Support of AEAD algorithms in 3GPP systems

Abstract

A method performed by a user equipment, UE, comprises sending a capability message to a network node in a communication network, the capability message indicating that the UE supports use of an Authenticated Encryption with Associated Data, AEAD, algorithm, wherein an AEAD algorithm is an algorithm that can be used for encryption of communications and 5 integrity protection of communications.

Description

[0001] SUPPORT OF AEAD ALGORITHMS IN 3GPP SYSTEMS BACKGROUND General description of AEAD algorithm An Authenticated Encryption with Associated Data (AEAD) algorithm can be used in two different modes: • Encrypt and authenticate • Encrypt-then-MAC (EtM) • Some AEAD algorithms use one key but other AEAD algorithms can use two keys (both options should be allowed) • Authenticate • MAC (no encryption) • Only using one key for integrity protection Depending on the AEAD algorithm instantiation, the algorithm can also be used as an only encryption algorithm. How a UE indicates its security capability to the network in 5G system A Registration Request message is sent by the User Equipment (UE) to the Access and Mobility Management Function (AMF) in order for the UE to register in the network. The Registration Request message is defined in the Third Generation Partnership Project (3GPP) Technical Specification (TS) 24.501 v18.4.0, in clause 8.2.6. 8.2.6 Registration request 8.2.6.1 Message definition The REGISTRATION REQUEST message is sent by the UE to the AMF. See table 8.2.6.1.1. Message type: REGISTRATION REQUEST Significance: dual Direction: UE to network Table 8.2.6.1.1: REGISTRATION REQUEST message content In TS 24.501 v18.4.0, clause 9.11.3.54, an Information Element (IE) named “UE security capability” is defined where the UE indicates to the network which algorithms it supports for encryption and integrity protection of Non-Access Stratum (NAS) messages between AMF and UE and of Access Stratum (AS) messages for encryption and integrity protection of AS messages between gNB and UE. This IE named “UE security capability” is included in Registration Request message. The IE (Information Element) named “UE security capability” is copied below. Clause 9.11.3.54 UE security capability • The UE security capability information element is used by the UE and by the network to indicate which security algorithms are supported by the UE in N1 mode for NAS security as well as which security algorithms are supported over NR and E-UTRA connected to 5GCN for AS security. Figure 9.11.3.54.1: UE security capability information element

[0002] Allocated Algorithm identifiers 3GPP TS 33.501 v18.2.0, clause 5.11.1, defines the already allocated algorithm identifier values as shown below. NEA4 – NEA7 defined in TS 33.501, which corresponds to 5G-EA4 – 5G-EA7 defined in 3GPP TS 24.501, are currently not occupied (not assigned to any particular algorithm) and NIA4 – NIA7 defined in 3GPP TS 33.501, which corresponds to 5G-EI4 – 5G-EI7 defined in 3GPP TS 24.501, are currently not occupied (not assigned to any particular algorithm). But other Security Algorithms Group of Expects (SAGE) 256-bit algorithms, which are not AEAD algorithms, will most likely be introduced in 5G System (5GS) already in Release 19 (Rel- 19) and they will probably be allocated to the currently unused NEA4 – NEA7 and NIA4 – NIA7, or at least some of these currently unused code points. If this is the case then CT1 needs to extend the UE Security Capability IE adding new code points, for example NEA8 – NEA15 and NIA8 – NIA15. It is more likely that any of NEA8 – NEA16 and NIA8 – NIA15 will be used instead to indicate UE support of AEAD algorithms to the network. Note that N2 interface and Xn interface have already been extended in 3GPP specifications as 16 code points are reserved for integrity algorithm indication, and 16 code points are reserved for encryption algorithm indication: - On N2 interface it is possible to map 16 code points for integrity algorithm indication and 16 code points for encryption algorithm indication, see 3GPP TS 38.413 v17.5.0, clause 9.3.1.86 UE Security Capabilities. - On Xn interface it is possible to map 16 code points for integrity algorithm indication and 16 code points for encryption algorithm, see 3GPP TS 38.423 v17.5.0, see clause 9.2.3.49 UE Security Capabilities. 5.11.1 Algorithm identifier values 5.11.1.1 Ciphering algorithm identifier values All identifiers and names specified in this sub-clause are for 5G NAS and New Radio. In relation to AS capabilities, the identifiers and names for E-UTRAN connected to 5GC are specified in TS 33.401

[0010] . Each encryption algorithm will be assigned a 4-bit identifier. The following values for ciphering algorithms are defined: ( [ ]) Full details of the algorithms are specified in Annex D. 5.11.1.2 Integrity algorithm identifier values All identifiers and names specified in the present sub-clause are for 5G NAS and New Radio. In relation to AS capabilities, the identifiers and names for E-UTRAN connected to 5GC are specified in TS 33.401

