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Re: Interoperability (was: Death to AH?)



>>>>> "Dan" == Dan Harkins <dharkins@cips.nokia.com> writes:

 Dan> On Fri, 02 Jun 2000 16:05:43 EDT you wrote
 >>  You mention several other problems.  Perhaps you could start your
 >> own thread on them :)'
 >> 
 >> Gee I don't liek the way IKE doesn't really define approaches for
 >> lifetimes for the ISAKMP SA.  Results in interop challenges......

 Dan> Here we go again Bob....

 Dan> Quite a while ago I attempted to define an approach to deal with
 Dan> things like lifetimes and key lengths and other attributes that
 Dan> do not have a simple boolean acceptance criteria and
 Dan> failed. There was no consensus.  But I'm willing to try again:

 Dan> If someone offers you a keylength for a variable-keylenght
 Dan> cipher which is greater than or equal to what you have
 Dan> configured, accept it. If it's less reject it.

I'd support that.

 Dan> If someone offers you a lifetime which is less than or equal to
 Dan> what you have configured, accept it. If it's more reject it.

I'd support that too.  

 Dan> The hardest one though is the Diffie-Hellman group. I know of
 Dan> quite a few people that will accept group 5 (and reject group 1)
 Dan> if they're configured for group 2 but even saying that an
 Dan> implementation SHOULD do that seemed to be too much for enough
 Dan> people to kill it.

Hm.  Weird.  Could we try that one again and see why this is?

 Dan> And where in the scale do you add new groups
 Dan> or groups of different types-- elliptic curve vs. prime modulus?

I think you have to leave that one out.  The reason is that, unlike
all the other examples, there is no clear order among these.  That
indeed is the problem with the group number: it only has a partial
order.

	paul


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