Key provision

Abstract

Methods, apparatuses, and systems for providing keys in a communication network are disclosed. An apparatus for communication comprises means for obtaining at least one secondary node counter list, where the secondary node counter list corresponds to mutually different ones of a plurality of secondary nodes, obtaining an indication of a secondary node of the plurality of secondary nodes, a secondary node key is generated based at least in part on the obtained at least one secondary node counter list and the indication of the secondary node, and the secondary node is accessed using the generated secondary node key.

Description

Technical Field

[0001] The following disclosure relates to the field of communication technology, in particular to communication networks, in particular to wireless communication networks. The present disclosure relates to key provision in wireless communication networks, in particular to keys for communication between user equipment and secondary nodes. Background Art

[0002] In modern communication technology, user equipment (UE) needs to access network nodes multiple times. For any access and / or communication session after access, encryption and integrity protection of transmitted and / or received messages are used to protect the communication from third parties. This encryption and integrity protection requires coordination between the network node and the UE, which enables them to decrypt the encrypted messages and verify the integrity of the messages received from the corresponding other entities. Specifically, both parties (UE and network node) need to be informed of at least one pair of (cryptographic) keys to decrypt and verify the integrity messages received from another corresponding other entity. Summary of the invention

[0003] The network nodes of a modern wireless communication network may be constructed as a master node (MN) and a secondary node (SN). A user equipment (UE) may communicate with the MN alone (so-called single connectivity) and may additionally (e.g., simultaneously) communicate with at least one (e.g., serving) SN (so-called dual connectivity). Dual connectivity may specifically relate to multi-RAT dual connectivity (MR-DC), such as EN-DC (E-UTRA-NR dual connectivity), NR-DC (New Radio Dual Connectivity), NGEN-DC (NG-RAN-E-UTRA dual connectivity) and NE-DC (NR-E-UTRA dual connectivity). The following disclosure specifically relates to UE access to a SN (specifically during UE to SN handover and / or selective activation of a SN), but is not limited to this case. When UE access to a SN is disclosed, UE to SN handover, specifically selective activation of a SN to which the UE switches, is also disclosed.

[0004] The corresponding node may provide at least one or more cells. For example, the MN may provide at least one primary cell (PCell). For example, the SN may provide at least one PSCell and / or at least one SCell. At least some or (e.g., all) cells referred to in the following disclosure (e.g., at a given time instance) may be part of the same cell group, such as a primary cell group (MSG) and / or a secondary cell group (SCG).

[0005] A first solution for providing keys to a UE and a network node (e.g., an MN or SN) may be to provide a (e.g., a single) key and / or a single piece of information from which a key may be derived to the network node and / or to the UE (e.g., as part of a configuration) for a given communication session and / or an upcoming access of the UE to a network node. The key may be specific to the network node (from the UE's perspective, specific to the UE from the network node's perspective) and may remain constant for a predefined period of time or until a predefined event occurs. It is recognized that in this case, the key may be reused. This may occur, for example, if the UE is disconnected from the network node (e.g., disconnected from a cell provided by the network node) and thereafter reconnects to the same network node (e.g., to the same or a different cell provided by the network node). Reusing keys is a security risk.

[0006] Another solution may be to provide a list of keys to be used to multiple SNs (e.g., some or all SNs of a given cell group). For any access by a UE, the SN will select the next key from the list. By using a list, re-use of the same key can be avoided. However, if all SNs obtain the same list of keys, a security vulnerability of one SN may compromise the communication security of all SNs configured to use the same list of keys. Moreover, when using a list from which keys are extracted for each new access by a UE, the SN needs to be aware of any access by the UE to any SN using the same list in order to select the correct key. The result is an increase in signaling and accounting overhead, while security weaknesses remain.

[0007] It is therefore one of the objects of the present disclosure to enable a particularly secure provision of keys to (eg secondary) network nodes while keeping the accounting and signalling overhead low.

[0008] According to a first example aspect, there is disclosed a method comprising:

[0009] obtaining (e.g. from a master node MN) at least one secondary node counter list (e.g. via RRC, e.g. in an RRC reconfiguration message), wherein the secondary node counter lists (e.g. respectively) correspond to (e.g. are associated with) mutually different secondary nodes of the plurality of secondary nodes (e.g. where the UE intends to request access to one of them and / or they are part of the same cell group as the MN and / or are between each other),

[0010] obtaining (e.g., from the master node MN) an indication (e.g., via RRC, e.g., the same RRC reconfiguration message) of a secondary node among the plurality of secondary nodes (e.g., one of the at least one secondary node corresponding to the secondary node counter list),

[0011] generating a secondary node key (e.g., which may involve selecting an unused counter in the list) based at least in part on the obtained at least one secondary node counter list and an indication of (e.g., the) secondary node,

[0012] The generated secondary node key is used to access (eg, perform a random access procedure to the secondary node) a secondary node (eg, an indication of (eg, indicated by) the secondary node).

[0013] For example, the method may be performed and / or controlled by an apparatus (e.g., a server). Alternatively, the method may be performed and / or controlled by more than one apparatus, such as a server cloud including at least two servers. Alternatively, the method may be performed and / or controlled, for example, by an electronic device (e.g., a node in a communication system) and / or by a user equipment (UE). For example, the method may be performed and / or controlled by using at least one processor in an electronic device.

[0014] According to a further example aspect, a computer program is disclosed which, when executed by a processor, causes an apparatus (eg a server, a network node or a UE) to perform and / or control the actions of the method according to the first example aspect.

[0015] The computer program may be stored on a computer-readable storage medium, in particular on a tangible and / or non-transient medium. The computer-readable storage medium may be, for example, a disk or a memory, etc. The computer program may be stored in a computer-readable storage medium in the form of instructions encoding the computer-readable storage medium. The computer-readable storage medium may be intended to participate in the operation of a device (such as an internal or external memory, such as a read (e.g., read-only) memory (ROM) or a hard disk of a computer), or intended for distribution of the program (such as an optical disk).

[0016] According to a further example aspect, an apparatus is disclosed, which is configured to perform and / or control or comprises corresponding means for performing and / or controlling the method according to the first example aspect.

[0017] The components of the device can be implemented using hardware and / or software. They may include, for example, at least one processor for executing a computer program code to perform a desired function, at least one memory for storing program code, or both. Alternatively, they may include, for example, a circuit system designed to implement the desired function, such as implemented in a chipset or chip, such as an integrated circuit. Typically, the component may include, for example, one or more processing components or processors.

[0018] The apparatus disclosed above according to any aspect may be a module or component for a device (e.g., a chip). Alternatively, the apparatus disclosed according to any aspect may be a device, such as a server or a server cloud. The apparatus disclosed according to any aspect may include (e.g., only include) the disclosed components, such as a part, a processor, a memory, or may also include one or more additional components.

[0019] For example, a user equipment (UE) may correspond to a mobile device, such as, for example, a mobile phone, a tablet computer, a smart watch, a laptop computer, a personal digital assistant (PDA) device, a wearable device, an Internet of Things (IoT) device, an IIOT (Industrial IoT) device, a vehicle, and / or a combination thereof. Such a user equipment may also be referred to as a user device.

[0020] A network node may correspond to a component of a communication network, such as, for example, a base transceiver station (BTS), a Node B, an evolved Node B (eNB), a next generation Node B (gNB), a distributed unit (DU), a central unit (CU), and / or a combination thereof. A network node may be referred to as a node.

[0021] Therefore, the method can be performed and / or controlled by a device, wherein the device can specifically be a UE. The method can be performed within an existing communication session. The communication session can be established between a device (e.g., a UE) and at least one network node (e.g., a primary network node). In addition to the primary node, the communication session can also involve a secondary node. The method can have the effect of adjusting an existing communication session, specifically adding, removing and / or changing a secondary node, such as implementing and / or maintaining dual connectivity (e.g., a communication session involving a primary node and a secondary node). The method can involve selectively activating a given SN for communication with a UE (e.g., in addition to a MN).

[0022] Here and hereinafter, a communication session between a UE and a network node (whether a secondary node or a primary node) includes the network node providing a cell in which the UE is located (e.g., a spatial coverage area in which the UE may be located while receiving radio signals from the network node and / or transmitting radio signals to the network node, and / or maintaining a communication session with the network node).

[0023] The method comprises: obtaining at least one secondary node counter list (SN counter list). The secondary node counter list may be obtained from a master node (MN), such as the MN to which the UE is currently connected in a communication session. The obtaining may be done by radio resource control (RRC), such as by means of an RRC reconfiguration message obtained by the device from the MN.

[0024] Here and in the following, obtaining may for example mean receiving the corresponding information (itself) (here, the secondary node counter list), for example by means of a radio communication link. Obtaining may specifically mean receiving as part of a radio resource control (RRC) message. Obtaining the information may also mean (e.g., only) receiving an indication (e.g., an index, a reference and / or a combination thereof) of the corresponding information. The indication may allow the obtaining entity (here, the device, such as the UE) to derive the information (here, the secondary node counter list).

[0025] The SN counter lists correspond to different secondary nodes in the plurality of secondary nodes, respectively. When the SN counter lists correspond to the respective SNs, this may, for example, mean that the SN counter lists are specific to the SNs, are associated with the SNs, are available (e.g., only) by the respective SNs and / or are configured specifically for the SNs (e.g., configured by the MN). The plurality of SNs may include at least one SN that the UE intends to access (e.g., request access and / or perform a random access procedure) (e.g., based on a trigger signal of the MN or based on (e.g., signal quality) measurement).

[0026] Additionally or alternatively, multiple SNs may be part of the same cell group, e.g. between each other and / or as MNs. If two or more network nodes (e.g. SNs and / or MNs) are part of the same cell group, this may, for example, mean that the network nodes respectively provide at least one cell as part of the same cell group. A cell group may, for example, correspond to a master cell group (MCG) or a secondary cell group (SCG). For example, multiple secondary nodes may be part of the same or different SCGs. For example, (e.g. the, e.g. all) SN counter lists may be specific to one cell group (e.g. SCG) to which the SN belongs (e.g. the SN counter list is provided to the cell group).

