Re: : FW: IPSec use with Diameter (from the IPSEC WG list)

> It is true that no protocol bindings occur in phase 1, and this
> complicates the task of using certs with granular (per-port) policies in
> IPsec, but what this says is wrong. It *is* possible to use uniquely
> configured root CAs for each application individually (assuming each
> application has its own port). The PAD described in 2401bis makes this
> more explicit, but it was allowed by 2401 and the IKE rfc family as well.

Without a protocol binding in phase 1, there isn't a way for the responder
to know what the SA is being brought up for.  Therefore it has no way to
tell the initiator what certs it will accept.  It can give the initiator
the union of all possible trust anchors, but then it once phase 2
completes, it is possible that the responder will learn that the initiator
chose the wrong certificate.  This isn't fixed in 2401bis, because it's
an inherent problem with IKEv1.