Re: Revised Pre-Shared and Public Key Sig modes??

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> 
> 
> The Main Mode exchanges for Pre-Shared keys (HASH_x) or Public Key 
> Signatures (SIG_x) are:

Matt,

IMHO :

I have not considered if the proposed xchg has any security holes.
But I think it has one drawback :

  It breaks the ISAKMP framework by introduce yet another new
  exchange types and saves only one msg.
  
I am not sure if it is worthwhile at this stage of standarization.


Pau-Chen

 
>    Initiator                            Responder
> 
>    HDR, SA                         -->
>                                   <--   HDR, SA
>    HDR, KE, Ni                     -->
>                                   <--   HDR, KE, Nr
>    HDR*, IDii, [HASH_I | SIG_I]    -->
>                                   <--   HDR*, IDir, [HASH_R | SIG_R]
> 
> Is there any reason why 1/2 a round trip could be not eliminated by 
> having  Revised versions of these modes such that):
> 
>    HDR, SA                         -->
>                                   <--   HDR, SA, KE, Nr
>    HDR, KE, Ni                     -->
>                                   <--   HDR*, IDir, [HASH_R | SIG_R]
>    HDR*, IDii, [HASH_I | SIG_I]    -->
> 
> Since the responder has selected a single proposal, he knows what 
> Diffie-Hellman group is being used so he can generate the correct 
> Diffie-Hellman payload and it does cut out 1/2 a round trip.
> 
> I'll write up a draft add these as new authentication methods
> unless someone convinces me this would be a bad idea.
> -- 
> Matt Thomas                    Internet:   [e-mail]
> AltaVista Internet Software    WWW URL:    <coming eventually>
> Digital Equipment Corporation  Disclaimer: This message reflects my own
> Littleton, MA                              warped views, etc.
>