[0027] A given SN counter list may include at least two SN counter values ​​sorted in a predefined order. For example, there may be a first SN counter value, a second SN counter value, etc. The SN counter list may, for example, include at least 3, 4, 5, 6, 7, 8, 9, 10, 15, 16, 20, 30, 32, 40, 50, 60, 64, 70, 80, 90, 100, 128 or more SN counter values. The number of SN counter values ​​in the list may correspond to the number of accesses that the device can perform to the corresponding SN before a new SN counter list is required. A given SN counter value may, for example, assume a discrete value from potential SN counter values. The SN counter value may, for example, assume a power of 2 value. For example, the SN counter value may assume a value between 0 and a given maximum value, where the maximum value may, for example, be 1, 3, 7, 15, 31, 63, 127, 255, 511, 1023, 2047, 4095, 2 13 , 214 , 2 15 , 2 16 , 2 24 , 2 32 or a higher power of 2-1. The maximum value may be given by the number of bits used to encode and / or provide and / or obtain the corresponding SN counter value (also referred to as the SN counter length). Although the SN counter list may be represented as a list of SN counter values, the SN counter list may additionally or alternatively be represented or stored as an array, a graph, a generating function and / or a combination thereof, for example.

[0028] The method also includes obtaining an indication of a secondary node among a plurality of secondary nodes. For example, the secondary node indicated by the indication of the secondary node may correspond to a secondary node corresponding to one of the SN counter lists obtained. For example, such an indication may include and / or correspond to a secondary node identifier, such as, for example, a secondary node group ID (SN group ID). The SN group ID may be an identifier associated with a given SN. The SN may be associated with a cell group (e.g., SCG). The SN group ID may be assigned by a master node, such as a master node that provides an SN counter list and / or an indication of the SN. The indication of the SN may enable a device that performs the method according to the first example aspect to identify a specific SN and / or select an SN counter list corresponding to the SN indicated by the indication of the SN. In the case where the plurality of SNs (e.g., only) include a single SN (e.g., only one SN counter list is obtained), the indication of the secondary node may be implicit, for example, by obtaining a message (e.g., a message that may include an indication of the SN at least in some cases) without an (e.g., explicit) indication of the SN (e.g., without the group ID of the secondary node).

[0029] The indication of the SN may be obtained from a master node (e.g., a master node from which at least one SN counter list was obtained in advance). The indication of the SN may be obtained separately (e.g., in separate signaling) from at least one secondary counter list. The indication of the SN may be obtained by means of RRC (e.g., in an RRC reconfiguration message). The RRC reconfiguration message may be the same as or different from the RRC reconfiguration message for obtaining at least one secondary node counter list. In other words, at least one SN counter list and the indication of the SN may be obtained in the same message or in different messages, where the message may be, for example, RRC signaling, such as from a MN to a UE (an apparatus performing a method according to the first example aspect).

[0030] The method also includes generating a second key. The generation is based at least in part on an SN counter list of at least one SN counter list obtained and an indication of a secondary node. For example, the generation may involve selecting an SN counter list corresponding to an SN indicated by the indication of the SN. Therefore, the SN counter list may be identifiable by the indication of the SN and / or associable with the indication of the SN. The generation may also involve selecting (e.g., unused) SN counter values ​​from (e.g., selected) SN counter lists. Unused SN counter values ​​may be SN counter values ​​(e.g., of the SN counter list) that have not been used to access the secondary node before. For example, the method may include selecting the next SN counter value from the SN counter list. For example, the method may include tracking the last selected SN counter value and selecting the next SN counter value. Based on the previously (e.g., last) selected SN counter value, the next SN counter value may be defined by a predefined order in which the SN counter values ​​are stored and / or sorted in the SN counter list. Additionally or alternatively, the used value may be discarded so that the method includes: selecting the first (according to the order of the SN counters in the list) remaining SN counter value. If no previously selected SN counter value is stored and / or known, the method may include selecting a first SN counter value from the SN counter list.

[0031] Generating a secondary node key may include providing an input to a generating function (which may be referred to as a key generator) and obtaining an output from the generating function in response to the provided input. The generation may be based on the selected SN counter value and may additionally be based on other values, such as a key associated with the master node (MN key). Additionally or alternatively, the generation may be based at least in part on the length of the SN counter.

[0032] By generating SN keys based on the SN counter list, SN-specific SN keys can be generated for any new access of the SN. The SN keys corresponding to the SN counter values ​​in the SN counter list can be (for example, all) pre-generated and stored. Additionally or alternatively, when SN keys are needed for the SNs to be accessed (for example, added or modified), SN keys can be generated one by one. Since the SN counter list corresponds to each SN respectively, the SN only needs to track the access of a given UE (the device executing the method according to the first aspect) to itself (for example, to a single SN), without tracking the access of the UE to multiple SNs. Since the method includes using an indication of the SN when generating the SN key, the UE is able to associate its SN access with a specific SN, and can, for example, count the access to any given SN separately from the access to other SNs. Through the SN key, other keys can be derived, such as specific protection for RRC messages (for example, Krrc enc, Krrc int) and / or for user plane messages Kupenc, Kupint.

[0033] The method also includes: accessing the secondary node in the indication of the secondary node (e.g., the SN indicated by the indication) using the generated secondary node key. Accessing may include: performing a random access procedure on the secondary node. Additionally or alternatively, accessing may include direct start of uplink (UL) and / or downlink (DL) traffic, e.g., without a random access procedure, which may be referred to as RACH-free handover (e.g., in this case, the UE may still use the generated SN key to ensure the message).

[0034] Using the SN key for accessing the SN may include using the SN key to encrypt, decrypt, or integrity protect at least one message transmitted to and / or received from the SN (eg, as part of a (eg, random) access procedure).

[0035] According to an embodiment of the first exemplary aspect,

[0036] The at least one secondary node counter list includes at least two secondary counter lists.

[0037] At least one SN counter list may include (e.g., at least) 2, 3, 4, 5, 6, 7, 8, 9, 10, 16, 20, 30, 32, 40, 50, 64, 70, 80, 90, 100, 110, 120, 128 or more SN counter lists. When two or more SN counter lists are provided, the obtained indication of the SN may include an (e.g., explicit) indication of the SN, such as, for example, an SN group ID.

[0038] By obtaining at least two SN counter lists, SN-specific SN counter values ​​can be used. A first SN associated with a first SN counter list may not be able to decrypt a message sent to another second SN that uses another second SN counter list to generate a key. This enhances security.

[0039] According to an embodiment of the first example aspect, the method further comprises:

[0040] The number of accesses to the corresponding secondary node is counted for (e.g., a device executing the method), wherein generating the secondary key is also based on the counted number of accesses (e.g., by the device) (e.g., by using the number as an index to the list).

[0041] The number of accesses of the respective secondary node may be counted. For example, the counting may be implemented as a memory of the last SN counter extracted from the respective SN counter list corresponding to the SN. The counting may additionally or alternatively include incrementing a number by a (e.g. fixed) value for a given access to the respective SN. For example, the number may be used, for example, as an index to the SN counter list. The counting may also be implemented by discarding (e.g. deleting, removing) an entry (e.g., a currently used SN counter value) in the SN counter list corresponding to the respective SN.

[0042] According to an embodiment of the first exemplary aspect,

[0043] The secondary node counter list (eg, respectively) includes a non-monotonic sequence of secondary node counter values, or

[0044] The secondary node counter lists (eg, lists) are different from each other (eg, respectively include different secondary node counter sequences from each other).

[0045] A non-monotonic sequence of SN counters may refer to a sequence of values ​​that is neither completely decreasing nor completely increasing. In other words, when traversing the SN counter values ​​in a predefined order of a given SN counter list, there is at least one increase from a given SN counter value to the next (e.g., immediately following) SN counter value and at least one decrease from one SN counter value to the next (e.g., immediately following) SN counter value. The SN counter values ​​in a given SN counter list may be unique within the list, e.g., there may be no repetition of counter values ​​within the SN counter list. Alternatively, there may be at least one repetition of a given SN counter value in the SN counter list. Additionally or alternatively, (e.g., any) two consecutive SN counter values ​​of a given SN counter list may be different from each other. Alternatively, at least one pair of consecutive SN counter values ​​may be identical to each other.

[0046] SN counter lists of different SNs (e.g., among a plurality of SNs) may differ from each other. At least one SN counter value may differ between SN counter lists (e.g., at a given (e.g., same) position within the respective counter lists). Specifically, for (e.g., any) given index of a (e.g., unchanged, as provided by the MN to the UE) SN counter list (e.g., taking the Nth SN counter from the respective SN counter list according to a predefined order of SN counter values ​​within the respective SN counter list) (e.g., at a location within it), the respective SN counter values ​​extracted from the respective SN counter list may differ. Additionally or alternatively, at least two SN counter lists may differ in the number of their SN counter values ​​and / or their respective maximum (e.g., possible) counter values ​​(e.g., SN counter lengths). Since the SN counter lists differ between SNs (e.g., of the same cell group), a security vulnerability of one first SN does not allow decryption of communications between the UE (performing the method) and another SN different from the first SN.

[0047] According to a second example aspect, there is disclosed a method comprising:

[0048] generating at least one secondary node counter list, wherein the secondary node counter lists correspond (eg, respectively) to mutually different secondary nodes among the plurality of secondary nodes,

[0049] providing an indication of at least one secondary node key to secondary nodes of the plurality of secondary nodes (e.g., which are part of the same cell group as the MN and / or between each other), wherein at least one secondary node key in the indication of at least one secondary node key corresponds to (e.g., can be derived therefrom by the UE) a secondary node counter value included by the generated secondary node counter list, the secondary node counter value corresponding to the secondary node of the plurality of secondary nodes (e.g., providing the following two items to the UE simultaneously, or at least as one logical action)

[0050] providing at least one of the generated secondary node counter lists to a user equipment (e.g., served by the apparatus), and

[0051] An indication of a secondary node among the plurality of secondary nodes is provided to the user equipment (eg, via RRC, eg, in the same message with the two generated SN counter lists).

[0052] For example, the method may be performed and / or controlled by a device (e.g., a server). Alternatively, the method may be performed and / or controlled by more than one device, such as a server cloud including at least two servers. Alternatively, the method may be performed and / or controlled, for example, by an electronic device (e.g., a network node in a communication system) and / or by a user equipment (UE). For example, the method may be performed and / or controlled by using at least one processor of an electronic device.

