Secure key management in dual connectivity operations

Abstract

The present disclosure relates, inter alia, to a user equipment configured to support dual connectivity operation to a primary node and a secondary node of a radio access network, the user equipment comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, transmit the instructions to the primary node and the secondary node. Causing the user equipment to perform at least the following: establishing a connection to a master node; configuration information is received from a primary node, where the configuration information includes key counter information defining a sequence of at least two different key counter values to generate at least two different security keys for at least two different target secondary nodes.

Description

Technical Field

[0001] The present disclosure relates to, but is not limited to, dual connectivity operations in the context of radio access networks defined by the Third Generation Partnership Project (3GPP) standards, such as the 5G standards also referred to as New Radio (NR). The present disclosure particularly relates to security key management in such dual connectivity operations, and more particularly to the management of security keys for secondary nodes of the dual connectivity operations. Background Art

[0002] Dual Connectivity (DC) is an operation mode in which a user equipment (UE) capable of multiple transmissions and receptions is configured to utilize resources provided by two different radio nodes. One node acts as a master node (MN) and the other node acts as a secondary node (SN). The MN and the SN are connected via a network interface, and at least the MN is connected to a core network. A master cell group (MCG) is a group of at least one serving cell associated with the MN, and a secondary cell group (SCG) is a group of at least one serving cell associated with the SN (e.g., see references [1], [2]).

[0003] In order to perform integrity protection and encryption for Radio Resource Control (RRC) signaling and user data, a security key K generated based on the Non-Access Stratum (NAS) level key is used. gNB . K gNB can be refreshed to ensure horizontal mobility on the nodes without changing the core network (see, for example, reference [3]).

[0004] In the case of DC, radio bearers can be assigned to MCG and SCG, and the mobility of UE on SCG can be independent of the mobility in MCG. Therefore, in order to refresh the security key for SCG bearers without affecting the ongoing security process of MCG bearers, a new security key K for SCG bearers is introduced. SN . K SN Refreshed by the UE based on the SN counter value provided by the MN to the UE (eg, see reference [4]). Summary of the invention

[0005] However, there is a problem, that is, according to the current 5G standard, after performing conditional addition or change (CPAC) of the primary cell in the secondary cell group (PSCell), or after performing conditional switching (CHO), the UE releases the CPAC or CHO configuration data after performing CPAC or CHO. In addition, the configuration message of CPAC or CHO may contain only one SN counter value. Therefore, whenever the UE moves from the previous serving SCG to the current serving SCG, the MN must send a new configuration message to prepare for the UE's subsequent cell group change to the possible future target SCG. In this context, the possible future target SCG also includes the previous serving SCG, because the UE must also prepare for switching back to the previous serving SCG. Since the configuration message is sent via RRC signaling, a large amount of RRC signaling overhead is generated, especially when a large number of CPAC or CHO are performed in a short period of time. In addition, the requirement to send a new configuration message before the subsequent cell group change can be performed limits the rapid mobility of the UE on different SCGs.

[0006] In view of the above, the exemplary embodiments of the present disclosure may have the effect of enabling the user equipment to perform autonomous security key refresh without involving the network. Therefore, in some cases, new configuration messages for CPAC or CHO may be omitted, so that RRC signaling overhead is reduced and rapid mobility of the UE on different SCGs is achieved to a greater extent.

[0007] According to a first exemplary aspect, a user equipment is disclosed. The user equipment may be configured to support dual connectivity operations to a primary node and a secondary node of a radio access network. The user equipment may include at least one processor and at least one memory. The at least one memory may store instructions that, when executed by the at least one processor, cause the user equipment to perform at least the following:

[0008] Establish a connection to the master node;

[0009] Configuration information is received from a primary node, wherein the configuration information may include key counter information defining a sequence of at least two different key counter values ​​to generate at least two different security keys for at least two different target secondary nodes.

[0010] The user device may be a stationary device or a mobile device. In particular, the user device may be a mobile device, such as a smartphone, a tablet computer, a wearable device, a smart watch, a low-power device, an IoT device, an IIoT device, a vehicle, a truck, a drone, an airplane, etc. The user device may be particularly capable of communicating with (sending signals and / or data to / receiving signals and / or data from) one or more other user devices. Additionally or alternatively, the user device may be particularly capable of communicating with (sending signals and / or data to / receiving signals and / or data from) at least one primary node of a radio access network, the primary node being configured to support dual connection operations to a secondary node of the radio access network and a user device. Additionally or alternatively, the user device may be particularly capable of communicating with (sending signals and / or data to / receiving signals and / or data from) at least one secondary node of a radio access network, the secondary node being configured to support dual connection operations to a primary node of the radio access network and a user device. In general, the user device may also be any device capable of communicating with a communication network and / or another user device.

[0011] A radio node (e.g., a master node or a secondary node) may be understood as a wireless communication station installed at a fixed or mobile location, and may be, or include, an entity of a radio access network of a wireless communication system in particular. For example, a radio node may be, or include, a base station of a wireless communication network of any generation (e.g., gNB, ng-eNB, eNodeB, NodeB, BTS, etc.) of a 3GPP standard, or may be a part thereof. Typically, a radio node may be, or include, a hardware or software component that implements a specific functionality. In an example, a radio node may be a location management function (LMF). In an example, a radio node may be an entity defined by a 3GPP 5G or NR standard (also referred to as a gNB). Therefore, although a radio node may be understood as being implemented in, or being a single device or module, a radio node may also be implemented on, or include, multiple devices or modules. Therefore, a radio node may be implemented in, or be a stationary device in particular. Multiple radio nodes may particularly establish a wireless communication system or network, which may particularly be an NR or 5G system, or any other wireless communication system defined by past or future standards, particularly a successor standard to the current 3GPP standard. In particular, multiple radio nodes (eg, a primary node and one or more secondary nodes) may be configured to support dual connectivity operations towards one or more user equipments.A radio node may be capable of communicating directly and / or indirectly with other radio nodes or user equipments.

[0012] As used herein, configuration information may be understood as any type of information on which the user equipment is or may be configured for dual connectivity operation and / or security key management. For example, the configuration information may be RRC reconfiguration information, in particular as part of an RRC reconfiguration request to the user equipment.

[0013] As used herein, key counter information may be understood as any kind of information defining at least one value of a key counter, the key counter being associated with a security key. For example, the key counter information may be, include, indicate, be capable of determining, or similarly explicitly or implicitly specify at least one previous, current, or future value of a key counter. For example, the key counter value may define the value of an SN counter.

[0014] As used herein, a sequence may be understood as an ordered sequence of similar elements that follow a particular pattern. As an example, a sequence may have an initial element and a final element, particularly if the sequence is a finite sequence. As another example, a sequence may have an initial element, but may not have a final element, particularly if the sequence is an infinite sequence. For example, a sequence may be an ordered sequence of numbers or values ​​that follow a particular pattern. For example, a sequence may be an ordered sequence of integers, particularly non-negative integers, wherein subsequent elements may be obtained from preceding elements by iteratively adding a predefined step value. For example, a predefined step value may be equal to 1.

[0015] As used herein, a key counter value may be understood as a value of a key counter, the key counter being associated with a security key. For example, the key counter value may be used as a freshness input for a subsequent derivation of a security key. For example, the key counter value may be a value of an SN counter. For example, the key counter value may be a number, in particular a non-negative integer.

[0016] As used herein, key counter information defining a sequence of at least two different key counter values ​​may be understood as such that at a present or future point in time, at least two different key counter values ​​may be derived from the key counter information in any conceivable manner. For example, the key counter information may define a sequence of at least two different key counter values, because the key counter information is, includes, indicates, is capable of determining, or similarly specifies explicitly or implicitly an initial element of the sequence, and rules for the derivation of other elements of the sequence. For example, the elements of the sequence may form a monotonically increasing sequence, in particular a sequence of non-negative integers that are monotonically increasing by 1. Thus, it may be prevented in a particularly simple manner that a key counter value is used to generate a security key more than once.

[0017] As used herein, a security key may be understood as a piece of information used for security purposes in a radio access network, in particular a string of characters. For example, the string of characters may include numbers, letters, symbols, special characters, etc. For example, the security key may be secret. For example, the security key may be a security key used for integrity protection and / or encryption of data, in particular for data exchanged between a user equipment and a secondary node of the radio access network. For example, the security key may be an upper-level security key, based on which a plurality of lower-level security keys for integrity protection and / or encryption are determined, in particular a first lower-level security key for integrity protection of RRC signaling, a second lower-level security key for encryption of RRC signaling, a third lower-level security key for integrity protection of user data, and a fourth lower-level security key for encryption of user data. For example, the security key may be K SN Security key.

[0018] As used herein, encryption may be understood as the general concept of converting information between so-called plaintext, which is a form of information that is easily decrypted in a format that is readable by humans or computers, and so-called ciphertext, which is a form of information that is encrypted in a format that is not readable by humans or computers without appropriate decryption. Thus, encryption includes encrypting information from plaintext to ciphertext, and decrypting information from ciphertext to plaintext.

[0019] As used herein, a target secondary node may be understood as a secondary node of a radio access network, whose associated secondary cell group (SCG) is eligible, or may be eligible, at a corresponding current or future time point to perform a conditional PSCell addition or change (CPAC) or conditional switching (CHO) to the SCG associated with the target secondary node. For example, the target secondary node is different from the source secondary node, wherein the source secondary node used herein may be understood as a secondary node associated with the current serving SCG. However, the target secondary node may also be the same as the source secondary node, because after performing a CPAC or CHO from the SCG associated with the source secondary node to the SCG associated with the target secondary node different from the source secondary node, the SCG associated with the source secondary node is eligible, or may be eligible, at a future time point to perform a subsequent CPAC or CHO returning to the SCG associated with the source secondary node.

[0020] According to the first exemplary aspect, the user equipment may establish a connection to the master node, thereby enabling data exchange between the UE and the MN. For example, the connection may be a secure connection, in particular a secure RRC signaling connection.

[0021] In addition, according to the first exemplary aspect, the user equipment may receive configuration information from the primary node, wherein the configuration information includes key counter information, the key counter information defining a sequence of at least two different key counter values ​​to generate at least two different security keys for at least two different target secondary nodes. Compared to the scenario in which the configuration message of the CPAC or CHO contains only one key counter value and the UE releases the CPAC or CHO configuration data after performing the CPAC or CHO, the exemplary embodiment of the first exemplary aspect may be advantageous because in some cases, the new configuration message of the CPAC or CHO can be omitted. For example, after the UE has performed a CPAC or CHO from the SCG associated with the source SN to the SCG associated with the first target SN, and the first key counter value derived from the key counter information is used to generate a first security key for exchanging data with the first target SN, the UE is able to derive a second key counter value from the key counter information and use the second key counter value to generate a second security key for exchanging data with the second target SN. Therefore, the UE can autonomously perform a security key refresh of the CPAC or CHO to the SCG associated with the second target SN without the MN sending the new configuration information of the CPAC or CHO to the UE. In this way, it is also possible to reduce RRC signaling overhead and achieve faster mobility of UE on different SCGs to a greater extent.

[0022] In an example embodiment of the first example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the user equipment to perform at least the following:

[0023] A first security key is generated using a first key counter value derived from the key counter information.

[0024] As used herein, deriving a first key counter value from key counter information may be understood as causing the user device to obtain the first key counter value based on the key counter information in any conceivable manner. For example, the user device may derive the first key counter value because it obtains a first key counter value that is identical to, included by, indicated by, capable of being determined by, or explicitly or implicitly similarly specified in the key counter information. As used herein, generating a first security key using the first key counter value may be understood as causing the user device to generate the first security key based on the first key counter value in any conceivable manner. For example, the user device may calculate the first security key using the first key counter value as a freshness input for the calculation. By generating the first security key using the first key counter value derived from the key counter information, a first security key for integrity protection and / or encryption of data may be achieved, in particular, data to be exchanged between the UE and the first target SN may be obtained by the UE.

[0025] In an example embodiment of the first example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the user equipment to perform at least the following:

[0026] The first security key is used for integrity protection and / or encryption of data exchanged between the user equipment and the first target secondary node.

[0027] In this way, it is possible to implement secure data exchange between the UE and the first target SN, especially secure data exchange according to the security architecture of the 5G standard.

[0028] In an example embodiment of the first example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the user equipment to perform at least the following:

[0029] The key counter information is processed such that the user equipment is enabled to derive at least a second key counter value from the processed key counter information, the second key counter value being different from the first key counter value.

