My 3GPP 33.501 notes - Revision history

Paul: /* C.2 Null-scheme */

2023-07-16T17:57:23Z

C.2 Null-scheme

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 :NOTE 1: The reason for mentioning the non-freshness is that, normally, in order to attain unlinkability (i.e., to make it infeasible for over-the-air attacker to link SUCIs together), it is necessary for newly generated SUCIs to be fresh. But, in case of the null-scheme, the SUCI does not conceal the SUPI. So unlinkability is irrelevant.
 :NOTE 2: The null-scheme provides no privacy protection.
 == Annex F (normative): 3GPP 5G profile for EAP-AKA' ==

Paul: /* Definitions */

2023-07-16T17:00:57Z

Definitions

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			== § 1 Scope ==

			This document specifies the security architecture, i.e., the security features and the security mechanisms for the 5G System and the 5G Core, and the security procedures performed within the 5G System including the 5G Core and the 5G New Radio.

	== Definitions ==		== Definitions ==
	=== 5G security context===		=== 5G security context===

Paul: /* 6.12.2 Subscription concealed identifier */

2023-02-09T19:23:23Z

6.12.2 Subscription concealed identifier

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	=== 6.12.2 Subscription concealed identifier ===		=== 6.12.2 Subscription concealed identifier ===

			;subscription concealed identifier: A one-time use subscription identifier, called the SUbscription Concealed Identifier (SUCI), which contains the Scheme-Output, and additional non-concealed information needed for home network routing and protection scheme usage.

	The SUbscription Concealed Identifier, called SUCI, is a privacy preserving identifier containing the concealed SUPI.		The SUbscription Concealed Identifier, called SUCI, is a privacy preserving identifier containing the concealed SUPI.

Paul: /* 6.7 Security algorithm selection, key establishment and security mode command procedure */

2023-02-08T20:46:26Z

6.7 Security algorithm selection, key establishment and security mode command procedure

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	For MO/MT SMS over NAS via 3GPP/non-3GPP when the UE has already activated NAS security with the AMF before sending/receiving SMS, the NAS Transport message shall be ciphered and integrity protected using the NAS security context by the UE/AMF as described in sub-clause 6.4 in the present document.		For MO/MT SMS over NAS via 3GPP/non-3GPP when the UE has already activated NAS security with the AMF before sending/receiving SMS, the NAS Transport message shall be ciphered and integrity protected using the NAS security context by the UE/AMF as described in sub-clause 6.4 in the present document.

			== 6.5 RRC security mechanisms ==

			See spec for details...

	== 6.7 Security algorithm selection, key establishment and security mode command procedure ==		== 6.7 Security algorithm selection, key establishment and security mode command procedure ==

Paul: /* 6.5 RRC security mechanisms */

2023-02-08T20:45:57Z

6.5 RRC security mechanisms

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	=== 6.7.2 NAS security mode command procedure ===		=== 6.7.2 NAS security mode command procedure ===

	~~See spec for details...~~

	~~== 6.5 RRC security mechanisms ==~~

	See spec for details...		See spec for details...

Paul: /* 6.4.6 Protection of initial NAS message */

2022-11-27T20:47:53Z

6.4.6 Protection of initial NAS message

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	The complete initial message is included in the NAS Security Mode Complete (SMC) message in a NAS Container when needed (e.g. AMF cannot find the used security context) in the latter case and always in the former case as described below.		The complete initial message is included in the NAS Security Mode Complete (SMC) message in a NAS Container when needed (e.g. AMF cannot find the used security context) in the latter case and always in the former case as described below.

			:Note: See 3GPP TS 24.501 5.4.2 for Security Mode Control procedure or [[My 3GPP 24.501 notes#5.4.2 Security mode control (SMC) procedure\|my security mode control notes]]

	In case the UE selects a PLMN other than Registered PLMN/EPLMN in the 5GMM-IDLE state and the UE has a NAS security context containing the NEA0, then the UE shall discard the NAS security context and shall follow the procedure specified in this clause for protection of initial NAS message.		In case the UE selects a PLMN other than Registered PLMN/EPLMN in the 5GMM-IDLE state and the UE has a NAS security context containing the NEA0, then the UE shall discard the NAS security context and shall follow the procedure specified in this clause for protection of initial NAS message.

Paul: /* 6.4.6 Protection of initial NAS message */

2022-11-27T20:42:59Z

6.4.6 Protection of initial NAS message

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	[[File:Protecting initial NAS message.png\|center\|Protecting initial NAS message]]		[[File:Protecting initial NAS message.png\|center\|Protecting initial NAS message]]