[0010] . Each integrity algorithm used for 5G will be assigned a 4-bit identifier. The following values for integrity algorithms are defined: Full details of the algorithms are specified in Annex D. How an AMF indicates the selected security algorithm to the UE in 5G system When the AMF receives the Registration Request message from the UE, then the AMF needs to: - select the security algorithm to be used for encryption of NAS messages sent between AMF and UE; and - select the security algorithm to be used for integrity protection of NAS messages sent between AMF and UE. This is described in TS 33.501, clause 6.7.2. The AMF needs to select an algorithm which is supported both by UE and AMF. Fig. 1 corresponds to Figure 6.7.2-1: NAS Security Mode Command procedure of TS 33.501, and shows the signalling between a UE and AMF. How an gNB indicates the selected security algorithm to the UE in 5G system When the AMF receives the Registration Request message from the UE, then the AMF needs to map the supported security algorithms which the UE indicated in the IE named “UE security capability” included in Registration Request message to the IE named “UE security capability” on N2 interface to the gNB. When the gNB receives the IE named “UE security capability” on N2 interface from the AMF, then the gNB needs to: - select the security algorithm to be used for encryption of AS messages sent between gNB and UE; and - select the security algorithm to be used for integrity protection of AS messages sent between gNB and UE. Each gNB shall be configured via network management with lists of algorithms which are allowed for usage. There shall be one list for integrity algorithms, and one for ciphering algorithms. These lists shall be ordered according to a priority decided by the operator. When AS security context is to be established in the gNB, the AMF shall send the UE 5G security capabilities to the gNB. The gNB shall choose the ciphering algorithm which has the highest priority from its configured list and is also present in the UE 5G security capabilities. This above is described in TS 33.501, clauses 6.7.3 and 6.7.4. The gNB needs to select an algorithm which is supported both by UE and gNB. Fig. 2 corresponds to Figure 6.7.4-1: AS Security Mode Command Procedure of TS 33.501, and shows the signalling between a UE and a gNB / ng-eNB. SUMMARY There currently exist certain challenge(s). In 3GPP, separate algorithms for encryption and integrity protection have been specified so far, where two different security keys are generated and used, i.e. a first security key for encryption and a second security key for integrity protection. This disclosure relates to a dedicated Authenticated Encryption (AE) algorithm which can be a single primitive for both encryption and integrity, using only a single key (e.g., Encrypt-then- MAC (EtM)). However, an AE algorithm can still be used only as an encryption algorithm or only as an integrity algorithm. Both a 128- or a 256-bit key length can be used with a dedicated AE algorithm and both options should be allowed. The following problems have been identified with the existing specifications in 3GPP: - It is not specified in 3GPP specifications, e.g. in TS 24.501, how the UE indicates support for a dedicated AE algorithm(s) which can be a single primitive for both encryption and integrity, using only a single key (e.g. Encrypt-then-MAC (EtM)), to the network. - It is not specified in 3GPP specifications, e.g. in TS 24.501 or in TS 33.501 how the AMF and gNB indicates the use of a dedicated AE algorithms to the UE. - It is not specified how a separate key is generated in the key hierarchy to be used with an AEAD algorithm, if this is needed. - The above problems also apply to a Next Generation-eNB (ng-eNB) connected to a 5G Core (5GC) or a LTE eNB connected to EPS. Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges. In some embodiments, a method performed by a user equipment, UE, comprises sending a capability message to a network node in a communication network, the capability message indicating that the UE supports use of an Authenticated Encryption with Associated Data, AEAD, algorithm, wherein an AEAD algorithm is an algorithm that can be used for encryption of communications and integrity protection of communications. In certain related embodiments, the capability message further indicates whether the UE supports the use of the AEAD algorithm for encryption, supports the use of the AEAD algorithm for integrity protection, or supports the use of the AEAD algorithm for encryption and integrity protection. In certain related embodiments, the capability message is a registration request for registering the UE to the communication network. In certain related embodiments, the capability message comprises, a UE security capability information element, IE. In some such embodiments, the support for the use of the AEAD algorithm is indicated in octet7 and / or octet8 of the UE Security capability IE. In certain related embodiments, the capability message indicates support for the use of the AEAD algorithm for encryption only if a field for an encryption algorithm in the capability message indicates the AEAD algorithm, and a field for an integrity protection algorithm in the message is empty or a null value, the capability message indicates support for the use of the AEAD algorithm for integrity protection only if a field for an integrity protection algorithm in the capability message indicates the AEAD algorithm, and a field for an encryption algorithm in the capability message is empty or a null value, and the capability message indicates support for the use of the AEAD algorithm for encryption and for integrity protection if a field for an encryption algorithm in the capability message indicates the AEAD algorithm, and a field for an integrity protection algorithm in the capability message indicates the AEAD algorithm. In some embodiments, a method performed by a user equipment, UE, comprises receiving a command message from a network node in a communication network, the command message indicating an Authenticated Encryption with Associated Data, AEAD, algorithm that is to be used for encryption of communications and / or integrity protection of communications. In certain related embodiments, the command message further indicates whether the AEAD algorithm is to be used for encryption of communications with the UE, integrity protection of communications with the UE, or both encryption and integrity protection of communications with the UE. In certain related embodiments, the command message is a security mode command for Non-Access Stratum, NAS, communications or a security mode command for Access Stratum, AS, communications. In some embodiments, a method performed by a network node in a communication network comprises receiving a capability message, the message indicating that a User Equipment, UE, supports use of an Authenticated Encryption with Associated Data, AEAD, algorithm, wherein an AEAD algorithm is an algorithm that can be used for encryption of communications and integrity protection of communications. In certain related embodiments, the received capability message further indicates whether the UE supports the use of the AEAD algorithm for encryption, supports the use of the AEAD algorithm for integrity protection, or supports the use of the AEAD algorithm for encryption and integrity protection. In certain related embodiments, the method further comprises selecting, based on the AEAD algorithm indicated in the received capability message, an AEAD algorithm for the UE to use for encryption of communications and / or for integrity protection of communications. In certain related embodiments, the method further comprises sending a command message to the UE, the command message indicating the selected AEAD algorithm that is to be used for encryption of communications and / or integrity protection of communications by the UE. BRIEF DESCRIPTION OF THE DRAWINGS The drawings illustrate various embodiments of the disclosed subject matter. Fig.1 shows an example of signalling between a UE and AMF. Fig.2 shows an example of signalling between a UE and a gNB / ng-eNB. Fig.3 shows another example of signalling between a UE and AMF. Fig.4 shows another example of signalling between a UE and AMF. Fig.5 shows yet another example of signalling between a UE and AMF. Fig.6 shows another example of signalling between a UE and a gNB / ng-eNB. Fig.7 shows yet another example of signalling between a UE and a gNB / ng-eNB. Fig.8 shows still another example of signalling between a UE and a gNB / ng-eNB. Fig.9 shows yet another example of signalling between a UE and AMF. Fig.10 shows yet another example of signalling between a UE and AMF. Fig.11 shows yet another example of signalling between a UE and AMF. Fig.12 shows another example of signalling between a UE and a gNB / ng-eNB. Fig.13 shows another example of signalling between a UE and a gNB / ng-eNB. Fig.14 shows another example of signalling between a UE and a gNB / ng-eNB. Fig.15 shows another example of signalling between a UE and AMF. Fig.16 shows another example of signalling between a UE and a gNB / ng-eNB Fig.17 shows another example of signalling between a UE and AMF. Fig.18 shows another example of signalling between a UE and a gNB / ng-eNB. Fig.19 shows another example of signalling between a UE and a gNB / ng-eNB. Fig.20 shows an example key hierarchy. Fig.21 shows an example of key derivation. Fig.22 shows example key distribution and derivation schemes for 5G for network nodes. Fig.23 shows three keys generated from a KNASaead which is derived from KAMF. Fig.24 shows an example key hierarchy for a 5G system. Fig.25 shows example Key distribution and derivation schemes for 5G for network nodes. Fig.26 shows how to derive new keys from KgNB. Fig.27 shows three keys generated from KRRC-saead, which is derived from KbNG. Fig.28 shows an example a communication system. Fig.29 shows an example wireless device. Fig.30 shows an example access network node. Fig.31 shows an example core network node. Fig.32 shows an example virtualization environment. DETAILED DESCRIPTION The following description presents various embodiments of the disclosed subject matter. These embodiments are presented as teaching examples and are not to be construed as limiting the scope of the disclosed subject matter. Embodiment Set 0 – Extend UE security capability IE with new code points In this set of embodiments, new code points (i.e. fields) are defined in octet7* (i.e. EEA8 – EEA15) and octet 8* (EIA8 – EIA15) in UE Security capability IE as shown below in Clause 9.11.3.54 of 3GPP TS 24.501 v18.4.0, where highlighted parts indicate new additions. Clause 9.11.3.54 UE security capability • The UE security capability information element is used by the UE and by the network to indicate which security algorithms are supported by the UE in N1 mode for NAS security as well as which security algorithms are supported over NR and E-UTRA connected to 5GCN for AS security. Figure 9.11.3.54.1: UE security capability information element Embodiment Set 1 (Option 1A, using unused code points in UE security capability IE): In some embodiments of Embodiment Set 1, the UE indicates its support of a 128-bit AEAD algorithm or a 256-bit AEAD algorithm and used mode of AEAD algorithm to the network: - The UE can use unused code points (i.e. fields), e.g. any unused code point as 5G IA4 – 5GIA7 in octet 4 or any unused code point as 5G IA8 – 5G IA15 in octet 7*-10* (to indicate support of the mode (on or off) of integrity protection, using a specific AEAD algorithm) and any unused code point as 5G EA4 – 5G EA7 in octet 3 or any unused code point defined as 5G EA8 – 5G EA15 in octet 7*-10* (to indicate support of the mode (on or off) of encryption, using a specific AEAD algorithm) in the existing UE security capability IE. - The example below assumes that 5G IA4 and 5G EA4 have been defined and selected to indicate support of an AEAD algorithm. However, as noted in the above bullet, any unused code point in octets 3, 4, 7*-10*, can be used. - Code points 5G IA4 and 5G EA4 indicate the support of the exact same AEAD algorithm, if the AEAD algorithm can be used for both encryption and integrity protection using single key. - This would indicate to the network that the UE can support the AEAD algorithm in the following modes: - The AEAD algorithm can be used only for integrity protection; - The AEAD algorithm can be used only for encryption; - The AEAD algorithm can be used for both encryption and integrity protection using single key. - These code points can indicate UE support of AEAD algorithm to the network, on N1 interface between UE and AMF, on N2 interface between AMF and gNB, on Xn interface between source gNB and target gNB, etc. The AMF can map the indicated / supported code points received from the UE in UE Security Capability IE in a Registration Request to the UE Security Capability IE on N2 interface (TS 38.413, see clause 9.3.1.86) and to the UE Security Capability IE on Xn interface (TS 38.423, see clause 9.2.3.49). - New updates of NAS protocol on N1 interface between UE and AMF may be required. This depends on whether the UE security capability IE needs to be extended with any octet (i.e. octet 7*-10*) to define new code points as 5G IA8 – 5G IA15 and as 5G- EA8 – 5G-EA15. - There is no new impact on protocols over N2 interface between AMF and gNB. There is no new impact on protocols over Xn interface between source gNB and target gNB. In another embodiment of Embodiment Set 1, the AMF / gNB selects and enables the indicated AEAD algorithm. If the UE has indicated support for the same AEAD algorithm in both 5G IA4 and 5G EA4, then this would indicate to the network that the UE can support the AEAD algorithm in the following modes: - The AEAD algorithm can be used only for integrity protection; - The AEAD algorithm can be used only for encryption; - The AEAD algorithm can be used for both encryption and integrity protection using single key. If the AMF / gNB selects the AEAD algorithm indicated in both 5G IA4 and 5G