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Re: IKEv2 SA rekeying - naming an initial SA



On Mon, Aug 18, 2003 at 05:08:08PM -0400, Michael Richardson wrote:
> 
> >>>>> "Nicolas" == Nicolas Williams <Nicolas.Williams@sun.com> writes:
>     Nicolas> I'm glad to see that there is some SA rekeying functionality in
>     Nicolas> IKEv2 that is somewhat like the rekeying functionality in SSHv2,
>     Nicolas> that is, that a new SA can be established under the protection
>     Nicolas> of and bound to a previous (still live) SA.
> 
>     Nicolas> Now, if only there was a concept similar to the SSHv2 session
>     Nicolas> ID.  (Or is it there and I just missed it?)
> 
>   I'd like to see such a thing as well.

Perhaps a quantity derived from SK_d and the SPIs of the initial IKE_SA,
or from SKEYSEED and the SPIs of the initial IKE_SA.  Perhaps it would
be useful generally to include AUTH or other material pertaining to
authentication in the derivation, but for use with CCM (the proposed
GSS-API mechanism, not the cipher mode) that is not necessary.

Background:

The Channel Conjunction Mechanism (CCM) is a GSS-API pseudo-mechanism
for negotiating the use of GSS-API channel bindings and the non-use of
session cryptographic protection at the application/GSS-API layer
because a lower layer provides acceptable session protection.  Thus, if
the GSS-API initiator and acceptor have the same channel bindings to a
lower layer session (e.g., an SSHv2 session, or an IKEv2 SA) and a GSS
security context bound to those channel bindings, and if these channel
bindings are derived from a key exchange involving DH, then there is no
MITM and the GSS-API need not provide any session cryptographic
protection.

Summary:  Authentication at one layer (application/GSS-API) bound to
secure sessions at a lower layer (IPsec).

See the NFSv4 list's archives from last December through May or so for
more information, including expected performance savings from using the
CCM GSS-API mechanism in conjunction with secure transports.

Cheers,

Nico
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