[0030] As used herein, processing key counter information may be understood as causing the user equipment to modify the key counter information in any conceivable manner. For example, processing key counter information may include modifying a sequence of key counter values ​​defined by the key counter information. For example, processing key counter information may include preventing a first key counter value from being reused to generate a security key other than a first security key. By processing the key counter information, it may be achieved that the UE is able to derive a second key counter value from the processed key counter information, and use the second key counter value to generate a second security key for exchanging data with a second target SN. Therefore, the UE may autonomously perform a security key refresh to a future CPAC or CHO of the SCG associated with the second target SN without the MN sending new configuration information of the CPAC or CHO to the UE. Thereby, it may also be possible to reduce RRC signaling overhead and achieve rapid mobility of the UE on different SCGs to a greater extent.

[0031] In an example embodiment of the first example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the user equipment to perform at least the following:

[0032] A second security key is generated using a second key counter value derived from the processed key counter information, the second security key being different from the first security key.

[0033] As used herein, deriving a second key counter value from processed key counter information may be understood as enabling the user device to obtain a second key counter value based on the processed key counter information in any conceivable manner. For example, the user device may derive a second key counter value because it obtains a second key counter value that is identical to, included by, indicated by, capable of being determined by, or explicitly or implicitly similarly specified in the processed key counter information. As used herein, generating a second security key using a second key counter value may be understood as enabling the user device to generate a second security key based on the second key counter value in any conceivable manner. For example, the user device may calculate a second security key using the second key counter value as a calculated freshness input. By generating a second security key using a second key counter value derived from the processed key counter information, it may be achieved that the UE may obtain a second security key for integrity protection and / or encryption of data, in particular data to be exchanged between the UE and the second target SN.

[0034] In an example embodiment of the first example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the user equipment to perform at least the following:

[0035] The second security key is used for integrity protection and / or encryption of data exchanged between the user equipment and a second target secondary node, the second target secondary node being different from the first target secondary node.

[0036] In this way, it is possible to implement secure data exchange between the UE and the second target SN, especially secure data exchange according to the security architecture of the 5G standard.

[0037] In an example embodiment of the first example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the user equipment to perform at least the following:

[0038] The key counter information is further processed such that the user device is enabled to derive at least a further key counter value from the further processed key counter information, the further key counter value being different from the first key counter value and different from the second key counter value.

[0039] As used herein, further processing of the key counter information may be understood as causing the user equipment to further modify the key counter information in any conceivable manner. For example, further processing of the key counter information may include further modifying the sequence of key counter values ​​defined by the key counter information. For example, further processing of the key counter information may include preventing the second key counter value from being reused to generate security keys other than the second security key. By further processing the key counter information, it can be achieved that the UE is able to derive additional key counter values ​​from the further processed key counter information, and use the additional key counter values ​​to generate additional security keys for exchanging data with another target SN. Therefore, the UE can autonomously perform a security key refresh to a future CPAC or CHO of an SCG associated with another target SN without the MN sending new configuration information of the CPAC or CHO to the UE. Thereby, it is also possible to reduce the RRC signaling overhead and achieve rapid mobility of the UE on different SCGs to a greater extent.

[0040] In an exemplary embodiment of the first exemplary aspect, the key counter information received from the master node may define a list of at least two different key counter values. As used herein, a list may be understood as a sequence having a final element. Therefore, a list may also be understood as a finite sequence. As used herein, the key counter information defining a list of key counter values ​​may be understood as making it possible to derive a list of key counter values ​​from the key counter information in any conceivable manner at a present or future point in time. For example, the key counter information may be, include, indicate, be able to determine, or similarly explicitly or implicitly specify a list of key counter values. For example, the key counter information may define a list of key counter values ​​because the key counter information explicitly specifies the individual key counter values ​​in the list, in particular all the individual key counter values ​​in the list. For example, the key counter information may define a list of key counter values ​​because the key counter information specifies a first key counter value and a maximum number of additions, wherein the first element in the list is obtained by selecting the first key counter value, and the remaining elements in the list are obtained by iteratively adding a step value to the first key counter value until the maximum number of additions is reached. For example, the step value may be predetermined by a user device or may be specified within the key counter information. For example, the step value may be equal to 1. For example, the key counter information may define a list of key counter values, because the key counter information specifies a range from a first non-negative integer key counter value to a final non-negative integer key counter value, wherein the list is obtained by selecting each non-negative integer in the specified range as an element in the list of key counter values. By defining a list of at least two different key counter values ​​by the key counter information received from the master node, a particularly simple definition of the at least two different key counter values ​​may be achieved by the key counter information, so that, for example, no complex calculation operations are required and corresponding processor resources are saved.

[0041] In an exemplary embodiment of the first exemplary aspect, generating the first security key may include: using a first list element in a list of key counter values ​​as the first key counter value. Thus, a particularly simple derivation of the first key counter value from the key counter information may be achieved, such that, for example, no complex calculation operations are required and corresponding processor resources are saved.

[0042] In an exemplary embodiment of the first exemplary aspect, processing the key counter information may include removing the first list element from the list of key counter values. Thereby, a particularly simple processing of the key counter information may be achieved, such that, for example, no complex calculation operations are required and corresponding processor resources are saved.

[0043] In an exemplary embodiment of the first exemplary aspect, generating the second security key may include: using a current first list element in the list of key counter values ​​as the second key counter value. Thereby, a particularly simple derivation of the second key counter value from the processed key counter information may be achieved, such that, for example, no complex calculation operations are required and corresponding processor resources are saved.

[0044] In an exemplary embodiment of the first exemplary aspect, further processing of the key counter information may comprise removing the current first list element from the list of key counter values. Thus, a particularly simple further processing of the key counter information may be achieved, such that, for example, no complex calculation operations are required and corresponding processor resources are saved.

[0045] In an exemplary embodiment of the first exemplary aspect, the configuration information may include key counter information defining a list of at least two different SN counter values ​​to generate at least two different K counters for at least two different target secondary nodes. SN security key. The first key counter value may be a first SN counter value. The second key counter value may be a second SN counter value. The first security key may be a first K SN The second security key may be a second K SN Security key.

[0046] In an exemplary embodiment of the first exemplary aspect, the configuration information may include a radio resource control reconfiguration request.

[0047] In an example embodiment of the first exemplary aspect, the configuration information may include information related to conditional addition or change of a primary cell in a secondary cell group associated with the first target secondary node, or related to conditional handover to the first target secondary node.

[0048] In an example embodiment of the first exemplary aspect, the configuration information may include information related to conditional addition or change of a primary cell in a secondary cell group associated with the second target secondary node, or related to conditional handover to the second target secondary node.

[0049] In an example embodiment of the first example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the user equipment to perform at least one of the following:

[0050] determining whether at least one condition for conditional addition or change of a primary cell in a secondary cell group associated with a first target secondary node, or at least one condition for conditional switching to the first target secondary node is satisfied;

[0051] Through the random access channel, using the first KSN A security key is used to initiate a random access process to the first target secondary node.

[0052] In particular, in response to determining that at least one condition for conditional addition or change of a primary cell in a secondary cell group associated with the first target secondary node or at least one condition for conditional switching to the first target secondary node is satisfied, a conditional switching to the primary cell in the secondary cell group associated with the first target secondary node may be performed via a random access channel (RACH) using the first K SN The random access procedure to the first target secondary node is initiated using the security key.

[0053] In an example embodiment of the first example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the user equipment to perform at least one of the following:

[0054] determining whether at least one condition for conditional addition or change of a primary cell in a secondary cell group associated with a second target secondary node, or at least one condition for conditional switching to the second target secondary node is satisfied;

[0055] Through the random access channel, using the second K SN security key, initiates a random access process to the second target secondary node.

[0056] In particular, in response to determining that at least one condition for conditional addition or change of a primary cell in a secondary cell group associated with the second target secondary node, or at least one condition for conditional switching to the second target secondary node is satisfied, a conditional switching to the second target secondary node using the second K can be performed via a random access channel (RACH). SN The random access procedure to the second target secondary node is initiated using the security key.

[0057] In an example embodiment of the first example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the user equipment to perform at least the following:

[0058] Sends a message to the master indicating a connection failure.

[0059] For example, the connection failure may be a connection failure between the user equipment and the target secondary node. For example, the connection failure may be a failure of a random access procedure from the user equipment to the target secondary node, in particular, a failure of a random access procedure via RACH. By sending information indicating the connection failure to the primary node, the MN may be notified of the connection failure so that the MN may take corresponding measures when necessary.

[0060] In an example embodiment of the first example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the user equipment to perform at least the following:

[0061] At least one additional list element in the list of key counter values ​​is received from the master node.

[0062] In particular, after determining whether the number of list elements in the list of key counter values ​​has not reached a predefined threshold, and in response to determining that the number of list elements in the list of key counter values ​​has not reached the predefined threshold, receiving at least one additional list element in the list of key counter values ​​from the master node can be performed. For example, the predefined threshold can be equal to 1. By receiving at least one additional list element in the list of key counter values ​​from the master node, the number of list elements in the list of key counter values ​​can be prevented from reaching a too low value, in particular zero. Accordingly, after one or more key counter values ​​are used to generate security keys for one or more target SNs and are removed from the list, the user equipment can be provided with additional key counter values, so that additional security keys can be generated for the additional target SNs. Therefore, the ability of the UE to perform CPAC or CHO to the SCG associated with the additional target SN can be maintained. In particular, by continuously receiving at least one additional list element in the list of key counter values ​​from the master node, the UE can be able to perform a theoretically unlimited number of CPAC or CHO, thereby performing a theoretically unlimited number of autonomous mobility events.

[0063] In an exemplary embodiment of the first exemplary aspect, the key counter information received from the master node may include: a key counter value, and an instruction to maintain the key counter value. As used herein, the key counter information including the key counter value may be understood as causing the key counter information to include information that explicitly specifies the key counter value. As used herein, the instruction to maintain the key counter value may be understood as an instruction to the user device not to release the key counter value but to continuously process the key counter value. In particular, after the key counter value is used to generate a security key, and / or after the security key has been used for the target secondary node, the user device may be instructed to process the key counter value. By including the key counter value and the instruction to maintain the key counter value in the key counter information received from the master node, it is possible to achieve a particularly simple derivation of the first key counter value from the key counter information, such that, for example, no complex calculation operations are required and corresponding processor resources are saved. In addition, possible target SNs do not have to be pre-provided with multiple security keys.

[0064] In an example embodiment of the first exemplary aspect, generating the first security key may include: using a key counter value received from the master node as the first key counter value. Thus, a particularly simple derivation of the first key counter value from the key counter information can be achieved, such that, for example, no complex calculation operations are required and corresponding processor resources are saved.

[0065] In an example embodiment of the first exemplary aspect, processing the key counter information may include adding a predefined step value to the key counter value received from the master node. For example, the predefined step value may be a positive integer, in particular 1. By adding the predefined step value to the key counter value, a particularly simple processing of the key counter information may be achieved, such that, for example, no complex calculation operations are required and corresponding processor resources are saved.

[0066] In an exemplary embodiment of the first exemplary aspect, generating the second security key may include using the current key counter value as the second key counter value. Thus, a particularly simple derivation of the second key counter value from the processed key counter information may be achieved, such that, for example, no complex calculation operations are required and corresponding processor resources are saved.

[0067] In an exemplary embodiment of the first exemplary aspect, further processing the key counter information may include adding a predefined step value to the current key counter value. Thus, a particularly simple further processing of the key counter information may be achieved, such that, for example, no complex calculation operations are required and corresponding processor resources are saved.

[0068] In an exemplary embodiment of the first exemplary aspect, the configuration information may include key counter information defining a list of at least two different SN counter values ​​to generate at least two different K counters for at least two different target secondary nodes. SN The key counter information received from the master node may include: an SN counter value, and an instruction to maintain the SN counter value, the first key counter value may be a first SN counter value. The second key counter value may be a second SN counter value. The first security key may be a first K SN The second security key may be a second K SN Security key.

[0069] In an example embodiment of the first exemplary aspect, the key counter information received from the master node may define a maximum allowed number of additions of a predefined step value to a key counter value received from the master node. The at least one memory may also store instructions that, when executed by the at least one processor, cause the user device to perform at least the following:

[0070] Determine whether the maximum allowed number of additions has been reached;

[0071] In response to determining that the maximum allowed number of additions has been reached, further addition of the predefined step value to the current key counter value is prevented.

[0072] Thus, when the MN initially sends configuration information including key counter information to the UE, the number of possible CPAC or CHO performed by the UE can be specified by the MN, so that the number of autonomous mobility events of the UE can be limited.

[0073] In an example embodiment of the first example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the user equipment to perform at least the following:

[0074] Using a further key counter value derived from the further processed key counter information, a further security key is generated, the further security key being different from the first security key and different from the second security key.