EA4, then the AMF / gNB would need to select which mode it wants to use the AEAD algorithm in, i.e.: - The AEAD algorithm shall be used only for integrity protection; - The AEAD algorithm shall be used only for encryption; - The AEAD algorithm shall be used for both encryption and integrity protection using single key. Below are three examples of how the AMF or gNB indicates to the UE in NAS Security Mode Command or in AS Security Mode Command, the AEAD algorithm to be used with the AMF or gNB, and in which mode. Example 1: If: - 5G-IA4 indicates an AEAD algorithm, and - 5G- EA4 indicates NULL algorithm the AEAD algorithm shall be used only for integrity protection. Example 2: If: - 5G IA4 indicates NULL algorithm, and - 5G EA4 indicates AEAD algorithm the AEAD algorithm shall be used only for encryption. Example 3: If: - 5G IA4 indicates an AEAD algorithm, and - 5G EA4 indicates an AEAD algorithm, and - 5GIA4 and 5G EA4 indicates the same AEAD algorithm the AEAD algorithm shall be used for encryption and integrity protection using a single key. Embodiment Set 2 (Option 1B, using existing unused code points in UE security capability IE): In this set of embodiments, the UE indicates its support of an AEAD algorithm and the mode to the network by combining the support AEAD algorithm and the supported mode into one single code point (i.e. field). For example: - 5G-IAx indicates the support for AEAD algorithm to be used in the mode of integrity protection only. - 5G-IAy indicates the support for AEAD algorithm to be used in the mode of encryption and integrity protection using single key. - 5G-EAx indicates the support for AEAD algorithm to be used in the mode of encryption only. - 5G-EAy indicates the support for AEAD algorithm to be used in the mode of encryption and integrity protection using single key. In these embodiments, two new code points among the unused code points of 5G-IA4 – 5G- IA15 and two new code points among the unused code points of 5G-EA4 – 5G EA15 need to be defined and selected, per each new supported AEAD algorithm. Although the following code points 5G-IA4, 5G-IA5, 5G-EA4, 5G-EA5 have been used as an example of these embodiments, any unused code point of 5G-IA4 – 5G-IA15 and 5G-EA4 – 5G EA15 can be used in this example. More than one AEAD algorithm can be supported by the UE. The UE support of a second AEAD algorithm would require two unused code points among the unused code points of 5G-IA4 – 5G-IA15 and two unused code points among the unused code points of 5G-EA4 – 5G EA15 to be selected and defined for the second AEAD algorithm. The use of the unused code points 5G-IA4, 5G-IA5, 5G-EA4 and 5G-EA5 by a UE in accordance with this Embodiment Set 2 is shown in the example below: o 5G-IA4 (to indicate support of a specific AEAD algorithm to be used in a specific single mode – i.e. integrity protection only mode); and / or o 5G-IA5 (to indicate support of a specific AEAD algorithm to be used in a specific single mode - encryption and integrity protection) in UE security capability IE. o 5G-EA4 (to indicate support of a specific AEAD algorithm to be used in a specific single mode – i.e. encryption only mode); and / or o 5G-EA5 (to indicate support of a specific AEAD algorithm to be used in a specific single mode –encryption and integrity protection) in UE security capability IE. o Note that 5G-IA5 and 5G-EA5 would indicate the support of the same AEAD algorithm to be used in the same mode (encryption and integrity protection). Example: The UE indicates support for the same AEAD algorithm in both 5G-IA4, 5G-IA5, 5G-EA4 and 5G-EA5. This would indicate to the network that the UE can support the AEAD algorithm in the following modes: - 5G-IA4 = AEAD; the AEAD algorithm can be used in a mode of only for integrity protection; - 5G-IA5 = AEAD; the AEAD algorithm can be used in a mode of both encryption and integrity protection using a single key; - 5G-EA4 = AEAD; the AEAD algorithm can be used in a mode of only for encryption; - 5G-EA5 = AEAD; the AEAD algorithm can be used in a mode of both encryption and integrity protection using a single key. These code points (5G-IA4, 5G-IA5, 5G-EA4, 5G-EA5) indicate UE support of this specific AEAD algorithm to the network, on N1 interface between UE and AMF, on N2 interface between AMF and gNB, on Xn interface between source gNB and target gNB etc. The AMF will map the code points received from the UE in UE Security Capability IE received in Registration Request to the UE Security Capability IE on N2 interface (TS 38.413, see clause 9.3.1.86) and to the UE Security Capability IE on Xn interface (TS 38.423, see clause 9.2.3.49). For this embodiment set, new updates of the NAS protocol on N1 interface between UE and AMF may be required. This depends on whether the UE security capability IE needs to be extended with any octet (i.e. octet 7*-10*). There is no new impact on protocols over N2 interface between AMF and gNB, and no new impact on protocols over Xn interface between source gNB and target gNB. AMF / gNB selecting and enabling the indicated AEAD algorithm: If the UE has indicated support for the same AEAD algorithm in 5G-IA4, 5G-IA5, 5G-EA4 and 5G-EA5, then this would indicate to the network that the UE can support the AEAD algorithm in the following modes: - The AEAD algorithm can be used in a mode of integrity protection only, - The AEAD algorithm can be used in a mode of encryption only, - The AEAD algorithm can be used for both encryption and integrity protection using a single key. If the AMF / gNB selects the AEAD algorithm indicated in 5G-IA4, 5G-IA5, 5G-EA4 and 5G-EA5, then the AMF / gNB would need to select which mode it wants to use the AEAD algorithm in: - The AEAD algorithm shall be used in a mode of integrity protection only, - The AEAD algorithm shall be used in a mode of encryption only, - The AEAD algorithm shall be used for both encryption and integrity protection using a single key. Below are three examples showing how the AMF or gNB can indicate to the UE in NAS Security Mode Command or in AS Security Mode Command the AEAD algorithm to be used with the AMF or gNB, and in which mode. Note that in the example below, NIA4 corresponds to 5G- NIA4, NIA5 corresponds to 5G-NIA5, NEA4 corresponds to 5G-EA4, and NEA5 corresponds to 5G-EA5. Example 1: If the AMF or gNB indicates the following to the UE: - Integrity algorithm = NIA4 which indicates an AEAD algorithm, and - Encryption algorithm = NEA0 which indicates NULL algorithm, the AEAD algorithm shall be used only for integrity protection. Example 2: If the AMF or gNB indicates the following to the UE: - Integrity algorithm = NIA0 which indicates NULL algorithm, and - Encryption algorithm = NEA4 which indicates AEAD algorithm, the AEAD algorithm shall be used only for encryption. Example 3: If the AMF or gNB indicates the following to the UE: - Integrity algorithm or Encryption algorithm = NIA5 or NEA5 indicates an AEAD algorithm (i.e. the same AEAD algorithm), the AEAD algorithm shall be used for encryption and integrity protection using a single key. Both 5G-IA5 and 5G-EA5 do not need to be selected and indicated to the UE. Embodiment Set 3 (Option 1C, using unused code points in UE security capability IE) In this set of embodiments, the UE can indicate its support of a 128-bit AEAD algorithm or a 256-bit AEAD algorithm and supported AEAD options (e.g. AEAD mode, …) to the network. The UE can use unused code point(s) (i.e. field(s)), e.g. any unused code point such as, e.g., 5G- IA4 in octet 4, or any unused code point in octet 7*-10* (to indicate support of a specific AEAD algorithm), and 5G-EA3 in octet 4 or any unused code point in octet 7*-10* (to indicate support of a specific AEAD algorithm) in the UE security capability IE. The example below assumes the use of 5G-IA4 and 5G-EA4 to indicate support of an AEAD algorithm. However, as noted above, any unused code point in octets 3, 4, 7*-10*, can be used. Code points 5G-IA4 and 5G-EA4 indicate the support of the exactly same AEAD algorithm. The example below assumes that 5G-IA5, 5G-IA6, 5G-IA7, 5G-EA5, 5G-EA6 and 5G-EA7 have been defined and selected to indicate support of different AEAD options to be used with an AEAD algorithm. An advantage of re-using these code points in this example are that the network interface as N1, N2 and Xn interfaces would not be impacted and there would not be a need to enhance them. However, as noted above, any unused code point in any octet in UE security capabilities IE defined in TS 24.501 can be used to indicate AEAD options. The UE can use one or several unused code points to indicate supported AEAD options (e.g. AEAD mode etc) with AEAD algorithms. For example there can be several AEAD options indicated by the UE. Below is one example of UE supported AEAD modes with an AEAD algorithm: Example 1 of UE indicating its supported AEAD modes with an AEAD algorithm: 5G-IA5 or 5G-EA5 - 0 = Not Applicable if AEAD algorithm is not supported by UE, - 1 = Integrity only. 5G-IA6 or 5G-EA6 - 0 = Not Applicable if AEAD algorithm is not supported by UE, - 1 = Encryption only. 5G-IA7 or 5G-EA7 - 0 = Not Applicable if AEAD algorithm is not supported by UE, - 1 = Encryption and integrity protection. The code points described in Embodiment Set 3 indicate UE support of AEAD algorithm and AEAD options (e.g. AEAD mode to be used with an AEAD algorithm etc.) indicated by UE to the network, need to be mapped on the N2 interface between AMF and gNB, and the Xn interface between source gNB and target gNB, etc. Embodiment Set 4 (Option 2, create new code points in NAS protocols) In this set of embodiments, a new algorithm list is created for AEAD algorithms to be used in AEAD mode for encryption and integrity protection. - The UE security capability IE could be extended with new octet and code points indicating support for new AEAD algorithms. - A completely new IE could be created with new code points indicating support for new AEAD algorithms. With this set of embodiments, updates of the NAS protocol is required which have impacts on the UE and AMF. Other protocols may also be impacted, such as the Next Generation Application Protocol (NG-AP) protocol over N2, the Xn-protocol over Xn interface etc. Embodiment Set 5 – Key hierarchy in NAS layer This set of embodiments uses new 128-bit or 256-bit key(s) in NAS layer: KNASaead. Option 1: A new KNASaeadcan be used only for both encryption and integrity protection, when both integrity and encryption are enabled, when AEAD algorithm is selected. Option 2: A new KNASaeadcan be used when: - only integrity protection (MAC) is enabled, - only encryption is enabled, and - for both encryption and integrity protection, when both integrity and encryption are enabled, when AEAD algorithm is selected. Option 3: Three new keys KNASaead-int, KNASaead-encand KNASaead-enc-intcan be used: - KNASaead-int is used when only integrity protection (MAC) is enabled, and - KNASaead-encis used when only encryption is enabled, and - KNASaead-enc-int is used for encryption and integrity protection, when both integrity and encryption are enabled, and a single key is used, when AEAD algorithm is selected. Embodiment Set 6 – Key hierarchy in AS layer This set of embodiments has several options. Option 1: KRRC-aeadand KUP-aeadcan be used only for encryption and integrity protection, when both integrity and encryption are enabled, when AEAD algorithm is selected. Option 2: KRRC-aead and KUP-aead can be used when: - only integrity protection (MAC) is enabled, - only encryption is enabled, and - also for encryption and integrity protection, when both integrity and encryption are enabled, when AEAD algorithm is selected. The same algorithm will be used for protection of Radio Resource Control (RRC) and User Plane (UP). Option 3: Three new keys KRRC-aead-int and KRRC-aead-enc-int can be used: - KRRC-aead-intis used when only integrity protection (MAC) of RRC messages is enabled and - KRRC-aead-enc is used when only integrity protection (MAC) of RRC messages is enabled and - KRRC-aead-enc-int is used for encryption and integrity protection, when both integrity and encryption are enabled, and a single key is used, when AEAD algorithm is selected. Option 4: This option is similar to Option 3. Three new keys KUP-aead-int, KUP-aead-encand KUP-aead-enc-int can be used: - KUP-aead-intis used when only integrity protection (MAC) of UP messages is enabled, - KUP-aead-encis used when only encryption for UP messages is enabled, and - KUP-aead-enc-int is used for encryption and integrity protection, when both integrity and encryption are enabled, and a single key is used, when AEAD algorithm is selected. Embodiment Set 7 – ng-eNB connected to 5GC or LTE eNB connected to EPC: The above Embodiment Sets 1-6 are applicable to a ng-eNB connected to 5GC and also a Long Term Evolution (LTE) eNB connected to Evolved Packet Core (EPC) (4thGeneration - 4G), with the difference that Evolved Packet System (EPS) code points (EEA4-EEA7) in octet 5* or any unused code point in octet 9*-10* are used; and octet 6* (EIA4-EIA7) or any unused code point in octet 9*-10* in the UE security capability IE specified in TS 24.501 are used instead of 5G code points (5G-EA4 – 5G-EA15 in octet 3 and octet 7 and 5G-EIA4 – 5G-EIA15 in octet 4). As noted above, new EPS code points specified in octet 7*-10* for EEA8 – EEA15 and EIA8 – EEA15, can be used as well. In Embodiment Set 7, new code points are defined in UE Security Capability IE in clause 9.11.3.54 in TS 24.501. The new code points are defined in octet 9* for new EPS encryption algorithms (i.e. EEA8 – EEA15) and octet 10* for new EPS integrity algorithms (EIA8 – EIA15) in the UE Security capability IE as described below with reference to Clause 9.11.3.54 of 3GPP TS 24.501 v18.4.0, where highlighted parts indicate new additions. Clause 9.11.3.54 UE security capability The UE security capability information element is used by the UE and by the network to indicate which security algorithms are supported by the UE in N1 mode for NAS security as well as which security algorithms are supported over NR and E-UTRA connected to 5GCN for AS security.

