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RE: Certificate Requesting



Roy Pereira writes:
> The additional exchange scenario that you do not agree with only happens
> if the initiator does not send a certificate and the responder does not
> have it.  The responder will then append a CertReq payload to the ISAKMP
> message.  If the initiator receives the CertReq in the sixth message of
> MainMode (RSA_SIG), then he must reply back with his certificate in a
> MainMode message.  He may also append a CertReq to that message if the
> responder did not include a certificate in the sixth message and he does
> not have it.  This would force the responder to reply back with his
> certificate.

And if responder again includes certificate request (it can, there is
no limitation that there must be only one of certificate request) the
initiator must again reply to it and so on. Is there any limit for
this?

I can see that someone might want to use this kind of system when they
don't want the other end even to know what CA's they need. They could
first ask can you provide certificate for this CA, and if so they know
OK, now it is ok to ask next level of CA etc.

I really don't like the exchange to be extended this way. I would
really like to explicitly say that certificate requests are only
allowed if the other end is going to reply this message anyway. You
can also expand the exchange from normal six or three messages if you
set commit bit. 

> This scenario was brought forth by a rather large software corporation
> since this is what they do in their IPSec implementation.

Is there really any real use for this? It makes the state machine even
more complicated than it is now, and the there are quite a lot of
different stuff there already given all the different authentications,
aggressive/main mode, commit bit etc. 
-- 
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Magnus Enckellin kuja 9 K 19, 02610, Espoo   Home : +358-9-502 1573


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