hash stringlengths 32 32 | doc_id stringlengths 5 12 | section stringlengths 5 1.47k | content stringlengths 0 6.67M |
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03f08e095da0e7d00cf764af0a02ab5a | 33.777 | 6.1.6.3 Evaluation
| Editor’s Note: Each solution should motivate how the potential security requirements of the key issues being addressed are fulfilled.
This solution fullfills the potential security requirements of key issue #1:
Sensing Service Consumer (AF) authentication and auhtorization at the NEF as well as integrity protection, confidentiality protection and replay protection for the communication between sensing service consumer and NEF is performed according to TS 33.501 [5].
The sensing service request from a sensing service consumer is authorized by the Sensing Function according to TS 23.700-14 [2].
Editor’s Note: Whether the solution fulfills all SA2 use cases is FFS.
6.1.7 Solution #1.7: Security of authorization of sensing service and sensing results exposure
|
03f08e095da0e7d00cf764af0a02ab5a | 33.777 | 6.1.7.1 Introduction
| This solution addresses the Key Issue #1 (security of sensing service authorization and sensing result exposure). Authentication, communication security, and authorization aspects for NEF and AF interaction have already been specified in Clause 12 of TS 33.501 [5]. The interface between the sensing service consumer acting as an AF and the NEF, is the same interface whose security is addressed in Clause 12 of TS 33.501 [5].
NEF sends the sensing service request to a Sensing Function (SF) after performing AF authorization. NEF and SF interaction can reuse the authentication, communication security, and authorization aspects specified in Clause 13 of TS 33.501 [5]. The SF performs authorization of the sensing service operation, considering, for instance, the received parameters for the requested sensing service (e.g., Target Sensing Area, Sensing Service Type) and information about the sensing service consumer (e.g., AF Identifier). The SF uses the local sensing policies to perform authorization of the sensing service operation.
If authorized, the sensing service is executed, the SF provides the final sensing results to NEF. The NEF exposes the final sensing results to the authorized AF. The authentication, communication security, and authorization aspects for final sensing results exposure from NEF to AF can reuse the Clause 12 of TS 33.501 [5].
Editor’s Note: The architecture and workflow needs to inline with SA2.
|
03f08e095da0e7d00cf764af0a02ab5a | 33.777 | 6.1.7.2 Solution details
| Two network entities may be involved to perform authorization of the sensing service requested by a sensing service consumer (AF) from the network. After receiving a sensing service request, NEF determines whether the sensing service consumer is authorized to invoke sensing APIs to the network. The security mechanism, specified in Clause 12 of TS 33.501 [5], is reused to address the security requirements of mutual authentication, integrity protection, confidentiality protection, replay protection, authorization for the communication between sensing service consumer and NEF.
In case the sensing service consumer is authorized to invoke sensing APIs to the network, the NEF determines parameters for the request and then sends the sensing service request to an SF. Otherwise, the NEF rejects the sensing service request due to authorization failure.
NOTE 1: How the NEF discovers and selects an SF to handle a specific sensing service request is outside the scope of this solution.
The security mechanism, specified in Clause 13 of TS 33.501 [5], is reused to address the security requirements of mutual authentication, integrity protection, confidentiality protection, replay protection, authorization for the communication between NEF and SF.
The SF performs a sensing request specific authorization in the implementation specific way, considering for instance, the received parameters for the requested sensing service (e.g., Target Sensing Area, Sensing Service Type, Sensing service time duration), information about the sensing service consumer (e.g., AF Identifier). The SF uses the local sensing policies to perform the sensing request authorization using the parameters of sensing request. Local sensing policies contains information about area restrictions, i.e. whether the application (based on AF Identifier) is authorized to request a sensing service in a particular area.
In case of successful authorization, the SF proceeds with the requested sensing service. If the SF determines not to grant the authorization, the sensing service request is rejected and the sensing service consumer is informed.
Procedure for a consumer-requested sensing service authorization performed by the core network entities is shown in Figure 6.1.7.2-1.
Figure 6.1.7.2-1: Procedure of the sensing service authorization and exposure
1. AF invokes a sensing service request to a NEF.
2. The NEF authenticates the AF and determines whether the AF is authorized to request sensing services from the network, i.e., to invoke sensing service-specific APIs using clause 12 of TS 33.501 [5].
3. If the authorization is not granted, the NEF sends the response to AF indicating that the authorization has failed, and all further steps are skipped.
4. If the authorization is granted, the NEF sends the sensing service request to the SF and includes parameters from the AF (e.g., Target Sensing Area, Sensing Service Type, Sensing service time duration) and information about the sensing service consumer (e.g., AF Identifier); if required, the NEF maps parameters from AF sensing service request to 3GPP internal parameters e.g., the External Target Sensing Area to a Target Sensing Area
5. The SF performs a sensing request specific authorization in the implementation specific way using the local sensing policies, considering, for instance, target sensing area, AF identifier, and other parameters from the sensing service request.
6-7. If the SF does not grant the authorization for the requested sensing service operation, the SF rejects the request and responds (via NEF) to the sensing service consumer indicating that the authorization has failed, and all further steps are skipped.
8. If the authorization is granted, the sensing service continues to provide the requested sensing result to SF.
9. SF provides the final sensing results to the NEF. The security mechanism, specified in Clause 13 of TS 33.501 [5], is reused to address the security requirements of mutual authentication, integrity protection, confidentiality protection, replay protection, authorization for the communication between SF and NEF.
10. NEF exposes the final sensing results to the AF. The security mechanism, specified in Clause 12 of TS 33.501 [5], is reused to address the security requirements of mutual authentication, integrity protection, confidentiality protection, replay protection, authorization for the communication between NEF and AF.
|
03f08e095da0e7d00cf764af0a02ab5a | 33.777 | 6.1.7.3 Evaluation
| The solution addresses the security of sensing service authorization and security of sensing results exposure. It fulfils all the security requirements mentioned in Key Issue #1.
Editor’s Note: Whether the solution fulfills all SA2 use cases is FFS.
|
03f08e095da0e7d00cf764af0a02ab5a | 33.777 | 6.2 Solutions to KI#2
| |
03f08e095da0e7d00cf764af0a02ab5a | 33.777 | 6.2.1 Solution #2.1: Security for sensing service operation
| |
03f08e095da0e7d00cf764af0a02ab5a | 33.777 | 6.2.1.1 Introduction
| This solution addresses the following requirement of Key Issue #2: Security protection for sensing service operations: “The 5G system shall be able to support integrity protection, confidentiality protection and replay protection for the connection between sensing entity and SF.”
|
03f08e095da0e7d00cf764af0a02ab5a | 33.777 | 6.2.1.2 Solution details
| The solution proposes a security mechanism to secure the connection between the sensing entity and SF.
For the interface between the sensing entities and SF, the communication between the sensing entity and the SF is secured by the NDS/IP security procedures specified in TS 33.210 [7].