[0003] Figure 9.11.3.54.1: UE security capability information element

[0004] When a LTE eNB is connected to EPC (4G), then the MS Network Capability IE defined in TS 24.301 needs to be enhanced with new code points for EPS encryption algorithm EEA8 – EEA15 and for new EPS integrity algorithms (EIA8 – EIA15). Thus, as shown by the above sets of embodiments, solutions are proposed for the indication of AEAD capabilities of the UE in the UE security capability IE, signalling the chosen AEAD algorithm and its usage from the AMF to UE in NAS security, and signalling the chosen AEAD algorithm and its usage from gNB to UE in AS security. As used herein, the term “code point” refers to a field, for example a code point / field in the UE security capability IE, that can have a value indicative of a particular algorithm. Embodiment Set 1 (Option 1A – using existing unused points in UE security capability IE) This set of embodiments is explained considering that there is only one AEAD algorithm, so 5G-EA4 and 5G-IA4 code points in UE security capability IE, 5G-EA4 and 5G-IA4 algorithm names in NAS security algorithms IE, and NEA4 and NIA4 algorithm names are referenced. When there is more than one AEAD algorithm, other codepoints and algorithm names (e.g., 5G- EA5, 5G-IA5, NEA5, NIA5) can be used. How the UE indicates its UE capability to support AEAD algorithm to the network: TS 24.501 – Registration Request Clause 9.11.3.54 UE security capability

