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Re: IPSEC Security Gateways & NAT
Well, it's not -random- DoS. The attacker must at least respond
to message 2 with message 3 before the responder will do any work.
This implies that the attacker must make their actual IP address
known to the attacked.
So, you may be forced to execute a DH exponentiation as a responder,
but you at least know _WHO_ (IP Address) caused you to perform the
operation.
-derek
"Chen, David" <dchen@ellacoya.com> writes:
> Dan,
>
> Exactly, today's phase 1
> do DH key number crunching before auth the peer.
> (well I think it is only intend to check integrity of the messages,
> but pre-shared key having more than that it also auth peer.)
>
> DH key generation cost much more than simple pass-phrase verification.
>
> Random DOS attacks can be reduced, if responder
> auth peer first (first tier auth) before crunching the DH-key.
>
> Regards,
>
> --- David
>
>
>
> -----Original Message-----
> From: Dan Harkins [mailto:dharkins@lounge.org]
> Sent: Thursday, June 14, 2001 2:36 PM
> To: Chen, David
> Cc: ipsec@lists.tislabs.com
> Subject: Re: IPSEC Security Gateways & NAT
>
>
> No, the DH secret is generated *before* authentication. Re-read the RFC.
>
> Dan.
>
> On Thu, 14 Jun 2001 12:45:39 EDT you wrote
> > Dan,
> >
> > Since the phase 1 goal is to auth DH-key exchange.
> > The DH key is generated *after* auth anyway.
> >
> > However,
> > the pre-shared key (pass-phrase) authetication cost less (and stateless)
> > for responder to verify than "public key" authentication.
> >
> > Regards,
> >
> > --- David
--
Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
Member, MIT Student Information Processing Board (SIPB)
URL: http://web.mit.edu/warlord/ PP-ASEL-IA N1NWH
warlord@MIT.EDU PGP key available
References: