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Re: IKE draft - Aggressive mode auth-ted with encryption

That's right. It does not really matter in what order
to process payloads, since the field "next payload"
in each payload defines the next payload type,
so the implementation will process all payloads
eventually regardless of the order. The most
important thing is to have all information
needed for a current stage of protocol.

I just compared other aggressive modes and
noticed the difference.

Yuri
Certicom Corp.


Daniel Harkins wrote:

>   The draft (RFC?) specifically states that payloads can be in any
> order unless otherwise stated. For example, the SA payload has to be
> first but after that you can put the KE payload next or the hash next.
>
> What you propose is perfectly fine to do. No need to change anything,
> just don't make your implementation expect a certain ordering because
> doing it differently is perfectly legal.
>
>   Dan.
>
> On Tue, 11 Aug 1998 22:36:52 EDT you wrote
> > Hi,
> >
> > I'd like to bring your attention to aggressive mode
> > authenticated with public key encryption described in section
> > 5.2 in "draft-ietf-ipsec-isakmp-oakley-08.txt".
> >
> > >   When using encryption for authentication, Main Mode is defined
> as
> > >   follows.
> > >
> > >        Initiator                        Responder
> > >       -----------                      -----------
> > >        HDR, SA                   -->
> > >                                  <--    HDR, SA
> > >        HDR, KE, [ HASH(1), ]
> > >          <IDii_b>PubKey_r,
> > >            <Ni_b>PubKey_r        -->
> > >                                         HDR, KE, <IDir_b>PubKey_i,
>
> > >                                  <--            <Nr_b>PubKey_i
> > >        HDR*, HASH_I              -->
> > >                                  <--    HDR*, HASH_R
> > >
> > >   Aggressive Mode authenticated with encryption is described as
> > >   follows:
> > >
> > >        Initiator                        Responder
> > >       -----------                      -----------
> > >        HDR, SA, [ HASH(1),] KE,
> > >          <IDii_b>Pubkey_r,
> > >           <Ni_b>Pubkey_r           -->
> > >                                         HDR, SA, KE,
> <IDir_b>PubKey_i,
> > >                                  <--         <Nr_b>PubKey_i,
> HASH_R
> > >        HDR, HASH_I               -->
> > >
> >
> > Aggressive mode reduces amount of messages in the protocol
> > by combining two messages into a single message.
> > It would be more reasonable, on my opinion, in aggressive
> > mode to keep the same order of payloads as used in main mode.
> > It would be easier to remember the payload order as well,
> > if we know that the payloads order in the main mode is
> > similar. I assume that there might not be the perfect
> > rule for each mode of protocol, but we should make it
> > so where it is possible.
> >
> > I propose that we change
> >
> > >        HDR, SA, [ HASH(1),] KE,
> >
> > to
> >
> > >        HDR, SA, KE, [ HASH(1),]
> >
> >
> > I know that it is not very critical for the
> > technical part of protocol. However, I think
> > there is no point to leave it as it is.
> >
> > Thanks.
> >
> > Yuri Poeluev
> > Certicom Corp.
> >
References: