4 Elementary procedures for handling of secure connection

3GPP44.318Generic Access Network (GAN)Mobile GAN interface layer 3 specificationRelease 17TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

4.1 General

All traffic over the Up interface shall be sent through the IPsec tunnel that is established as a result of the authentication procedure.

4.2 Establishment of the secure connection

4.2.1 General

The MS and GANC-SEGW shall set up one IKE Secure Association (SA) and one CHILD_SA for IPsec ESP according to the profiles defined in [37]. The MS shall act as initiator, and the GANC-SEGW as responder. For MS with SIM only, the MS and GANC-SEGW shall use EAP-SIM for mutual authentication of the MS and the core network according to sub-clause 4.3. For MS with USIM, the MS and GANC-SEGW shall use EAP-AKA for mutual authentication of the MS and the core network according to sub-clause 4.4.

The MS shall use certificates for authentication of the GANC-SEGW according to sub-clause 4.2.5.

Furthermore, the MS shall:

– use Configuration Payload according to [27] to acquire/renew an internal IP address in the network protected by the GANC-SEGW

– act as initiator in the Traffic Selector (TS) negotiation. The MS shall use the following value for the traffic selector-initiator and traffic selector-responder payloads:

TSi = (0, 0-65535, 0.0.0.0-255.255.255.255)

TSr = (0, 0-65535, 0.0.0.0-255.255.255.255)

The GANC-SEGW shall use the following value for the traffic selector-initiator and traffic selector-responder payloads:

TSi = (0, 0-65535, ms_internal_address – ms_internal_address), where ms_internal_address is the IP address in the network protected by the GANC-SEGW that is assigned to the MS

TSr = (0, 0-65535, 0.0.0.0-255.255.255.255)

Either the MS or GANC-SEGW may initiate re-keying of the SA based on their individual lifetime policy on the SA.

4.2.2 Identities

The MS shall send its EAP-SIM or EAP-AKA identity (composed according to sub-clauses 4.3.2 and 4.4.2) as initiator identity IDi.

The MS shall include the GANC-SEGW identity that it wishes to communicate with in the Identity Responder (IDr) payload in the IKE_SA_AUTH Request (message 3) as follows:

– If the MS derived the FQDN of the Provisioning GANC-SEGW from the IMSI (as described in [3]), it shall include the derived FQDN in the Identification Data field of the IDr payload and indicate Identity Type 2 (ID_FQDN) in the ID Type field of the IDr payload;

– If the MS was provisioned with an IPv4 address of the Provisioning GANC-SEGW, or received it in the GA-RC DISCOVERY ACCEPT message or GA-RC REGISTER REDIRECT message for the Default or a Serving GANC-SEGW, it shall include that IPv4 address in the Identification Data field of the IDr payload and indicate Identity Type 1 (ID_IPV4_ADDR) in the ID Type field of the IDr payload;

– If the MS was provisioned with an IPv6 address of the Provisioning GANC-SEGW, or received it in the GA-RC DISCOVERY ACCEPT message or GA-RC REGISTER REDIRECT message for the Default or a Serving GANC-SEGW, it shall include that IPv6 address in the Identification Data field of the IDr payload and indicate Identity Type 5 (ID_IPV6_ADDR) in the ID Type field of the IDr payload;

– If the MS was provisioned with a FQDN of the Provisioning GANC-SEGW, or received it in the GA-RC DISCOVERY ACCEPT message or GA-RC REGISTER REDIRECT message for the Default or a Serving GANC-SEGW, it shall include that FQDN in the Identification Data field of the IDr payload and indicate Identity Type 2 (ID_FQDN) in the ID Type field of the IDr payload;

The GANC-SEGW shall provide the GANC-SEGW identity in the Identity Payload (IDr) as following:

Identity Type = 2 (ID_FQDN) or 1 (ID_IPV4_ADDR) or 5 (ID_IPV6_ADDR)

Identity Data = GANC-SEGW FQDN or IPv4 address or IPv6 address, respectively

Identity Type shall match the Type of the SubjectAltName contained in the GANC-SEGW certificate as well as what was provisioned in the MS for Provisioning GANC-SEGW or provided in GA-RC DISCOVERY ACCEPT for Default GANC-SEGW or GA-RC REGISTER REDIRECT for Serving GANC-SEGW.

4.2.3 Crypto negotiation

The MS and GANC-SEGW negotiate the cryptographic suite to use for the SA, as per [27].

The MS shall include all the algorithms for integrity and confidentiality (defined in the profile for IPsec ESP in [37]) that it supports in the proposal. The GANC-SEGW signals back the selected algorithms that will be used for confidentiality and integrity protection, based on core network policy.

4.2.4 NAT traversal

The MS and GANC-SEGW shall use the IKEv2 mechanisms for detection of NAT, NAT traversal and keep-alive (as specified in [27]). If NAT is detected, the MS and GANC-SEGW shall use the UDP encapsulation of ESP packets mechanism (as specified in [30]).

4.2.5 Certificate Handling and Authentication

As the MS and GANC-SEGW use EAP-SIM or EAP-AKA for mutual authentication, IKEv2 mandates that this is used in conjunction with a public key signature based authentication of the GANC-SEGW to the MS.

The MS requirements for certificate authentication and handling are listed in 3GPP TS 33.402 [56].

In addition to the requirements listed in 3GPP TS 33.402 [56], the MS shall take the following actions for received GANC-SEGW certificates:

– match the SubjectAltName in the end entity certificate with the IDr payload, and with GANC-SEGW identity obtained from derivation of the Provisioning GANC-SEGW FQDN, provisioning, discovery or register redirect.