[0053] According to a further example aspect, a computer program is disclosed which, when executed by a processor, causes an apparatus (eg a server, a network node or a UE) to perform and / or control the actions of the method according to the second example aspect.

[0054] The computer program may be stored on a computer-readable storage medium, in particular on a tangible and / or non-transient medium. The computer-readable storage medium may be, for example, a disk or a memory, etc. The computer program may be stored in a computer-readable storage medium in the form of instructions encoding the computer-readable storage medium. The computer-readable storage medium may be intended to participate in the operation of a device (such as an internal or external memory, such as a read (e.g., read-only) memory (ROM) or a hard disk of a computer), or intended for distribution of the program (such as an optical disk).

[0055] According to a further example aspect, an apparatus is disclosed, which is configured to perform and / or control or comprises corresponding components for performing and / or controlling the method according to the second example aspect.

[0056] The components of the device can be implemented using hardware and / or software. They may include, for example, at least one processor for executing a computer program code to perform a desired function, at least one memory for storing program code, or both. Alternatively, they may include, for example, a circuit system designed to implement the desired function, such as implemented in a chipset or chip, such as an integrated circuit. Typically, the component may include, for example, one or more processing components or processors.

[0057] The apparatus disclosed above according to any aspect may be a module or component for a device (e.g., a chip). Alternatively, the apparatus disclosed according to any aspect may be a device, such as a server or a server cloud. The apparatus disclosed according to any aspect may include (e.g., only include) the disclosed components, such as a part, a processor, a memory, or may also include one or more additional components.

[0058] Therefore, the method can be performed and / or controlled by a device, wherein the device can specifically be a network node, specifically a master node. The method can be performed within an existing communication session. The communication session can be established between a device (e.g., a master node MN) and at least one UE (e.g., a UE that performs the method according to the first example aspect). In addition to the master node, the communication session can also involve a secondary node. The method can have the effect of adjusting an existing communication session, specifically adding, removing and / or changing a secondary node, for example, to achieve dual connectivity (e.g., a communication session involving a master node and a secondary node).

[0059] The method comprises: generating at least one secondary node counter list. The secondary node counter lists correspond to different secondary nodes among the plurality of secondary nodes, respectively. The generation may comprise: selecting an SN counter length, a number of SN counters of the SN counter list, an SN counter value and / or an order of SN counter values. At least one of these aspects (particularly the SN counter value) may be selected using a (e.g. pseudo) random process or a (e.g. deterministic) rule. Multiple SN counter lists for different SNs may be generated in a coordinated manner to ensure that they are different from each other.

[0060] The method also includes: providing an indication of at least one secondary node key (SN key) to a secondary node in a plurality of secondary nodes. At least one secondary node key in the indication of at least one secondary node key corresponds to a secondary node counter value included by a generated secondary node counter list, the secondary node counter value corresponding to a secondary node in a plurality of secondary nodes. If the SN counter value corresponds to an SN key, this may include the possibility (for example, for an apparatus performing the method according to the first example aspect) of deriving the SN key based at least in part on the SN counter value. In other words, the SN counter value included by the generated SN counter list corresponds to the SN key indicated by the provided SN key indication. As disclosed with respect to the first example aspect, for example, a key generator can be used to convert from an SN counter value to an SN key. The method according to the second example aspect may use a similar method or a substantially identical key generator (similar to the key generator used by the method according to the first example aspect) to obtain an SN key corresponding to an SN counter value included in an SN counter list corresponding to an SN providing an indication of at least one SN key.

[0061] Here and in the following, providing (an indication of information) may for example mean transmitting the corresponding information (itself) (here, at least one SN Key), for example by means of a radio communication link. Providing may specifically mean transmitting as part of a Radio Resource Control (RRC) message. Providing an indication of information may also mean (e.g. only) receiving an indication of the corresponding information (e.g. an index, a reference and / or a combination thereof). The indication may allow an obtaining entity (here, a device, such as a secondary network node) to derive the information (here, at least one SN Key).

[0062] The method further comprises: providing at least one of the generated secondary node counter lists to a user equipment (UE). The UE may be configured to perform and / or control the method according to the first example aspect. The apparatus performing the method according to the second apparatus may act as a (serving) master node of the UE.

[0063] The method further includes: providing an indication of a secondary node among the plurality of secondary nodes to the user equipment. The indication of the secondary node indicates a secondary node corresponding to one of the generated SN counter lists.

[0064] At least one of providing an indication of at least one secondary node key, providing at least one secondary SN counter list in a generated secondary SN counter list, or providing an indication of a secondary node can be performed as one logical action and / or simultaneously (e.g., substantially, for example, within a time span of less than 100μs, 1ms, 10ms or 100ms), or alternatively as at least two separate logical actions and / or at different times.

[0065] According to an embodiment of the second exemplary aspect,

[0066] The at least one secondary node counter list includes at least two secondary counter lists.

[0067] According to an embodiment of the second exemplary aspect,

[0068] Prior to receiving (e.g., via an RRC reconfiguration complete message) an indication that the user equipment is about to access a secondary node using a secondary node key indicated by the indication of at least one secondary node key (e.g., from the user equipment), providing (e.g., via an SN modification request, an SN add request, an SN release request / procedure or via Class 2 signaling) an indication of at least one secondary node key (e.g., completed).

[0069] The indication of the upcoming access of a secondary node (e.g., a secondary node to which an indication of at least one SN key is provided) by a UE (e.g., a UE to which at least one SN counter list and an indication of an SN are provided) may be, for example, RRC signaling and / or may correspond to an RRC reconfiguration complete message obtained from the UE by an MN performing the method according to the second example aspect. The RRC reconfiguration complete message may include a further RRC reconfiguration complete message directed to the SN. The RRC reconfiguration complete message may indicate that a condition (e.g., a PSCell condition, e.g., a condition of a CPAC) is met on the UE side in order to initiate access to the corresponding SN. An indication that the UE is about to access a secondary node may be received from the UE.

[0070] In this embodiment, the SN key may not be used immediately (eg, in the next signaling action of the SN), but may be used for future and / or upcoming access of the UE to the SN (eg, addition or modification of the SN).

[0071] In this case, the provisioning may correspond to and / or be done as part of a secondary node modification request, a secondary node addition request, a secondary node release request (e.g., release of a (e.g., previous) communication session using an SN key different from the (e.g., any) SN key indicated by the indication of at least one SN key provided). The provisioning may (e.g., in this case) be done additionally or alternatively via Class 2 and / or Xn signaling.

[0072] According to an embodiment of the second exemplary aspect,

[0073] The indication of at least one secondary node key corresponds to a list of secondary node keys (e.g., which may be generated by the MN), the list of secondary node keys corresponding to a generated list of secondary node counters corresponding to the secondary network nodes, and

[0074] (e.g., provided (e.g., completed) (e.g., via RRC) as part of at least one of the following:

[0075] Secondary node modification request, or

[0076] Secondary node addition request.

[0077] The indication of at least one SN key may correspond to a secondary node key list. The SN key list may include a list of SN keys in a predefined order. The SN key list may correspond to a generated SN counter list. Specifically, the SN keys in the SN key list may correspond to the SN counter values ​​in the generated SN counter list (e.g., one by one). For example, when iterating over the SN counter list (e.g., selecting one SN counter value in turn in a predefined order), generating SN keys based on (e.g., each) selected SN counter value (and potentially other factors and / or variables, such as MN keys and / or SN counter lengths), and storing them sequentially as a sequence in the order in which they were generated based on the SN counter values, the SN key list may be obtained. The SN key list may include SN keys corresponding to (e.g., all) SN counter values ​​contained in the SN counter list, or may alternatively correspond to (e.g., only) a subset of the SN counter values ​​contained in the SN counter list.

[0078] In this case, the provisioning may be done through RRC signaling.The provisioning may additionally or alternatively be done as part of an SN modification request and / or an SN addition request.

[0079] Providing the SN with a list of SN keys has the advantage of very fast access, since no individual keys need to be provided to the SN for a new access by a UE.

[0080] According to an embodiment of the second exemplary aspect,

[0081] the indication of the at least one secondary node key corresponds to a (eg, single) secondary node key for access to the secondary network node by the user equipment, and

[0082] (e.g., provided (e.g., completed) (e.g., via RRC) as part of at least one of the following:

[0083] A secondary node addition request (e.g. of the SN to which the counter / key corresponds), or a secondary node release request (e.g. of a session established during a random access procedure using different SN keys and / or with different SNs).

[0084] The indication of at least one secondary node key may correspond to the (eg single) SN key itself. For example, the SN key may be transmitted by the MN to the SN. The SN key may enable and / or be used for access of the UE to the SN.

[0085] Here, the provision may be performed by RRC. Additionally or alternatively, the provision may be performed as part of an SN add request, for example, a request for adding an SN counter list and / or an SN corresponding to an SN key. Additionally or alternatively, the provision may be performed as part of an SN release request, for example, a request to release a communication session established (e.g., previously and / or to be released) using a different SN key (e.g., with the same UE).

[0086] In this case, the SN key may be provided for future access of the SN by the UE. Sharing a single key early provides strong security. In this case, the SN may be referred to as a candidate SN because it is prepared (by providing the SN key) for an upcoming access by a UE (e.g., a UE that has previously been connected to the SN), while the access process (by the MN, e.g., SN modification and / or addition) has not yet begun. In other words, in this embodiment, the SN key is provided to the SN, the MN has not yet started preparing for access of the UE to the SN (and / or started the CPAC process), but may start such access in the future.

[0087] According to an embodiment of the second exemplary aspect,

[0088] providing (e.g., via an SN reconfiguration complete message) an indication of at least one secondary node key (e.g., completed), after receiving an indication that the user equipment is about to access a secondary node using the secondary node key in the indication of at least one secondary node key, or

[0089] Prior to receiving an indication that the user equipment is about to access a secondary node using a secondary node key in an indication of at least one secondary node key, providing an indication of at least one secondary node key (e.g., completed), wherein at least one of the following items:

[0090] The indication of at least one secondary node key comprises: a secondary node key for access by a user equipment to a secondary network node, or

[0091] Provided (eg, Completed) as part of a Secondary Node Reconfiguration Complete message (eg, from MN to SN).