Editor’s Note: Whether using direct connection between sensing function and sensing entity for control sensing operation and report sensing data needs to align with SA WG2.
|
03f08e095da0e7d00cf764af0a02ab5a | 33.777 | 6.2.1.3 Evaluation
| This solution addresses the following requirement of Key Issue #2: Security protection for sensing service operations: “The 5G system shall be able to support integrity protection, confidentiality protection and replay protection for the connection between sensing entity and SF.”
This solution is based on the assumption that there is a direct connection between SF and sensing entity for control sensing operation and report sensing data.
This solution reuses existing mechanism to secure the communication between sensing entity and SF. No new mechanism is introduced.
6.2.2 Solution #2.2: Security of the connection between Sensing Entity and SF
|
03f08e095da0e7d00cf764af0a02ab5a | 33.777 | 6.2.2.1 Introduction
| This solution aims to address Key Issue #2.
This solution to secure the connection between Sensing Entity and Sensing Function (SF). SF is responsible for to handle both sensing service control and sensing data processing.
|
03f08e095da0e7d00cf764af0a02ab5a | 33.777 | 6.2.2.2 Solution details
| The SF supports a direct interface (e.g. Nx interface) to send the sensing service control signalling to sensing entity, and the sensing entity uses the same interface to reply the sensing data to the SF.
In this architecture, the integrity protection, confidentiality protection and replay protection for the connection between sensing entity and SF are offered by:
• IPsec ESP and IKEv2 certificates-based authentication as specified in sub-clause 9.1.2 of [5]. IPsec is mandatory to implement on the Sensing Entity. On the SF side, a SEG may be used to terminate the IPsec tunnel.
• In addition to IPsec, DTLS shall be supported as specified in RFC 6083 [11]. Security profiles for DTLS implementation and usage shall follow the TLS profile given in clause 6.2 of TS 33.210 [7] and the certificate profile given in clause 6.1.3a of TS 33.310 [6]. The identities in the end entity certificates shall be used for authentication and policy checks.
|
03f08e095da0e7d00cf764af0a02ab5a | 33.777 | 6.2.2.3 Evaluation
| This solution assumes the SF and sensing entity are connected via direct connection.
This solution reuses existing mechanisms to address the following security requirement: The 5G system shall be able to support integrity protection, confidentiality protection and replay protection for the connection between sensing entity and SF.
6.2.3 Solution #2.3: Security protection for sensing service operations between sensing entity and SF
|
03f08e095da0e7d00cf764af0a02ab5a | 33.777 | 6.2.3.1 Introduction
| This solution is for security protection for sensing service operations between sensing entity and Sensing Function (SF) Security.
|
03f08e095da0e7d00cf764af0a02ab5a | 33.777 | 6.2.3.2 Solution details
| Security between SF (Sensing Function) and sensing entity is same as security procedures for non-service based interface security defined in clause 9 of 33.501 [5] using DTLS/IPsec.
Security profiles for DTLS implementation and usage shall follow the TLS profile given in clause 6.2 of TS 33.210 [6] and the certificate profile given in clause 6.1.3a of TS 33.310 [7].
Editor’s Note: This solution is under the assumption that deployment option is direct connection between sensing entity and SF. Need to update according to sensing architecture progress in TR 23.700-14.
|
03f08e095da0e7d00cf764af0a02ab5a | 33.777 | 6.2.3.3 Evaluation
| Editor’s Note: Each solution should motivate how the potential security requirements of the key issues being addressed are fulfilled.
6.X Solutions to KI#X
6.X.Y Solution #X.Y: <Solution Title>
6.X.Y.1 Introduction
Editor’s Note: Each solution should list the key issues being addressed.
6.X.Y.2 Solution details
6.X.Y.3 Evaluation
Editor’s Note: Each solution should motivate how the potential security requirements of the key issues being addressed are fulfilled.
|
03f08e095da0e7d00cf764af0a02ab5a | 33.777 | 7 Conclusions
| Editor's Note: This clause contains the agreed conclusions that will form the basis for any normative work.
7.X Conclusions for KI#1
If the sensing service consumer is the third-party AF, already existing security mechanisms in clause 12 of TS 33.501 [5] are reused to provide mutual authentication, authorisation, integrity protection, confidentiality protection and replay protection between sensing service consumer and the NEF.
NOTE: third-party AF, as defined in TS 33.501, corresponds to the AF outside the trusted domain in section 7.2 of TR 23.700-14.
Editor’s Note: Further conclusion is FFS.
Annex X:
Change history
Change history
Date
Meeting
TDoc
CR
Rev
Cat
Subject/Comment
New version
2025-08
SA3#123
S3-252869
Skeleton for ISAC Security TR
0.0.0
2025-09
SA3#123
S3-253011
Implemented S3-252693, S3-253012, S3-253013 and S3-253014
0.1.0
2025-10
SA3#124
S3-253728
Included changes from S3-253744, S3 253856, S3-253849, S3-253850. S3-253746, S3-253747, S3-253748, S3-253851,S3-253751, S3-251750, S3-253852, S3-253357
0.2.0
2025-11
SA3#125
S3-254538
Included changes from S3-254603, S3-254750, S3-254751, S3-254604, S3-254196, S3-254605, S3-254606, S3-254249, S3-254607, S3-254608, S3-254609, S3-254610, S3-254611, S3-254612, S3-254151, S3-254613, S3-254614, S3-254615, S3-254616
0.3.0
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 1 Scope
| The present document identifies potential challenges and requirements for supporting AEAD algorithms specified in TS 35.240 [2], TS 35.243 [3], and TS 35.246 [4] for NAS and AS security (including control and user plane security) in the 6G System, including the following:
- Impact to AS and NAS security
- Key hierarchy and management to support AEAD algorithms
NOTE 1: Key hierarchy includes long term key (i.e. full key hierarchy) for usage of AEAD. Procedure aspects (e.g. AKA framework) are not covered in the present document.
- Negotiation of encryption and/or integrity protection when using AEAD algorithms
- Creation and handling of AEAD algorithm inputs, such as Nonce and Associated Data
Co-existence of AEAD-compatible systems and legacy deployments and algorithms (i.e., only AEAD algorithms or both AEAD and standalone algorithms) is taken into account.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 2 References
| The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
- References are either specific (identified by date of publication, edition number, version number, etc.) or non‑specific.
- For a specific reference, subsequent revisions do not apply.
- For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.
[1] 3GPP TR 21.905: “Vocabulary for 3GPP Specifications”.
[2] 3GPP TS 35.240 Specification of the Snow 5G based 256-bits algorithm set: specification of the 256-NEA4 encryption, the 256-NIA4 integrity, and the 256-NCA4 authenticated encryption algorithm for 5G; Document 1: algorithm specification
[3] 3GPP TS 35.243 Specification of the AES based 256-bits algorithm set: Specification of the 256-NEA5 encryption, the 256-NIA5 integrity, and the 256-NCA5 authenticated encryption algorithm for 5G; Document 1: algorithm specification
[4] 3GPP TS 35.246 Specification of the ZUC based 256-bits algorithm set: Specification of the 256-NEA6 encryption, the 256-NIA6 integrity, and the 256-NCA6 authenticated encryption algorithm for 5G; Document 1: algorithm specification
[5] 3GPP TS 33.501: “Security architecture and procedures for 5G System”.
