站对所述源基站的信任等级低于所述信任阈值的情况下，所述第三指示信息用于请求更新密钥。
  4. 如权利要求2所述的方法，其特征在于，所述第一请求消息还包括第四指示信息，所述第四指示信息用于请求更新密钥或请求不更新密钥；
    在所述第四指示信息用于请求更新密钥的情况下，所述第三指示信息用于请求更新密钥；或，
    在所述第四指示信息用于请求不更新密钥的情况下，所述第三指示信息用于请求不更新密钥。
  5. 如权利要求2至4中任一项所述的方法，其特征在于：
    在所述第一指示信息用于指示所述第一密钥是未更新的密钥以及所述第三指示信息用于请求更新密钥的情况下，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥。
  6. 如权利要求5所述的方法，其特征在于，所述方法还包括：
    所述目标基站从所述源基站接收下一跳链计数器NCC；
    所述目标基站根据所述NCC，生成第二密钥，所述第二密钥为所述终端设备与所述目标基站之间的接入层密钥；
    所述目标基站向所述终端设备发送所述NCC。
  7. 如权利要求1至4中任一项所述的方法，其特征在于：
    在所述第一指示信息用于指示所述第一密钥是更新后的密钥的情况下，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥；
    所述方法还包括：所述目标基站从所述源基站接收NCC，并向所述终端设备发送所 述NCC。
  8. 如权利要求1至4中任一项所述的方法，其特征在于：
    在所述第一指示信息用于指示所述第一密钥是未更新的密钥的情况下，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是未更新的密钥。
  9. 如权利要求1至8中任一项所述的方法，其特征在于，所述终端设备处于未激活态，所述第一请求消息用于请求恢复所述终端设备的无线资源控制RRC连接；
    所述第二指示信息携带在第一响应消息中，所述第一响应消息用于指示所述终端设备保持未激活态；或，所述第一响应消息用于指示所述终端设备恢复RRC连接。
  10. 如权利要求1至9中任一项所述的方法，其特征在于，所述第二请求消息用于请求获取所述终端设备的上下文；
    所述第一指示信息携带在第二响应消息中，所述第二响应消息包含所述终端设备的上下文，所述终端设备的上下文包含所述第一密钥。
  11. 一种通信方法，其特征在于，包括：
    源基站从目标基站接收第二请求消息，所述第二请求消息包含第二标识信息，所述第二标识信息用于指示终端设备；
    所述源基站根据所述第二请求消息，向所述目标基站发送第一密钥和第一指示信息，其中，所述第一指示信息用于指示所述第一密钥是更新后的密钥或未更新的密钥。
  12. 如权利要求11所述的方法，其特征在于：
    在所述第二请求消息还包含第三指示信息，且所述第三指示信息用于请求更新密钥的情况下，所述第一指示信息用于指示所述第一密钥为更新后的密钥；或，
    在所述源基站对所述目标基站的信任等级低于信任阈值的情况下，第一指示信息用于指示所述第一密钥为更新后的密钥。
  13. 如权利要求12所述的方法，其特征在于，所述方法还包括：
    所述源基站向所述目标基站发送用于生成所述第一密钥的下一跳链计数器NCC。
  14. 如权利要求11所述的方法，其特征在于，
    在所述源基站对所述目标基站的信任等级高于或等于信任阈值的情况下，所述第一指示信息用于指示所述第一密钥为未更新的密钥。
  15. 如权利要求11至14中任一项所述的方法，其特征在于，所述第二请求消息用于请求获取所述终端设备的上下文；
    所述第一指示信息携带在第二响应消息中，所述第二响应消息包含所述终端设备的上下文，所述终端设备的上下文包含所述第一密钥。
  16. 一种通信方法，其特征在于，包括：
    终端设备向目标基站发送第一请求消息，所述第一请求消息包含第一标识信息，所述第一标识信息用于指示所述终端设备以及源基站；
    所述终端设备接收所述目标基站发送的第二指示信息，所述第二指示信息用于指示所述目标基站与所述终端设备之间的接入层密钥是更新后的密钥或未更新的密钥。
  17. 如权利要求16所述的方法，其特征在于，所述第一请求消息包含第四指示信息，所述第四指示信息用于请求更新密钥或不更新密钥。
  18. 如权利要求17所述的方法，其特征在于：
    在所述终端设备的未更新密钥次数大于或等于计数阈值的情况下，所述第四指示信息用于请求更新密钥，其中，所述终端设备的未更新密钥次数为所述终端设备的上一次更新密钥的时刻至当前时刻之间的时间区间内的未更新密钥次数；或，
