rfc9593v2.txt   rfc9593.txt 
Internet Engineering Task Force (IETF) V. Smyslov Internet Engineering Task Force (IETF) V. Smyslov
Request for Comments: 9593 ELVIS-PLUS Request for Comments: 9593 ELVIS-PLUS
Category: Standards Track June 2024 Category: Standards Track July 2024
ISSN: 2070-1721 ISSN: 2070-1721
Announcing Supported Authentication Methods in the Internet Key Exchange Announcing Supported Authentication Methods in the Internet Key Exchange
Protocol Version 2 (IKEv2) Protocol Version 2 (IKEv2)
Abstract Abstract
This specification defines a mechanism that allows implementations of This specification defines a mechanism that allows implementations of
the Internet Key Exchange Protocol Version 2 (IKEv2) to indicate the the Internet Key Exchange Protocol Version 2 (IKEv2) to indicate the
list of supported authentication methods to their peers while list of supported authentication methods to their peers while
skipping to change at line 409 skipping to change at line 409
Generally in IKEv2 each party independently determines the way it Generally in IKEv2 each party independently determines the way it
authenticates itself to the peer. In other words, authentication authenticates itself to the peer. In other words, authentication
methods selected by the peers need not be the same. However, some methods selected by the peers need not be the same. However, some
IKEv2 extensions break this rule. IKEv2 extensions break this rule.
The prominent example is "Secure Password Framework for Internet Key The prominent example is "Secure Password Framework for Internet Key
Exchange Version 2" [RFC6467], which defines a framework for using Exchange Version 2" [RFC6467], which defines a framework for using
secure password authentication in IKEv2. With this framework, peers secure password authentication in IKEv2. With this framework, peers
negotiate using one of the secure password methods in the IKE_SA_INIT negotiate using one of the secure password methods in the IKE_SA_INIT
exchange -- the initiator sends a list of supported PAKE methods in exchange -- the initiator sends a list of supported methods in the
the request, and the responder picks one of them and sends it back in request, and the responder picks one of them and sends it back in the
the response. response.
If peers negotiate secure password authentication, then the selected If peers negotiate secure password authentication, then the selected
method is used by both initiator and responder, and no other method is used by both initiator and responder, and no other
authentication methods are involved. For this reason, there is no authentication methods are involved. For this reason, there is no
point to announce supported authentication methods in this case. point to announce supported authentication methods in this case.
Thus, if the peers choose to go with secure password authentication, Thus, if the peers choose to go with secure password authentication,
they MUST NOT send the SUPPORTED_AUTH_METHODS notification. they MUST NOT send the SUPPORTED_AUTH_METHODS notification.
In the situation when peers are going to use Multiple Authentication In the situation when peers are going to use Multiple Authentication
Exchanges [RFC4739], they MAY include multiple SUPPORTED_AUTH_METHODS Exchanges [RFC4739], they MAY include multiple SUPPORTED_AUTH_METHODS
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