[6] RFC 5116, “Authenticated Encryption with Associated Data”
[7] 3GPP TR 33.801-01: “Study on Security for the 6G System”.
3 Definitions and abbreviations
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 3.1 Terms
| For the purposes of the present document, the terms given in TR 21.905 [1] and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905 [1].
Example: text used to clarify abstract rules by applying them literally.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 3.2 Symbols
| For the purposes of the present document, the following symbols apply:
<symbol> <Explanation>
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 3.3 Abbreviations
| For the purposes of the present document, the abbreviations given in TR 21.905 [1] and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in TR 21.905 [1].
AEAD Authenticated Encryption with Associated Data
AKA Authentication and Key Agreement
AMF Access and Mobility Management
AS SMC Access Stratum Security Mode Command
NAS SMC Non-Access Stratum Security Mode Command
RAN Radio Access Network
TMSI Temporary Mobile Subscriber Identity
UE User Equipment
USIM Universal Subscriber Identity Module
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 4 Overview and assumption
| Editor’s Note: This clause gives a brief explanation for background information of this SID, e.g. security assumption, existing algorithm specifications and a brief description of AEAD.
The solution of present document does not cover architecture dependent procedure aspects, such as Xn handover, but will cover architecture independent procedure, such as NAS and AS SMC. Therefore, the objective of present document is to conclude general solutions to enable AEAD support algorithms in NAS and AS. Based on the conclusion made in this document (e.g., enhancement for NAS SMC or AS SMC and interface for AEAD algorithms), TR 33.801-01 [7] can develop AEAD related solutions for SA/RAN dependent procedure in its security areas, e.g. develop solutions in key issue security algorithm negotiation in security areas of RAN security or UE to Core Network Security.
One of the main issues in the consideration of supporting AEAD algorithms is whether to use AEAD only or AEAD-standalone co-existence. The discussion on pros and cons for choosing AEAD only or AEAD-standalone co-existence is expected after analysing different aspects.
Editor’s Note: Definition for AEAD-standalone co-existence is ffs.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 5 Key issues
| Editor’s Note: This clause contains all key issues identified during the study. Due to the nature of this study, not all issues are derived from security threats but all are essential for the adoption of AEAD algorithms in 6G System.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 5.1 Key issue #1: Algorithm selection
| |
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 5.1.1 Key issue details
| The current 5G System uses dedicated algorithms for encryption (NEA0, 128-NEA1, 128-NEA2, 128-NEA3) and integrity protection (NIA0, 128-NIA1, 128-NIA2, 128-NIA3) which are selected independently. This means a given session may use the same or different algorithms for encryption and integrity protection (including NULL), on both AS and NAS layer. Even when using AEAD algorithms that combine encryption and integrity protection, the option to select the NULL algorithm may still be required to signal the use of encryption only or integrity protection only.
Having to support both dedicated encryption and integrity protection algorithms and combined algorithms may complicate implementations without a tangible security benefit. Additionally, providing encryption and integrity protection with a single AEAD algorithm may be preferable in terms of performance to running the dedicated algorithms twice.
Depending on the security policy or scenario, AEAD can provide following protections:
1. Encryption,
2. Integrity protection or
3. Encryption and integrity protection.
When negotiating the AEAD algorithm, it can also be necessary to decide which protections are required.
The key issue is to study following:
- whether AEAD only is sufficient or AEAD and standalone algorithms are required, and
- how to enhance algorithm selection for AEAD algorithms and their protections.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 5.1.2 Security threat
| There is a threat where unintended algorithm being selected if there is no clear definition of the algorithm selection.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 5.1.3 Potential requirements
| Algorithm selection may need an enhancement to support AEAD algorithms.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 5.2 Key issue #2: AEAD algorithm interface
| |
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 5.2.1 Key issue details
| One of the advantages of using a combined AEAD mode is that some important security decisions have already been made in the construction of the mode, such as in which order encryption and integrity protection is applied. From SA3 perspective, this means that we don’t need to discuss in which order operations are to be applied in PDCP and NAS.
Many different AEAD constructs are available and by using a generic interface, it is possible to treat the AEAD as a black box where the underlying construction is transparent to the user of the interface. One such interface is specified in RFC 5116 [6].
Existing interfaces for encryption and integrity algorithms in Annex D.2 and Annex D.3 of TS 33.501 [5] cannot be used for the new AEAD algorithms directly. This is because the new algorithms combine both operations and also require additional input parameters as described in TS 35.240 [2], TS 35.243 [3], TS 35.246 [4]. For example, in addition to the key and IV, an AAD parameter (as described in TS 35.240 [2], TS 35.243 [3], TS 35.246 [4]) is required to enable flexible partial encryption, the output parameters include both the ciphertext and the MAC.
Consequently, how to set the input parameters for NAS and PDCP needs to be further studied because the existing requirements in clause 6.4.3, 6.4.4, 6.5.1, 6.5.2, 6.6.3, 6.6.4 of TS 33.501 [5] cannot be directly applied.
Existing construction of IV for encryption and integrity algorithms in Annex D.2 and Annex D.3 of TS 33.501 [5] contains a 32-bit COUNT, a 5-bit BEARER, a 1-bit DIRECTION. The entropy for the IV might need to increase from the 38 bits defined by 3GPP. Hence, an extra entropy field called EXTRA_IV of 6 bytes is introduced as described in TS 35.240 [2], TS 35.243 [3], TS 35.246 [4].
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 5.2.2 Security threats
| There is a threat to system evolution. For example, if the interface is not designed well from day one, it will not be stable for future enhancements and there can be problems to add new functionality. This will not only increase complexity of the system but will also make it more difficult to analyze from a security perspective, and hence the risk for missing threats increases.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 5.2.3 Potential security requirements
| The input and output parameters (e.g. format, sizes and allowed values) of the AEAD algorithms shall be specified in a way that is independent of the realisation of the AEAD algorithm.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 5.3 Key issue #3: AEAD Keys
| |
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 5.3.1 Key issue details
| The AEAD algorithms differ from the current set of algorithms as they use a single key for both encryption and integrity protection. However, the existing key hierarchy does not include single keys to be used by AEAD algorithms.
As described in clause 6.2 of TS 33.501 [5], the existing 5G key hierarchy is derived from a long-term key to NAS, RRC, and UP keys. These keys follow a structure where two separate 128-bit keys are used: one for encryption and the other for integrity protection. In contrast, AEAD algorithms utilize a single key to perform both encryption and integrity protection.
The key issue is to study how the key derivation needs to be enhanced to cover the key need for the AEAD algorithms.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 5.3.2 Security threats
| Inappropriate AEAD key derivation can lead to breach of confidentiality or integrity.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 5.3.3 Potential security requirements
| 6GS shall support key derivation for the AEAD algorithms.
NOTE: Full key hierarchy is studied in the scope of TR 33.801-01 [7].
5.X Key issue #X: <Key issue name>
Editor’s Note: This clause contains all the key issues identified during the study. Not all key issues may have security threats due to the nature of this study.