[0092] This embodiment covers the case where the SN key is provided for the UE to access the SN (e.g., immediately). The SN key can be provided as part of an SN reconfiguration complete message (e.g., an RRC message). In this embodiment, it may have been confirmed that the UE will connect to the SN (e.g., immediately) and the SN will not be referred to as a candidate SN. In other words, here, the SN key is provided to the SN after the MN has started preparing the UE for access to the SN (e.g., SN modification and / or SN addition) and / or has started the CPAC process.

[0093] According to an embodiment of the second example aspect, the method further comprises:

[0094] A number of accesses to the respective secondary node by the respective user equipment is counted, wherein the indication of the at least one secondary key is based at least in part on the counted number of accesses.

[0095] The MN can track accesses of at least one or more UEs to a corresponding SN. This may be particularly the case if the MN provides a (e.g., a single) SN key to a corresponding (candidate) SN. In order to select the correct entry from the SN counter list and / or the SN key list and / or generate the correct SN key, the MN needs to be informed of the SN counter that the UE will select from its own SN counter list. Counting the number of accesses enables the MN to provide the correct SN key to the SN. In an embodiment, where an SN key list is provided to the SN, the SN can track the number of accesses and the MN does not have the burden of monitoring UE accesses. Tracking multiple accesses can be accomplished by discarding (e.g., used) SN counter values ​​from the SN counter list and / or abandoning (e.g., used) SN keys from the SN key list.

[0096] According to an embodiment of the second exemplary aspect,

[0097] The secondary node counter lists respectively include: a non-monotonic sequence of secondary node counters, or the secondary node counter lists are different from each other.

[0098] Therefore, the SN Key Lists that may be provided to (eg, different) SNs may be different from each other.

[0099] Where applicable, the disclosure presented with respect to the first example aspect is also disclosed with respect to the second example aspect.

[0100] According to a third example aspect, there is disclosed a method comprising:

[0101] obtaining an indication of at least one secondary node key from a master node (e.g., of the same cell group as the apparatus performing and / or controlling the method according to the third example aspect), wherein the at least one secondary node key corresponds to a counter included by a generated secondary node counter list (e.g., corresponding to the apparatus performing and / or controlling the method according to the third example aspect),

[0102] A random access procedure is performed (eg, initiated by the user equipment) with the user equipment (eg, by accepting the random access procedure) using one of the at least one secondary node keys indicated by the indication of obtaining the at least one secondary node key.

[0103] For example, the method may be performed and / or controlled by a device (e.g., a server). Alternatively, the method may be performed and / or controlled by more than one device, such as a server cloud including at least two servers. Alternatively, the method may be performed and / or controlled, for example, by an electronic device (e.g., a network node in a communication system) and / or by a user equipment (UE). For example, the method may be performed and / or controlled by using at least one processor of an electronic device.

[0104] According to a further example aspect, a computer program is disclosed which, when executed by a processor, causes an apparatus (eg a server, a network node or a UE) to perform and / or control the actions of the method according to the third example aspect.

[0105] The computer program may be stored on a computer-readable storage medium, in particular on a tangible and / or non-transient medium. The computer-readable storage medium may be, for example, a disk or a memory, etc. The computer program may be stored in a computer-readable storage medium in the form of instructions encoding the computer-readable storage medium. The computer-readable storage medium may be intended to participate in the operation of a device (such as an internal or external memory, such as a read (e.g., read-only) memory (ROM) or a hard disk of a computer), or intended for distribution of the program (such as an optical disk).

[0106] According to a further example aspect, an apparatus is disclosed, which is configured to perform and / or control or comprises corresponding components for performing and / or controlling the method according to the third example aspect.

[0107] The components of the device can be implemented using hardware and / or software. They may include, for example, at least one processor for executing a computer program code to perform a desired function, at least one memory for storing program code, or both. Alternatively, they may include, for example, a circuit system designed to implement the desired function, such as implemented in a chipset or chip, such as an integrated circuit. Typically, the component may include, for example, one or more processing components or processors.

[0108] The apparatus disclosed above according to any aspect may be a module or component for a device (e.g., a chip). Alternatively, the apparatus disclosed according to any aspect may be a device, such as a server or a server cloud. The apparatus disclosed according to any aspect may include (e.g., only include) the disclosed components, such as a part, a processor, a memory, or may also include one or more additional components.

[0109] Thus, the method may be performed and / or controlled by an apparatus, wherein the apparatus may specifically be a network node, specifically a secondary node. The method may be performed at least in part within an existing communication session. The communication session may be established between an apparatus (e.g., a secondary node SN) and at least one UE (e.g., a UE executing the method according to the first example aspect). The method may have the effect of adjusting an existing communication session, specifically adding and / or releasing a secondary node, for example to implement dual connectivity (e.g., a communication session involving a primary node and a secondary node).

[0110] The indication of at least one SN Key may be obtained from a master node, wherein the master node is part of the same cell group as the apparatus (eg a secondary node) performing the method according to the third example aspect.

[0111] At least one secondary node key corresponds to a counter included by a generated SN counter list corresponding to an apparatus performing the method according to the third example aspect. Thus, at least one SN key corresponds to an SN counter list specific to the apparatus performing the method. The at least one SN key may specifically be different from (e.g., any) SN key received by another SN (e.g., within the same cell group).

[0112] The indication of at least one SN key may be associated with and / or correspond to a UE. The method may include associating the indication of at least one SN key and / or at least one SN key in the indication with the respective UE, for example with a conditional PSCell addition and change (CPAC) context which may be specific to the UE, for example. The method may include storing a plurality of indications of at least one SN key and / or a plurality or at least one SN key in the indication for different UEs, respectively.

[0113] The method includes: performing access by a user equipment. For example, this may include accepting a (random) access request by the UE. Access may be initiated by the UE. The device (and / or the UE) may be configured to perform access using one of the at least one secondary node keys indicated by an indication of the acquisition of at least one secondary node key. Therefore, by receiving an indication of at least one secondary node key, the method enables a device performing a method according to the third example aspect to perform access with a UE performing a method according to the first example aspect and / or to perform access in coordination with a primary node performing a method according to the second example aspect. This allows the UE to access a device (e.g., a secondary node) performing a method according to the third example aspect particularly securely but quickly.

[0114] According to an embodiment of the third exemplary aspect,

[0115] obtaining an indication (e.g., completed) of at least one secondary node key as part of a secondary node modification request (e.g., where the apparatus is currently serving a UE) or a secondary node add request (e.g., from a MN to the apparatus), or

[0116] As part of a secondary node modification request or a secondary node addition request, an indication of at least one secondary node key is obtained (e.g., completed), wherein the indication of at least one secondary node key corresponds to a secondary node key list (e.g., which can be generated by the MN), and the secondary node key list corresponds to a generated secondary node counter list corresponding to the device.

[0117] The secondary node modification request may be received in a communication session in which the apparatus performing the method according to the third example aspect is currently serving a UE. The secondary node addition request may be received by the apparatus performing the method according to the third example aspect when disconnected from the UE, e.g., not serving the UE. The SN modification request and / or the SN addition request may be received from the primary node.

[0118] The indication of at least one secondary node key may correspond to a secondary node key list. The secondary node key list may be generated by the master node and corresponds to a generated secondary node counter list corresponding to an apparatus (e.g., a secondary node) executing the method according to the third example aspect.

[0119] According to an embodiment of the third exemplary aspect,

[0120] obtaining an indication (e.g., completed) of at least one secondary node key following a secondary node add request or as part of a secondary node reconfiguration complete message (e.g., from the MN to the device), or

[0121] As part of a secondary node reconfiguration complete message, an indication of at least one secondary node key is obtained (e.g., completed), wherein the indication of at least one secondary node key corresponds to a (e.g., single) secondary node key for access to the device by a user device (e.g., occurring immediately thereafter).

[0122] In this embodiment, the (e.g., single) SN key may be obtained before (e.g., quickly) the device performing the method according to the third example aspect needs it. For example, the MN may have started preparing for the UE to access the SN before the indication of obtaining the (e.g., single) SN key by the SN. For example, the SN key may be obtained after the CPAC process (e.g., to the SN) (e.g., by the MN) may have started.

[0123] According to an embodiment of the third exemplary aspect,

[0124] obtaining an indication (e.g., completed) of at least one secondary node key as part of a secondary node add request (e.g., to a device) or a secondary node release request (e.g., from a MN at the end of a communication session initiated using another SN key), or

[0125] As part of a secondary node add request or a secondary node release request, an indication of at least one secondary node key is obtained (e.g., completed), wherein the indication of at least one secondary node key corresponds to a (e.g., single) secondary node key for (e.g., future, potential) access to the device by a user device.

[0126] In this embodiment, the (e.g., single) SN key may be obtained (e.g., well before the device performing the method according to the third example aspect needs it. For example, the MN may not have started preparing for the UE to access the SN before the indication of the (e.g., single) SN key is obtained by the SN. The SN key may be obtained by the SN before the CPAC process (e.g., to the SN) (e.g., performed by the MN) may have started. Conversely, such preparation may be performed thereafter. In this embodiment, the device performing the method according to the third example aspect may be referred to as a candidate SN.

[0127] An indication of at least one SN key may be obtained as part of a secondary node add request. At this stage, it is not known when the UE may exactly attempt to access the apparatus performing the method according to the third example aspect. Additionally or alternatively, an indication of at least one SN key may be obtained as part of an SN release request. The SN release request may be obtained at the end of a communication session with the UE using an SN key different from the SN key indicated by the indication of the SN key obtained as part of the SN release request. By previously having provided the UE with a communication session, the network (e.g., MN) may consider the apparatus performing the method according to the third example aspect as a candidate SN for future access by the UE.

[0128] According to an embodiment of the third example aspect, the method further comprises:

[0129] Counting the number of accesses of a corresponding user equipment (eg, an apparatus for executing and / or controlling the method), and

[0130] Based on the counted number of accesses, a secondary node key (eg, one for UE access) is selected from the secondary node key list.

[0131] In case the indication of at least one SN key comprises an SN key list, the apparatus performing the method according to the third example aspect may need to track access of the corresponding UE in order to select the correct SN key from the SN key list.