[0075] As used herein, deriving additional key counter values ​​from further processed key counter information may be understood as enabling the user equipment to obtain additional key counter values ​​based on the further processed key counter information in any conceivable manner. For example, the user equipment may derive additional key counter values ​​because it obtains additional key counter values ​​that are identical to, included by, indicated by, capable of being determined by, or similarly specified in the further processed key counter information, either explicitly or implicitly. As used herein, using additional key counter values ​​to generate additional security keys may be understood as enabling the user equipment to generate additional security keys based on additional key counter values ​​in any conceivable manner. For example, the user equipment may use additional key counter values ​​as calculated freshness inputs to calculate additional security keys. By using additional key counter values ​​derived from further processed key counter information to generate additional security keys, it may be achieved that the UE may obtain additional security keys for integrity protection and / or encryption of data, particularly data to be exchanged between the UE and another target SN.

[0076] In an example embodiment of the first example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the user equipment to perform at least the following:

[0077] The further security key is used for integrity protection and / or encryption of data exchanged between the user equipment and a further target secondary node, the further target secondary node being different from the second target secondary node.

[0078] Thus, it is possible to implement secure data exchange between the UE and another target SN, in particular secure data exchange according to the security architecture of the 5G standard. Regarding the other target auxiliary node, it is only necessary that the other target auxiliary node is different from the second target auxiliary node, in particular in the exemplary case where the user equipment performs CPAC or CHO from the SCG associated with the second target auxiliary node to the SCG associated with the other target auxiliary node. However, the other target auxiliary node may be the same as the first target auxiliary node, for example in particular in the case where the user equipment first performs CPAC or CHO from the SCG associated with the first target auxiliary node to the SCG associated with the second target auxiliary node, and then performs CPAC or CHO from the SCG associated with the second target auxiliary node back to the SCG associated with the first (or other) target auxiliary node.

[0079] In an example embodiment of the first example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the user equipment to perform at least the following:

[0080] Further processing the key counter information so that the user device is enabled to derive at least one additional key counter value from the further processed key counter information, the at least one additional key counter value being different from the first key counter value, different from the second key counter value, and different from any other key counter value previously derived from the unprocessed, processed, or further processed key counter information.

[0081] As used herein, further processing of the key counter information may be understood as causing the user equipment to further modify the key counter information in any conceivable manner. For example, further processing of the key counter information may include further modifying the sequence of key counter values ​​defined by the key counter information. For example, further processing of the key counter information may include preventing a specific additional key counter value from being reused to generate a security key other than a specific additional security key. By further processing the key counter information, it may be achieved that the UE is able to derive at least one additional key counter value from the further processed key counter information, and use the at least one additional key counter value to generate at least one additional security key for exchanging data with at least one additional target SN. Therefore, the UE may autonomously perform a security key refresh to a future CPAC or CHO of an SCG associated with at least one additional target SN without the need for the MN to send new configuration information of the CPAC or CHO to the UE. Thus, it is also possible to reduce the RRC signaling overhead and achieve rapid mobility of the UE on different SCGs to a greater extent.

[0082] By iteratively performing the actions of generating additional security keys, using additional security keys for integrity protection and / or encryption, and further processing the key counter information, the UE may be able to perform a theoretically unlimited number of CPACs or CHOs, and thereby a theoretically unlimited number of autonomous mobility events. As a result, a significant reduction in RRC signaling overhead may also be achieved, and rapid mobility of the UE on different SCGs may be achieved to a significantly greater extent. However, in some cases, it may also be desirable to limit the maximum number of possible CPACs or CHOs, and thereby the maximum number of autonomous mobility events, for example by defining a list of key counter values ​​with a limited number of list elements, or by defining a predefined step value and a maximum allowed number of additions of a key counter value received from the master node.

[0083] In an exemplary embodiment of the first exemplary aspect, the configuration information may further include information indicating at least one target secondary cell for which no security key generation is required. As used herein, a cell may, for example, cover at least a portion of a geographical area served by a radio access network, in particular so as to provide radio services for at least a portion of the geographical area. For example, a cell may be associated with (e.g., served by) at least one radio node. For example, serving a cell may be understood as providing radio services within a cell. For example, a network node may be associated with (e.g., serve) at least one cell. For example, at least two cells may form a cell group, in particular an SCG. By including information indicating at least one target secondary cell for which no security key generation is required in the configuration information, it is possible to avoid unnecessary derivation of key counter values ​​from key counter information, unnecessary generation of security keys, and / or unnecessary processing of key counter information, in particular when a user equipment moves or switches between cells within the same SCG. For example, such movement or switching between cells within the same SCG may be referred to as intra-SN selective activation. They may be performed by the UE without requiring a new security key, for example because the target secondary cell is still associated with the same SN.

[0084] According to the first exemplary aspect, a corresponding method is also disclosed. The method according to the first exemplary aspect may be performed by a user equipment. The user equipment may be configured to support dual connection operation to a primary node and a secondary node of a radio access network. The method may include at least the following items:

[0085] Establish a connection to the master node;

[0086] Configuration information is received from a primary node, wherein the configuration information includes key counter information defining a sequence of at least two different key counter values ​​to generate at least two different security keys for at least two different target secondary nodes.

[0087] Within the first exemplary aspect, disclosure of any instructions that, when executed by at least one processor of a user device, cause the user device to perform an action should also be considered disclosure of the corresponding action of the method.

[0088] According to the first exemplary aspect, a corresponding device is also disclosed. The device according to the first exemplary aspect may include a component for performing the method according to the first exemplary aspect. Within the first exemplary aspect, the disclosure of any method action should also be regarded as the disclosure of the component for performing the corresponding method action. Similarly, the disclosure of any component for performing the method action should also be regarded as the disclosure of the method action itself. The device according to the first exemplary aspect may be a user equipment. The user equipment may be configured to support dual connection operation to a primary node and a secondary node of a radio access network.

[0089] The components or functionality of the user equipment according to the first exemplary aspect may be implemented in hardware and / or software. They may include one or more modules or units that provide the corresponding functionality. They may include, for example, at least one processor for executing a computer program code to perform the 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, for example, 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.

[0090] According to the first exemplary aspect, a corresponding non-transitory computer-readable medium is also disclosed. The non-transitory computer-readable medium according to the first exemplary aspect may include program instructions, which, when executed by a user equipment, cause the user equipment to at least perform the method according to the first exemplary aspect. The user equipment may be configured to support dual connectivity operation to a primary node and a secondary node of a radio access network.

[0091] The non-transitory computer-readable medium according to the first exemplary aspect may be, for example, a disk or a memory, etc. The program instructions may be stored in the computer-readable medium in the form of instructions encoding the computer-readable storage medium. The computer-readable medium may be intended to participate in the operation of the device, such as an internal or external memory, such as a read-only memory (ROM) or a hard disk of a computer, or intended to distribute the program, such as an optical disk.

[0092] According to the first exemplary aspect, a corresponding computer program is also disclosed. The computer program according to the first exemplary aspect may include instructions, which when executed by a user equipment, cause the user equipment to at least perform the method according to the first exemplary aspect. The user equipment may be configured to support dual connectivity operation to a primary node and a secondary node of a radio access network.

[0093] The computer program according to the first exemplary aspect may be stored on a computer readable storage medium, in particular a tangible and / or non-transitory computer readable storage medium. In particular, the computer program according to the first exemplary aspect may be stored on a non-transitory computer readable medium according to the first exemplary aspect.

[0094] According to a second exemplary aspect, a primary node of a radio access network is disclosed. The primary node may be configured to support dual connectivity operations to a secondary node of the radio access network and a user equipment. The primary node may include at least one processor and at least one memory. The at least one memory may store instructions that, when executed by the at least one processor, cause the primary node to at least perform the following:

[0095] Establishing a connection to the user device;

[0096] Configuration information is sent to a user equipment, wherein the configuration information includes key counter information defining a sequence of at least two different key counter values ​​to generate at least two different security keys for at least two different target secondary nodes.

[0097] By establishing a connection to the user equipment through the master node, data exchange between the UE and the MN can be achieved. For example, the connection can be a secure connection, in particular a secure RRC signaling connection.

[0098] By sending configuration information to the user equipment, wherein the configuration information includes key counter information, the key counter information defining a sequence of at least two different key counter values ​​to generate at least two different security keys for at least two different target secondary nodes, an exemplary embodiment of the second exemplary aspect may be advantageous because the user equipment may be able to perform an autonomous security key refresh, and thus, in some cases, a new configuration message for CPAC or CHO may be omitted, as already explained in the context of the first exemplary aspect. Thereby, it is also possible to achieve a reduction in RRC signaling overhead and to achieve faster mobility of the UE on different SCGs to a greater extent.

[0099] In an exemplary embodiment of the second exemplary aspect, the key counter information sent to the user equipment may define a list of at least two different key counter values. Thus, it can be achieved that at least two different key counter values ​​are particularly simply defined by the key counter information, so that, for example, no complex calculation operations are required and corresponding processor resources are saved.

[0100] In an example embodiment of the second example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the master node to perform at least the following:

[0101] A list of at least two different security keys is generated, the list corresponding to the list of at least two different key counter values ​​defined by the key counter information sent to the user device.

[0102] As used herein, a list of security keys corresponding to a list of key counter values ​​may be understood as making at least one element in the list of security keys associated with a corresponding element in the list of key counter values, and vice versa. In particular, each element in the list of security keys may be associated with a corresponding element in the list of key counter values, and vice versa. For example, the correspondence may be such that for each number n between 1 and N (where N is the total number of list elements), the nth element in the list of security keys is a security key generated in particular by the master node using the nth element in the list of key counter values. Vice versa, for each number n between 1 and N (where N is the total number of list elements), the nth element in the list of key counter values ​​is used or has been used to generate the nth element in the list of security keys. However, the ordering of the corresponding elements in the two lists is not necessarily the same. For example, an element at position n in one list may correspond to an element at position n+x in another list, where x is different from zero. By generating a list of at least two different security keys, the list corresponds to a list of at least two different key counter values ​​defined by the key counter information sent to the user device, a list of corresponding security keys may be provided.

[0103] In an example embodiment of the second example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the master node to perform at least the following:

[0104] A request message is sent to at least one target secondary node, wherein the request message includes the list of generated security keys.

[0105] As used herein, request information may be understood as any kind of information related to dual-connection operations and / or security key management relative to at least one target secondary node. For example, the request information may be the same as, or included by, a request to add or modify an SN to at least one target secondary node. For example, at least one target secondary node may include at least one target secondary node associated with an SCG, which should be able to perform CPAC or CHO to the SCG. For example, at least one target secondary node may also include a source secondary node associated with a current serving SCG, which is eligible or may be eligible to perform a subsequent CPAC or CHO returned to the SCG associated with the source secondary node at a future time point. By sending a request message to at least one target secondary node (wherein the request message includes a list of generated security keys), it is possible to provide at least one target SN with a security key consistent with a security key generated by an element in a list of key counter values ​​used by the UE, so that at least one target SN can securely exchange data with the UE, especially after the UE performs CPAC or CHO to the SCG associated with at least one target SN. Furthermore, a particular advantage of sending a list of at least two different security keys to the target SN is that, when performing CPAC or CHO to an SCG associated with the target SN, the target SN is able to autonomously select a security key from the list, so that no further involvement of the MN, in particular the SN modification procedure of the MN, is required. In addition, the time requirement for preparing the target SN for CPAC or CHO execution is reduced, so that fast mobility of the UE on different SCGs is achieved to a greater extent.

[0106] In an example embodiment of the second example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the master node to perform at least the following:

[0107] Information indicating a security key switch is received from the first target secondary node.

[0108] As used herein, a security key switch may be understood as an event in which a previous security key (particularly a previous security key used for integrity protection and / or encryption of data exchanged between a user equipment and a secondary node associated with a previous serving SCG) is exchanged with a current security key, particularly a current security key used for integrity protection and / or encryption of data exchanged between a user equipment and a secondary node associated with a current serving SCG. As used herein, information indicating a security key switch may be understood as any information providing an indication of a security key switch in any conceivable manner. For example, the information indicating a security key switch may be information sent by a first target secondary node indicating that a CPAC or CHO has been performed to the SCG associated with the first target secondary node. By receiving information indicating a security key exchange from the first target secondary node, the MN may track the security key exchange and thus, for example, also track the CPAC or CHO that occurred, and perform actions to achieve that security key management of the UE and the target SN is maintained.

[0109] In an example embodiment of the second example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the master node to perform at least the following:

[0110] An instruction to remove the first list element from the list of security keys is sent to at least one other target secondary node, wherein the at least one other target secondary node is different from the first target secondary node.

[0111] As used herein, removing a first list element from a list of security keys may be understood as any action performed by at least one other target secondary node that prevents the first list element in the list of security keys from being used as a security key for integrity protection and / or encryption. For example, the first list element may be removed from the list of security keys because the first list element has been completely deleted, so that the number of list items is reduced by one. For example, the first list element may be removed from the list of security keys because the first list element is modified to an empty list element. For example, the first list element may be removed from the list of security keys because the first list element is marked as deactivated or unavailable. In the above context, at least one other target secondary node may include, for example, at least one other target secondary node associated with an SCG, and CPAC or CHO to the SCG may be performed at a future point in time. By sending an instruction to remove the first list element from the list of security keys to at least one other target secondary node (where at least one other target secondary node is different from the first target secondary node), at least one other target SN may modify its list of security keys so that the list of security keys is consistent with the list of key counter values ​​processed by the UE.