5.X.1 Key issue details
5.X.2 Security threat
Editor’s Note: Place holder for a security threat if any.
5.X.3 Potential requirements
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6 Solutions
| Editor’s Note: This clause addresses potential requirements on procedures and protocols to support AEAD algorithms.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.0 Mapping of solutions to key issues
| Table 6.0-1: Mapping of solutions to key issues
Solutions
KI#1
KI#2
KI#3
KI#4
KI#5
Solution 1: NAS and AS SMC enhancement with AEAD
X
Solution 2: enhancement for security mode command
X
Solution 3: NAS SMC enhancement to support AEAD algorithms
X
Solution 4: AEAD Algorithm negotiation
X
Solution 5: AEAD algorithm negotiation
X
Solution 6: AEAD algorithms negotiation
X
Solution 7: AEAD key usage for NAS and AS algorithm
X
Solution 8: Input & output definition
X
Solution 9: Interface of AEAD
X
Solution 10: Creation of EXTRA_IV
X
Solution 11: Key Derivation for NAS and AS AEAD
X
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.1 Solution 1: NAS and AS SMC enhancement with AEAD
| Existing NAS Security mode command procedure, AS security mode procedure, RRC reconfiguration procedure is enhanced with AEAD algorithm selection.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.1.1 Introduction
| This solution addresses the key issue#1.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.1.2 Solution details
| Editor’s Note: Definition/clarification of the AEAD mode is FFS.
Editor’s Note: Clarification on the reuse of the procedures is FFS.
Editor’s Note: Explanation of the purpose of sending the NAS SMC both in plaintext and encrypted is FFS.
NAS and AS procedure (option1)
Overview: With this approach, the AMF and RAN will use AEAD algorithm with NULL encryption option or integrity only mode selected, so only the NAS / AS SMC is integrity protected, when sending it towards UE. UE can verify the integrity of the NAS/AS SMC and send the response NAS SMC with integrity and ciphering, AS SMC with integrity protection alone.
Detailed steps
Step 1 Registration and Authentication is successful.
Step 2 and step 3 The AMF generates NAS AEAD Key. AMF will use selected Algorithm AEAD ID (example: 256-NCA4), the NAS_EXTRA_IV (this value could be newly generated or known value at AMF and UE could be used) to generate MAC-I (AEAD algo is used with NULL encryption or integrity only mode). NAS security mode command which is only integrity protected is sent with selected AEAD algorithm, AEAD mode.
Step 4 The UE will use NAS_Extra_IV (if this value is generated at AMF, then it is sent to UE or if configured at UE and AMF, the same is used) to verify the MAC-I. UE will start the integrity and encryption using AEAD algorithm for the response NAS security mode complete.
Step 3 NGAP initial context setup message with UE capabilities indicating supported AEAD algorithms, gNB key is sent to gNB. The gNB will generate the AS AEAD key.
Step 4 The RAN could generate AS Extra_IV and start integrity protection using AEAD algorithm with NULL encryption or encryption only mode. AS security mode command is sent to UE.
Step 5 UE will verify the MAC and AS_Extra_IV. UE will start integrity protection and ciphering using AEAD algorithm.
NAS and AS procedure (option2)
Overview: With this approach, the AMF and RAN will use AEAD algorithm, so only the NAS / AS SMC is both integrity protected and ciphered. When sending the NAS/AS SMC the AMF/RAN towards UE, the selected AEAD algorithm is ciphered / integrity protected and as plain text as well. UE can verify the integrity of the NAS/AS SMC and send the response NAS/AS SMC complete with integrity and ciphering.
Step 1 UE will have the RRC connection established.
Step 2 The initial NAS message is sent with UE security capabilities with AEAD expanded IE.
Step 3 Further AKA challenge of authentication procedure is completed.
Step 4 AMF will start the ciphering and integrity protection using selected AEAD algorithm. The NAS security mode command will carry the selected AEAD algorithm is ciphered / integrity protected and as plain text as well. UE can verify the MAC and de-cipher the message with help of the selected AEAD algorithm sent in plain text and after de-ciphering the same context is cross checked.
Step 5 RAN will start the ciphering and integrity protection using selected AEAD algorithm. The AS security mode command will carry the selected AEAD algorithm is ciphered / integrity protected and as plain text as well. UE can verify the MAC and de-cipher with help of the selected AEAD algorithm sent in plain text and after de-ciphering the same context is cross checked.
User Plane procedure
The RRC connection reconfiguration procedure is used to add DRBs as part of the PDU session establishment after RRC security has been activated. The gNB sends UP AEAD activation indication including AEAD mode IE for the activation of either UP integrity and ciphering or combined integrity+ ciphering or even NULL ciphering and NULL integrity for each DRB. UE verifies the RRC connection reconfiguration message.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.1.3 Evaluation
| TBD
Editor’s Note: Further evaluation to be added.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.2 Solution 2: enhancement for security mode command
| |
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.2.1 Introduction
| This solution address KI#1: Algorithm selection. Clause 5.11.1 of TS 33.501 [5] defines algorithm identifiers for encryption and integrity protection algorithms. In NAS and AS security mode command message, these identifiers are exchanged between UE and network to decide which algorithm is used for a session. The identifier is 4-bit long, and one identifier is assigned for encryption algorithms, and another is for integrity protection algorithms. Therefore, the current mechanism can support up to 16 encryption algorithms and 16 integrity protection algorithms. There are three 128-bit algorithms and one NULL algorithm. And three 256-bit encryption algorithms and three 256-bit NCA algorithms are defined. Supporting all these algorithms consumes 10 identifiers, which means only 6 are reserved for future extension. The same can be applied to the integrity protection algorithms. In order to reserve room for future extensions, this solution proposes an enhancement to SMC to support more algorithms without consuming many algorithm identifier values. This solution also achieves UE and network to determine in which mode NCA algorithm is performed.
Editor’s Note: The identity space seems to be sufficient. It is ffs why identity space can be a problem and needs to be reserved for future extensions.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.2.2 Solution details
| During the security mode command message exchange, UE sends its security capability. Based on the received security capability, network selects the algorithm and notifies to the UE. This solution proposes to split the security mode command procedures into two phases as shown in Figure 6.2.2-1.
Figure 6.2.2-1 Security mode command with AEAD support
1. In the first message, UE sends its security capability. In this message UE notifies the list of supporting 128-bit algorithms and its ability to use NCA algorithm(s). One identifier is assigned to indicate that UE supports at least one of 256-NCA algorithms, but this does not identify which. After receiving UE capability, the network chooses the algorithm. When one of 128-bit algorithms is chosen, the network notifies the selected algorithm to UE. When one of NCA algorithms is chosen, network send back the identifier which indicates the support of NCA algorithms.
2. Upon receiving the identifier which indicates the supporting NCA algorithms, UE send the list of all NCA algorithms it supports.
3. Network chooses one of NCA algorithms from the list of identifiers based on its policy.
4. Network notifies the selected NCA algorithm to UE.
5. UE sends Security Mode Complete to the network.
The algorithm identifier can be also used to notify in which mode NCA algorithm is performed. The identifier values sent in the second phase can be constructed as to indicate algorithm and its mode, which means three values are allocated for one algorithm.