[0132] According to an embodiment of the third exemplary aspect,

[0133] The secondary node counter list includes: a non-monotonic sequence of secondary node counters, or

[0134] The secondary node counter lists are different from each other.

[0135] Thus, the SN key list may be specific to an apparatus performing the method according to the third example aspect.

[0136] Where applicable, the disclosure presented with respect to the first example aspect or the second example aspect is also disclosed with respect to the third example aspect.

[0137] As a fourth example aspect, a system is disclosed, comprising: executing and / or controlling at least one UE according to the method of the first example aspect, executing and / or controlling at least one MN according to the method of the second example aspect, and executing and / or controlling at least one secondary node according to the method of the first example aspect.

[0138] For example, the system includes a user equipment UE, a master node MN and a secondary node SN, wherein

[0139] The UE is configured to:

[0140] obtaining (e.g. from a master node MN) at least one secondary node counter list (e.g., via RRC, e.g., in an RRC reconfiguration message), wherein the secondary node counter lists respectively correspond to (e.g., are associated with) mutually different secondary nodes of the plurality of secondary nodes, including secondary nodes (e.g., where the UE intends to request access to one of them and / or they are part of the same cell group as the MN and / or are between each other),

[0141] obtaining (e.g., via RRC, such as the same RRC reconfiguration message) an indication of a secondary node (e.g., one of the at least one secondary node corresponding to the secondary node counter list) among the plurality of secondary nodes (e.g., from the master node MN),

[0142] generating a secondary node key based at least in part on one of the obtained secondary node counter lists and an indication of the secondary node (e.g., which may involve selecting an unused counter in the list),

[0143] accessing (e.g., performing a random access procedure on a secondary node) a secondary node indicated by a secondary node (e.g., indicated by the secondary node) using the generated secondary node key,

[0144] The MN is configured as:

[0145] generating at least one secondary node counter list, wherein the secondary node counter lists respectively correspond to different secondary nodes among the plurality of secondary nodes, including the secondary nodes,

[0146] providing an indication of at least one secondary node key to a secondary node of the plurality of secondary nodes (e.g., which is part of the same cell group as the MN and / or between each other), wherein at least one secondary node key in the indication of at least one secondary node key corresponds to (e.g., can be derived therefrom by the UE) a secondary node counter value included by the generated secondary node counter list, the secondary node counter value corresponding to the secondary node of the plurality of secondary nodes (e.g., providing the following two items to the UE simultaneously, or at least as one logical action)

[0147] providing at least one of the generated secondary node counter lists to a user equipment (e.g., served by the MN), and

[0148] providing an indication of a secondary node of the plurality of secondary nodes to the user equipment (e.g. via RRC, e.g. in the same message with the two generated SN counter lists), and

[0149] SN is configured as:

[0150] obtaining an indication of at least one secondary node key from a master node (e.g., of the same cell group as the SN), wherein the at least one secondary node key corresponds to a counter included by a generated secondary node counter list corresponding to the SN,

[0151] Access of the user equipment (e.g., initiated by the user equipment) (e.g., a random access procedure with the user equipment) is performed using one of the at least one secondary node key in the obtained indication of the at least one secondary node key (e.g., by accepting the random access procedure).

[0152] Where applicable, the disclosure presented with respect to the first example aspect, the second example aspect or the third example aspect is also disclosed with respect to the fourth example aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0153] In the accompanying drawings, it is shown:

[0154] Figure 1a , 1b Two example embodiments of a user equipment switching a secondary cell according to all example aspects;

[0155] Figure 2 Example embodiments of key generation according to all example aspects;

[0156] Figure 3 Example embodiments of key generation according to all example aspects;

[0157] Figures 4a to 4d Signaling diagram according to example embodiments of all example aspects;

[0158] Figures 5a to 5c Signaling diagram according to example embodiments of all example aspects;

[0159] Figures 6a to 6d Signaling diagram according to example embodiments of all example aspects;

[0160] Figure 7 Flowchart of a method according to an embodiment of the first example aspect;

[0161] Figure 8 A flow chart of a method according to an embodiment of the second example aspect;

[0162] Fig. 9 A flowchart of a method according to an embodiment of the third example aspect;

[0163] Fig.10 illustrates a block diagram of an embodiment according to a first example aspect;

[0164] Fig.11 illustrates a block diagram of an embodiment according to a second example aspect;

[0165] Fig.12 illustrates a block diagram of an embodiment according to a third example aspect;

[0166] Fig.13 Examples of storage media. DETAILED DESCRIPTION

[0167] Figure 1a A dual connectivity scenario is shown, where UE 100 first moves from a cell PSCell 1a provided by network node 200 (SN1) to another cell PSCell 2a provided by network node 200a (SN2). PSCell is a primary cell in a secondary cell group (SCG). It can be combined with a secondary cell (SCell) in an SCG with carrier aggregation (CA). Initial access to the PSCell can be performed.

[0168] In the next step, UE 100 moves away from cell PSCell 2a again and returns to cell PSCell 1a. In this scenario, according to the prior art, UE 100 may not receive any configuration for cell PSCell 1a during the process. That is, UE 100 may use the same configuration previously obtained for accessing cell PSCell 1a, including the corresponding key for accessing cell PSCell 1a (i.e., node 200 (SN1) providing cell PSCell 1a). UE 100 may add cell PSCell 1a in the selective activation step. In addition to cell PSCell 1a and / or cell PSCell 2a, UE 100 may also be connected to a master node (not shown) so as to achieve dual connectivity involving the master node and secondary nodes (network nodes 200 (SN1), 200a (SN2)).

[0169] exist Figure 1b In FIG. 1 , a similar scenario is presented, where the UE 100 also first moves from a cell PSCell 1a provided by a first network node 200 (SN1) to another cell PSCell 2a provided by a second network node 200a (SN2). The UE then moves back to the cell provided by the network node 200 (SN1) from which it originated, with the only difference being that now it is connected to a network node 200 (SN1) within a different cell PSCell 1b also provided by the network node 200 (SN1). Here, according to the prior art, the UE 100 can also perform a selective activation that reuses a previously obtained configuration for the network node 200 (SN1). In this case, it can also reuse the key to access the network node 200 (SN1).

[0170] Figure 1a and 1b Both scenarios shown will cause security problems in the prior art because the same key (SN key) is used to access the secondary nodes 200, 200a. The key (usually denoted as SK gNB ) can be derived from the sk counter in the conditional reconfiguration performed. The same SK gNB , until a new configuration is obtained. The proposed solution now provides the UE 100 with a plurality of SN counter values ​​(as a SN counter list) for at least one or more secondary nodes (200, 200a). Figure 1a and 1bAs shown, when accessing the secondary node (200, 200a) for the second time (or third time, fourth time or higher), it will use the unused SN counter value to access the secondary network node (here network node 200 (SN1) and also 200a (SN2)). The UE can change the SN counter value at any SN change.

[0171] To illustrate SN key generation, Figure 2 A key generator 110 is shown, which may for example reside in a UE (performing a method according to the first exemplary aspect) or a master node (performing a method according to the second exemplary aspect), for example as a functional unit, for example as a functional block within a computer code stored in a memory, which, when executed by a processor, performs the functionality now described. The key generator 110 may receive a key K specific to a network node (particularly a master node). gNB In addition, it also receives the SN counter value. The SN counter value may be received, for example, from a master node (eg, with the master node key K) previously received (in the case of a UE). gNB Optionally, the key generator 110 may obtain an SN counter length, which may, for example, indicate a range of possible values ​​that the SN counter value may assume. Based at least on the MN key K gNB and SN counter value and optionally SN counter length, the key generator outputs the secondary node key K SN The key generator 110 may for this purpose perform mathematically defined operations which create keys suitable for the end-to-end encryption method used between the UE and the SN.

[0172] In other words, when the UE is configured with dual connectivity, the UE needs the SN key K SN to secure and encrypt its connection to the serving SN. In the current MR-DC scenario, the SN key is generated by the UE using the SN counter value provided by the MN (e.g. as part of the SN counter list), (optionally) the length of the SN counter and the MN key K_gNB, as Figure 2 The serving SN should also be aware of the SN key that the UE will use for end-to-end encryption. Since the MN can determine the SN counter value for the UE, the MN may already know that the key will be generated by the UE using a counter, and the MN can then use the appropriate counter value (e.g., by using Figure 2 100) to calculate the SN key and inform the SN of the SN key to be used before the SN becomes a serving SN (in SN addition or SN change). For example, in SN addition or SN change, the MN may share the K with the candidate SN during preparation. SNSuch provision may be performed, for example, by RRC, for example as part of an S Node Addition Request message or other message detailed below.

[0173] Figure 3 Now one of the concepts of the present disclosure is presented. On the left, a table is shown illustrating a plurality of SN counter lists (i.e., in the claim language, at least on the secondary node counter lists). The columns can be thought of as one SN counter list specific to a secondary node SN1, SN2, or SN3. For a given SN counter value (e.g., counter 1.1), the corresponding SN key (e.g., K SN 1.1) associated. The SN key can be used Figure 2 The key generator shown is derived (and / or derivable) from the associated SN counter value. Additionally, the MN key K may be used gNB and / or SN counter length. At least one SN counter list ( Figure 3 One of the columns shown in ) may be generated by the MN, provided (eg, by the MN) to the UE and / or obtained by the UE.

[0174] Here and in any other embodiments, the UE may, for example, obtain the SN counter length and / or the master node key from the master node. Here and in any other embodiments, the master node may provide the SN counter length and / or the master node key to the UE.

[0175] The secondary node needs to know the SN keys that the UE will use for the upcoming access (e.g., subsequent CPAC) to the SN. For example, the SN keys may be provided to the secondary node as an indication of at least one SN key. For example, at least one entry or (e.g., the entire) left column of SN keys (a so-called SN key list) may be provided to the secondary node SN1. The SN is then enabled to decrypt a message transmitted by the UE based on one of the SN keys in the SN key list.