[0112] In an example embodiment of the second example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the master node to perform at least the following:

[0113] Information indicating a security key switch is received from a second target secondary node, wherein the second target secondary node is different from the first target secondary node.

[0114] For example, the information indicating the security key switch may be information sent by the second target secondary node, indicating that a CPAC or CHO has been performed to the SCG associated with the second target secondary node. By receiving information indicating the security key exchange from the second target secondary node (where the second target secondary node is different from the first target secondary node), the MN may track the security key exchange, and therefore, for example, also track the CPAC or CHO that occurred, and perform actions so that the security key management of the UE and the target SN is maintained.

[0115] In an example embodiment of the second example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the master node to perform at least the following:

[0116] An instruction to remove the current first list element from the list of security keys is sent to at least one further target secondary node, wherein the at least one further target secondary node is different from the second target secondary node.

[0117] As used herein, the current first list element should be understood as the first active or available list element in the list of security keys at a given current point in time. For example, the first active or available list element in the list of security keys does not have to coincide with the first element in the list, especially when the first element in the list is an empty list element or a list element marked as disabled or unavailable. As used herein, removing the current first list element from the list of security keys can be understood as any action performed by at least one other target auxiliary node that prevents the current first list element in the list of security keys from being used as a security key for integrity protection and / or encryption. For example, the current first list element can be removed from the list of security keys because the current first list element has been completely deleted, reducing the number of list items by one. For example, the current first list element can be removed from the list of security keys because the current first list element is modified to an empty list element. For example, the current first list element can be removed from the list of security keys because the current first list element is marked as disabled or unavailable. In the above context, at least one other target auxiliary node may include, for example, at least one other target auxiliary node associated with an SCG, and CPAC or CHO to the SCG can be performed at a future point in time. For example, at least one other target secondary node may also include the first target secondary node, particularly when the SCG associated with the first target secondary node is eligible, or may be eligible, to obtain a CPAC or CHO returned to the SCG associated with the first target secondary node at a future point in time. By sending an instruction to remove the current first list element from the list of security keys to at least one other target secondary node (wherein at least one other target secondary node is different from the second target secondary node), at least one other target SN may modify its list of security keys so that the list of security keys is consistent with the list of key counter values ​​processed by the UE.

[0118] In an example embodiment of the second example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the master node to perform at least the following:

[0119] Information indicating a connection failure is received from a user device.

[0120] For example, the connection failure may be a connection failure between the user equipment and the target secondary node. For example, the connection failure may be a failure of a random access procedure from the user equipment to the target secondary node, in particular, a failure of a random access procedure via RACH. By receiving information indicating the connection failure from the user equipment, the MN may be notified of the connection failure so that the MN may take corresponding measures when necessary.

[0121] In an example embodiment of the second example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the master node to perform at least the following:

[0122] An instruction to remove the current first list element from the list of security keys is sent to at least one target secondary node.

[0123] For example, sending an instruction to remove the current first list element from the list of security keys to at least one target secondary node may be performed in response to receiving information indicating a connection failure from a user equipment. In this context, the at least one target secondary node may include, for example, a target secondary node associated with an SCG, and CPAC or CHO to the SCG is not possible due to a connection failure, in particular a connection failure between the user equipment and the target secondary node. For example, the at least one target secondary node may also include at least one target secondary node associated with an SCG, and CPAC or CHO to the SCG may be performed at a future time point. For example, the at least one target secondary node may also include a source secondary node associated with a current serving SCG, which is eligible, or may be eligible, for subsequent CPAC or CHO returned to the SCG associated with the source secondary node at a future time point. By sending an instruction to remove the current first list element from the list of security keys to at least one target secondary node, it is possible to achieve that the list of security keys of at least one target SN is consistent with the list of key counter values ​​processed by the UE, especially in the case where a connection failure occurs and the UE has processed the list of key counter values ​​so that the previous first key counter value has been irreversibly removed.

[0124] In an example embodiment of the second example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the master node to perform at least the following:

[0125] At least one additional list element of the list of key counter values ​​is sent to the user equipment.

[0126] In particular, after determining whether the number of list elements in the list of key counter values ​​has not reached a predefined threshold, and in response to determining that the number of list elements in the list of key counter values ​​has not reached the predefined threshold, sending at least one additional list element in the list of key counter values ​​to the user equipment may be performed. For example, the predefined threshold may be equal to 1. By sending at least one additional list element in the list of key counter values ​​to the user equipment, it may be achieved that the ability of the UE to perform CPAC or CHO is maintained, as already explained in the context of the first exemplary aspect.

[0127] In an example embodiment of the second example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the master node to perform at least the following:

[0128] At least one additional list element of the list of security keys is sent to at least one target secondary node.

[0129] For example, at least one additional list element in the list of security keys sent to at least one target secondary node may correspond to at least one additional list element in the list of key counter values ​​sent to the user equipment. For example, the correspondence may be such that at least one additional list element in the list of security keys is a security key that has been generated specifically by the master node using at least one additional list element in the list of key counter values. By sending at least one additional list element in the list of security keys to at least one target secondary node, it may be achieved that the list of security keys of at least one target SN is consistent with the list of key counter values ​​processed by the UE. In addition, it may be avoided that the number of list elements in the list of security keys reaches a value that is too low, in particular zero. Therefore, it may also be achieved that the ability of the UE to perform CPAC or CHO to the SCG associated with at least one target SN is maintained.

[0130] In an exemplary embodiment of the second exemplary aspect, the key counter information sent to the user device may include: a key counter value, and an instruction to maintain the key counter value. Thus, it is possible to achieve a particularly simple derivation of the first key counter value from the key counter information, such that, for example, no complex calculation operations are required and corresponding processor resources are saved.

[0131] In an example embodiment of the second example aspect, the master node may include a gNB-CU-CP node. The gNB-CU-CP node may include at least one processor and at least one memory, wherein instructions may be stored on the at least one memory of the gNB-CU-CP node to be executed by the at least one processor of the gNB-CU-CP node. As used herein, a gNB-CU-CP node may be understood as a logical node hosting an RRC and control plane portion of a packet data convergence protocol (PDCP) for a gNB central unit (gNB-CU) of an en-gNB or gNB.

[0132] In an exemplary embodiment of the second exemplary aspect, the configuration information may further include: information indicating at least one target secondary cell for which no security key generation is required. Thus, it is possible to avoid unnecessary derivation of a key counter value from the key counter information, unnecessary generation of a security key, and / or unnecessary processing of the key counter information, as already explained in the context of the first exemplary aspect.

[0133] According to a second exemplary aspect, a corresponding method is also disclosed. The method according to the second exemplary aspect may be performed by a primary node of a radio access network. The primary node may be configured to support dual connection operations to a secondary node of the radio access network and a user equipment. The method may include at least the following items:

[0134] Establishing a connection to the user device;

[0135] Configuration information is sent to a user equipment, wherein the configuration information includes key counter information defining a sequence of at least two different key counter values ​​to generate at least two different security keys for at least two different target secondary nodes.

[0136] Within the second exemplary aspect, disclosure of any instructions that, when executed by at least one processor of the master node, cause the master node to perform an action should also be considered disclosure of the corresponding action of the method.

[0137] According to the second exemplary aspect, a corresponding device is also disclosed. The device according to the second exemplary aspect may include a component for performing the method according to the second exemplary aspect. Within the second exemplary aspect, the disclosure of any method action should also be regarded as the disclosure of the component for performing the corresponding method action. Similarly, the disclosure of any component for performing the method action should also be regarded as the disclosure of the method action itself. The device according to the second exemplary aspect can be a master node. The master node can be configured to support dual connection operation to a secondary node of a radio access network and a user equipment.

[0138] The components or functionality of the master node according to the second exemplary aspect can be implemented in hardware and / or software. They may include one or more modules or units that provide corresponding functionality. They may include, for example, at least one processor for executing a computer program code to perform the 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.

[0139] According to a second exemplary aspect, a corresponding non-transitory computer-readable medium is also disclosed. The non-transitory computer-readable medium according to the second exemplary aspect may include program instructions, which, when executed by a primary node, cause the primary node to at least perform a method according to the second exemplary aspect. The primary node may be configured to support dual connectivity operations to a secondary node of a radio access network and a user equipment.

[0140] The non-transitory computer-readable medium according to the second exemplary aspect may be, for example, a disk or a memory, etc. The program instructions may be stored in the computer-readable medium in the form of instructions encoding the computer-readable storage medium. The computer-readable medium may be intended to participate in the operation of the device, such as an internal or external memory, such as a read-only memory (ROM) or a hard disk of a computer, or intended to distribute the program, such as an optical disk.

[0141] According to a second exemplary aspect, a corresponding computer program is also disclosed. The computer program according to the second exemplary aspect may include instructions, which when executed by a primary node, cause the primary node to at least perform the method according to the second exemplary aspect. The primary node may be configured to support dual connectivity operations to a secondary node of a radio access network and a user equipment.

[0142] The computer program according to the second exemplary aspect may be stored on a computer readable storage medium, in particular a tangible and / or non-transitory computer readable storage medium. In particular, the computer program according to the second exemplary aspect may be stored on a non-transitory computer readable medium according to the second exemplary aspect.

[0143] According to a third exemplary aspect, a secondary node of a radio access network is disclosed. The secondary node may be configured to support dual connectivity operations to a primary node of the radio access network and a user equipment. The secondary node may include at least one processor and at least one memory. The at least one memory may store instructions that, when executed by the at least one processor, cause the secondary node to perform at least the following:

[0144] A request message is received from a master node, wherein the request message includes a list of at least two different security keys.

[0145] Thereby, it can be achieved that the secondary node is able to securely exchange data with the user equipment, in particular after the user equipment performs a CPAC or CHO to the SCG associated with the secondary node, as already explained in the context of the second exemplary aspect. In addition, a specific advantage of the SN receiving a list of at least two different security keys is that, when performing a CPAC or CHO to the SCG associated with the SN, the SN is able to autonomously select a security key from the list, so that no further involvement of the MN, in particular the SN modification process of the MN, is required. In addition, the time requirements for preparing the target SN for CPAC or CHO execution are reduced, so that fast mobility of the UE on different SCGs is achieved to a greater extent.

[0146] In an example embodiment of the third example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the secondary node to perform at least the following:

[0147] determining whether the user equipment establishes or attempts to establish a connection to the secondary node;

[0148] In response to determining that the user equipment establishes or attempts to establish a connection to the secondary node, a currently first list element in the list of security keys is used for integrity protection and / or encryption of data exchanged between the secondary node and the user equipment.

[0149] In this way, secure data exchange between the UE and the SN can be implemented, especially secure data exchange according to the security architecture of the 5G standard.

[0150] In an example embodiment of the third example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the secondary node to perform at least the following:

[0151] Send information to the master node indicating a security key switch.

[0152] Thereby, the MN is able to track security key exchanges, and thus for example also CPAC or CHO occurring, and perform actions to achieve that security key management of the UE and the SN is maintained, as already explained in the context of the second exemplary aspect.

[0153] In an example embodiment of the third example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the secondary node to perform at least the following:

[0154] Removes the current first list element from the list of security keys.

[0155] For example, in response to using the current first list element in the list of security keys for integrity protection and / or encryption of data exchanged between the secondary node and the user equipment, or in response to sending information indicating security key switching to the primary node, the current first list element may be removed from the list of security keys. By removing the current first list element from the list of security keys, the list of security keys of the SN may be kept consistent with the list of key counter values ​​processed by the UE.

[0156] In an example embodiment of the third example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the secondary node to perform at least the following:

[0157] An instruction is received from the master node to remove a current first list element from the list of security keys.

[0158] Thereby, it may be achieved that the secondary node modifies its list of security keys such that the list of security keys of the SN is consistent with the list of key counter values ​​processed by the UE, as already explained in the context of the second exemplary aspect.

[0159] In an example embodiment of the third example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the secondary node to perform at least the following:

[0160] Removes the current first list element from the list of security keys.

[0161] For example, in response to receiving an instruction from the master node to remove the current first list element from the list of security keys, the current first list element can be removed from the list of security keys. By removing the current first list element from the list of security keys, the list of security keys of the SN can be kept consistent with the list of key counter values ​​processed by the UE.

[0162] In an example embodiment of the third example aspect, the at least one memory may further store instructions that, when executed by the at least one processor, cause the secondary node to perform at least the following:

[0163] At least one additional list element in the list of security keys is received from the master node.