Editor’s note: It is ffs whether this solution fits into the existing authentication procedures.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.2.3 Evaluation
| Editor’s Note: Place holder for an evaluation if necessary.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.3 Solution 3: NAS SMC enhancement to support AEAD algorithms
| Editor’s Note: This clause contains solutions for key issues. Not all solutions may have evaluation due to the nature of this study.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.3.1 Introduction
| This solution addresses Key Issue #1: Algorithm selection.
This solution proposes to take the existing NAS SMC procedure in clause 6.7.2 of TS 33.501 [5] as baseline and introduce adaption to support AEAD algorithm selection.
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f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.3.2 Solution details
| The enhanced NAS SMC procedure is as depicted in figure 6.3.2-1.
Figure 6.3.2-1: Enhanced NAS Security Mode Command procedure
1a. The AMF decides whether AEAD mode is to be used. If AEAD mode is not to be used, the existing procedures are used for NAS SMC. Otherwise, the AMF derives KNASaead and activates the NAS integrity protection.
1b. The AMF sends the NAS Security Mode Command message to the UE. The NAS Security Mode Command message contains: the replayed UE security capabilities, the selected NAS AEAD algorithm, the ngKSI for identifying the KAMF, and other parameters as specified in clause 6.7.2 of TS 33.501[5].
This message is integrity protected (but not ciphered) with NAS AEAD key KNASaead using the selected AEAD algorithm with “integrity-only” mode.
1c. The AMF activates NAS uplink deciphering after sending the NAS Security Mode Command message.
2a. The UE verifies the NAS Security Mode Command message. This includes checking the UE security capabilities and verifying the integrity protection using the indicated NAS AEAD algorithm with “integrity-only” mode and the NAS AEAD key KNASaead based on the KAMF indicated by the ngKSI.
If the verification of the integrity of the NAS Security Mode Command message is successful, the UE starts NAS integrity protection and ciphering/deciphering with the security context indicated by the ngKSI.
2b. The UE sends the NAS Security Mode Complete message to the AMF ciphered and integrity protected using the selected AEAD algorithm with “integrity+encryption” mode.
The AMF de-ciphers and checks the integrity protection on the NAS Security Mode Complete message using the key KNASaead and the selected AEAD algorithm with “integrity+encryption” mode. NAS downlink ciphering at the AMF with this security context starts after receiving the NAS Security Mode Complete message.
1d. The AMF activates NAS downlink ciphering.
Editor’s Note: How to support optional use of ciphering for NAS security is FFS.
Editor’s Note: Clarification of what is reused and what is the new changes is FFS.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.3.3 Evaluation
| Editor’s Note: Place holder for an evaluation if necessary.
TBD
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.4 Solution 4: AEAD Algorithm negotiation
| |
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.4.1 Introduction
| This solution addresses the key issue #1. The solution lists possible AEAD algorithm negotiation for both AEAD-only and AEAD & standalone options.
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f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.4.2 Solution details
| UE sends UE 6G Security capabilities to the network entity.
The network entity select AEAD algorithm based on the UE 6G Security capabilities and algorithm priority list.
AEAD-only:
The UE 6G Security capabilities only include NCA algorithms, i.e. NCA4, NCA5, NCA6.
The selected AEAD algorithm (e.g. NCA4) is indicated to the UE.
AEAD & standalone:
The UE 6G Security capabilities include NIA and NEA algorithms, e.g. NIA4, NEA4, NIA5, NEA5. Once the UE supports both NIA and NEA for the same algorithm, it means that the UE also supports related NCA. For example, if the UE support both NIA4 and NEA4, it implies that UE also supports NCA4.
Editor’s Note: For case that UE supports both NIA and NEA for the same algorithm, but does not support the related NCA is ffs.
Editor’s Note: For AEAD & standalone algorithms, whether signaling NCA algorithms as UE security capability is sufficient is ffs.
The selected AEAD algorithm (e.g. NCA4) is indicated to the UE.
For both options:
In case that signalling encryption is not activated (e.g. NAS encryption is not activated), an additional indication is indicated to the UE by the network side along with the selected AEAD algorithm. Upon receiving the indication, the UE uses AEAD algorithm to integrity protect the message only.
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f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.4.3 Evaluation
| TBA.
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f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.5 Solution 5: AEAD algorithm negotiation
| |
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.5.1 Introduction
| This solution is proposed to address the key issue#1 on algorithm selection.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.5.2 Solution details
| Each network entity (e.g., RAN, AMF) is assumed to be configured with be one list for NAS AEAD algorithms, similarly to how it is done in TS 33.501[5].
The network entity then initiates a security mode command procedure, and include the chosen algorithm. If the AEAD algorithm is chosen, the whole message including the selected algorithm identifier is put as the input of AAD, which is integrity protected but not ciphered with AEAD key. Based on the local policy, the network entity decides whether to activate the ciphering protection for the subsequent signalling messages. An additional indication on the signalling security activation status is also included.
The UE verifies the Security Mode Command message. If the AEAD algorithm is chosen, the integrity of this message will be verified with AEAD key and the whole message is considered as the input of AAD. The ciphering will be activated or not for the subsequent signalling messages based on the signalling security activation status.
For UP security activation, the existing procedure as specified in clause 6.6 in TS 33.501[5] can be reused.
Editor’s Note: For NAS, it is ffs whether the current NAS SMC procedure is changed. In the current procedure, encryption is not optional after the first message.
Editor’s Note: For UP, it is ffs why such signalling is needed and whether the current procedures that use policies is changed.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.5.3 Evaluation
| TBD
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.6 Solution 6: AEAD algorithms negotiation
| |
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.6.1 Introduction
| This solution proposes to address the security requirement of Key Issue #1.
Based on the UE security capability and network security capability, the UE and the network can negotiate the AEAD algorithms. If the AEAD algorithms are supported by both the UE and network, the network selects one AEAD algorithm for integrity-only protection, confidentiality-only protection, and integrity and confidentiality protection.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.6.2 Solution details
| For AEAD algorithms negotiation, the UE provides its security capability to the network. The network selects the algorithms considering the UE security capability and the associated priority. The network provides the selected algorithms to the UE. The negotiation can be categorized into the following cases:
Case 1: The UE only supports AEAD algorithms, and the network supports both AEAD and standalone algorithms.
Case 2: Both the UE and network support AEAD algorithms and standalone algorithms
For Cases 1 and 2, the AEAD algorithms are prioritized over the standalone algorithms on the network side. One of the AEAD algorithms is selected by the network. The selected AEAD algorithm can be used for integrity-only protection, confidentiality-only protection, or integrity and confidentiality protection.
Editor’s Note: For Case 1 and 2, how to indicate which mode to be used is FFS.
Editor’s Note: AEAD algorithm prioritization is FFS.
Editor’s Note: Whether and how to use AEAD for confidentiality-only protection is FFS.
Case 3: The UE only supports standalone algorithms, and the network supports both AEAD and standalone algorithms.