[0176] FIG4 illustrates an example embodiment as a signaling diagram. Signals exchanged between a UE (e.g., performing a method according to the first example aspect), a master node (MN) (e.g., performing a method according to the second example aspect), a first subnode (SN1), and a second subnode (SN2) are shown (e.g., where SN1 and / or SN2 perform a method according to the third example aspect, respectively). In the illustrated embodiment, a list of SN keys (rather than a single SN key) is shared with the subnodes SN1 and SN2.

[0177] Signaling 401: The UE is connected to the master node MN and the primary node SN1 PSCell1. In this step, the UE is using the SN key K for SN1 in the PSCell-1 link. SN 1.0.

[0178] Signaling 402: The MN generates a list of SN counters for SN1 (SN counter list) (i.e. the SN counter list may be specific to the first time node SN1). In this embodiment, the MN also generates an SN1 key corresponding to the generated list of SN1 counters. Such key generation may be conditional on SN1 being considered for selective activation, i.e. the UE 'returns' to SN1 at a later stage (see Figure 1a and 1b ).

[0179] Signaling 403: MN will share SN1's K with SN1 via the SN modification procedure (eg, as part of an SN modification request). SN List (SN Key List) (e.g., for selective activation).

[0180] Signaling 404: When SN1 receives the SN1 Keys, it may in particular not update any keys used for ongoing transmissions (communication sessions) between SN1 and the UE. Such updates may be done in conventional behavior. Here, the update of the keys for the current communication session may be omitted, since the obtained / provided SN Keys are intended to be used by SN1 for UE return, e.g. as part of selective activation, i.e. if the UE switches to another SN and switches back to SN1. SN1 saves those lists of SN Keys with the UE context (e.g. associates the SN Key list with the UE).

[0181] Signaling 405: SN1 confirms the SN modification request.

[0182] Signaling 406: MN generates a list of SN counters for SN2. The MN will also generate a SN2 key corresponding to the list of SN2 counters.

[0183] Signaling 407: MN will share the SN2 key list (SN Key List) with SN2 via the SN Addition procedure.

[0184] Signaling 408: When the UE switches SN2 in a subsequent manner, for example following the order of the SN2 key list, SN2 will keep all SN2 keys shared by the MN and use them sequentially.

[0185] Signaling 409: SN2 confirms the SN adding request.

[0186] Signaling 410: MN configures SCPAC preparation of SN1 and SN2 for UE. MN provides the UE with the list of SN1 and SN2 counters generated in the previous step. These counter values ​​are provided as a list of SN counters (SN Counter List) and SN Key Group ID (Indication of SN).

[0187] Here and in any other embodiments, the MN may assign a unique SN Key Group ID to (eg, each) SN (eg, participating in selective activation).

[0188] The MN includes an 'SN Key Group ID' (as an indication of the SN) in (e.g. each) candidate configuration. When the UE switches from the current serving cell (e.g. SN1) to a new (serving) cell (e.g. SN2) as part of a selective activation and / or if there is a change in the SN Group ID, the UE applies the 'unused' SN counter value from the obtained SN counter list, which SN counter value may correspond to the new SN Key Group ID (indication / identification of the SN to switch to), in order to generate the SN to be used in the target cell. eNB and / or SK gNB , for example, accessing the target SN (eg, SN2).

[0189] Signaling 411: The UE sends RRC Reconfiguration Complete when completing the RRC reconfiguration received from the MN.

[0190] Signaling 412: The UE may evaluate that PScell-2 meets the CPAC condition. The UE may then compare the SN group ID (e.g., of a given SN counter list) with the CPAC ID and decide to use a new SN key after performing CPAC to PSCell-2 because PSCell-2 is under a different SN (SN2) than the previous serving SN (SN1). The UE may extract the SN counters of the relevant SN group and / or the relevant SN counter list corresponding to the correct SN and generate the SN key accordingly.

[0191] Signaling 413 to 414: UE sends RRC Reconfiguration Complete to MN, which includes SN RRC Reconfiguration Complete. MN forwards SN RRC Reconfiguration Complete to the target SN, i.e., SN2.

[0192] Signaling 415: The UE initiates a random access procedure (RACH) to SN2, and the UE will use the next SN key K-SN 1.1 generated by using the next SN1 counter.

[0193] Signaling 416: SN2 will identify the first time the UE accesses SN2, so SN2 will extract the next K-SN (K-SN 2.1) from the SN2 key list provided by the MN. SN2 will discard this key in future CPAC procedures because the same key will not be used twice.

[0194] Signaling 417: A change from SN1 to SN2 will follow a change from SN2 to SN1, i.e., the PSCell-1 condition is met. The UE identifies that it needs to extract the next SN1 counter and generate a new SN1 key for this access (same process as described in signaling 412). The UE will discard this counter for future use and retain the other SN1 counters.

[0195] Signaling 418 to 420: the same as signaling 413 to 415.

[0196] Signaling 421: Same as signaling 416, SN1 will identify that the UE is accessing SN1 from another SN, so SN1 will extract the next K from the SN1 key list provided by the MN. SN , (K-SN 1.1). SN1 will discard the key or mark it for future CPAC processes, as the same key will not be used twice.

[0197] Signaling 422 to 426: Same as the procedure described in signaling 412 to 416. Given here is a diagram showing how SN2 and the UE will use different keys in those steps (different from those in signaling 12 to 16).

[0198] FIG5 shows a signaling diagram for another embodiment solution, where the SN key is provided on demand, i.e., shortly before it is needed. The entities involved and their relationship to the various aspects are the same as described with respect to FIG4. Some signaling that differs from FIG4 is described below, while some signaling may be the same.

[0199] In signaling 6, the MN does not share the next SN Key with the candidate SNs until they need to know it. The MN also does not provide a (eg, complete) list of SN Keys.

[0200] Once the UE performs an inter-SN (i.e., changes secondary node) CPC (Conditional PSCell Change) (signaling 10, 11), the MN extracts the SN2 key (generated in signaling 5), which the UE will use. The MN will share the SN2 key with the SN2. For example, the key is provided as part of the SN Reconfiguration Complete message.

[0201] This will be repeated in subsequent SN changes, with the MN sharing the SN key with the new SN that the UE switches to. For example, once the UE performs inter-SN CPC again (signaling 15, 16), the MN extracts the SN1 key (generated in signaling 2) that the UE will use, and shares it with SN1.

[0202] Figure 6 shows a signaling diagram of another embodiment solution. The entities involved and their relationship to the various aspects are the same as described with respect to Figures 4 and 5. Some signaling that differs from Figures 4 and 5 is described below, while some signaling may be the same.

[0203] In signaling 2 and 5, the MN generates SN1 and SN2 keys and SN1 and SN2 counters. The MN will extract the first SN2 key from the list of SN2 keys to be shared with SN2. As of today, the MN shares this extracted key with SN2. Therefore, SN2 will know (e.g., only know) the next key that the UE will use.

[0204] When the UE switches from SN1 to SN2, SN1 becomes a candidate for CPAC (the UE can now switch back to SN1). Therefore, in signaling 15, the MN informs SN1 of the next SN1 key that the UE will use in case the UE switches back to SN1. In this case, SN1 is a candidate SN. It is not certain whether the UE will actually switch back to SN1.

[0205] The MN may inform SN1 of the next SN1 key via the SN release procedure (at the end of the previous communication session between UE and SN1) or via Class 2 signaling, which would be, for example, one-way signaling without a confirmation message.

[0206] Alternatively, the next SN1 key may be added to the KS for the first CPAC in the SN Add Request. eNB and / or KS gNB The MN may provide (e.g. only) the next key for subsequent return. The next key may be a key used by the UE in the future during access at a time unknown to SN1. When the SGNB reconfiguration is sent for the first cell change, the next key is again provided with the next value from the list.

[0207] Figure 7is a flowchart illustrating a method according to a first example aspect. The method may be performed by a UE, for example, in an existing communication session with a master node. In a first action M100, at least one secondary node counter list is obtained, for example, from an MN that performs a method according to a second example aspect. For example, more than one NS counter list may be obtained, wherein the SN counter list is associated with a separate SN, respectively. The method also includes, in action M102, obtaining an indication of an SN. For example, obtaining such an indication of an SN may enable the UE to identify an SN counter list for generating an SN key to access the SN indicated by the indication of the SN. In action M104, a secondary node key is generated. For example, the generation involves selecting an SN counter list based on the indication obtained, and may also include: selecting an SN counter value from the selected SN counter list. The SN counter value may be typed (for example, together with an SN counter length and / or an MN key) into a key generator, for example, a piece of code implemented in a memory of a device that performs the method. In action M106, the method also includes: using the generated key to access the secondary node indicated by the indication of the secondary node. The secondary node may perform a method according to a third example aspect. The SN to be accessed is also provided with the correct SN Key, for example by one of the processes outlined in Figures 4 to 6.

[0208] Figure 8 A flowchart illustrating a method according to a second example aspect is shown. The method may be performed by a master node. In action M200, the method includes: generating at least one secondary node counter list. The SN counter list may be generated for a specific SN (e.g., performing a method according to a third example aspect) and may be different from an SN counter list generated for another SN (e.g., of the same cell group). In action M202, an indication of at least one SN key is provided to the SN. The SN key may correspond to an SN counter value included in the generated SN counter list. In action M204, at least one of the generated secondary node counter lists is provided to the UE (e.g., performing a method according to the first example aspect), for example in RRC signaling. Thus, the UE is able to access the SN corresponding to one of the SN counter lists in the SN counter list. In action M206, an indication of (e.g., the) secondary node is provided to a user equipment (i.e., UE) to which at least one generated SN counter list has been provided in action M204.

[0209] Fig. 9A flow chart of a method according to a third example aspect is shown, which can be performed, for example, by a secondary node. In action M300, an indication of at least one SN key can be obtained, for example, from an MN (e.g., performing a method according to the second example aspect). The indication of at least one SN key can, for example, include one (e.g., a single) SN key or multiple SN keys, such as an SN key list. The method also includes, in action M302, access performed by a user equipment (e.g., performing a method according to the first example aspect). In other words, the SN performing the method shown can accept and / or respond to an access request from a UE, for example as part of a random access procedure. The UE and / or SN can use one of the SN keys provided to the SN by the MN in action M300 for access and / or for subsequent communications.