[0164] For example, at least one additional list element in the list of security keys received by the secondary node from the primary node may correspond to at least one additional list element in the list of key counter values ​​sent from the primary node to the user equipment. For example, the correspondence may be such that at least one additional list element in the list of security keys is a security key that has been generated specifically by the primary node using at least one additional list element in the list of key counter values. By receiving at least one additional list element in the list of security keys from the primary node, it may also be achieved that the list of security keys of the SN is consistent with the list of key counter values ​​processed by the UE, particularly in the case where the MN sends at least one additional list element in the list of key counter values ​​to the UE. In addition, it may be possible to avoid the number of list elements in the list of security keys from reaching a value that is too low, particularly zero. Therefore, it may also be achieved that the ability of the UE to perform CPAC or CHO to the SCG associated with the SN is maintained.

[0165] According to a third exemplary aspect, a corresponding method is also disclosed. The method according to the third exemplary aspect may be performed by a secondary node of a radio access network. The secondary node may be configured to support dual connection operation to a primary node of the radio access network and a user equipment. The method may include at least the following items:

[0166] A request message is received from a master node, wherein the request message includes a list of at least two different security keys.

[0167] Within the third exemplary aspect, disclosure of any instructions that, when executed by at least one processor of a secondary node, cause a secondary node to perform an action should also be considered disclosure of a corresponding action of the method.

[0168] According to the third exemplary aspect, a corresponding device is also disclosed. The device according to the third exemplary aspect may include a component for performing the method according to the third exemplary aspect. Within the third exemplary aspect, the disclosure of any method action should also be regarded as the disclosure of the component for performing the corresponding method action. Similarly, the disclosure of any component for performing the method action should also be regarded as the disclosure of the method action itself. The device according to the third exemplary aspect can be a secondary node. The secondary node can be configured to support dual connection operation to the primary node of the radio access network and the user equipment.

[0169] The components or functionality of the auxiliary node according to the third exemplary aspect can be implemented in hardware and / or software. They may include one or more modules or units that provide the corresponding functionality. They may include, for example, at least one processor for executing a computer program code to perform the 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, for example, 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.

[0170] According to a third exemplary aspect, a corresponding non-transitory computer-readable medium is also disclosed. The non-transitory computer-readable medium according to the third exemplary aspect may include program instructions, which, when executed by a secondary node, cause the secondary node to at least perform the method according to the third exemplary aspect. The secondary node may be configured to support dual connectivity operations to a primary node of a radio access network and a user equipment.

[0171] The non-transitory computer-readable medium according to the third exemplary aspect may be, for example, a disk or a memory, etc. The program instructions may be stored in a computer-readable medium in the form of instructions encoding the computer-readable storage medium. The computer-readable medium may be intended to participate in the operation of the device, such as an internal or external memory, such as a read-only memory (ROM) or a hard disk of a computer, or intended to distribute the program, such as an optical disk.

[0172] According to a third exemplary aspect, a corresponding computer program is also disclosed. The computer program according to the third exemplary aspect may include instructions, which when executed by a secondary node, cause the secondary node to at least perform the method according to the third exemplary aspect. The secondary node may be configured to support dual connectivity operations to a primary node of a radio access network and a user equipment.

[0173] The computer program according to the third exemplary aspect may be stored on a computer-readable storage medium, in particular a tangible and / or non-transitory computer-readable storage medium. In particular, the computer program according to the third exemplary aspect may be stored on a non-transitory computer-readable medium according to the third exemplary aspect.

[0174] It is to be understood that the embodiments disclosed herein are presented by way of example only and are non-limiting.

[0175] Other features of the present disclosure will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed for illustrative purposes only and not as a definition of the limitations of the present disclosure, for which reference should be made to the appended claims. It should also be understood that the drawings are not drawn to scale and that they are intended only to conceptually illustrate the structures and processes described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0176] Some example embodiments will now be described with reference to the accompanying drawings, in which:

[0177] Figure 1 A radio environment in which example embodiments of the present disclosure may be performed is schematically illustrated in the diagram;

[0178] Figure 2 An example embodiment of the method according to the first aspect, the second aspect and the third aspect is shown in a signaling flow chart;

[0179] Figure 3 An example embodiment of the method according to the first and second aspects is shown in a signaling flow chart;

[0180] Figure 4 In a schematic block diagram an example embodiment of a user equipment according to the first aspect is shown;

[0181] Figure 5 In a schematic diagram an example embodiment of a radio node (such as a master node or a secondary node) according to the second aspect or the third aspect is shown;

[0182] Figure 6 Examples of tangible and non-transitory computer-readable storage media are shown in the schematic diagrams. DETAILED DESCRIPTION

[0183] The following description is used to deepen the understanding of the present disclosure, and should be understood as supplementing and reading together with the description of example embodiments of the present disclosure provided in the above Summary section of this specification.

[0184] In the following and with reference to Figure 1, describes an example radio environment in which the present disclosure may be applied. Although the specific radio system in the following example is a 5G system, this is merely to be regarded as a non-limiting example.

[0185] As an example of a UE according to the first exemplary aspect, Figure 1 A user equipment (UE) 101 is exemplarily illustrated; a master node (MN) 102 is illustrated as an example of an MN according to the second exemplary aspect; and a source secondary node (S-SN) 103, a first target secondary node (T-SN1) 104, and a second target secondary node (T-SN2) 105 are illustrated as an example of an SN according to the third exemplary aspect. The MN 102, the S-SN 103, the T-SN1 104, and the T-SN2 105 can together establish a wireless communication system or network serving the geographical area where the UE 101 is located. The UE 101, the MN 102, and the SNs 103, 104, 105 can operate in a dual connectivity mode.

[0186] UE 101 may be connected to MN 102 and one or more of SN 103, SN 104, and SN 105 by means of a radio link (not shown), for example, the radio link may correspond to a 5G / NR Uu interface. MN 102 may be connected to one or more of SN 103, SN 104, and SN 105 by means of a radio link (not shown), for example, the radio link may correspond to a 5G / NR Xn interface. The radio link may enable information and / or signals to be sent and / or received between the respective devices.

[0187] At some point in time, UE 101 moves from a first location to a second location, as indicated by arrow 110. Although at the first location, the UE may have been served by a serving cell associated with S-SN 103, a cell associated with T-SN1 104 may be serving the UE at the second location. Therefore, during the movement of UE 101 along arrow 110, CPAC or CHO of UE 101 from S-SN 103 to T-SN1 104 may have been performed.

[0188] Now go to Figure 2 , shows a signaling flow chart of an example embodiment of the method according to the first aspect, the second aspect and the third aspect. More specifically, it shows a series of actions and signaling between a user equipment (UE) 201, a master node (MN) 202, a source secondary node (S-SN) 203, a first target secondary node (T-SN1) 104 and a second target secondary node (T-SN2) 205. UE 201, MN 202 and SN 203, SN 204, SN 205 can generally operate in a dual connectivity mode.

[0189] At a given point in time indicated by 210a, 210b, and 210c, UE 201 is connected to MN 202 after establishing a connection to MN 202. In addition, UE 201 is connected to S-SN 203 and is served by a serving cell associated with S-SN 203. UE 201, MN 202, and S-SN 203 operate in a dual connectivity mode to each other.

[0190] In action 211, UE 201 sends first state information to MN 202. In this example embodiment, the first state information comprises measurement information related to signal strength measurements of one or more SNs, in particular S-SN 202.

[0191] In action 212, MN 202 decides to configure the selective activation of T-SN1 204 and T-SN2 205 based on the first status information received from UE 201. In addition, MN 202 generates a security key K SN List of SN counter values ​​and the corresponding K SN Here, the SN counter value constitutes a non-limiting example of a key counter value according to the present disclosure, and the security key K SN In this particular example embodiment, a list of three different SN counter values ​​and three different corresponding K SN However, this is only a non-limiting example, and in general the number of list elements of the two lists may be less or greater. In this particular example embodiment, the 1st element, the 2nd element, and the 3rd element in the list using the SN counter value are used to calculate K respectively. SN The first K in the list of security keys SN Security Key, Second K SN Security Keys and the Third K SN Security key, so that K SN The first (second, third) K in the list of security keys SN The security key corresponds to the first (second, third) SN counter value in the list of SN counter values. However, in general, the correspondence between the two lists may also be different.

[0192] In action 213, MN 202 sends a request message to T-SN1 204. Here, the request message includes an SN addition or change request. In addition, the request message includes the K generated in action 212. SN A list of security keys.

[0193] In action 214, MN 202 also sends a request message to T-SN2 205. Here, the request message also includes an SN addition or change request. In addition, the request message also includes the K generated in action 212. SN A list of security keys.

[0194] In action 215, MN 202 sends configuration information to UE 201. Here, the configuration information includes an RRC reconfiguration request, and corresponding CPAC or CHO configuration information for T-SN1 204 and T-SN2 205. In particular, the configuration information includes a list of SN counter values ​​generated in action 212. Since the list of SN counter values ​​defines a sequence of key counter values, and more precisely, in this specific non-limiting exemplary embodiment, three different key counter values ​​are defined, the list of SN counter values ​​constitutes an example of key counter information according to the present disclosure.

[0195] Hereinafter, a first CPAC or CHO performed by the UE 201 is described.

[0196] In action 230, UE 201 determines whether the requirement for CPAC or CHO to one or more possible target SNs is met. In response to determining that the requirement for CPAC or CHO to T-SN1 204 is met, UE 201 derives a first SN counter value by selecting the first element in the list of SN counter values. In this context, a list of key counter values ​​is advantageous because it allows the first SN counter value to be derived in a particularly simple manner, such that, for example, no complex calculation operations are required and corresponding processor resources are saved. Using the first SN counter value as freshness input, UE 201 then calculates the first K counter value of T-SN1 204. SN Security key.

[0197] In action 231, UE 201 sends second status information to MN 202. In this example embodiment, the second status information indicates the completion of the RRC reconfiguration. After sending the second status information, UE 201 may attempt to establish a connection to T-SN1 204.

[0198] In action 232, UE 202 sends third status information to T-SN1 204. In this example embodiment, the third status information indicates the completion of the reconfiguration, in particular the RRC reconfiguration of UE 201.

[0199] In action 233, T-SN1 204 determines whether UE 201 attempts to establish a connection to T-SN1 204. In response to determining that UE 201 attempts to establish a connection to T-SN1 204, T-SN1 204 selects K received from MN 202 in action 213. SN The first K in the list of security keys SN Security key, in preparation for subsequent data exchange.

[0200] In action 234, UE 201 and T-SN1 204 establish a connection. In this particular example embodiment, UE 201 initiates a random access procedure to T-SN1 204 via RACH to establish the connection. After the connection is established, UE 201 and T-SN1 204 use the first K SN The UE 201 calculates the first K by using the first SN counter value as the freshness input. SN Security key to obtain the first K SN Security key, T-SN 1204 selects K in action 233 SN The first list element in the list of security keys is used to obtain the first K SN In this particular example embodiment, UE 201 and T-SN1 204 establish a secure key based on a first K SN The security key calculation has a total of four subordinate security keys. The first subordinate security key is used for integrity protection of RRC signaling. The second subordinate security key is used for encryption of RRC signaling. The third subordinate security key is used for integrity protection of user data. The fourth subordinate security key is used for encryption of user data. By establishing a connection and exchanging data, UE 201 can now be served by the serving cell associated with T-SN1 204. UE 201, MN 202 and T-SN1 204 can operate in dual connectivity mode to each other.

[0201] In action 235, the UE 201 processes the list of SN counter values ​​as it deletes the first element in the list. Thus, the current second element in the list of SN counter values ​​becomes the new first element, and the current third element becomes the new second element. However, it is also generally conceivable that the first element in the list is not completely deleted, but is simply modified to be an empty list element, or is marked as unavailable, for example. By processing the list of SN counter values, the UE 201 is able to derive a second SN counter value from the processed list of SN counter values ​​at a later point in time to generate a second K value for exchanging data with a second target SN. SNIn this context, the second target SN may be T-SN2 205 or S-SN 203. Therefore, UE 201 may autonomously perform a K transfer to CPAC or CHO of the SCG associated with the second target SN. SN The MN 202 does not need to send new configuration information for the CPAC or CHO. Thus, the RRC signaling overhead can be reduced, and the fast mobility of the UE 201 on different SCGs can be achieved to a greater extent.

[0202] In action 236, T-SN1 204 sends information indicating a key switch to MN 202. In this particular example, the key switch is a switch to a first K for integrity protection and / or encryption of data exchanged between UE 201 and T-SN1 204. SN Switching of security keys.

[0203] In action 237, T-SN1 204 responds to the first K SN The security key is used for integrity protection and / or encryption of data exchanged between UE 201 and T-SN1 204. SN Remove the first K from the list of security keys SN Security key. In this way, K SN The current second element in the list of security keys becomes the new first element, and the current third element becomes the new second element. However, it is also generally conceivable that the first element in the list is not completely deleted, but is simply modified to an empty list element, or is marked as unusable, for example. By deleting the first K SN Security key, can achieve T-SN1 204 K SN The list of security keys is consistent with the list of SN counter values ​​processed by UE 201 .

