In either of the methods 100 or 200 in FIGS. 4 and 5, the message 20 may be an IKE_AUTH request message according to an Internet Key Exchange, IKE, protocol and/or the response 24 may be an IKE_AUTH response to the IKE_AUTH request message. Alternatively or additionally, the initiator 12 may be an IKE initiator and the responder 14 may be an IKE responder. Also in either of the methods 100 or 200 in FIGS. 4 and 5, the message 20 may further indicate that an Extensible Authentication Protocol, EAP, is to be used for authenticating at least the initiator 12 to the responder 14.