[0210] Fig.10 An example block diagram of a UE 100 is shown. The UE may perform the method according to the first example aspect. The UE comprises a user interface A160, a program memory A110, a main memory A120, and a data memory A140. Further, it comprises a processor A130. The apparatus 100 may also comprise functional units A131 to A134, which correspond to Figure 7 The actions shown in the flowchart of . The SN counter list obtainer A131 can, for example, obtain at least one SN counter list from the MN (for example, executing the method according to the second exemplary aspect). The functional units A131 to A134 can, for example, be connected to the communication interface A150 and / or control the communication interface A150 in order to obtain corresponding information and / or perform access to the SN (accessor A134).

[0211] Fig.11 An example block diagram of a master network node (MN) is shown. The MN may perform a method according to the second example aspect. The MN may include a user interface A260, a program memory A210, a main memory A220, and a data memory A240. Further, it includes a processor A230. The network node 200 may also include functional units A231 to A234, which correspond to Figure 8 The actions shown in the flowchart of . Functional units A232 to A234 can work together with communication interface A250, for example.

[0212] Fig.12 An example block diagram of a secondary network node (SN) is shown. The SN may perform a method according to the third example aspect. The SN may include a user interface A360, a program memory A310, a main memory A320, and a data memory A340. Further, it includes a processor A330. The network node 200 may also include functional units A331 to A332, which correspond to Fig. 9The actions shown in the flowchart of . Functional units A331 to A332 can work together with the communication interface A350, for example.

[0213] Fig.13 is a schematic illustration of an example of a tangible, non-transitory computer-readable storage medium according to the present invention, which can be used, for example, to implement Figures 7 to 9 The program and / or main memory A110, A120, A140, A210, A220, A240, A310, A320, A340 of the UE 100, SN 200 or MN. Fig.13 Shown is a flash memory 1300 which may be, for example, soldered or bonded to a printed circuit board, a solid-state drive 1301 comprising a plurality of memory chips (e.g., flash memory chips), a disk drive 1302, a secure digital (SD) card 1303, a universal serial bus (USB) memory stick 1304, an optical storage medium 1305 (such as, for example, a CD-ROM or DVD), and a magnetic storage medium 1306.

[0214] Some examples include:

[0215] Embodiment 1:

[0216] A method, for example according to the first exemplary aspect, comprises:

[0217] obtaining at least one secondary node counter list, wherein the secondary node counter list corresponds to different secondary nodes among the plurality of secondary nodes,

[0218] obtaining an indication of a secondary node among a plurality of secondary nodes,

[0219] generating a secondary node key based at least in part on the obtained at least one secondary node counter list and the indication of the secondary node,

[0220] Use the generated secondary node key to access the secondary node.

[0221] Embodiment 2:

[0222] The method according to any one of embodiment 1, wherein

[0223] The at least one secondary node counter list includes at least two secondary counter lists.

[0224] Embodiment 3:

[0225] The method according to embodiment 1 or 2, wherein the method further comprises:

[0226] The number of accesses of the corresponding secondary node (eg, the device executing and / or controlling the method) is counted, wherein the generation of the secondary key is also based on the counted number of accesses.

[0227] Embodiment 4:

[0228] The method according to any one of embodiments 1 to 3, wherein at least one of the following items:

[0229] The minor node counter list consists of a non-monotonic sequence of minor node counter values, or

[0230] The secondary node counter lists are different from each other.

[0231] Embodiment 5:

[0232] A method, for example according to the second exemplary aspect, comprises:

[0233] generating at least one secondary node counter list, wherein the secondary node counter list corresponds to different secondary nodes among the plurality of secondary nodes,

[0234] providing an indication of at least one secondary node key to a secondary node of the plurality of secondary nodes, wherein at least one secondary node key in the indication of at least one secondary node key corresponds to a secondary node counter value included by the generated secondary node counter list, the secondary node counter value corresponding to a secondary node of the plurality of secondary nodes,

[0235] providing at least one of the generated secondary node counter lists to the user equipment, and

[0236] An indication of a secondary node of the plurality of secondary nodes is provided to a user equipment.

[0237] Embodiment 6:

[0238] The method according to embodiment 5, wherein

[0239] The at least one secondary node counter list includes at least two secondary counter lists.

[0240] Embodiment 7:

[0241] The method according to embodiment 5 or 6, wherein at least one of the following items:

[0242] The indication of the at least one secondary node key is provided prior to receiving an indication that the user equipment is about to access a secondary node using the secondary node key indicated by the indication of the at least one secondary node key.

[0243] Embodiment 8:

[0244] The method according to any one of embodiments 5 to 7, wherein

[0245] the indication of at least one secondary node key corresponds to a list of secondary node keys corresponding to a generated list of secondary node counters corresponding to the secondary network nodes, and

[0246] Provided as part of at least one of the following:

[0247] Secondary node modification request, or

[0248] Secondary node addition request.

[0249] Embodiment 9:

[0250] The method according to any one of embodiments 5 to 8, wherein

[0251] the indication of at least one secondary node key corresponds to a secondary node key for access to the secondary network node by the user equipment, and

[0252] Provided as part of at least one of the following:

[0253] Secondary node addition request, or

[0254] Secondary node release request.

[0255] Embodiment 10:

[0256] The method according to any one of embodiments 5 to 9, wherein at least one of the following:

[0257] providing an indication of at least one secondary node key after receiving an indication that the user equipment is about to access a secondary node using a secondary node key in an indication of at least one secondary node key, or

[0258] Prior to receiving an indication that a user equipment is about to access a secondary node using a secondary node key in an indication of at least one secondary node key, providing an indication of at least one secondary node key, wherein at least one of the following items is:

[0259] The indication of at least one secondary node key comprises: a secondary node key for access by a user equipment to a secondary network node, or

[0260] Provided as part of the Secondary Node Reconfiguration Complete message.

[0261] Embodiment 11:

[0262] The method according to any one of embodiments 5 to 10, wherein the method further comprises:

[0263] A number of accesses to the respective secondary node by the respective user equipment is counted, wherein the indication of the at least one secondary key is based at least in part on the counted number of accesses.

[0264] Embodiment 12:

[0265] The method according to any one of embodiments 5 to 11, wherein at least one of the following:

[0266] The secondary node counter list includes: a non-monotonic sequence of secondary node counter values, or

[0267] The secondary node counter lists are different from each other.

[0268] Embodiment 13:

[0269] For example, the method according to the third exemplary aspect includes:

[0270] obtaining an indication of at least one secondary node key from a primary node, wherein the at least one secondary node key corresponds to a secondary node counter value included by a generated secondary node counter list (e.g., corresponding to an apparatus performing and / or controlling the method),

[0271] Accessing of the user equipment is performed using one of the at least one secondary node key in the obtained indication of the at least one secondary node key.

[0272] Embodiment 14:

[0273] The method according to embodiment 13, wherein at least one of the following items:

[0274] as part of a secondary node modification request or a secondary node add request, obtain an indication of at least one secondary node key, or

[0275] As part of a secondary node modification request or a secondary node addition request, an indication of at least one secondary node key is obtained, wherein the indication of at least one secondary node key corresponds to a secondary node key list, which corresponds to a generated secondary node counter list (for example, corresponding to an apparatus for executing and / or controlling the method).

[0276] Embodiment 15:

[0277] The method according to embodiment 13 or 14, wherein at least one of the following items:

[0278] obtaining an indication of at least one secondary node key at least one of following a secondary node add request or as part of a secondary node reconfiguration complete message, or

[0279] As part of the secondary node reconfiguration complete message, an indication of at least one secondary node key is obtained, wherein the indication of at least one secondary node key corresponds to a secondary node key for access by a user equipment (e.g., an apparatus performing and / or controlling the method).

[0280] Embodiment 16:

[0281] The method according to any one of embodiments 13 to 15, wherein at least one of the following:

[0282] as part of a secondary node add request or a secondary node release request, obtain an indication of at least one secondary node key, or

[0283] As part of a secondary node add request or a secondary node release request, an indication of at least one secondary node key is obtained, wherein the indication of at least one secondary node key corresponds to a secondary node key for access by a user device (e.g., an apparatus for performing and / or controlling the method).

[0284] Embodiment 17:

[0285] The method according to any of embodiments 13 to 16 of any preceding claim, wherein the component is further configured to:

[0286] Counting the number of accesses of a corresponding user equipment (eg, an apparatus for executing and / or controlling the method), and

[0287] Based on the counted number of accesses, a secondary node key is selected from the secondary node key list.

[0288] Embodiment 18:

[0289] The method according to any one of embodiments 13 to 17, wherein at least one of the following:

[0290] The secondary node counter list includes: a non-monotonic sequence of secondary node counter values, or

[0291] The secondary node counter lists are different from each other.

[0292] Embodiment 19:

[0293] A first device, such as a UE, includes corresponding components for executing the method of any one of embodiments 1 to 4.

[0294] Embodiment 20:

[0295] A first device, such as a UE, includes at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, causes the device to at least execute and / or control a method according to any one of embodiments 1 to 4.

[0296] Embodiment 21:

[0297] A second device, such as a (eg, master) network node, comprises corresponding components for executing the method of any one of embodiments 5 to 12.

[0298] Embodiment 22:

[0299] A second device, such as a (e.g., master) network node, comprises at least one processor; and at least one memory storing instructions which, when executed by at least one processor, cause the device to at least execute and / or control a method according to any one of embodiments 5 to 12.

[0300] Embodiment 23:

[0301] A third device, such as a (eg, secondary) network node, comprises corresponding components for performing the method of any one of embodiments 13 to 18.

[0302] Embodiment 24:

[0303] A third device, such as a (e.g., secondary) network node, comprises at least one processor; and at least one memory storing instructions that, when executed by at least one processor, cause the device to at least execute and / or control a method according to any one of embodiments 13 to 18.

[0304] Embodiment 25:

[0305] A computer program, when executed by a processor, causes a device (e.g., a device according to Embodiment 19 or 20) to perform and / or control the actions and / or steps of a method according to any one of Embodiments 1 to 4.

[0306] Embodiment 26:

[0307] A computer program product comprises a computer program according to embodiment 25.

[0308] Embodiment 25:

[0309] A computer program, when executed by a processor, causes a device (e.g., a device according to embodiment 21 or 22) to perform and / or control the actions and / or steps of a method according to any one of embodiments 5 to 12.