[0204] In action 238, MN 202 sends an instruction to T-SN2 205 to delete the K received from MN 202 in action 214. SN The first K in the list of security keys SN Security key.

[0205] In action 239, T-SN2 205 deletes its K SN The first K in the list of security keys SN Security key. In this way, K SNThe current second element in the list of security keys becomes the new first element, and the current third element becomes the new second element. However, it is also generally conceivable that the first element in the list is not completely deleted, but is simply modified to an empty list element, or is marked as unusable, for example. By deleting the first K SN Security key, can realize T-SN2 205 K SN List of security keys and T-SN1 204 K SN The list of security keys and the list of SN counter values ​​processed by UE 201 remain consistent.

[0206] Hereinafter, a second CPAC or CHO performed by the UE 201 is described.

[0207] In action 250, UE 201 determines whether the requirement for CPAC or CHO to one or more possible target SNs is met. In response to determining that the requirement for CPAC or CHO to T-SN2 205 is met, UE 201 derives a second SN counter value by selecting the current first element in the list of SN counter values. In this context, a list of key counter values ​​is advantageous because it allows the second SN counter value to be derived in a particularly simple manner, such that, for example, no complex calculation operations are required and corresponding processor resources are saved. Using the second SN counter value as freshness input, UE 201 then calculates the second K counter value of T-SN2 205. SN Security key.

[0208] In action 251, UE 201 sends fourth status information to MN 202. In this example embodiment, the fourth status information indicates the completion of RRC reconfiguration. After sending the fourth status information, UE 201 may attempt to establish a connection to T-SN2205.

[0209] In action 252, UE 202 sends fifth status information to T-SN2 205. In this exemplary embodiment, the fifth status information indicates the completion of the reconfiguration, in particular the RRC reconfiguration of UE 201.

[0210] In action 253, T-SN2 205 determines whether UE 201 attempts to establish a connection to T-SN2 205. In response to determining that UE 201 attempts to establish a connection to T-SN2 205, T-SN2 205 selects K SN The current first K in the list of security keys SN Security key, in preparation for subsequent data exchange. SN The security key is combined with the K received from MN 202 in action 214. SNThe second K in the original list of security keys SN The security keys are the same.

[0211] In action 254, UE 201 and T-SN2 205 establish a connection. In this particular example embodiment, UE 201 initiates a random access procedure to T-SN2 205 via RACH to establish the connection. After the connection is established, UE 201 and T-SN2 205 use the second K SN The UE 201 calculates the second K by using the second SN counter value as the freshness input. SN security key to obtain the second K SN Security key, T-SN 1204 selects K in action 253 SN The first element in the list of security keys is used to obtain the second K SN In this particular example embodiment, UE 201 and T-SN2 205 use a second K SN The security key calculation has a total of four subordinate security keys. The first subordinate security key is used for integrity protection of RRC signaling. The second subordinate security key is used for encryption of RRC signaling. The third subordinate security key is used for integrity protection of user data. The fourth subordinate security key is used for encryption of user data. By establishing a connection and exchanging data, UE 201 can now be served by the serving cell associated with T-SN2 205. UE 201, MN 202 and T-SN2 205 can operate in dual connectivity mode to each other.

[0212] In action 255, the UE 201 further processes the list of SN counter values, as it deletes the current first element in the list. Thus, the current second element in the list of SN counter values ​​will become the new first element. However, it is also generally conceivable that the current first available element in the list is not completely deleted, but is only modified to an empty list element, or is marked as unavailable, for example. By further processing the list of SN counter values, the UE 201 is able to derive further SN counter values ​​from the further processed list of SN counter values ​​at a later point in time to generate further K values ​​for exchanging data with further target SNs. SN In this context, the additional target SN may be T-SN1 204, S-SN 203, or Figure 2 Therefore, UE 201 can autonomously perform a K-transfer to the CPAC or CHO of the SCG associated with the additional target SN. SNThe MN 202 does not need to send new configuration information for the CPAC or CHO. Thus, the RRC signaling overhead can be reduced, and the fast mobility of the UE 201 on different SCGs can be achieved to a greater extent.

[0213] In action 256, T-SN2 205 sends information indicating a key switch to MN 202. In this particular example, the key switch is a switch to a second K for integrity protection and / or encryption of data exchanged between UE 201 and T-SN2 205. SN Switching of security keys.

[0214] In action 257, T-SN2 205 responds to the current first K SN The security key is used for integrity protection and / or encryption of data exchanged between UE 201 and T-SN 2205, and the K is deleted from the list of its security keys. SN Security key. In this way, K SN The current second element in the list of security keys becomes the new first element. However, it is also generally conceivable that the current first available element in the list is not completely deleted, but is only modified to an empty list element or, for example, marked as unavailable. By deleting the current first K SN Security key, can realize T-SN2 205 K SN The list of security keys is consistent with the list of SN counter values ​​processed by UE 201 .

[0215] In action 258, MN 202 sends an instruction to T-SN1 204 to delete the K received from MN 202 in action 213. SN The current first K in the list of security keys SN Security key.

[0216] In action 259, T-SN1 204 deletes the current first K in its list of security keys in response to receiving a corresponding instruction from MN 202. SN Security key. In this way, K SN The current second element in the list of security keys becomes the new first element. However, it is also generally conceivable that the current first available element in the list is not completely deleted, but is only modified to an empty list element or, for example, marked as unavailable. By deleting the current first K SN Security key, can achieve T-SN1 204 K SN List of security keys and T-SN2 205 K SN The list of security keys and the list of SN counter values ​​further processed by UE 201 remain consistent.

[0217] although Figure 2 Not shown, UE 201 may perform further CPAC or CHO similar to the first CPAC or CHO and the second CPAC or CHO explained above.

[0218] At any suitable point in time, in particular, one or more of the UE 201 or T-SN1 204 and T-SN2 205 determines a list or K of SN counter values. SN After the list of security keys respectively does not reach the predefined threshold, one or more of UE 201 or T-SN1 204 or T-SN2 205 may send corresponding information to MN 202. In response to receiving the list or K indicating the SN counter value respectively, SN In case that the list of security keys does not reach the threshold, MN 202 may send at least one additional list element in the list of SN counter values ​​to UE 201, and send K to SN1 204 and / or T-SN2 205. SN At least one additional list element in the list of security keys. Thereby, it can be achieved that the ability of the UE to perform CPAC or CHO towards the SCG associated with the target SN is maintained.

[0219] Figure 3 A signaling flow chart of an example embodiment of the method according to the first aspect and the second aspect is shown. More specifically, a series of actions and signaling between a user equipment (UE) 301, a master node (MN) 302, a source secondary node (S-SN) 303, a first target secondary node (T-SN1) 304, and a second target secondary node (T-SN2) 305 are shown. UE 301, MN 302, and SNs 303, 304, 305 can generally operate in a dual connectivity mode.

[0220] At a given point in time indicated by 310a, 310b, and 310c, UE 301 is connected to MN 302 after establishing a connection to MN 302. In addition, UE 301 is connected to S-SN 303 and is served by a serving cell associated with S-SN 303. UE 301, MN 302, and S-SN 303 operate in a dual connectivity mode to each other.

[0221] In action 311, S-SN 303 sends first status information to MN 302. In this example embodiment, the first status information indicates that CPAC or CHO is required.

[0222] In action 312, MN 302 sends a request message to T-SN1 304. In this example embodiment, the request message includes an SN addition or change request.

[0223] In action 313, T-SN1 304 sends second status information to MN 302. In this example embodiment, the second status information indicates confirmation of the SN addition or change request.

[0224] In action 314, MN 302 sends a request message to T-SN2 305. In this example embodiment, the request message includes an SN addition or change request.

[0225] In action 315, T-SN2 305 sends third status information to MN 302. In this example embodiment, the third status information indicates confirmation of the SN addition or change request.

[0226] In action 316, MN 302 sends configuration information to UE 301. Here, the configuration information includes: RRC reconfiguration request, and corresponding CPAC or CHO configuration information. In particular, the configuration information includes: security key K SN The SN counter value of the security key K is an example of a key counter value according to the present disclosure, and an instruction to maintain the SN counter value, that is, to continuously process the SN counter value instead of releasing it. SN Furthermore, the SN counter value, and the instruction to maintain the SN counter value, constitute an example of key counter information according to the present disclosure, because a list of at least two different SN counter values ​​is defined thereby to generate at least two different K keys for at least two different target SNs. SN A particular advantage of the configuration information including the SN counter value, and instructions for maintaining the SN counter value, is that potential target SNs do not have to be pre-provisioned with multiple K SN Security keys, as will also be illustrated in more detail below.

[0227] In action 317, UE 301 sends fourth status information to MN 302. In this exemplary embodiment, the fourth status information indicates the completion of the RRC reconfiguration.

[0228] Hereinafter, a first CPAC or CHO performed by the UE 301 is described.

[0229] In action 330, UE 301 determines whether the requirements for CPAC or CHO to one or more possible target SNs are met.

[0230] In action 331, UE 301 determines that the requirement for CPAC or CHO to T-SN1 304 is met. In response to determining that the requirement for CPAC or CHO to T-SN1 304 is met, UE 301 derives a first SN counter value by using the SN counter value received from MN 302 in action 316 as the first SN counter value. In this context, a particularly simple derivation of the first SN counter value can be achieved by the SN counter information received from MN 302 in action 316, including the SN counter value, and the instruction to maintain the SN counter value, so that, for example, no complex calculation operations are required and corresponding processor resources are saved.

[0231] In action 332, UE 301 calculates the first K of T-SN1 304 using the derived first SN counter value as freshness input. SN security key. Furthermore, the UE 301 processes the SN counter information in that it adds a predefined step value, here in particular a step value of 1, to the SN counter value received from the master node. In other words, the UE 301 increases the SN counter by the step value, which in this specific non-limiting example is equal to 1. However, in general, step values ​​different from 1 are easily conceivable. By adding the predefined step value to the SN counter value received from the master node, a second element in the sequence of SN counter values ​​is obtained. In this way, the UE 301 is able to derive a second SN counter value from the processed SN counter at a later point in time to generate a second K for exchanging data with the second target SN. SN In this context, the second target SN may be T-SN2 305 or S-SN 303. Therefore, UE 301 may autonomously perform a K transfer to CPAC or CHO of the SCG associated with the second target SN. SN The MN 302 does not need to send new configuration information for the CPAC or CHO. Thus, the RRC signaling overhead can be reduced, and the fast mobility of the UE 301 on different SCGs can be achieved to a greater extent.

[0232] In action 333, UE 301 sends fifth status information to MN 302. In this exemplary embodiment, the fifth status information indicates CPAC or CHO to T-SN1 304.

[0233] In action 334, MN 302 sends another request message to T-SN1 304. In this example embodiment, the other request message includes an SN modification request and includes a first K SN Security key, the first K SN The security key is calculated by MN 302 independently of UE 301 .

[0234] In action 335, T-SN1 304 sends sixth status information to MN 302. In this example embodiment, the sixth status information indicates confirmation of the SN modification request.

[0235] In action 336, MN 302 sends seventh state information to S-SN 303. In this exemplary embodiment, the seventh state information indicates CPAC or CHO, specifically CPAC or CHO to T-SN1304.

[0236] In action 337, MN 302 sends eighth status information to T-SN1 304. In this example embodiment, the eighth status information indicates the completion of the SN modification.

[0237] In action 338, UE 301 and T-SN1 304 establish a connection. UE 301 and T-SN1 304 use the first K SN The security keys are used to exchange data with each other for integrity protection and / or encryption. In this specific example embodiment, UE 301 and T-SN1 304 exchange data with each other based on the first K SN The security key calculation has a total of four subordinate security keys. The first subordinate security key is used for integrity protection of RRC signaling. The second subordinate security key is used for encryption of RRC signaling. The third subordinate security key is used for integrity protection of user data. The fourth subordinate security key is used for encryption of user data. By establishing a connection and exchanging data, UE 301 can now be served by the serving cell associated with T-SN1 304, so that CPAC or CHO is completed. UE 301, MN 302 and T-SN1 304 can operate in dual connectivity mode to each other.

[0238] Hereinafter, the second CPAC or CHO performed by the UE 301 is described.

[0239] In action 350, UE 301 determines whether the requirements for CPAC or CHO to one or more possible target SNs are met.

[0240] In action 351, UE 301 determines that the requirement for CPAC or CHO to S-SN 303 is met. In response to determining that the requirement for CPAC or CHO returned to S-SN 303 is met, UE 301 derives a second SN counter value by using the current SN counter value (i.e., the SN counter value received from MN 302 increased by 1) as the second SN counter value. In this context, a particularly simple derivation of the second SN counter value can be achieved by receiving the SN counter information, including the SN counter value, and the instruction to maintain the SN counter value from MN 302 in action 316, so that, for example, no complex calculation operations are required and corresponding processor resources are saved.