Case 4: The UE supports both AEAD and standalone algorithms, and the network only supports standalone algorithms.
For Cases 3 and 4, the negotiation of standalone algorithms is reused.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.6.3 Evaluation
| Editor’s Note: Place holder for an evaluation if necessary.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.7 Solution 7: AEAD key usage for NAS and AS algorithm
| |
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.7.1 Introduction
| This solution addresses the key issue#2.
Like the existing NAS algorithms and AS algorithms for integrity protection and ciphering (reference from Annex D of TS 33.501 [5]), the combined algorithm needs to be shown for the AS and NAS module usage.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.7.2 Solution details
|
Figure 6.7.2-1: Derivation of MAC-I
The input parameters to the NCA (NG Combined Algorithm) algorithm are 256-bit (array of 32 bytes) security Key (example: KNASAEAD or KRRCAEAD or KUPAEAD), 32-bit NAS or PDCP COUNT (UL or DL COUNT),1 bit of MODE of 0(encrypt) or 1(decrypt), 5-bits of BEARER identity, DIRECTION bit could be 0 for uplink and 1 for downlink and 6 bytes of Extra entropy for the IV(Initial Value).
EXTRA_IV called as EXTRA_IVNAS or EXTRA_IVRRC or EXTRA_IVUP is a Random number generated by AMF/RAN and exchanged with UE during NAS or AS Security mode command or RRC Reconfiguration message.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.7.3 Evaluation
| TBD
Editor’s Note: Further evaluation to be added.
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f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.8 Solution 8: Input & output definition
| |
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.8.1 Introduction
| This solution addresses KI#2: AEAD algorithm input and output.
The input and output for AEAD algorithm basically follow the definition of RFC 5116 [6]. It defines the input of the AEAD as 1) a secret key, 2) a nonce, 3) a plaintext, 4) the associated data, and the output as a ciphertext. The ciphertext also includes data for integrity protection. Considering AEAD can be used only for the encryption, this solution proposes to define the output as a pair of (C, T) where C is the ciphertext of P and T is the MAC tag. This solution also proposes a new parameter to indicate the AEAD algorithm is operated in encryption only mode.
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f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.8.2 Solution details
| The input for encryption is defined as (K, N, AD, P, ENC_ONLY).
- The key K is a secrete key only known to a sender and a receiver. Clause 6.2 of TS 33.501[5] defines the key hierarchy for 5G from long term key to algorithm keys. The key for AEAD can be defined in the similar way.
- A nonce N can be public but cannot be reused to maintain the security. The nonce can be constructed by using the existing COUNT, BEARER and DIRECTION parameters as defined in Annex D.2 and Annex D.3 of TS 33.501 [5].
- The associated data AD is input to AEAD algorithm only for integrity protection. When AEAD is used only for the integrity protection of input data, it can be input as the associated data. The associated data is not encrypted.
- A plaintext P input into AEAD algorithm to be encrypted.
- A parameter ENC_ONLY is used to indicate whether AEAD algorithm is to be performed for encryption only.
Editor’s Note: It is ffs why "ENC_ONLY" is needed. AEAD itself supports ciphering-only and "ENC_ONLY" is not defined by ETSI.
Editor’s Note: It is ffs how to use an encryption only parameter for generic AEAD algorithms.
NOTE: When AEAD is used for integrity protection only, input data is the associated data AD. When AEAD is used for encryption and integrity protection, input data is the plaintext P.
The output for encryption is defined as (C, T).
- A ciphertext C is the encryption P. The ciphertext C can be omitted when AEAD algorithm is used only for the integrity protection.
- A tag T is generated to ensure the ciphertext C is not modified. The tag T can be omitted when AEAD algorithm is used only for the encryption.
The input for decryption is defined as (K, N, AD, C, T, ENC_ONLY).
- The ciphertext C can be omitted when AEAD algorithm is used only for the integrity protection.
- The tag T can be omitted when AEAD algorithm is used only for the encryption.
The output for decryption is defined as (P, VeriRes).
- The VeriRes is the verification result of the tag T, and it is either SUCCESS or FAILURE.
- The plaintext P is generated only if VeriRes is set to SUCCESS. When algorithm is operated in encryption only, VeriRes is omitted and the plaintext P is always generated.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.8.3 Evaluation
| TBD
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.9 Solution 9: Interface of AEAD
| |
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.9.1 Introduction
| This solution is proposed to address the key issue#2 on AEAD interface.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.9.2 Solution details
| The input parameters to the AEAD algorithm include:
• a 256-bit AEAD key named KEY,
• a 48-bit EXTRA_IV,
• a 32-bit COUNT,
• a 5-bit bearer identity BEARER,
• the 1-bit direction of the transmission i.e. DIRECTION. The DIRECTION bit shall be 0 for uplink and 1 for downlink.
• 1-bit MODE. The MODE bit shall be 0 for encryption and 1 for decryption.
• 5-bit MAC_BYTES,
• the length of the Additional Authenticated Data (AAD) required i.e. 32-bit AAD_LENGTH,
• and the length of the Input Bit Stream(IBS) required i.e. 32-bit S_LENGTH.
Figure 6.9.2-1: Interface of AEAD algorithm
Based on the input parameters, the output ciphertext Output Bit Stream (OBS) is generated. Based on these input parameters the sender computes a message authentication code (MAC-I/NAS-MAC). The message authentication code is then appended to the message when sent.
The receiver computes the expected message authentication code XMAC-I/XNAS-MAC.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.9.3 Evaluation
| |
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.10 Solution 10: Creation of EXTRA_IV
| Editor’s Note: This clause contains solutions for key issues. Not all solutions may have evaluation due to the nature of this study.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.10.1 Introduction
| Editor’s Note: Each solution should list the key issues being addressed.
This solution addresses key issue #2 “AEAD algorithm interface”. Specifically, this proposal addresses the issue of the generation of EXTRA_IV.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.10.2 Solution details
| When deriving keys for AEAD algorithms, the EXTRA_IV can also be derived at the same time using an EXTRA_IV distinguisher.
For example, the following parameters can be used to form the string S.
- FC = 0xZZ
- P0 = algorithm type distinguisher
- L0 = length of algorithm type distinguisher (i.e. 0x00 0x01)
- P1 = “EXTRA_IV”
- L1 = length of “EXTRA_IV”
The algorithm type distinguisher shall be N-NAS-aead-alg for NAS AEAD algorithms and N-RRC-aead-alg for RRC AEAD algorithms, N-UP-aead-alg for UP AEAD algorithms.
The input key KEY can be the upper-layer key of the AEAD algorithm key.
The 48 least significant bits of the KDF output can be used as the EXTRA_IV.
Editor’s Note: It is ffs why EXTRA_IV needs to be generated with KDF and what problems it solves.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.10.3 Evaluation
| Editor’s Note: Place holder for an evaluation if necessary.
TBD
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.11 Solution 11: Key Derivation for NAS and AS AEAD
| |
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.11.1 Introduction
| This solution addresses the key issue#3.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.11.2 Solution details
| Keys for NAS signalling:
- KNASAEAD is a key derived for particular combined algorithm (256-NCA4/256-NCA5/256-NCA6).