[0005] Code points 5G IA4 and 5G EA4 indicate the UE support of exactly the same AEAD algorithm. This would indicate to the network that the UE can support the AEAD algorithm in the following modes: - The AEAD algorithm can be used only for integrity protection, - The AEAD algorithm can be used only for encryption, - The AEAD algorithm can be used for both encryption and integrity protection using single key. How the AMF indicates to the UE to use the AEAD algorithm (for integrity protection and / or encryption): This section refers to TS 24.501, procedure Security Mode Command, clause 9.11.3.34 NAS security algorithms IE. The purpose of the NAS security algorithms IE is to indicate from the AMF to the UE the 5G algorithms to be used for ciphering and integrity protection. In the following table, taken from clause 9.11.3.34 NAS security algorithms IE, highlighted parts indicate new additions, and struck-through parts indicate new deletions. Table 9.11.3.34.1: NAS security algorithms information element T B 4 0 0 0 0 0 0 0 0 A T B 8 0 0 0 0 0 0 0 0 A Fig.3 shows signalling between a UE and AMF according to an Example 1 of this set of embodiments. Fig. 3 is based on TS 33.501, Figure 6.7.2-1: NAS Security Mode Command procedure. In step 1b of Fig.3, it can be seen that: - Integrity algorithm = 5G IA4 = NIA4, which indicates an AEAD algorithm; and - Encryption algorithm = 5G EIA4 = NEA4, which indicates an AEAD algorithm; and - 5GIA4 and 5G EIA4 indicates the same AEAD algorithm; - So the AEAD algorithm shall be used for both encryption and integrity protection using a single key. Fig. 4 shows signalling between a UE and AMF according to an Example 2 of this set of embodiments. Fig. 4 is based on TS 33.501, Figure 6.7.2-1: NAS Security Mode Command procedure. In step 1b of Fig.4, it can be seen that: - Integrity algorithm = 5G IA4 = NIA4, which indicates an AEAD algorithm, - Encryption algorithm = 5G EIA0 = NEA0, which indicates NULL algorithm, - So the AEAD algorithm shall be used only for integrity protection. Fig.5 shows signalling between a UE and AMF according to an Example 3 of this set of embodiments. Fig. 5 is based on TS 33.501, Figure 6.7.2-1: NAS Security Mode Command procedure. In step 1b of Fig.5, it can be seen that: - Integrity algorithm = 5G IA0 = NIA0, which indicates NULL algorithm, - Encryption algorithm = 5G EIA4 = NEA4, which indicates NEA4 algorithm, - So the AEAD algorithm shall be used only for encryption. How AMF indicates to the gNB that UE supports AEAD algorithm (for integrity protection and / or encryption): The AMF will map the UE indicated support of NEA4 and NIA4 to gNB on N2 interface. How gNB indicates to the UE to use AEAD algorithm (for integrity protection and / or encryption): This is illustrated with reference to 3GPP TS 38.331 v17.5.0, procedure AS Security Mode Command, clause SecurityAlgorithmConfig, where highlighted parts indicate new additions and struck-through parts indicate new deletions. – SecurityAlgorithmConfig The IE SecurityAlgorithmConfig is used by gNB to configure AS integrity protection algorithm and AS ciphering algorithm for SRBs and DRBs to the UE. SecurityAlgorithmConfig information element Fig.6 shows signalling between a UE and a gNB / ng-eNB according to Example 1 of this set of embodiments (as described above with reference to Fig.3). Fig.6 is based on TS 33.501, Figure 6.7.4-1: AS Security Mode Command Procedure. In step 1b of Fig.6, it can be seen that: - Integrity algorithm = NIA4, which indicates an AEAD algorithm; and - Encryption algorithm = NEA4, which indicates an AEAD algorithm; and - NIA4 and NEA4 indicates the same AEAD algorithm; - So the AEAD algorithm shall be used for both encryption and integrity protection using a single key. Fig.7 shows signalling between a UE and a gNB / ng-eNB according to Example 2 of this set of embodiments (as described above with reference to Fig.4). Fig.7 is based on TS 33.501, Figure 6.7.4-1: AS Security Mode Command Procedure. In step 1b of Fig.7, it can be seen that: - Integrity algorithm = NIA4; which indicates an AEAD algorithm; and - Encryption algorithm = NEA0; which indicates NULL algorithm; - So the AEAD algorithm shall be used only for integrity protection. Fig.8 shows signalling between a UE and a gNB / ng-eNB according to Example 3 of this set of embodiments (as described above with reference to Fig.4). Fig.8 is based on TS 33.501, Figure 6.7.4-1: AS Security Mode Command Procedure. In step 1b of Fig.8, it can be seen that: - Integrity algorithm = NIA0; which indicates NULL algorithm; and - Encryption algorithm = NEA4; which indicates NEA4 algorithm; - So the AEAD algorithm shall be used only for encryption. Embodiment Set 2 (Option 1B, re-using existing code points in UE security capability IE) How the UE indicates its UE capability to support AEAD algorithm to the network: This section relates to enhancements to the UE security capability IE in clause 9.11.3.54 in TS 24.501, which is included in the Registration Request message. In particular, the Registration Request message could be updated in the following way: TS 24.501 – Registration Request Clause 9.11.3.54 UE security capability The UE indicates its support of AEAD algorithm and the mode to network: The UE uses unused code points, for example: - 5G IA4 (to indicate support of a specific AEAD algorithm to be used in a specific single mode – i.e. integrity protection only mode); and / or - 5G IA5 (to indicate support of a specific AEAD algorithm to be used in a specific single mode - encryption and integrity protection) in UE security capability IE. - 5G EA4 (to indicate support of a specific AEAD algorithm to be used in a specific single mode – i.e. encryption only mode); and / or - 5G EA5 (to indicate support of a specific AEAD algorithm to be used in a specific single mode – encryption and integrity protection) in UE security capability IE. 5G IA5 and 5G EA5 would indicate the support of the same AEAD algorithm to be used in the same mode. Example: As an example, the UE indicates support for the same AEAD algorithm in both 5G IA4, 5G IA5, 5G EA4 and 5G EA5. This would then indicate to the network that the UE can support the AEAD algorithm in the following modes: - 5G IA4 = AEAD, the AEAD algorithm can be used in a mode of only for integrity protection; - 5G IA5 = AEAD, the AEAD algorithm can be used in a mode of both encryption and integrity protection using a single key; - 5GEA4 = AEAD, the AEAD algorithm can be used in a mode of only for encryption; - 5G EA5 = AEAD, the AEAD algorithm can be used in a mode of both encryption and integrity protection using single key. How AMF indicates to the UE to support AEAD algorithm (for integrity protection and / or encryption): This section refers to TS 24.501, procedure Security Mode Command, clause 9.11.3.34 NAS security algorithms IE. The purpose of the NAS security algorithms IE is to indicate from the AMF to the UE the 5G algorithms to be used for ciphering and integrity protection. In the following table, taken from clause 9.11.3.34 NAS security algorithms IE, highlighted parts indicate new additions, and struck-through parts indicate new deletions. Table 9.11.3.34.1: NAS security algorithms information element Fig.9 shows signalling between a UE and AMF according to an Example 1 of Embodiment Set 2. Fig.9 is based on TS 33.501, Figure 6.7.2-1: NAS Security Mode Command procedure. In step 1b of Fig.9, it can be seen that: - Integrity algorithm = NIA4, which indicates an AEAD algorithm to be used in mode ‘integrity only’, - Encryption algorithm = NEA0, which indicates NULL algorithm, - So the AEAD algorithm shall be used only for integrity protection. Fig.10 shows signalling between a UE and AMF according to an Example 2 of Embodiment Set 2. Fig.10 is based on TS 33.501, Figure 6.7.2-1: NAS Security Mode Command procedure. In step 1b of Fig.10, it can be seen that: - Integrity algorithm = NIA5, which indicates AEAD algorithm to be used for both encryption and integrity protection; - Encryption algorithm = NEA0, which indicates NULL algorithm; - So the AEAD algorithm shall be used for both encryption and integrity protection. Alternatively, (although not shown in Fig.10), step 1b of Fig.10 could indicate: - Encryption algorithm = NEA5, which indicates AEAD algorithm to be used for both encryption and integrity protection; - Integrity algorithm = NIA0, which indicates NULL algorithm; - So the AEAD algorithm shall be used for both encryption and integrity protection. Fig.11 shows signalling between a UE and AMF according to an Example 3 of Embodiment Set 2. Fig.11 is based on TS 33.501, Figure 6.7.2-1: NAS Security Mode Command procedure. In step 1b of Fig.11, it can be seen that: - Integrity algorithm = NIA0, which indicates NULL algorithm; - Encryption algorithm = NEA4, which indicates AEAD algorithm to be used in mode ‘encryption only’; - So the AEAD algorithm shall be used only for encryption. How AMF indicates to the gNB that UE supports AEAD algorithm (for integrity protection and / or encryption): The AMF will map the UE indicated support of NEA4, NEA5, NIA4 and NIA5 to gNB on N2 interface. How gNB indicates to the UE to use AEAD algorithm (for integrity protection and / or encryption): This is illustrated with reference to 3GPP TS 38.331 v17.5.0, procedure AS Security Mode Command, clause SecurityAlgorithmConfig, where highlighted parts indicate new additions and struck-through parts indicate new deletions. *** – SecurityAlgorithmConfig The IE SecurityAlgorithmConfig is used to configure AS integrity protection algorithm and AS ciphering algorithm for SRBs and DRBs. SecurityAlgorithmConfig information element Fig. 12 shows signalling between a UE and a gNB / ng-eNB according to Example 1 of Embodiment Set 2 (as described above with reference to Fig.9). Fig.12 is based on TS 33.501, Figure 6.7.4-1: AS Security Mode Command Procedure. In step 1b of Fig.12, it can be seen that: - Integrity algorithm = NIA4, which indicates AEAD algorithm to be used in mode ‘integrity only’; and - Encryption algorithm = NEA0, which indicates NULL algorithm; and - So the AEAD algorithm shall be used only for integrity protection. Fig. 13 shows signalling between a UE and a gNB / ng-eNB according to Example 2 of Embodiment Set 2 (as described above with reference to Fig.10). Fig.13 is based on TS 33.501, Figure 6.7.4-1: AS Security Mode Command Procedure. In step 1b of Fig.7, it can be seen that: - Integrity algorithm = NIA5, which indicates AEAD algorithm to be used for both encryption and integrity protection; - Encryption algorithm = NEA0, which indicates NULL algorithm; - So the AEAD algorithm shall be used for both encryption and integrity protection. Alternatively, (although not shown in Fig.13), step 1b of Fig.13 could indicate: - Encryption algorithm = NEA5, which indicates AEAD algorithm to be used for both encryption and integrity protection; - Integrity algorithm = NIA0, which indicates NULL algorithm; - So the AEAD algorithm shall be used for both encryption and integrity protection. Fig. 14 shows signalling between a UE and a gNB / ng-eNB according to Example 3 of Embodiment Set 2 (as described above with reference to Fig.11). Fig.14 is based on TS 33.501, Figure 6.7.4-1: AS Security Mode Command Procedure. In step 1b of Fig.14, it can be seen that: - Integrity algorithm = NIA0, which indicates NULL algorithm; - Encryption algorithm = NEA4, which indicates AEAD algorithm to be used in mode ‘encryption only’; - So the AEAD algorithm shall be used only for encryption. Embodiment Set 3 (Option 1C, re-using existing code points in UE security capability IE) How the UE indicates its UE capability to support AEAD algorithm to the network: This section relates to enhancements to the UE security capability IE in clause 9.11.3.54 in TS 24.501, which is included in the Registration Request message. In particular, the Registration Request message could be updated in the following way: TS 24.501 – Registration Request Clause 9.11.3.54 UE security capability The UE indicates its support of AEAD algorithm and mode to network: The UE uses unused code point(s), for example: 5G-IA4 (to indicate support of a specific AEAD algorithm for integrity protection) and 5G-EA4 (to indicate support of a specific AEAD algorithm for encryption) in UE security capability IE. The UE can use unused code point(s) to indicate supported modes with AEAD algorithms, for example: - 5G-IA5 or some other unused code point – to indicate the supported AEAD mode to be used with an AEAD algorithm: - 0 = Not Applicable if 5G-IA4 is not supported, - 1 = Integrity only. - 5G-IA6 or some other unused code point – to indicate the supported AEAD mode to be used with an AEAD algorithm: - 0 = NA if 5G-IA4 is not supported, - 1 = Encrypt only. - 5G-IA7 or some other unused code point – to indicate the supported AEAD mode to be used with an AEAD algorithm: - 0 = NA if 5G-IA4 is not supported, - 1 = Encryption and integrity protection with single key. Another option is to use three unused bits, which could be an already defined octet in UE security capability IE if three bits are available and unused. Alternatively it could be an extension of the UE security capability IE with a new octet (octet 07, 08, 09 or 10) How AMF indicates to the UE to use AEAD algorithm (for integrity protection and / or encryption): This section refers to TS 24.501, procedure Security Mode Command, clause 9.11.3.34 NAS security algorithms IE. The purpose of the NAS security algorithms IE is to indicate the 5G algorithms to be used for ciphering and integrity protection. In the following table, taken from clause 9.11.3.34 NAS security algorithms IE, highlighted parts indicate new additions, and struck- through parts indicate new deletions. Table 9.11.3.34.1: NAS security algorithms information element