[0241] In action 352, UE 301 calculates a second K of S-SN 303 using the derived second SN counter value as freshness input. SN security key. Furthermore, the UE 301 further processes the SN counter information in that it again adds the predefined step value to the current SN counter value. In other words, the UE 301 again increases the SN counter by the step value, which in this specific non-limiting example is equal to 1. By adding the predefined step value to the current SN counter value, a third element in the sequence of SN counter values ​​is obtained. In this way, the UE 301 is able to derive further SN counter values ​​from the further processed SN counter at a later point in time to generate further K for exchanging data with further target SNs. SN In this context, the additional target SN may be T-SN1 304, T-SN2 305, or Figure 3 Therefore, UE 301 can autonomously perform a K-transfer to CPAC or CHO of an SCG associated with another target SN. SN The MN 302 does not need to send new configuration information for the CPAC or CHO. Thus, the RRC signaling overhead can be reduced, and the fast mobility of the UE 301 on different SCGs can be achieved to a greater extent.

[0242] In action 353, UE 301 sends ninth status information to MN 302. In this exemplary embodiment, the ninth status information indicates CPAC or CHO to S-SN 303.

[0243] In action 354, MN 302 sends another request message to S-SN 303. In this example embodiment, the other request message includes an SN modification request and includes a second K SN Security key, the second K SN The security key is calculated by MN 302 independently of UE 301 .

[0244] In action 355, S-SN 303 sends tenth status information to MN 302. In this exemplary embodiment, the tenth status information indicates confirmation of the SN modification request.

[0245] In action 356, MN 302 sends eleventh status information to T-SN1 304. In this exemplary embodiment, the eleventh status information indicates CPAC or CHO, specifically, CPAC or CHO to S-SN 303.

[0246] In action 357, MN 302 sends twelfth status information to S-SN 303. In this exemplary embodiment, the twelfth status information indicates the completion of the SN modification.

[0247] In action 358, UE 301 and S-SN 303 establish a connection. UE 301 and S-SN 303 use the second K SN The security key is used to exchange data with each other for integrity protection and / or encryption. In this specific example embodiment, UE 301 and S-SN 303 exchange data with each other based on the second K SN The security key calculation has a total of four subordinate security keys. The first subordinate security key is used for integrity protection of RRC signaling. The second subordinate security key is used for encryption of RRC signaling. The third subordinate security key is used for integrity protection of user data. The fourth subordinate security key is used for encryption of user data. By establishing a connection and exchanging data, UE 301 can now be served by the serving cell associated with S-SN 303 again, so that CPAC or CHO is completed. UE 301, MN 302 and S-SN 303 can operate in dual connectivity mode to each other.

[0248] although Figure 3 Not shown, UE 301 may perform further CPAC or CHO similar to the first CPAC or CHO and the second CPAC or CHO explained above.

[0249] In an example embodiment, the key counter information included in the reconfiguration information sent from MN 302 to UE 301 in action 316 may define the maximum allowed number of additions of the predefined step value to the SN counter value received from the master node. For example, the key counter information may include a stop value of the SN counter, which may not be exceeded. UE 301 may then determine (particularly when processing or further processing the SN counter) whether the maximum allowed number of additions has been reached. For example, UE 301 may determine whether the stop value has been reached. If it is determined that the maximum allowed number of additions has been reached, UE 301 may prevent further addition of the predefined step value to the current SN counter value. In addition, UE 301 may send corresponding information to MN 302. Through the above process, when MN 302 initially sends configuration information to UE 301, MN 302 may specify the number of possible CPAC or CHO performed by UE 301, so that the number of autonomous mobility events of UE 301 can be limited.

[0250] In combination Figure 2 and 3 In the described example embodiment, the configuration information may also indicate to the UE 201, 301 that it is not necessary to generate K SN Thereby, unnecessary derivation of SN counter value and K SN Unnecessary generation of security keys, and / or unnecessary processing of key counter information, particularly when the UE 201, 301 moves or hands over between cells within the same SCG.

[0251] In combination Figure 2 and 3 In the described example embodiment, the MN 202, 302 may include a gNB-CU-CP node that performs the described actions of the MN 202, 302.

[0252] Now go to Figure 4 , a block diagram of an example embodiment of a UE 400 according to the first aspect is shown. For example, the UE 400 may be one of the following: a smart phone, a tablet computer, a notebook computer, a smart watch, a smart bracelet, an IoT device, or a vehicle or a part thereof.

[0253] UE 400 includes a processor 401. Processor 401 may represent a single processor, or two or more processors, for example at least partially coupled, for example via a bus. Processor 401 executes program code stored in program memory 402 (e.g., program code that, when executed on processor 401, causes UE 400 to perform one or more embodiments of the method according to the present disclosure or parts thereof in conjunction with radio node 500), and interfaces with main memory 403. Program memory 402 may also contain an operating system for processor 401. Some or all of memory 402 and memory 403 may also be included in processor 401.

[0254] One or both of the processor's main memory and program memory (e.g. program memory 402 and main memory 403) may be fixedly connected to the processor (e.g. processor 401), or at least partially removable from the processor, e.g. in the form of a memory card or memory stick.

[0255] The program memory (e.g., program memory 402) may, for example, be a non-volatile memory. For example, it may be any one of a flash memory (or a portion thereof), a ROM, a PROM, an EPROM, an MRAM or a FeRAM (or a portion thereof), or a hard disk (or a portion thereof), to name a few examples. For example, the program memory may, for example, include: a first memory segment that is fixedly mounted, and a second memory segment that is removable, for example in the form of a removable SD memory card.

[0256] The main memory (e.g., main memory 403) may be, for example, a volatile memory. To give a non-limiting example, it may be, for example, a DRAM memory. For example, when executing an operating system, an application, a program, etc., it may be used as a working memory of the processor 401.

[0257] The processor 401 may also control a communication interface 404 (e.g., a radio interface) configured to receive and / or send data and / or information. For example, the communication interface 404 may be configured to send and / or receive radio signals from a radio node such as a primary node or a secondary node, in particular as described herein. It is to be understood that any computer program code-based processing required to receive and / or evaluate radio signals may be stored in the communication interface 404's own memory and may be executed by the communication interface 404's own processor, and / or it may be, for example, stored in the memory 403 and, for example, executed by the processor 401.

[0258] The communication interface 404 may be particularly configured to communicate according to a cellular communication system such as 2G / 3G / 4G / 5G or a next generation cellular communication system. The UE 400 may use the radio interface 404 to communicate with a radio node, such as a primary node or a secondary node, in particular as described herein.

[0259] For example, the communication interface 404 may also include a BLE and / or Bluetooth radio interface, including a BLE transmitter, receiver or transceiver. For example, the radio interface 404 may additionally or alternatively include a WLAN radio interface, which includes at least a WLAN transmitter, receiver or transceiver.

[0260] For example, the components 402, 403, and 404 of the UE 400 may be connected to the processor 401 by means of one or more serial and / or parallel buses.

[0261] It is to be understood that the UE 400 may include various other components. For example, the UE 400 may optionally include a user interface (eg, a touch-sensitive display, a keyboard, a touchpad, a display, etc.).

[0262] Figure 5 is a block diagram of an example embodiment of a radio node 500, such as a primary node 500, or a secondary node 500. For example, as described above, the radio node 500 may be configured to schedule signals and / or send signals to a UE 400 and / or one or more other radio nodes 500.

[0263] The radio node 500 includes a processor 501. The processor 501 may represent a single processor, or two or more processors, which are coupled, for example, at least in part, for example, via a bus. The processor 501 executes program codes stored in a program memory 502 (e.g., when executed on the processor 501, the program codes that cause the radio node 500 to execute alone, together with the UE 400, and / or together with one or more other radio nodes 500 to execute one or more embodiments of the method according to the present disclosure or parts thereof) and is connected to a main memory 503 interface.

[0264] Program memory 502 may also include an operating system for processor 501. Some or all of memories 502 and 503 may also be included in processor 501.

[0265] In addition, the processor 501 can control the communication interface 504, which is configured to communicate according to a cellular communication system such as a 2G / 3G / 4G / 5G cellular communication system. The communication interface 504 of the radio node 500 can be implemented by a radio head, for example, and can be provided for communication between a network device and a terminal device.

[0266] For example, the components 502, 503 and 504 of the radio node 500 may be connected to the processor 501 by means of one or more serial and / or parallel buses.

[0267] It is to be understood that the radio node 500 may include various other components.

[0268] Figure 6 is a schematic illustration of an example of a tangible and non-transitory computer-readable storage medium according to the present disclosure, which can be used, for example, to implement Figure 4 Memory 402, or Figure 5 Memory 502. To this end, Figure 6 Shown is a flash memory 600 which may, for example, be soldered or bonded to a printed circuit board, a solid-state drive 601 comprising a plurality of memory chips (e.g., flash memory chips), a magnetic hard drive 602, a secure digital (SD) card 603, a universal serial bus (USB) memory stick 604, an optical storage medium 605 (such as, for example, a CD-ROM or DVD), and a magnetic storage medium 606.

[0269] Any connections presented in the described embodiments will be understood in a manner that the components involved are operationally coupled. Therefore, the connection may be direct or indirect, it may have any number or combination of intermediate elements, and there may only be a functional relationship between the components.

[0270] Further, as used herein, the term "circuitry" refers to any of the following:

[0271] (a) hardware circuit implementation only (such as implementation only in analog and / or digital circuitry);

[0272] (b) a combination of circuitry and software (and / or firmware) such as:

[0273] (i) a combination of processors, or

[0274] (ii) processor(s) / software (including digital signal processor(s)), software and memory(s) sections which work together to enable a device such as a mobile phone to perform various functions; and

[0275] (c) Circuitry that requires software or firmware to operate, such as microprocessor(s), or sections of microprocessor(s), even if the software or firmware is not physically present.

[0276] This definition of "circuitry" applies to all uses of the term herein, including in any claims. As a further example, as used herein, the term "circuitry" would also cover an implementation of merely a processor (or multiple processors) or segment of a processor and its (or their) accompanying software and / or firmware. The term "circuitry" would also cover, for example, a baseband integrated circuit or an applications processor integrated circuit of a mobile phone.

[0277] Any processor mentioned herein (particularly but not limited to Figure 4 and Figure 5 Processor 401 and processor 501) can be any suitable type of processor. Any processor may include, but is not limited to, one or more microprocessors, one or more processors with accompanying (multiple) digital signal processors, one or more processors without accompanying (multiple) digital signal processors, one or more special-purpose computer chips, one or more field programmable gate arrays (FPGAS), one or more controllers, one or more application-specific integrated circuits (ASICS), or one or more computers. The relevant structure / hardware has been programmed in such a way as to perform the described functions.

[0278] In addition, any actions or steps 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.

[0279] As used herein, “at least one of the following: ” and “at least one of ” and similar expressions (wherein a list of two or more elements is joined by “and” or “or”) refer to at least any one of the elements, or at least any two or more of the elements, or at least all of the elements.

[0280] The phrase "A, or B, or C, or a combination thereof" or "at least one of A, B, and C" may be understood as non-exhaustive and includes at least the following: (i) A, or (ii) B, or (iii) C, or (iv) A and B, or (v) A and C, or (vi) B and C, or (vii) A, B, and C.

[0281] It is to be understood that the embodiments disclosed herein are exemplary only, and any feature presented for a specific exemplary embodiment may be used alone, or with any aspect of the disclosure, or in combination with any feature presented for the same or another specific exemplary embodiment, and / or in combination with any other features not mentioned. It will also be understood that any feature presented for an exemplary embodiment in a particular category may also be used in a corresponding manner in any other category of exemplary embodiments.

[0282] abbreviation

[0283] 3GPP Third Generation Partnership Project

[0284] CHO Condition Switch

[0285] CPAC Condition PSCell Addition or Change

[0286] DC Dual Connection

[0287] LMF Location Management Function

[0288] MCG Master Cell Group

[0289] MN Master Node

[0290] NAS Non-Access Stratum

[0291] NR New Radio

[0292] Primary cell of PSCell SCG (primary SCG cell)

[0293] RACH Random Access Channel

[0294] SCG Secondary Cell Group

[0295] SN Secondary Node

[0296] S-SN Source Secondary Node

[0297] RRC Radio Resource Control

[0298] T-SN Target Secondary Node

[0299] UE User Equipment

[0300] References

[0301] [1] 3GPP TS 36.300 V 17.1.0 “Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 (Release 17)”, published in June 2022.

[0302] [2] 3GPP TS 37.340 V17.1.0 “Evolved Universal Terrestrial Radio Access (E-UTRA) and NR; Multi-connectivity; Stage 2 (Release 17)”, published in June 2022.

