Re: [IPsec] [Fwd: New Version Notification for draft-detienne-ikev2-recovery-00]

Frederic Detienne writes:
> Reading through, I think we need to expose a little more of our
> rationale.

I have not read the draft (yet), but from your discussion it seems
that the real solution to the problem is to use birth certificates,
not adding more round trips to get more protection (from
http://tools.ietf.org/html/draft-ietf-ipsec-ikev2-rationale-00 section
3.1 changes we considered and rejected):

----------------------------------------------------------------------
   - adding in Bill Sommerfeld's "birth certificate" idea. In this idea
   Bob keeps a number in nonvolatile memory that increments each time
   the node restarts. When Bob restarts, he signs a "birth certificate"
   stating what the value of that counter is. This birth certificate is
   transmitted as a payload in message 4. Alice keeps this value. If Bob
   ever receives an ESP packet that doesn't decrypt properly or with an
   unknown SPI, he responds to that packet with his birth certificate.
   If the recipient has an SA for Bob with an older birth certificate,
   this lets them know Bob has restarted and forgotten state for that
   SA. We decided not to add that to this version of the draft, although
   we think it is a good idea, until it's been written up in a separate
   draft and there has been an opportunity for people to understand it
   and give feedback.
----------------------------------------------------------------------

The counter could of course be also the timestamp, as that is already
available for systems which are using certificates. I.e. instead of
sending non-authenticated invalid IKE SA notify, Bob would send his
birth certificate, so Alice can see whether Bob has rebooted or not,
and as the certificate is signed with Bobs key it means Alice can
trust that information. 
-- 
kivinen@safenet-inc.com
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