– If the MS was provisioned with an IP address of the GANC-SEGW, (or received it in the GA-RC DISCOVERY ACCEPT or GA-RC REGISTER REDIRECT message), then the certificate shall contain an IPaddress SubjectAltName that matches that address.

– If the MS was provisioned with an FQDN of the GANC-SEGW, or received it in the GA-RC DISCOVERY ACCEPT or GA-RC REGISTER REDIRECT message, then the certificate shall contain a DNSname SubjectAltName that matches that FQDN.

– If the MS derived the FQDN of the Provisioning GANC-SEGW, then the certificate shall contain a DNSname SubjectAltName that matches that FQDN.

– If a single SubjectAltName extension contains several IPaddress or DNSname components, at least one of them shall match the expected value.

4.2.6 Abnormal cases

If the MS and GANC-SEGW are not able to set up the SA for any other reason than EAP-SIM or EAP-AKA authentication failure, and the current GANC-SEGW is the SEGW associated to the Default GANC or a Serving GANC, the MS shall act as if a "Lower layer failure in the MS" has occurred and act as defined in sub-clause 6.2.4.2.

If the MS and GANC-SEGW are not able to set up the SA for any other reason than EAP-SIM or EAP-AKA authentication failure, and the current GANC-SEGW is the SEGW associated to the Provisioning GANC, the MS shall act as if a "Lower layer failure in the MS" has occurred and act as defined in sub-clause 5.6.2.

4.3 EAP-SIM authentication

4.3.1 General

After the initial IKEv2 exchanges, EAP-SIM authentication is invoked by deferring the sending of the AUTH payload, as per [27].

The GANC-SEGW shall:

– compose an EAP Response/Identity message containing the IDi of the MS and send this message to the AAA server. This will trigger the EAP-SIM authentication procedure.

– communicate with the local AAA server over the Wm interface, and relay traffic between the local AAA server and MS.

After the MS has received the EAP Success message (i.e. EAP-SIM authentication procedure was successful), the MS and GANC-SEGW complete the setup of the SA.

4.3.2 EAP-SIM Identity

The MS sends its identity as part of the initial IKE exchanges, and this also serves as identify for the EAP-SIM exchange. The identity is composed compliant with the Network Access Identifier (NAI) format specified in [42] and [3].

4.3.3 EAP-SIM Fast Re-authentication

The MS may use the re-authentication identity that was provided during the previous EAP-SIM authentication procedure to authenticate using EAP-SIM fast re-authentication instead of the full authentication procedure. The MS shall use the realm part provided by the EAP-SIM server as part of the fast re-authentication identity, as specified in [23].

The MS may attempt to use the fast re-authentication procedure when it has an unused re-authentication identity available. The MS shall not use one re-authentication identity more than once. The fast re-authentication procedure shall not be used for the first authentication after the MS has powered up, in that case it shall use the full authentication procedure.

4.3.4 Abnormal cases

If the EAP-SIM authentication procedure fails, and the current GANC-SEGW is the SEGW associated to the Default GANC or a Serving GANC fails, the MS shall act as if it had received GA-RC REGISTER REJECT with the Reject Cause value ‘IMSI not allowed’ as defined in sub-clause 6.2.3.3.

If the EAP-SIM authentication procedure fails, and the current GANC-SEGW is the SEGW associated to the Provisioning GANC, the MS shall act as if it had received GA-RC DISCOVERY REJECT with the Reject Cause value ‘IMSI not allowed’ as defined in sub-clause 5.5.2.

4.4 EAP-AKA authentication

4.4.1 General

After the initial IKEv2 exchanges, EAP-AKA authentication is invoked by deferring the sending of the AUTH payload, as per [27].

The GANC-SEGW shall:

– compose an EAP Response/Identity message containing the IDi of the MS and send this message to the AAA server. This will trigger the EAP-AKA authentication procedure.

– communicate with the local AAA server over the Wm interface, and relay traffic between the local AAA server and MS.-

After the MS has received the EAP Success message (i.e. EAP-AKA authentication procedure was successful), the MS and GANC-SEGW complete the setup of the SA.

4.4.2 EAP-AKA Identity

The MS sends its identity as part of the initial IKE exchanges, and this also serves as identify for the EAP-AKA exchange. The identity is composed compliant with the Network Access Identifier (NAI) format specified in [42] and [3].

4.4.3 EAP-AKA Fast Re-authentication

The MS may use the re-authentication identity that was provided during the previous EAP-AKA authentication procedure to authenticate using EAP-AKA fast re-authentication instead of the full authentication procedure. The MS shall use the realm part provided by the EAP-AKA server as part of the fast re-authentication identity, as specified in [41].

4.4.4 Abnormal cases

If the EAP-AKA authentication procedure fails, and the current GANC-SEGW is the SEGW associated to the Default GANC or a Serving GANC fails, the MS shall act as if it had received GA-RC REGISTER REJECT with the Reject Cause value ‘IMSI not allowed’ as defined in sub-clause 6.2.3.3.

If the EAP-AKA authentication procedure fails, and the current GANC-SEGW is the SEGW associated to the Provisioning GANC, the MS shall act as if it had received GA-RC DISCOVERY REJECT with the Reject Cause value ‘IMSI not allowed’ as defined in sub-clause 5.5.2.

4.5 Release of the secure connection

The SA is closed according the procedures defined in [27].