    在所述终端设备的未更新密钥次数小于所述计数阈值的情况下，所述第四指示信息用于请求不更新密钥；或，
    在所述终端设备的第一状态信息改变的情况下，所述第四指示信息用于请求更新密钥，其中，所述第一状态信息包含以下任意一项：所述终端设备的跟踪区标识TAI、所述终端设备当前所属的无线接入网RAN组和所述终端设备当前使用的无线接入技术RAT；或，
    在所述终端设备的第一状态信息未改变的情况下，所述第四指示信息用于请求不更新密钥。
  19. 如权利要求17或18所述的方法，其特征在于，所述方法还包括：
    在所述第四指示信息用于请求更新密钥，且所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是未更新的密钥的情况下，所述终端设备断开与所述目标基站之间的连接，并重新选择接入的基站。
  20. 如权利要求16至18中任一项所述的方法，其特征在于，所述方法还包括：
    所述终端设备接收所述目标基站发送的下一跳链计数器NCC；
    在所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥为更新后的密钥的情况下，所述终端设备根据所述NCC，生成第三密钥，所述第三密钥为所述终端设备与所述目标基站之间的接入层密钥。
  21. 如权利要求16至20中任一项所述的方法，其特征在于，所述终端设备处于未激活态，所述第一请求消息用于请求恢复所述终端设备的无线资源控制RRC连接，所述第二指示信息携带在第一响应消息中；
    其中，所述第一响应消息用于指示所述终端设备保持未激活态；或，所述第一响应消息用于指示所述终端设备恢复RRC连接。
  22. 一种基站，其特征在于，所述基站为目标基站，包括：
    接收单元，用于从终端设备接收第一请求消息，所述第一请求消息包括第一标识信息，所述第一标识信息用于指示所述终端设备和源基站；
    发送单元，用于根据所述第一请求消息，向所述源基站发送第二请求消息，所述第二请求消息包括第二标识信息，所述第二标识信息用于指示所述终端设备；
    所述接收单元还用于从所述源基站接收第一密钥和第一指示信息，其中，所述第一指示信息用于指示所述第一密钥是更新后的密钥或未更新的密钥；
    所述发送单元还用于根据所述第一指示信息，向所述终端设备发送第二指示信息，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥或未更新的密钥。
  23. 如权利要求22所述的基站，其特征在于，所述第二请求消息还包括第三指示信息，所述第三指示信息用于请求更新密钥或不更新密钥。
  24. 如权利要求23所述的基站，其特征在于：
    在所述目标基站对所述源基站的信任等级高于信任阈值的情况下，所述第三指示信息 用于请求不更新密钥；或，
    在所述目标基站对所述源基站的信任等级低于所述信任阈值的情况下，所述第三指示信息用于请求更新密钥。
  25. 如权利要求23所述的基站，其特征在于，所述第一请求消息还包括第四指示信息，所述第四指示信息用于请求更新密钥或请求不更新密钥；
    在所述第四指示信息用于请求更新密钥的情况下，所述第三指示信息用于请求更新密钥；或，
    在所述第四指示信息用于请求不更新密钥的情况下，所述第三指示信息用于请求不更新密钥。
  26. 如权利要求23至25中任一项所述的基站，其特征在于：
    在所述第一指示信息用于指示所述第一密钥是未更新的密钥以及所述第三指示信息用于请求更新密钥的情况下，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥。
  27. 如权利要求26所述的基站，其特征在于，
    所述接收单元还用于从所述源基站接收下一跳链计数器NCC；
    所述基站还包括生成单元，所述生成单元用于根据所述NCC，生成第二密钥，所述第二密钥为所述终端设备与所述目标基站之间的接入层密钥；
    所述发送单元还用于向所述终端设备发送所述NCC。
  28. 如权利要求22至25中任一项所述的基站，其特征在于：
    在所述第一指示信息用于指示所述第一密钥是更新后的密钥的情况下，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是更新后的密钥；
    所述接收单元还用于从所述源基站接收NCC，所述发送单元还用于向所述终端设备发送所述NCC。
  29. 如权利要求22至25中任一项所述的基站，其特征在于：
    在所述第一指示信息用于指示所述第一密钥是未更新的密钥的情况下，所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是未更新的密钥。