[0006] T B 4 0 0 0 0 0 0 0 0 A T B 8 0 0 0 0 0 0 0 0 A For this Embodiment Set, a new parameter can be defined in UE security capability: IE: AEAD mode to use (octet XX, bit x1 to x2) B 0 0 1 1 The following Examples show in more detail how the negotiation and selection are determined by AMF and UE. Fig.15 shows signalling between a UE and AMF according to Example 1 of Embodiment Set 3. Fig.15 is based on TS 33.501, Figure 6.7.2-1: NAS Security Mode Command procedure. In step 1b of Fig.15, it can be seen that the AMF selects and indicates to UE: - Integrity algorithm = NIA4, - Encryption / ciphering algorithm = NEA4, - New parameter is included in NAS Security Mode Command: - AEAD options: (AEAD options may contain several parameters, AEAD mode is one such parameters) - … - AEAD mode to use - = integrity only, then enable integrity only, - = encrypt only, then enable encryption only, - = encryption and integrity protection with single key, enable both integrity protection and encryption. How gNB indicates to the UE to use AEAD algorithm (for integrity protection and / or encryption): This is illustrated with reference to 3GPP TS 38.331 v17.5.0, procedure AS Security Mode Command, clause SecurityAlgorithmConfig, where highlighted parts indicate new additions and struck-through parts indicate new deletions. – SecurityAlgorithmConfig The IE SecurityAlgorithmConfig is used to configure AS integrity protection algorithm and AS ciphering algorithm for SRBs and DRBs. SecurityAlgorithmConfig information element A new parameter is included in SecurityAlgorithmConfig information element in AS Security Mode Command: - AEAD options: (AEAD options may contain several parameters, AEAD mode is one such parameter) - … - AEAD mode to use - = integrity only, then enable integrity only, - = encrypt only, then enable encryption only, - = encryption and integrity protection with single key, enable both integrity protection and encryption. New parameter: AEAD options: - …; - AEAD mode to use (octet XX, bit x1 to x2) B 0 0 1 1 Fig. 16 shows signalling between a UE and a gNB / ng-eNB according to Example 1 of Embodiment Set 3. Fig.16 is based on TS 33.501, Figure 6.7.4-1: AS Security Mode Command Procedure. In step 1b of Fig.16, it can be seen that the AMF selects and indicates to the UE: - Integrity algorithm = NIA4, - Encryption algorithm = NEA4, - New parameter is included in AS Security Mode Command: - AEAD options (AEAD options may contain several parameters, AEAD mode is one such parameter): - … - AEAD mode to use - = integrity only, then enable integrity only, - = encrypt only, then enable encryption only, - = encryption and integrity protection with single key, enable both integrity protection and encryption. Embodiment Set 4 (Option 2, create new code points in NAS protocols) In this set of embodiments a New algorithm list is created for AEAD algorithms in AEAD mode for encryption and integrity protection or “Encrypt-then-MAC”. - The UE security capability IE could be extended with new octets with new code points indicating support for new AEAD security algorithms; or - A new IE could be created in Registration Request message with new code points indicating support for new AEAD security algorithms. Updates to the NAS protocol are required which have an impact on UE and AMF. Other protocols may also be impacted, such as NG-AP protocol over N2, Xn-protocol over Xn interface etc. How UE indicates its UE capability to support AEAD algorithm to the network: This section relates to enhancements to the UE security capability IE in clause 9.11.3.54 in TS 24.501, which is included in the Registration Request message. In particular, the Registration Request message could be updated in the following way: TS 24.501 – Registration Request Clause 9.11.3.54 UE security capability 8 7 6 5 4 3 2 1 5 E 5 I E E There are two options: 1. Extend the UE security capability IE above, and use any of octet 7*-10* or 11*; or 2. Create a new IE, e.g. UE security capability-2 IE in the Registration Request message. In option 2, for types of algorithm for both encryption and integrity protection, a new UE security capability IE (e.g. UE security capability-2 IE) would be required for indicating the type of AEAD algorithm used for both encryption and integrity protection. The NAS protocol would be needed to be updated. An exemplary UE security capability-2 IE is shown below: 8 7 6 5 4 3 2 1 128-5G-EA1 or 256-5G-EA1 indicates an AEAD algorithm (AEAD-1) used in AEAD mode for both encryption and integrity protection. 128-5G-EA2 or 256-5G-EA2 indicates an AEAD algorithm (AEAD-2) used in AEAD mode for both encryption and integrity. 128-5G-EA3 or 256-5G-EA3 indicates an AEAD algorithm (AEAD-3) used in AEAD mode for both encryption and integrity protection. How AMF indicates to the UE to use AEAD algorithm (for integrity protection and / or encryption): This section refers to TS 24.501, procedure Security Mode Command, clause 9.11.3.34 NAS security algorithms IE. The purpose of the NAS security algorithms IE is to indicate from the 5G algorithms to be used for ciphering and integrity protection. In the following table, taken from clause 9.11.3.34 NAS security algorithms IE, highlighted parts indicate new additions, and struck- through parts indicate new deletions. Table 9.11.3.34.1: NAS security algorithms information element

