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Re: Comments on draft-ietf-ipsec-ike-01.txt
On 22 Jun 99 at 18:54, Dan Harkins wrote:
> The paper goes on to suggest changing SAi_b in the authenticating
> hash calculation to SAr_b. But this will allow an attacker to modify
> the Initiator's offers and remove certain offers-- for instance the
> offer is [(3DES, group 5, etc) || (CAST, group 5, etc) || (DES, group 1,
> etc)] and it becomes a single offer of [(DES, group 1, etc)].
>
> The suggested change is flawed but if the working group thinks this
> attack is serious we can include both SAi_b and SAr_b in the hash
> calculations to prevent this.
Dan, if you are going to change hash calculation, maybe more
general solution would be Tero Kivinen's proposal for these HASHes to
be the hash of all packets received/sent so far. It will authenticate
all auxiliary payloads either. Please, see his message
<199809062326.CAA29797@torni.ssh.fi> to the list from 7 Sep 1998 for
details.
> Dan.
Regards,
Valery.
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