[0303] [3] 3GPP TS 38.331 V17.1.0 “NR; Radio Resource Control (RRC) protocol specification (Release 17)”, published in June 2022.

[0304] [4] 3GPP TS 33.501 V17.6.0 “Security architecture and procedures for 5G system (Release 17)”, published in June 2022.

Claims

1. A user equipment, the user equipment being configured to support dual connectivity operation to a primary node and a secondary node of a radio access network, the user equipment comprising at least one processor and at least one memory, the at least one memory storing instructions, the instructions, when executed by the at least one processor, causing the user equipment to at least perform the following items: establishing a connection to the master node; Configuration information is received from the primary node, wherein the configuration information includes key counter information defining a sequence of at least two different key counter values ​​to generate at least two different security keys for at least two different target secondary nodes.

2. The user equipment according to claim 1, wherein the at least one memory further stores instructions, which, when executed by the at least one processor, cause the user equipment to perform at least one of the following items: generating a first security key using a first key counter value derived from the key counter information; Using the first security key for integrity protection and / or encryption of data exchanged between the user equipment and the first target secondary node; The key counter information is processed such that the user equipment is enabled to derive at least a second key counter value from the processed key counter information, the second key counter value being different from the first key counter value.

3. The user equipment according to claim 2, wherein the at least one memory further stores instructions, which, when executed by the at least one processor, cause the user equipment to perform at least one of the following items: generating a second security key using the second key counter value derived from the processed key counter information, the second security key being different from the first security key; using the second security key for integrity protection and / or encryption of data exchanged between the user equipment and a second target secondary node, where the second target secondary node is different from the first target secondary node; The key counter information is further processed such that the user equipment is enabled to derive at least a further key counter value from the further processed key counter information, the further key counter value being different from the first key counter value and different from the second key counter value.

4. The user equipment of claim 1, wherein the key counter information received from the master node defines a list of at least two different key counter values.

5. The user equipment according to claims 2 and 4, wherein generating the first security key comprises: The first list element in the list of key counter values ​​is used as the first key counter value, wherein processing the key counter information comprises removing the first list element from the list of key counter values.

6. The user equipment according to claims 3 and 5, wherein generating the second security key comprises: Using a current first list element in the list of key counter values ​​as the second key counter value, wherein further processing the key counter information comprises: removing the current first list element from the list of key counter values.

7. The user equipment according to claim 6, wherein the configuration information includes key counter information, the key counter information defining a list of at least two different SN counter values ​​to generate at least two different K keys for at least two different target secondary nodes; SN Security Key, wherein the first key counter value is a first SN counter value, wherein the second key counter value is a second SN counter value, wherein the first security key is a first K SN security key, wherein the second security key is a second K SN Security Key, The configuration information also includes a radio resource control reconfiguration request. The configuration information also includes: information related to conditional addition or change of a primary cell in a secondary cell group associated with the first target secondary node, or information related to conditional switching to the first target secondary node, The configuration information further includes: information related to conditional addition or change of a primary cell in a secondary cell group associated with the second target secondary node, or information related to conditional switching to the second target secondary node, The at least one memory further stores instructions, which, when executed by the at least one processor, cause the user equipment to perform at least one of the following: determining whether at least one condition for conditional addition or change of a primary cell in a secondary cell group associated with the first target secondary node, or at least one condition for conditional switching to the first target secondary node is satisfied; Through a random access channel, using the first K SN security key, initiating a random access process to the first target secondary node; determining whether at least one condition for conditional addition or change of a primary cell in a secondary cell group associated with the second target secondary node, or at least one condition for conditional switching to the second target secondary node is satisfied; Through a random access channel, using the second K SN security key, and initiate a random access process to the second target secondary node.

8. The user equipment according to claim 4, wherein the at least one memory further stores instructions, which, when executed by the at least one processor, cause the user equipment to perform at least the following items: At least one additional list element in the list of key counter values ​​is received from the master node.

9. The user equipment according to claim 1, wherein the key counter information received from the master node comprises: A key counter value, and instructions for maintaining the key counter value.

10. The user equipment according to claims 2 and 9, wherein generating the first security key comprises: The key counter value received from the master node is used as the first key counter value, wherein processing the key counter information includes adding a predefined step value to the key counter value received from the master node.

11. The user equipment according to claims 3 and 10, wherein generating the second security key comprises: Using a current key counter value as the second key counter value, wherein further processing the key counter information comprises: adding the predefined step value to the current key counter value.

12. The user equipment according to claim 11, wherein the configuration information includes key counter information, the key counter information defining a list of at least two different SN counter values ​​to generate at least two different K keys for at least two different target secondary nodes; SN Security Key, The key counter information received from the master node includes: SN counter value, and instructions for maintaining the SN counter value, wherein the first key counter value is a first SN counter value, wherein the second key counter value is a second SN counter value, wherein the first security key is a first K SN security key, wherein the second security key is a second K SN Security Key, The configuration information also includes a radio resource control reconfiguration request. The configuration information further includes: information related to conditional addition or change of a primary cell in a secondary cell group associated with the first target secondary node, or information related to conditional switching to the first target secondary node, The configuration information further includes: information related to conditional addition or change of a primary cell in a secondary cell group associated with the second target secondary node, or information related to conditional switching to the second target secondary node, The at least one memory further stores instructions, which, when executed by the at least one processor, cause the user equipment to perform at least one of the following: determining whether at least one condition for conditional addition or change of a primary cell in a secondary cell group associated with the first target secondary node, or at least one condition for conditional switching to the first target secondary node is satisfied; Through a random access channel, using the first K SN security key, initiating a random access process to the first target secondary node; determining whether at least one condition for conditional addition or change of a primary cell in a secondary cell group associated with the second target secondary node, or at least one condition for conditional switching to the second target secondary node is satisfied; Through a random access channel, using the second K SN security key, and initiate a random access process to the second target secondary node.

13. The user equipment according to claim 10, wherein the key counter information received from the master node defines a maximum allowed number of additions of the predefined step value to the key counter value received from the master node, and the at least one memory further stores instructions, which, when executed by the at least one processor, cause the user equipment to at least perform the following items: Determining whether the maximum allowed number of additions has been reached; In response to determining that the maximum allowed number of additions has been reached, further addition of the predefined step value to the current key counter value is prevented.

14. The user equipment according to claim 3, wherein the at least one memory further stores instructions, which, when executed by the at least one processor, cause the user equipment to perform at least one of the following items: generating a further security key different from the first security key and different from the second security key using the further key counter value derived from the further processed key counter information; using the further security key for integrity protection and / or encryption of data exchanged between the user equipment and a further target secondary node, the further target secondary node being different from the second target secondary node; further processing the key counter information so that the user device is enabled to derive at least one additional key counter value from the further processed key counter information, the at least one additional key counter value being different from the first key counter value, different from the second key counter value, and different from any other key counter value previously derived from the unprocessed, processed, or further processed key counter information.

15. The user equipment according to claim 1, wherein the configuration information further comprises: Information indicating at least one target secondary cell for which security key generation is not required.

16. A method performed by a user equipment, the user equipment being configured to support dual connectivity operation towards a primary node and a secondary node of a radio access network, wherein the method comprises at least the following items: establishing a connection to the master node; Configuration information is received from the primary node, wherein the configuration information includes key counter information defining a sequence of at least two different key counter values ​​to generate at least two different security keys for at least two different target secondary nodes.

17. A non-transitory computer readable medium comprising program instructions, which when executed by a user equipment configured to support dual connectivity operations to a primary node and a secondary node of a radio access network, cause the user equipment to perform at least the following: establishing a connection to the master node; Configuration information is received from the primary node, wherein the configuration information includes key counter information defining a sequence of at least two different key counter values ​​to generate at least two different security keys for at least two different target secondary nodes.

18. A primary node of a radio access network, the primary node being configured to support dual connectivity operations to a secondary node of the radio access network and a user equipment, the primary node comprising at least one processor and at least one memory, the at least one memory storing instructions which, when executed by the at least one processor, cause the primary node to at least perform the following: establishing a connection to the user equipment; Configuration information is sent to the user equipment, wherein the configuration information includes key counter information, the key counter information defining a sequence of at least two different key counter values ​​to generate at least two different security keys for at least two different target secondary nodes.

19. The master node of claim 16, wherein the key counter information sent to the user equipment defines a list of at least two different key counter values.

20. The master node of claim 17, wherein the at least one memory further stores instructions, which, when executed by the at least one processor, cause the master node to at least perform the following: generating a list of at least two different security keys, said list corresponding to said list of at least two different key counter values ​​defined by said key counter information sent to said user device; A request message is sent to at least one target secondary node, wherein the request message includes the list of generated security keys.

21. The master node of claim 18, wherein the at least one memory further stores instructions that, when executed by the at least one processor, cause the master node to perform at least one of the following: receiving information indicating a security key switch from the first target secondary node; An instruction to remove the first list element from the list of security keys is sent to at least one other target secondary node, wherein the at least one other target secondary node is different from the first target secondary node.

22. The master node of claim 19, wherein the at least one memory further stores instructions that, when executed by the at least one processor, cause the master node to perform at least one of the following: receiving information indicating a security key switch from a second target secondary node, wherein the second target secondary node is different from the first target secondary node; An instruction to remove the present first list element from the list of security keys is sent to at least one further target secondary node, wherein the at least one further target secondary node is different from the second target secondary node.

23. The master node according to claim 18, wherein the at least one memory further stores instructions, which, when executed by the at least one processor, cause the master node to at least perform the following: sending at least one additional list element of the list of key counter values ​​to the user equipment; At least one additional list element of the list of security keys is sent to at least one target secondary node.

24. The master node of claim 16, wherein the key counter information sent to the user device comprises: A key counter value, and instructions for maintaining the key counter value.

25. The master node of claim 16, wherein the master node comprises a gNB-CU-CP node, the gNB-CU-CP node comprising at least one processor and at least one memory, wherein the instructions are stored on the at least one memory of the gNB-CU-CP node to be executed by the at least one processor of the gNB-CU-CP node.

26. The master node according to claim 16, wherein the configuration information further comprises: Information indicating at least one target secondary cell for which security key generation is not required.

27. A method performed by a primary node of a radio access network, the primary node being configured to support dual connectivity operations towards a secondary node of the radio access network and a user equipment, wherein the method comprises at least the following items: establishing a connection to the user equipment; Configuration information is sent to the user equipment, wherein the configuration information includes key counter information, the key counter information defining a sequence of at least two different key counter values ​​to generate at least two different security keys for at least two different target secondary nodes.

28. A non-transitory computer readable medium comprising program instructions, which when executed by a primary node of a radio access network, wherein the primary node is configured to support dual connectivity operations to a secondary node of the radio access network and a user equipment, causes the primary node to perform at least the following: establishing a connection to the user equipment; Configuration information is sent to the user equipment, wherein the configuration information includes key counter information, the key counter information defining a sequence of at least two different key counter values ​​to generate at least two different security keys for at least two different target secondary nodes.

29. A secondary node of a radio access network, the secondary node being configured to support dual connectivity operations to a primary node of the radio access network and a user equipment, the secondary node comprising at least one processor and at least one memory, the at least one memory storing instructions which, when executed by the at least one processor, cause the secondary node to perform at least the following: Receive a request message from the master node, wherein the request message includes: A list of at least two different security keys.

30. The secondary node of claim 27, the at least one memory further storing instructions that, when executed by the at least one processor, cause the secondary node to perform at least one of the following: determining whether the user equipment establishes or attempts to establish a connection to the secondary node; In response to determining that the user equipment establishes or attempts to establish a connection to the secondary node, using a currently first list element in the list of security keys for integrity protection and / or encryption of data exchanged between the secondary node and the user equipment; Sending information indicating a security key switch to the master node; The current first list element is removed from the list of security keys.

31. The secondary node of claim 27, wherein the at least one memory further stores instructions that, when executed by the at least one processor, cause the secondary node to at least perform the following: receiving from the master node an instruction to remove the current first list element from the list of security keys; The current first list element is removed from the list of security keys.

32. The secondary node of claim 27, wherein the at least one memory further stores instructions that, when executed by the at least one processor, cause the secondary node to at least perform the following: At least one additional list element in the list of security keys is received from the master node.

33. A method performed by a secondary node of a radio access network, the secondary node being configured to support dual connectivity operations towards a primary node of the radio access network and a user equipment, wherein the method comprises at least the following items: Receive a request message from the master node, wherein the request message includes: A list of at least two different security keys.

34. A non-transitory computer readable medium comprising program instructions, which when executed by a secondary node of a radio access network, wherein the secondary node is configured to support dual connectivity operations to a primary node of the radio access network and a user equipment, causes the secondary node to perform at least the following: Receive a request message from the master node, wherein the request message includes: A list of at least two different security keys.

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