Subject: [MSEC] MIKEY Question

From: "Steffen Fries" <[email-masked]>
Date: Mon, 24 Nov 2003 11:24:50 +0100

Hi Elisabetta,

do you have any recommendation in which SIP return message the 
second MIKEY message in case of DH based key exchange should be 
sent? 
It might be a matter of implementation, but imagine a scenario, 
where a caller sends a SETUP to a callee (including the MIKEY 
message). Now, he gets a RINGING back. Should the ringing 
already contain the second MIKEY message or the OK? In case of 
RINGING, the call may not be completed, and thus, the MIKEY  
data have been exchanged without actually being used. In case 
of okay, the callee may already start sending RTP data before 
the OK message arrives at the caller.

Is there any recommendation, which message should be taken?

Regards
	Steffen

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From: "Elisabetta Carrara (KI/EAB)" <[email-masked]>
Date: Fri, 28 Nov 2003 10:43:36 +0100

Hi Steffen,
one issue with provisional responses is that they might be 
sent not reliably (however SIP has an extension mechanism
to add reliability to them). 
It seems then better to use the formulation "the offer and the 
answer to the offer" (the answer is intended as the 
first reliable answer). 
You might have implementations accepting some clipping at the 
beginning, otherwise they might e.g. use the reliable provisional 
response. Please also look at the new security pre-condition 
draft in mmusic (Mark is one of the authors), I understand 
it is exactly to avoid RTP arriving before the security is 
set up. 

Cheers
/Elisabetta

> -----Original Message-----
> From: Steffen Fries [mailto:[email-masked]]
> Sent: den 24 november 2003 11:25
> To: Elisabetta Carrara (KI/EAB)
> Cc: [email-masked]
> Subject: MIKEY Question
> 
> 
> Hi Elisabetta,
>