[0310] Embodiment 26:

[0311] A computer program product comprises a computer program according to embodiment 25.

[0312] Embodiment 27:

[0313] A computer program, when executed by a processor, causes a device (e.g., a device according to embodiment 23 or 24) to perform and / or control the actions and / or steps of a method according to any one of embodiments 13 to 18.

[0314] Embodiment 28:

[0315] A computer program product comprising the computer program according to embodiment 27.

[0316] Embodiment 29:

[0317] A system comprising:

[0318] At least one first device according to any one of embodiments 19 or 20,

[0319] At least one second device according to any one of embodiments 21 or 22, and at least one third device according to any one of embodiments 23 or 24.

[0320] In this specification, any connection presented in the described embodiments is to be understood in a manner that the components involved are operationally coupled. Therefore, the connection may be direct or indirect, it has any number of intermediate elements or combinations of intermediate elements, and there may only be a functional relationship between the components.

[0321] In addition, any method, process, and action described or illustrated herein may be implemented using executable instructions in a general or special purpose processor and may be stored in a computer readable storage medium (e.g., disk, memory, etc.) for execution by such a processor. References to 'computer readable storage medium' should be understood to cover special purpose circuits such as FPGAs, ASICs, signal processing devices, and other devices.

[0322] The expression "A and / or B" is considered to include any of the following three scenarios: (i) A, (ii) B, (iii) A and B. Having the same meaning as the expression "A or B", the expression "at least one of A or B" may be used herein. In addition, the article "a" should not be understood as "an", that is, the use of the expression "an element" does not exclude the presence of other elements. The term "comprising" should be understood in an open sense, that is, by the way that an object "comprising element A" may also include other elements in addition to element A.

[0323] It is to be understood that all presented embodiments are (e.g., only) examples, and that any feature presented for a particular example embodiment may be used alone or in combination with any feature presented for the same or another particular example embodiment and / or in combination with any other feature not mentioned in any aspect. Specifically, the example embodiments presented in this specification should also be understood to be disclosed in all possible combinations with each other, as long as it is technically reasonable and the example embodiments are not alternatives to each other. It will also be understood that any feature presented for an example embodiment in a particular category (method / device / computer program / system) may also be used in a corresponding manner in example embodiments of any other category. It should also be understood that the presence of a feature in the presented example embodiment does not necessarily mean that the feature forms an essential feature and cannot be omitted or replaced.

[0324] A feature statement comprising at least one of the subsequently enumerated features is not mandatory, since the feature comprises all subsequently enumerated features, or at least one of a plurality of subsequently enumerated features. Likewise, it is possible to select the enumerated features in any combination, or to select (e.g. only) one of the enumerated features. Specific combinations of all subsequently enumerated features are also conceivable. Moreover, a plurality of or (e.g. only) one of the enumerated features may be possible.

[0325] The sequence of all method actions presented above is not mandatory, and alternative sequences may also be possible. However, the specific sequence of method actions exemplarily shown in the drawings should be regarded as one possible sequence of method actions of the corresponding embodiments described by the corresponding drawings.

[0326] The subject matter has been described above by means of example embodiments. It should be noted that there are alternatives and variations that are obvious to those skilled in the art and may be implemented without departing from the scope of the appended claims.

[0327] List of abbreviations

[0328] ACK Acknowledgement

[0329] RRC Radio Resource Control

[0330] UE User Equipment

[0331] MN Master Node

[0332] SN Secondary Node

[0333] MR-DC Multi-RAT Dual Connectivity

[0334] PCell Primary Cell

[0335] PSCell primary and secondary cells

[0336] SCell Subcell

[0337] SCG Sub-Cell Group

[0338] MCG Master Cell Group

[0339] CPAC Conditional PSCell Additions and Changes

Claims

1. An apparatus for communication, comprising means for: obtaining at least one secondary node counter list, wherein the secondary node counter list corresponds to different secondary nodes among the plurality of secondary nodes, obtaining an indication of a secondary node of the plurality of secondary nodes, generating a secondary node key based at least in part on the obtained at least one secondary node counter list and the indication of the secondary node, The secondary node is accessed using the generated secondary node key.

2. The device according to claim 1, wherein The at least one secondary node counter list includes at least two secondary counter lists.

3. The device according to claim 1 or 2, wherein the component is further configured to: The number of accesses of the device to the corresponding secondary node is counted, wherein the generation of the secondary key is also based on the counted number of accesses.

4. The device according to any one of claims 1 to 3, wherein at least one of the following items: The secondary node counter list comprises a non-monotonic sequence of secondary node counter values, or The secondary node counter lists are different from each other.

5. An apparatus for communication, comprising means for: generating at least one secondary node counter list, wherein the secondary node counter list corresponds to different secondary nodes among the plurality of secondary nodes, providing an indication of at least one secondary node key to a secondary node of the plurality of secondary nodes, wherein the at least one secondary node key in the indication of at least one secondary node key corresponds to a secondary node counter value included by the generated secondary node counter list, the secondary node counter value corresponding to the secondary node of the plurality of secondary nodes, providing at least one of the generated secondary node counter lists to a user equipment, and An indication of the secondary node of the plurality of secondary nodes is provided to the user equipment.

6. The device according to claim 5, wherein The at least one secondary node counter list includes at least two secondary counter lists.

7. The device according to claim 5 or 6, wherein at least one of the following items: The indication of at least one secondary node key is provided prior to receiving an indication that the user equipment is about to access the secondary node using the secondary node key indicated by the indication of at least one secondary node key.

8. The device according to any one of claims 5 to 7, wherein The indication of at least one secondary node key corresponds to a list of secondary node keys corresponding to the generated list of secondary node counters corresponding to the secondary network node, and Provided as part of at least one of the following: Secondary node modification request, or Secondary node addition request.

9. The device according to any one of claims 5 to 8, wherein said indication of at least one secondary node key corresponds to a secondary node key for said access to said secondary network node by said user equipment, and Provided as part of at least one of the following: Secondary node addition request, or Secondary node release request.

10. The device according to any one of claims 5 to 9, wherein at least one of the following: providing the indication of at least one secondary node key after receiving an indication that the user equipment is about to access the secondary node using the secondary node key in the indication of at least one secondary node key, or Prior to receiving an indication that the user equipment is about to access the secondary node using the secondary node key in the indication of at least one secondary node key, providing the indication of at least one secondary node key, wherein at least one of the following items: The indication of at least one secondary node key comprises: the secondary node key used for the access of the user equipment to the secondary network node, or Provided as part of the Secondary Node Reconfiguration Complete message.

11. The apparatus according to any one of claims 5 to 10, wherein the component is further configured to: A number of accesses to the respective secondary node by the respective user equipment is counted, wherein the indication of at least one secondary key is based at least in part on the counted number of accesses.

12. The device according to any one of claims 5 to 11, wherein at least one of the following: The secondary node counter lists respectively include: A non-monotonic sequence of secondary node counter values, or The secondary node counter lists are different from each other.

13. An apparatus for communication, comprising means for: obtaining an indication of at least one secondary node key from a primary node, wherein the at least one secondary node key corresponds to a secondary node counter value included by a generated secondary node counter list corresponding to the device, Accessing of the user equipment is performed using one of the at least one secondary node key in the obtained indication of at least one secondary node key.

14. The apparatus of claim 13, wherein at least one of the following: obtaining said indication of at least one secondary node key as part of a secondary node modification request or a secondary node addition request, or As part of a secondary node modification request or a secondary node addition request, the indication of at least one secondary node key is obtained, wherein the indication of at least one secondary node key corresponds to a secondary node key list, and the secondary node key list corresponds to the secondary node counter list generated corresponding to the device.

15. The device according to claim 13 or 14, wherein at least one of the following: obtaining said indication of at least one secondary node key at least one of following a secondary node add request or as part of a secondary node reconfiguration complete message, or Said indication of at least one secondary node key is obtained as part of a secondary node reconfiguration complete message, wherein said indication of at least one secondary node key corresponds to a secondary node key for access to said apparatus by said user equipment.

16. The device according to any one of claims 13 to 15, wherein at least one of the following: obtaining said indication of at least one secondary node key as part of a secondary node add request or a secondary node release request, or The indication of at least one secondary node key is obtained as part of a secondary node add request or a secondary node release request, wherein the indication of at least one secondary node key corresponds to a secondary node key for access to the apparatus by the user equipment.

17. The apparatus according to any one of claims 13 to 16, wherein the component is further configured to: Counting the number of times the corresponding user equipment accesses the device, and Based on the counted number of accesses, the secondary node key is selected from the secondary node key list.

18. The device according to any one of claims 13 to 17, wherein at least one of the following: The secondary node counter lists respectively include: A non-monotonic sequence of secondary node counter values, or The secondary node counter lists are different from each other.

19. A system for communication, comprising a user equipment UE, a master node MN, and a secondary node SN, wherein The UE is configured to: obtaining at least one secondary node counter list, wherein the secondary node counter lists respectively correspond to different secondary nodes among a plurality of secondary nodes, including the secondary node, obtaining an indication of a secondary node of the plurality of secondary nodes, generating a secondary node key based at least in part on one of the obtained secondary node counter list and the indication of the secondary node, accessing said secondary node in said indication of a secondary node using said generated secondary node key, The MN is configured as: generating at least one secondary node counter list, wherein the secondary node counter lists respectively correspond to different secondary nodes among a plurality of secondary nodes, including the secondary node, providing an indication of at least one secondary node key to the secondary node of the plurality of secondary nodes, wherein the at least one secondary node key in the indication of at least one secondary node key corresponds to a secondary node counter value included by the generated secondary node counter list, the secondary node counter value corresponding to the secondary node of the plurality of secondary nodes, providing at least one of the generated secondary node counter lists to the user equipment [eg, served by the apparatus], and providing an indication of the secondary node of the plurality of secondary nodes to the user equipment, and The SN is configured as: obtaining an indication of at least one secondary node key from the primary node, wherein the at least one secondary node key corresponds to a counter included by the secondary node counter list generated corresponding to the SN, Accessing of said user equipment is performed using one of said at least one secondary node key in said obtained indication of at least one secondary node key.

Images