http://www.rfc-editor.org/rfc/rfc6467.txt
RFC 6467: Secure Password Framework for Internet Key Exchange Version 2 (IKEv2), T. Kivinen2011-12-01T23:00:00-00:00This document defines a generic way for Internet Key Exchange version 2 (IKEv2) to use any of the symmetric secure password authentication methods. Multiple methods are already specified in other documents, and this document does not add any new one. This document specifies a way to agree on which method is to be used in the current connection. This document also provides a common way to transmit, between peers, payloads that are specific to secure password authentication methods.