  30. 如权利要求22至29中任一项所述的基站，其特征在于，所述终端设备处于未激活态，所述第一请求消息用于请求恢复所述终端设备的无线资源控制RRC连接；
    所述第二指示信息携带在第一响应消息中，所述第一响应消息用于指示所述终端设备保持未激活态；或，所述第一响应消息用于指示所述终端设备恢复RRC连接。
  31. 如权利要求22至30中任一项所述的基站，其特征在于，所述第二请求消息用于请求获取所述终端设备的上下文；
    所述第一指示信息携带在第二响应消息中，所述第二响应消息包含所述终端设备的上下文，所述终端设备的上下文包含所述第一密钥。
  32. 一种基站，其特征在于，所述基站为源基站，包括：
    接收单元，用于从目标基站接收第二请求消息，所述第二请求消息包含第二标识信息，所述第二标识信息用于指示终端设备；
    发送单元，用于根据所述第二请求消息，向所述目标基站发送第一密钥和第一指示信息，其中，所述第一指示信息用于指示所述第一密钥是更新后的密钥或未更新的密钥。
  33. 如权利要求32所述的基站，其特征在于：
    在所述第二请求消息还包含第三指示信息，且所述第三指示信息用于请求更新密钥的情况下，所述第一指示信息用于指示所述第一密钥为更新后的密钥；或，
    在所述源基站对所述目标基站的信任等级低于信任阈值的情况下，第一指示信息用于指示所述第一密钥为更新后的密钥。
  34. 如权利要求33所述的基站，其特征在于，所述发送单元还用于向所述目标基站发送用于生成所述第一密钥的下一跳链计数器NCC。
  35. 如权利要求32所述的基站，其特征在于，
    在所述源基站对所述目标基站的信任等级高于或等于信任阈值的情况下，所述第一指示信息用于指示所述第一密钥为未更新的密钥。
  36. 如权利要求32至35中任一项所述的基站，其特征在于，所述第二请求消息用于请求获取所述终端设备的上下文；
    所述第一指示信息携带在第二响应消息中，所述第二响应消息包含所述终端设备的上下文，所述终端设备的上下文包含所述第一密钥。
  37. 一种终端设备，其特征在于，包括：
    发送单元，用于向目标基站发送第一请求消息，所述第一请求消息包含第一标识信息，所述第一标识信息用于指示所述终端设备以及源基站；
    接收单元，用于接收所述目标基站发送的第二指示信息，所述第二指示信息用于指示所述目标基站与所述终端设备之间的接入层密钥是更新后的密钥或未更新的密钥。
  38. 如权利要求37所述的终端设备，其特征在于，所述第一请求消息包含第四指示信息，所述第四指示信息用于请求更新密钥或不更新密钥。
  39. 如权利要求38所述的终端设备，其特征在于：
    在所述终端设备的未更新密钥次数大于或等于计数阈值的情况下，所述第四指示信息用于请求更新密钥，其中，所述终端设备的未更新密钥次数为所述终端设备的上一次更新密钥的时刻至当前时刻之间的时间区间内的未更新密钥次数；或，
    在所述终端设备的未更新密钥次数小于所述计数阈值的情况下，所述第四指示信息用于请求不更新密钥；或，
    在所述终端设备的第一状态信息改变的情况下，所述第四指示信息用于请求更新密钥，其中，所述第一状态信息包含以下任意一项：所述终端设备的跟踪区标识TAI、所述终端设备当前所属的无线接入网RAN组和所述终端设备当前使用的无线接入技术RAT；或，
    在所述终端设备的第一状态信息未改变的情况下，所述第四指示信息用于请求不更新密钥。
  40. 如权利要求38或39所述的终端设备，其特征在于，所述终端设备还包括处理单元，
    所述处理单元用于在所述第四指示信息用于请求更新密钥，且所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥是未更新的密钥的情况下，所述终端设备断开与所述目标基站之间的连接，并重新选择接入的基站。
  41. 如权利要求37至39中任一项所述的终端设备，其特征在于，
    所述接收单元还用于接收所述目标基站发送的下一跳链计数器NCC；
    所述终端设备包括生成单元，所述生成单元用于：在所述第二指示信息用于指示所述终端设备与所述目标基站之间的接入层密钥为更新后的密钥的情况下，所述终端设备根据所述NCC，生成第三密钥，所述第三密钥为所述终端设备与所述目标基站之间的接入层密钥。
  42. 如权利要求37至41中任一项所述的终端设备，其特征在于，所述终端设备处于未激活态，所述第一请求消息用于请求恢复所述终端设备的无线资源控制RRC连接，所述第二指示信息携带在第一响应消息中；
    其中，所述第一响应消息用于指示所述终端设备保持未激活态；或，所述第一响应消息用于指示所述终端设备恢复RRC连接。
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