[0007] T B 4 0 0 0 0 0 0 0 0 A T B 8 0 0 0 0 0 0 0 0 A New enhancements: 128-5G-IA4 or 256-5G-IA4 indicates to the UE that this AEAD algorithm shall be used for integrity protection. 128-5G-EA4 or 256-5G-EA4 indicates to the UE that this AEAD algorithm shall be used for encryption. T m B 4 0 0 0 0 0 0 0 0 A The following Scenarios 1 and 2 are examples, and describe in more detail how the negotiation and selection are determined by AMF and UE. Fig. 17 shows signalling between a UE and AMF according to Example Scenario 1 of Embodiment Set 4. Fig.17 is based on TS 33.501, Figure 6.7.2-1: NAS Security Mode Command procedure. In step 1b of Fig.17, it can be seen that the AMF selects and indicates to UE: Option 1: - NIA0 and NEA0 SHALL BE INDICATED as Integrity algorithm and Ciphering algorithm when NEIA1 is selected and indicated in step 1b of Fig.17; or, Option 2: - If NEIA1 takes precedence over the Integrity algorithm indicated as either NIA0 / 1 / 2 / 3 / 4 and Ciphering algorithm indicated as NEA0 / 1 / 2 / 3 / 4, then it does not matter which integrity algorithm or ciphering algorithm are indicated in step 1b and it is okay. Both integrity protection and encryption are enabled with NEIA1 using single key How gNB indicates to the UE to use AEAD algorithm (for integrity protection and / or encryption): This is illustrated with reference to 3GPP TS 38.331 v17.5.0, procedure AS Security Mode Command, clause SecurityAlgorithmConfig, where highlighted parts indicate new additions and struck-through parts indicate new deletions. – SecurityAlgorithmConfig The IE SecurityAlgorithmConfig is used to configure AS integrity protection algorithm and AS ciphering algorithm for SRBs and DRBs. SecurityAlgorithmConfig information element A new algorithm list is included in SecurityAlgorithmConfig information element in AS Security Mode Command. Fig.18 shows signalling between a UE and a gNB / ng-eNB according to Example Scenario 1 of this set of embodiments (as described above with reference to Fig.17). Fig.18 is based on TS 33.501, Figure 6.7.4-1: AS Security Mode Command Procedure. In step 1b of Fig.18, it can be seen that: Option 1: - NIA0 and NEA0 SHALL BE INDICATED as Integrity algorithm and Ciphering algorithm when NEIA1 for “encryption and integrity protection” is selected and indicated; or, Option 2: - If NEIA1 for “encryption and integrity protection” is selected and indicated, then it takes precedence over Integrity algorithm indicated as either NIA0 / 1 / 2 / 3 / 4 and Ciphering algorithm indicated as NEA0 / 1 / 2 / 3 / 4. It does not matter which integrity algorithm or ciphering algorithm are indicated in step 1b and it is okay. Both integrity protection and encryption enabled with NEIA1 using single key. Fig.19 shows signalling between a UE and a gNB / ng-eNB according to Example Scenario 2 of this set of embodiments. Fig.19 is based on TS 33.501, Figure 6.7.4-1: AS Security Mode Command Procedure. In step 1b of Fig.19, it can be seen that: - NEA0 or NEA1 or NEA2 or NEA3 or NEA4 or NEA5 or NEA6 or NEA7 is selected as the encryption algorithm. NIA1 or NIA2 or NIA3 or NIA4 or NIA5 or NIA6 or NIA6 is selected as integrity algorithm. - The AMF is only allowed to select and indicate NEA1 / 2 / 3 / 4 / 5 / 6 / 7 and NEA0 / 1 / 2 / 3 / 4 / 5 / 6 / 7, if NEIA0 for “encryption and integrity protection” is indicated. Embodiment Set 5 – Key hierarchy in NAS layer In this set of embodiments, a new 128-bit or 256-bit key(s) are used in NAS layer. This new key is denoted KNASaead. Option 1: A new KNASaeadcan be used only for usage of AEAD for both encryption and integrity protection, when both integrity and encryption are enabled, and when AEAD algorithm is selected. Option 2: A new KNASaead can be used when AEAD algorithm is selected, and when: - only integrity protection (MAC) is enabled; - only encryption is enabled; and - for both encryption and integrity protection, when both integrity and encryption are enabled. Option 3: Three new keys KNASaead-enc, KNASaead-int and KNASaead-enc-then-MAC can be used when AEAD algorithm is selected, and when: - KNASaead-intis used when only integrity protection (MAC) is enabled; and - KNASaead-encis used when only encryption is enabled; and - KNASaead-enc-intis used for AEAD usage of both encryption and integrity protection, when both integrity and encryption are enabled, and a single key is used. Option 1 and Option 2 are illustrated in Figs.20 and 21. Fig.20 shows the key hierarchy, and Fig. 21 shows the derivation of the keys. In Fig. 21, * = “N-NAS-aead-alg” is a textstring, and “Alg-ID” is the code point in integrity algorithm list or encryption algorithm list. If the key length of the AEAD algorithm is 256-bit, then no truncation operation is executed. Option 3 is illustrated in Fig.22, which shows a key distribution and key derivation scheme for 5G for network nodes. New 256-bit keys in NAS layer KNAS-aead-int, KNAS-aead-enc-intand KNAS-aead-encare shown. In Fig. 22, (*1) = “N-NAS-aead-int-alg” is a textstring, and “Alg-ID” is the code point in integrity algorithm list. (*2) = “N-NAS-aead-enc-int-alg” is a textstring, and “Alg- ID” is the code point in integrity algorithm list or encryption algorithm list. (*3) = “N-NAS-aead- enc-alg” is a textstring, and “Alg-ID” is the code point in encryption algorithm list. If the key length of the AEAD algorithm is 128-bit, then truncation operation of 256-bit keys are executed as shown in Fig.22. Another option is shown in Fig.23 where three keys are generated from the KNASaeadwhich is derived from KAMFas for Option 1 and 2. From the intermediate key, KNAS-aead, three new keys are derived or generated: - an integrity key, KNAS-aead-enc-int, for integrity protection of NAS signalling. - an encryption key, KNAS-aead-enc, for encryption of NAS signalling. - a single key for encryption and integrity protection, KNAS-aead-enc-int, for encryption and integrity protection of NAS signalling. In Fig. 23, (*1) = “N-NAS-aead-int-alg” is a textstring, and “Alg-ID” is the code point in integrity algorithm list or encryption algorithm list. (*2) = “N-NAS-aead-enc-int-alg” is a textstring, and “Alg-ID” is the code point in integrity algorithm list or encryption algorithm list. (*3) = “N-NAS-aead-enc-alg” is a textstring, and “Alg-ID” is the code point in encryption algorithm list. Embodiment Set 6 – Key hierarchy in AS layer Option 1: When the AEAD algorithm is selected, KRRC-aead and KUP-aead can be used only for AEAD for the encryption and integrity protection, when both integrity and encryption are enabled. Option 2: When the AEAD algorithm is selected, KRRC-aead and KUP-aead can be used when: - only integrity protection (MAC) is enabled, and - only encryption is enabled, and - also for both encryption and integrity protection in AEAD, when both integrity and encryption are enabled. In this Option, the same algorithm will be used for protection of RRC and UP. Option 3: When the AEAD algorithm is selected, three new keys KRRC-aead-enc, KRRC-aead-intand KRRC-aead-enc-int can be used: - KRRC-aead-intis used when only integrity protection (MAC) of user plane data traffic is enabled, and - KRRC-aead-encis used when only encryption of user plane data traffic is enabled, and - KRRC-aead-enc-intis used for AEAD for encryption and integrity protection of user plane data traffic, when both integrity and encryption are enabled, and a single key is used. Option 4: This option is similar to Option 3. When the AEAD algorithm is selected, three new keys KUP-aead-enc, KUP-aead-int and KUP-aead-enc-int can be used: - KUP-aead-intis used when only integrity protection (MAC) of RRC messages is enabled, and - KUP-aead-encis used when only encryption of RRC messages is enabled, and - KUP-aead-enc-intis used for AEAD for encryption and integrity protection, when both integrity and encryption are enabled, and a single key is used. Figs. 24 and 25 illustrates Options 1 and 2. Fig.24 shows the legacy key hierarchy in 5G system specified in TS 33.501, and Fig.25 shows the legacy Key distribution and key derivation scheme for 5G for network nodes specified in TS 33.501, with an extension of two new intermediate keys: KUP-aead and KRRC-aead. KUP-aeadis a new key generated from KgNBwhich is defined as a new master key for user plane protection and is used to derive or generate further keys as: - encryption key (KUP-aead-enc) for encryption of user plane traffic; and - integrity key (KUP-aead-int) for integrity protection of user plane traffic; and - a new type of key when using a single key (KUP-aead-enc-int) for encrypting and integrity protection of user data traffic. These new keys ((KUP-aead-enc, KUP-aead-int, KUP-aead-enc-int) are not shown in Fig.25. KRRC-aeadis a new key generated from KgNBwhich is defined as a new master key for radio signalling protection and is used to derive or generate further keys: - encryption key (KRRC-aead-enc) for encryption of RRC signalling; and - integrity key (KRRC-aead-int) for RRC signalling; and - a new type of key when using a single key (KRRC-aead-enc-int) for encrypting and integrity protection for RRC signalling. These new keys ((KRRC-aead-enc, KRRC-aead-int, KRRC-aead-enc-int) are not shown in Fig.25. If the key length of the AEAD algorithm is 128-bit, then truncation operation of 256-bit keys are executed. In Option 3, there are three new 256-bit keys in the AS layer for RRC: KRRC-aead-enc, KRRC-aead-intand KRRC-aead-enc-int, and three new 256-bit keys in AS layer for UP: KUP-aead-enc, KUP-aead-intand KUP-aead-enc-int. This is illustrated in Fig.26 showing how to derive these new keys from KgNB. Fig. 26 shows the legacy key distribution and key derivation scheme for 5G for network nodes specified in TS 33.501, with an extension of six potential new keys. The following keys are generated directly from KgNB: - encryption key ( KUP-aead-enc) for encryption of user plane traffic; and - integrity key (KUP-aead-int) for integrity protection of user plane traffic; and - a new type of key when using a single key (KUP-aead-enc-int) for encrypting and integrity protection of user data traffic. - encryption key (KRRC-aead-enc) for encryption of RRC signalling; and - integrity key (KRRC-aead-int) for RRC signalling; and - a new type of key when using a single key (KRRC-aead-enc-int) for encrypting and integrity protection for RRC signalling. These new keys (KUP-aead-enc, KUP-aead-int, KUP-aead-enc-int,KRRC-aead-enc, KRRC-aead-int, KRRC-aead-enc-int) are shown in Fig.26. If the key length of the AEAD algorithm is 128-bit, then truncation operation of 256-bit keys are executed. In Fig.26, (*1) = “N-RRC-aead-int-alg” is a textstring, and “Alg-ID” is the code point in integrity algorithm list or encryption algorithm list. (*2) = “N-RRC-aead-enc-int -alg” is a textstring, and “Alg-ID” is the code point in integrity algorithm list or encryption algorithm list. (*3) = “N-UP-aead-int-alg” is a textstring, and “Alg-ID” is the code point in integrity algorithm list or encryption algorithm list. (*4) = “N-UP-aead-enc-int -alg” is a textstring, and “Alg-ID” is the code point in integrity algorithm list or encryption algorithm list. (*5) = “N-RRC-aead-enc- alg” is a textstring, and “Alg-ID” is the code point in encryption algorithm list. (*6) = “N-UP- aead-enc-alg” is a textstring, and “Alg-ID” is the code point in encryption algorithm list. Another option is illustrated in Fig. 27 where three keys are generated from the KRRC-saead which is derived from KbNGas for Option 1 and 2. From the intermediate key, KRRC-aead, three new keys are derived or generated: - an integrity key, KRRC-aead-enc-int, used for integrity protection of RRC signalling. - an encryption key, KRRC-aead-enc, used for encryption of RRC signalling. - a single key for encryption and integrity protection, KRRC-aead-enc-int, used for encryption and integrity protection of RRC signalling. In Fig. 27, (*1) = “N-RRC-aead-int-alg” is a textstring, and “Alg-ID” is the code point in integrity algorithm list. (*2) = “N-RRC-aead-enc-int -alg” is a textstring, and “Alg-ID” is the code point in integrity algorithm list or encryption algorithm list. (*3) = “N-RRC-aead-enc-alg” is a textstring, and “Alg-ID” is the code point in encryption algorithm list. FIG. 28 shows an example of a communication system 3100 in accordance with some embodiments. In the example, the communication system 3100 includes a telecommunication network 3102 that includes an access network 3104, such as a radio access network (RAN), and a core network 3106, which includes one or more core network nodes 3108. The access network 3104 includes one or more access network nodes, such as access network nodes 3110a and 3110b (which are interchangeably referred to as RAN network nodes 3110 herein), or any other similar 3rdGeneration Partnership Project (3GPP) access node or non-3GPP access point (AP). Moreover, as will be appreciated by those of skill in the art, a RAN network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, the telecommunication network 3102 includes one or more Open-RAN (ORAN) network nodes. An ORAN network node is a node in the telecommunication network 3102 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other nodes to implement one or more functionalities of any node in the telecommunication network 3102, including one or more network nodes 3110 and / or core network nodes 3108. The access network nodes 3110 facilitate direct or indirect connection of wireless devices (also referred to interchangeably herein as user equipment (UE)), such as by connecting UEs 3112a, 3112b, 3112c, and 3112d (one or more of which may be generally referred to as UEs 3112) to the core network 3106 over one or more wireless connections. The access network nodes 3110 may be, for example, access points (APs) (e.g. radio access points), base stations (BSs) (e.g. radio base stations, Node Bs, evolved Node Bs (eNBs) and New Radio (NR) NodeBs (gNBs)). Unless otherwise indicated, the general term ‘network node’ as used herein refers to access network nodes 3110 and core network nodes 3108. In the depicted example, the core network 3106 connects the access network nodes 3110 to one or more hosts, such as host 3116. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network 3106 includes one more core network nodes (e.g. core network node 3108) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the wireless devices / UEs, access network nodes, and / or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node 3108. In the example illustrated in FIG.28, the hub 3114 communicates with the access network 3104 to facilitate indirect communication between one or more UEs (e.g. UE 3112c and / or 3112d) and access network nodes (e.g. access network node 3110b). FIG.29 shows a wireless device or UE 3200 in accordance with some embodiments. The UE 3200 includes processing circuitry 3202 that is operatively coupled via a bus 3204 to an input / output interface 3206, a power source 3208, a memory 3210, a communication interface 3212, and / or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in FIG.29. The level of integration between the components may vary from one UE to another UE. Further, certain UEs may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc. The processing circuitry 3202 may be configured to communicate with an access network or other network using the communication interface 3212. The communication interface 3212 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 3222. The communication interface 3212 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g. another UE or a network node in an access network). Each transceiver may include a transmitter 3218 and / or a receiver 3220 appropriate to provide network communications (e.g. optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 3218 and receiver 3220 may be coupled to one or more antennas (e.g. antenna 3222) and may share circuit components, software or firmware, or alternatively be implemented separately. FIG.30 shows an access network node 3300 or RAN network node 3300 in accordance with some embodiments. The RAN network node 3300 includes processing circuitry 3302, a memory 3304, a communication interface 3306, and a power source 3308, and / or any other component, or any combination thereof. The RAN network node 3300 may be composed of multiple physically separate components (e.g. a NodeB component and a RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. In certain scenarios in which the RAN network node 3300 comprises multiple separate components (e.g. BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, the RAN network node 3300 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g. separate memory 3304 for different RATs) and some components may be reused (e.g. a same antenna 3310 may be shared by different RATs). The RAN network node 3300 may also include multiple sets of the various illustrated components for different wireless technologies integrated into RAN network node 3300, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, LoRaWAN, Radio Frequency Identification (RFID) or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within RAN network node 3300. Fig.31 shows a core network node 3700 in accordance with some embodiments. The core network node 3700 includes processing circuitry 3702, a memory 3704, a communication interface 3706, and a power source 3708, and / or any other component, or any combination thereof. The core network node 3700 may be composed of multiple physically separate components, which may each have their own respective components. In certain scenarios in which the core network node 3700 comprises multiple separate components, one or more of the separate components may be shared among several core network nodes. FIG.32 is a block diagram illustrating a virtualization environment 3500 in which functions implemented by some embodiments may be virtualized. In particular, the functions or operations of the AMF, or other type of mobility management node can be virtualized using virtualization environment 3500. Applications 3502 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment 3500 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein. Hardware 3504 includes processing circuitry, memory that stores software and / or instructions executable by hardware processing circuitry, and / or other hardware devices as described herein, such as a network interface, input / output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers 3506 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 3508a and 3508b (one or more of which may be generally referred to as VMs 3508), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. The virtualization layer 3506 may present a virtual operating platform that appears like networking hardware to the VMs 3508. The foregoing merely illustrates various principles of the disclosure. Various modifications and alterations to the described embodiments will be apparent to those skilled in the art in view of the teachings herein. It will thus be appreciated that those skilled in the art will be able to devise numerous systems, arrangements, and procedures that, although not explicitly shown or described herein, embody the principles of the disclosure and can be thus within the scope of the disclosure. Various exemplary embodiments can be used together with one another, as well as interchangeably therewith, as should be understood by those having ordinary skill in the art.