	Step 1: The UE shall send the initial NAS message to the AMF. If the UE has no NAS security context, the initial NAS message shall only contain the <span style="color:red">cleartext IEs, i.e. subscription identifiers (e.g. SUCI or GUTIs)</span>, UE security capabilities, ngKSI, indication that the UE is moving from EPC, Additional GUTI, and IE containing the TAU Request in the case idle mobility from LTE.		Step 1: The UE shall send the initial NAS message to the AMF.
			* If the UE has no NAS security context, the initial NAS message shall only contain the <span style="color:red">cleartext IEs, i.e. subscription identifiers (e.g. SUCI or GUTIs)</span>, UE security capabilities, ngKSI, indication that the UE is moving from EPC, Additional GUTI, and IE containing the TAU Request in the case idle mobility from LTE.
	If the UE has a NAS security context, the message sent shall contain the information given above in cleartext and the complete initial NAS message ciphered in a NAS container which is ciphered. With a NAS security context, the sent message shall also be integrity protected. In the case that the initial NAS message was protected and the AMF has the same security context, then steps 2 to 4 may be omitted In this case the AMF shall use the complete initial NAS message that is in the NAS container as the message to respond to..		*If the UE has a NAS security context, the <span style="color:red">message sent shall contain the information given above in cleartext and the complete initial NAS message ciphered in a NAS container</span> which is ciphered. With a NAS security context, the sent message shall also be integrity protected. In the case that the initial NAS message was protected and the AMF has the same security context, then steps 2 to 4 may be omitted In this case the AMF shall use the complete initial NAS message that is in the NAS container as the message to respond to..

	Step 2: If the AMF is not able to find the security context locally or from last visited AMF, or if the integrity check fails, then the AMF shall initiate an authentication procedure with the UE. If the AMF fetches old security context from the last visited AMF, the AMF may decipher the NAS container with the same security context, and get the initial NAS message, then the step 2b to 4 may be omitted. If the AMF fetches new K<sub>AMF</sub> from the last visited AMF (receiving keyAmfChangeInd), the step 2b may be omitted.		Step 2: If the AMF is not able to find the security context locally or from last visited AMF, or if the integrity check fails, then the AMF shall initiate an authentication procedure with the UE. If the AMF fetches old security context from the last visited AMF, the AMF may decipher the NAS container with the same security context, and get the initial NAS message, then the step 2b to 4 may be omitted. If the AMF fetches new K<sub>AMF</sub> from the last visited AMF (receiving keyAmfChangeInd), the step 2b may be omitted.

Paul: /* 6.4.6 Protection of initial NAS message */

2022-11-27T20:35:38Z

6.4.6 Protection of initial NAS message

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	Step 4: The UE shall send the NAS Security Mode Complete message to the network in response to a NAS Security Mode Command message. The NAS Security Mode Complete message shall be ciphered and integrity protected. Furthermore the NAS Security Mode Complete message shall include the complete initial NAS message in a NAS Container if either requested by the AMF or the UE sent the initial NAS message unprotected. The AMF shall use the complete initial NAS message that is in the NAS container as the message to respond to.		Step 4: The UE shall send the NAS Security Mode Complete message to the network in response to a NAS Security Mode Command message. The NAS Security Mode Complete message shall be ciphered and integrity protected. Furthermore the NAS Security Mode Complete message shall include the complete initial NAS message in a NAS Container if either requested by the AMF or the UE sent the initial NAS message unprotected. The AMF shall use the complete initial NAS message that is in the NAS container as the message to respond to.

	Step 5: The AMF shall send its response to the Initial NAS message. This message shall be ciphered and integrity protected.		Step 5: <span style="color:red">The AMF shall send its response to the Initial NAS message. This message shall be '''ciphered and integrity''' protected</span>.

	=== 6.4.7 Security aspects of SMS over NAS ===		=== 6.4.7 Security aspects of SMS over NAS ===

Paul: /* 6.4.1 General */

2022-11-27T20:31:17Z

6.4.1 General

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	=== 6.4.1 General ===		=== 6.4.1 General ===

	This sub-clause describes the security mechanisms for the protection of NAS signalling and data between the UE and the AMF over the N1 reference point. This protection involves both integrity and confidentiality protection. The security parameters for NAS protection are part of the 5G security context described in sub-clause 6.3 of the present document.		This sub-clause describes the security mechanisms for the protection of NAS signalling and data between the UE and the AMF over the N1 reference point. This protection involves both integrity and confidentiality protection. The security parameters for NAS protection are part of the <span style="color:red">5G security context</span> described in sub-clause 6.3 of the present document.

	=== 6.4.2 Security for multiple NAS connections ===		=== 6.4.2 Security for multiple NAS connections ===

Paul: /* C.2 Null-scheme */

2022-11-27T20:30:18Z

C.2 Null-scheme

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	The null-scheme shall be implemented such that it returns the same output as the input, which applies to both encryption and decryption.		The null-scheme shall be implemented such that it returns the same output as the input, which applies to both encryption and decryption.

	When using the null-scheme, the SUCI does not conceal the SUPI and therefore the newly generated SUCIs do not need to be fresh.		<span style="color:red">When using the null-scheme, the SUCI does not conceal the SUPI and therefore the newly generated SUCIs do not need to be fresh</span>.
	:NOTE 1: The reason for mentioning the non-freshness is that, normally, in order to attain unlinkability (i.e., to make it infeasible for over-the-air attacker to link SUCIs together), it is necessary for newly generated SUCIs to be fresh. But, in case of the null-scheme, the SUCI does not conceal the SUPI. So unlinkability is irrelevant.		:NOTE 1: The reason for mentioning the non-freshness is that, normally, in order to attain unlinkability (i.e., to make it infeasible for over-the-air attacker to link SUCIs together), it is necessary for newly generated SUCIs to be fresh. But, in case of the null-scheme, the SUCI does not conceal the SUPI. So unlinkability is irrelevant.
	:NOTE 2: The null-scheme provides no privacy protection.		:NOTE 2: The null-scheme provides no privacy protection.