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Chinh Nguyen wrote:
> So my query is this. There is a statement in the RFC that since
> there is no KE payload (and nonces) in the IKE_AUTH, this implies
> that the DH group should be NONE or omitted. I don't understand
> logically why the latter follows from the former.
> I thought an SA proposal is to enumerate supported/acceptable
> transforms (and one possible usage is the inclusion of a DH group
> in the CHILD_SA SA proposals to signal PFS in rekey).
The SA proposal here enumerates the transforms to be used for *this* CHILD_SA creation (not future CHILD_SAs; those exchanges have their own SA payloads, which may contain different things). Since no Diffie-Hellman calculation is done when this CHILD_SA is created, you can't get negotiate the Diffie-Hellman transform here.