Claims

CLAIMS:

1. A method performed by a user equipment, UE, comprising: sending a capability message to a network node in a communication network, the capability message indicating that the UE supports use of an Authenticated Encryption with Associated Data, AEAD, algorithm, wherein an AEAD algorithm is an algorithm that can be used for encryption of communications and integrity protection of communications.

2. The method of claim 1, wherein the capability message further indicates whether the UE supports the use of the AEAD algorithm for encryption, supports the use of the AEAD algorithm for integrity protection, or supports the use of the AEAD algorithm for encryption and integrity protection.

3. The method of claim 1 or 2, wherein the capability message is a registration request for registering the UE to the communication network.

4. The method of any of claims 1-3, wherein the capability message comprises, a UE security capability information element, IE.

5. The method of claim 4, wherein the support for the use of the AEAD algorithm is indicated in octet7 and / or octet8 of the UE Security capability IE.

6. The method of any of claims 1-5, wherein: (i) the capability message indicates support for the use of the AEAD algorithm for encryption only if a field for an encryption algorithm in the capability message indicates the AEAD algorithm, and a field for an integrity protection algorithm in the message is empty or a null value; (ii) the capability message indicates support for the use of the AEAD algorithm for integrity protection only if a field for an integrity protection algorithm in the capability message indicates the AEAD algorithm, and a field for an encryption algorithm in the capability message is empty or a null value; (iii) the capability message indicates support for the use of the AEAD algorithm for encryption and for integrity protection if a field for an encryption algorithm in the capability message indicates the AEAD algorithm, and a field for an integrity protection algorithm in the capability message indicates the AEAD algorithm.

7. The method of any of claims 1-6, wherein the network node is a mobility management node.

8. A method performed by a user equipment, UE, the method comprising: receiving a command message from a network node in a communication network, the command message indicating an Authenticated Encryption with Associated Data, AEAD, algorithm that is to be used for encryption of communications and / or integrity protection of communications.

9. The method of claim 8, wherein the command message further indicates whether the AEAD algorithm is to be used for encryption of communications with the UE, integrity protection of communications with the UE, or both encryption and integrity protection of communications with the UE.

10. The method of claim 8 or 9, wherein the command message is a security mode command for Non-Access Stratum, NAS, communications or a security mode command for Access Stratum, AS, communications.

11. The method of any of claims 8-10, wherein: (i) the command message indicates the UE is to use the AEAD algorithm for encryption only if a field for an encryption algorithm in the command message indicates the AEAD algorithm, and a field for an integrity protection algorithm in the command message is empty or a null value; (ii) the command message indicates the UE is to use the AEAD algorithm for integrity protection only if a field for an integrity protection algorithm in the command message indicates the AEAD algorithm, and a field for an encryption algorithm in command the message is empty or a null value; (iii) the command message indicates the UE is to use the AEAD algorithm for encryption and for integrity protection if a field for an encryption algorithm in the command message indicates the AEAD algorithm, and a field for an integrity protection algorithm in the command message indicates the AEAD algorithm.

12. The method of any of claims 8-11, wherein the network node is a mobility management node or a radio access network, RAN, node.

13. The method of any of claims 1-7, further comprising the method of any of claims 8-12.

14. A method performed by a network node in a communication network, comprising: receiving a capability message, the message indicating that a User Equipment, UE, supports use of an Authenticated Encryption with Associated Data, AEAD, algorithm, wherein an AEAD algorithm is an algorithm that can be used for encryption of communications and integrity protection of communications.

15. The method of claim 14, wherein the received capability message further indicates whether the UE supports the use of the AEAD algorithm for encryption, supports the use of the AEAD algorithm for integrity protection, or supports the use of the AEAD algorithm for encryption and integrity protection.

16. The method of claim 14 or 15, further comprising: selecting, based on the AEAD algorithm indicated in the received capability message, an AEAD algorithm for the UE to use for encryption of communications and / or for integrity protection of communications.

17. The method of claim 16, further comprising: sending a command message to the UE, the command message indicating the selected AEAD algorithm that is to be used for encryption of communications and / or integrity protection of communications by the UE.

18. The method of claim 17, wherein the command message is a security mode command for Non-Access Stratum, NAS, communications or a security mode command for Access Stratum, AS, communications.

19. The method of claim 17 or 18, wherein: (i) the command message indicates the UE is to use the selected AEAD algorithm for encryption only if a field for an encryption algorithm in the command messageindicates the selected AEAD algorithm, and a field for an integrity protection algorithm in the command message is empty or a null value; (ii) the command message indicates the UE is to use the selected AEAD algorithm for integrity protection only if a field for an integrity protection algorithm in the command message indicates the selected AEAD algorithm, and a field for an encryption algorithm in command the message is empty or a null value; (iii) the command message indicates the UE is to use the selected AEAD algorithm for encryption and for integrity protection if a field for an encryption algorithm in the command message indicates the selected AEAD algorithm, and a field for an integrity protection algorithm in the command message indicates the selected AEAD algorithm.

20. The method of any of claims 14-19, wherein the network node is a mobility management node, the capability message is received from the UE, and the method further comprises: sending a further capability message to a radio access network, RAN, node, the further capability message indicating the AEAD algorithm supported by the UE.

21. The method of any of claims 14-20, wherein the received capability message is a registration request for registering the UE to the communication network.

22. The method of any of claims 14-19, wherein the network node is a radio access network, RAN, node, and the capability message is received from a mobility management node in the communication network.

23. The method of any of claims 14-22, wherein the capability message is, or comprises, a UE security capability information element, IE.

24. The method of claim 23, wherein the support for the use of the AEAD algorithm is indicated in octet7 and / or octet8 of the UE Security capability IE.

25. The method of any of claims 14-24, wherein: (iv) the received capability message indicates support for the use of the AEAD algorithm for encryption only if a field for an encryption algorithm in the receivedcapability message indicates the AEAD algorithm, and a field for an integrity protection algorithm in the received message is empty or a null value; (v) the received capability message indicates support for the use of the AEAD algorithm for integrity protection only if a field for an integrity protection algorithm in the received capability message indicates the AEAD algorithm, and a field for an encryption algorithm in the received capability message is empty or a null value; (vi) the received capability message indicates support for the use of the AEAD algorithm for encryption and for integrity protection if a field for an encryption algorithm in the received capability message indicates the AEAD algorithm, and a field for an integrity protection algorithm in the received capability message indicates the AEAD algorithm.

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