Keys for UP traffic:
- KUPAEAD is a key derived for a particular combined algorithm(256-NCA4/256-NCA5/256-NCA6).
Keys for RRC signalling:
- KRRCAEAD is a key derived for a particular integrity & encryption (combined) algorithm(256-NCA4/256-NCA5/256-NCA6).
Algorithm key derivation functions
When deriving keys for NAS integrity and NAS encryption algorithms from KAMF in the AMF and UE or ciphering and integrity keys from KgNB/ KSN in the gNB and UE, the following parameters shall be used to form the string S.
- FC = 0x69
- P0 = algorithm type distinguisher
- L0 = length of algorithm type distinguisher (i.e. 0x00 0x01)
- P1 = algorithm identity
- L1 = length of algorithm identity (i.e. 0x00 0x01)
The algorithm type distinguisher shall be N-NAS-enc-alg for NAS encryption algorithms and N-NAS-int-alg for NAS integrity protection algorithms. The algorithm type distinguisher shall be N-RRC-enc-alg for RRC encryption algorithms, N-RRC-int-alg for RRC integrity protection algorithms, N-UP-enc-alg for UP encryption algorithms and N-UP-int-alg for UP integrity protection algorithms, N-NAS-AEAD-alg for NAS AEAD algorithms, N-RRC-AEAD-alg for RRC AEAD algorithm and N-UP-AEAD-alg for UP AEAD algorithm (see table A.8-1). The values 0x00 and 0x0a to 0xf0 are reserved for future use, and the values 0xf1 to 0xff are reserved for private use.
Table 6.11.2-1: Algorithm type distinguishers
Algorithm distinguisher
Value
N-NAS-enc-alg
0x01
N-NAS-int-alg
0x02
N-RRC-enc-alg
0x03
N-RRC-int-alg
0x04
N-UP-enc-alg
0x05
N-UP-int-alg
0x06
N-NAS-AEAD-alg
0x07
N-RRC-AEAD-alg
0x08
N-UP-AEAD-alg
0x09
The algorithm identity (as specified in clause 5 of TS 33.501 [5]) shall be put in the four least significant bits of the octet. The two least significant bits of the four most significant bits are reserved for future use, and the two most significant bits of the most significant nibble are reserved for private use. The entire four most significant bits shall be set to all zeros.
For the derivation of integrity and ciphering keys or AEAD key used between the UE and gNB, the input key shall be the 256-bit KgNB// KSN. For the derivation of integrity and ciphering keys or AEAD key used between the UE and AMF, the input key shall be the 256-bit KAMF.
For an algorithm key of length n bits, where n is less or equal to 256, the n least significant bits of the 256 bits of the KDF output shall be used as the algorithm key.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 6.11.3 Evaluation
| TBD
Editor’s Note: Further evaluation to be added.
6.Y Solution Y: <Solution Name>
Editor’s Note: This clause contains solutions for key issues. Not all solutions may have evaluation due to the nature of this study.
6.Y.1 Introduction
Editor’s Note: Each solution should list the key issues being addressed.
6.Y.2 Solution details
6.Y.3 Evaluation
Editor’s Note: Place holder for an evaluation if necessary.
|
f12fa66a3c153eea0bbe41f49f769527 | 33.771 | 7 Conclusion
| 7.Z Key Issue #Z: <Key Issue Name>
Editor’s Note: This clause contains the agreed conclusions for Key Issue #Z.
Annex A: Introduction to AEAD
A.1 Protection provided by AEAD
The key characteristic of Authenticated Encryption (AE) is that ciphering, and integrity protection are executed in a combined operation. This way, data encryption and authentication can ideally be provided in a single pass. Authenticated Encryption with Associated Data (AEAD) additionally allows for input that is authenticated, but not encrypted. This can be leveraged in use cases where solely data integrity is required while the plain text remains visible for processing.
Additionally, AEAD algorithms allow selective ciphering and integrity protection as needed. If only ciphering is required, it may be possible depending on the AEAD algorithm to only output the ciphertext. If only integrity protection is required, all input data can be processed as associated data. Finally, it is also possible to combine both approaches and provide ciphering and integrity protection for one part of a message while another part is only integrity protected (e.g., because certain message contents need to be accessible in plain text).
The 256-bit cryptographic algorithms specified in TS 35.240 [2], TS 35.243 [3] and TS 35.246 [4] are all based on AEAD1, which also allows for confidentiality protection, integrity protection, and a combined AEAD mode.
Table A.1-1: List of 256-bit cryptographic algorithms
Cryptographic algorithm
•
Snow 5G
AES-256
ZUC-256
Operating mode
Confidentiality
256-NEA4
256-NEA5
256-NEA6
•
Integrity
256-NIA4
256-NIA5
256-NIA6
•
Authenticated Encryption with Associated Data (AEAD)
256-NCA4
256-NCA5
256-NCA6
A.2 Algorithm inputs and outputs
AEAD algorithms can take a unique nonce, a single cryptographic key, plaintext and associated data as inputs. The plaintext is an optional when only integrity protection is required. The associated data is an optional if there is no data which requires only integrity protection.
A.3 Order of operations
When using an AEAD algorithm, important security decisions are already made such that in which order encryption and integrity protection is applied.
Annex X:
Change history
Change history
Date
Meeting
Tdoc
CR
Rev
Cat
Subject/Comment
New version
2025-10
SA3#124
S3-253743
Implemented S3-253189, S3-253782, S3-253783, S3-253785, S3-253787
0.1.0
2025-11
SA3#125
S3-254546
Implemented S3-254657, S3-254658, S3-254659, S3-254660,S3-254661,S3-254662, S3-254663, S3-254664, S3-254665, S3-254666, S3-254667, S3-254668, S3-254669, S3-254670, S3-254671
0.2.0
|
78aa6a85972743b91dba1779a75243c8 | 33.778 | 2 References
| The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
- References are either specific (identified by date of publication, edition number, version number, etc.) or non‑specific.
- For a specific reference, subsequent revisions do not apply.
- For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.
[1] 3GPP TR 21.905: "Vocabulary for 3GPP Specifications".
[2] 3GPP TS 33.501: "Security architecture and procedures for 5G system".
[3] IETF RFC 9000: "QUIC: A UDP-Based Multiplexed and Secure Transport".
[4] IETF RFC 9001: "Using TLS to Secure QUIC".
[5] draft-ietf-quic-multipath: "Multipath Extension for QUIC".
[6] IETF RFC 8446: “The Transport Layer Security (TLS) Protocol Version 1.3”.
[7] 3GPP TS 33.210: “Network Domain Security (NDS); IP network layer security”.
[8] 3GPP TS 23.501: "System architecture for the 5G System (5GS)".
[9] 3GPP TS 23.502: "Procedures for the 5G System (5GS)".
[10] 3GPP TS 33.535: "Authentication and key management for applications based on 3GPP credentials in the 5G System (5GS)".
|
78aa6a85972743b91dba1779a75243c8 | 33.778 | 3 Definitions of terms, symbols and abbreviations
| |
78aa6a85972743b91dba1779a75243c8 | 33.778 | 3.1 Terms
| For the purposes of the present document, the terms given in TR 21.905 [1] and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905 [1].
example: text used to clarify abstract rules by applying them literally.
|
78aa6a85972743b91dba1779a75243c8 | 33.778 | 3.2 Symbols
| For the purposes of the present document, the following symbols apply:
<symbol> <Explanation>
|
78aa6a85972743b91dba1779a75243c8 | 33.778 | 3.3 Abbreviations
| For the purposes of the present document, the abbreviations given in TR 21.905 [1] and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in TR 21.905 [1].
<ABBREVIATION> <Expansion>
|
78aa6a85972743b91dba1779a75243c8 | 33.778 | 4 Architecture assumption
| Annex AA in TS 33.501[2] is the starting point of this study.
|
78aa6a85972743b91dba1779a75243c8 | 33.778 | 5 Key issues
| |
78aa6a85972743b91dba1779a75243c8 | 33.778 | 5.1 Key issue #1: PSK support for MPQUIC TLS
| |
78aa6a85972743b91dba1779a75243c8 | 33.778 | 5.1.1 Key issue details
| In TS 33.501 [1] Annex AA.2, server authentication for MPQUIC/TLS [2], [3], [5] is specified. The scope of this key issue is to cover the PSK-based option for MPQUIC/TLS. Solutions to this key issue are expected to provide the means for enabling the PSK option for MPQUIC/TLS. More specifically, the PSK option refers to TLS 1.3 PSK with (EC)DHE key establishment (psk_dhe_ke), since MPQUIC/TLS [4] uses TLS 1.3 [6] and TS 33.210 [7] prohibits the use of PSK-only mode (psk_ke) in TLS 1.3.
|
78aa6a85972743b91dba1779a75243c8 | 33.778 | 5.1.2 Security threats
| N/A
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78aa6a85972743b91dba1779a75243c8 | 33.778 | 5.1.3 Potential security requirements
| The 5G system shall be able to securely derive, deliver, update, and use the PSK (i.e., TLS 1.3 psk_dhe_ke) between UE and UPF to be used for authentication with MPQUIC/TLS.
5.X Key Issue #X: key issue names
5.X.1 Key issue details
Editor’s Note: This clause is going to capture the key issue detail of a key issue.
5.X.2 Security threats
Editor’s Note: This clause is going to capture the security threat of a key issue.
5.X.1 Potential security requirements
Editor’s Note: This clause is going to capture the potential security requirements of a key issue.
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78aa6a85972743b91dba1779a75243c8 | 33.778 | 6 Solutions
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78aa6a85972743b91dba1779a75243c8 | 33.778 | 6.1 Solution #1: MPQUIC/TLS using PSK derived from KAMF
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78aa6a85972743b91dba1779a75243c8 | 33.778 | 6.1.1 Introduction
| This solution addresses Key issue #1 by enabling a secure UP communication channel between the UE and the UPF. The approach leverages the current KAMF to derive a pre-shared key (UPF_PSK) and a corresponding identifier (UPF_PSK ID). The UPF_PSK/ID is delivered to the UPF and then used for a mutual-authentication and key exchange using TLS 1.3 PSK psk_dhe_ke.
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78aa6a85972743b91dba1779a75243c8 | 33.778 | 6.1.2 Solution details
| Assumptions and scope:
- UE is registered to the 5GS and has established a KAMF with the network.
- Distribution path for UPF_PSK/ID: AMF/SMF → UPF over N2/N4.
Key derivation and identifiers:
- UE and AMF derive UPF_PSK and UPF_PSK ID using current KAMF.
- Input parameters for the KDF include at least the PDU Session ID and a freshness parameter. UPF_PSK derivation can additionally be bound to the selected UPF identity (e.g., FQDN or IP).
Setup procedure (PDU Session establishment):
- UE requests a PDU Session indicating support for MPQUIC/TLS using PSK.
- SMF selects a suitable UPF and provides UE with UPF addressing (e.g., IP, port) and obtains UPF_PSK/ID from AMF.
- AMF derives UPF_PSK/ID from current KAMF. SMF forwards UPF_PSK/ID to UPF via N4.
- Upon successful PDU Session Establishment, UE initiates MPQUIC/TLS with the UPF using UPF_PSK, referencing UPF_PSK ID for UPF to locate and use UPF_PSK to perform mutual authentication with the UE.
UPF_PSK update triggers and handling:
- UE CM-IDLE → CM-CONNECTED transition:
- UE and AMF derive new UPF_PSK/ID.
- AMF/SMF updates the UPF with the new UPF_PSK.
- UE initiates MPQUIC/TLS with the UPF using the new UPF_PSK/ID.
The MPQUIC/TLS connection may timeout while the UE is in an IDLE state, with no other active path available. The update trigger is to ensure the UE and UPF can run a mutual authentication using a fresh UPF_PSK when the PDU Session is re-activated (following a service request procedure). Derivation UPF_PSK using an input freshness parameter as described above ensures that a fresh key is used each time the UE needs to (re)connect with the UPF.
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78aa6a85972743b91dba1779a75243c8 | 33.778 | 6.1.3 Evaluation
| This solution depends on the visited network supporting the relevant functionality of this solution.
The solution fully addresses Key issue #1 requirement, including derivation, delivery, update and usage of the PSK between UE and UPF used for authentication with MPQUIC/TLS.
Impacts:
- AMF and UE derive a new UPF_PSK/ID using KAMF as input key and input parameters (PDU Session ID, freshness parameter, FQDN/IP of UPF).
- SMF obtains UPF_PSK/ID from AMF and delivers it to UPF during PDU Session establishment or re-activation.
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78aa6a85972743b91dba1779a75243c8 | 33.778 | 6.2 Solution #2: PSK derivation bound with MA PDU session
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78aa6a85972743b91dba1779a75243c8 | 33.778 | 6.2.1 Introduction
| According to TS 23.501 [8] clause 5.32.6, for steering functionalities based on MPQUIC that apply the QUIC protocol and its multipath extensions, the MPQUIC functionality(ies) in the UE communicates with the associated MPQUIC Proxy functionality(ies) in the UPF. The MPQUIC functionality in the UE and the associated MPQUIC Proxy functionality in the UPF uses the "MPQUIC link-specific multipath" addresses/prefixes for transmitting traffic flows over non-3GPP access and over 3GPP access. The "MPQUIC link-specific multipath" IP addresses/prefixes are allocated by the UPF and provided to the UE via SM NAS signalling. For multiple paths sharing the same TLS tunnel, it is proposed that:
- On the UE side, the PSK is derived by the UE and used by the MPQUIC functionality in the UE.
- On the network side, the PSK is used by the associated MPQUIC Proxy functionality in the UPF. The PSK is derived by the SMF or the AMF which holds the root key for PSK derivation and the derived PSK is delivered to the UPF.
- The PSK is bound with a specific MA PDU session, in which way the old PSK used on authentication for an existing MA PDU session cannot be reused on authentication for a new MA PDU session.
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