Subject: RE: [AVT] RE: I-D ACTION:draft-ietf-avt-srtp-03.txt - More Feedba ck

From: Euchner Martin ICN M SR 3 <[email-masked]>
Date: Tue, 7 May 2002 12:26:56 +0200

Marc,

thanks for your answers.

Martin,
   Elisabetta and Mats pointed out to me that there is a
"NULL salt" defined in 3.1.1.  So,...

>2.)     optional master salt: section 3.1.1 says that " in addition, for
>each master key, srtp may choose to specify the following associated
>values:" however, the key derivation procedures in section 4.3.1 make the
>master salt integral part of the prf procedures. thus, i would say that the
>four lines on the master salt in 3.1.1 should be moved upwards and become
>mandatory.

I think we can leave this as it is.  Do you agree?

Yes, I agree. You are right. I've overseen that tiny detail. 

I'm keen on seeing your newest SRTP draft!

With kind regards

Martin Euchner.
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 -----Original Message-----
From: 	Mark Baugher [mailto:[email-masked]] 
Sent:	Monday, May 06, 2002 9:21 PM
To:	Euchner Martin  ICN M SR 3
Cc:	[email-masked]
Subject:	Re: [AVT] RE: I-D ACTION:draft-ietf-avt-srtp-03.txt - More
Feedback

Martin,
   Elisabetta and Mats pointed out to me that there is a
"NULL salt" defined in 3.1.1.  So,...

At 12:35 PM 5/6/2002 +0200, Euchner Martin  ICN M SR 3 wrote:
>hi srtp folks,
>
>i have some more comments and questions on srtpv3:
>
>1.)     figure 3 shows in the middle part "encrypted portion of rtp
packet".
>i guess, this should be the unencrypted portion of the rtp packet?
>
>2.)     optional master salt: section 3.1.1 says that " in addition, for
>each master key, srtp may choose to specify the following associated
>values:" however, the key derivation procedures in section 4.3.1 make the
>master salt integral part of the prf procedures. thus, i would say that the
>four lines on the master salt in 3.1.1 should be moved upwards and become
>mandatory.

I think we can leave this as it is.  Do you agree?

Mark

>3.)     section 3.3: the sentence " * if the mki indicator in the
>cryptographic context is zero, the master keys is determined by the current
>srtp index, even though srtcp has its own index." seems to have some
>language problems. is it referring to just one master key or are there
>actually several (2?) master keys involved? (which one then: the srtp
master
>key or the srtcp master key)?
>
>4.)     section 4.3.1: " and a default prf transform is defined in section
>4.3.2." this reference should in fact point to section 4.3.3.
>
>5.)     sections 12.1.1 and 12.1.2: this a question on clarification and
>understanding how the situation would be in case of
>
>a)      unidirectional rtp stream: i guess this involves 6 distinct session
>keys (encryption and authentication session key for the rtp payload,
>encryption and authentication session key for the rtcp sender to receiver
>direction, and another session key pair for the reverse rtcp direction).
but
>i am not quite certain whether there are actually 2 separate unidirectional
>rtcp contexts or there might be a bi-directional rtcp context, thereby
>reducing the number of session keys?
>b)      bi-directional rtp stream: since there is some redundancy on the
>rtcp forward and reverse channels, there are in total four session key
pairs
>(encryption + authentication).
>
>                 this my view correct?
>
>
>with kind regards
>
>
>
>martin euchner.
>-----------------------------------------------------------------------
>| dipl.-inf.                     rapporteur q.g/sg16
>| martin euchner                 phone: +49 89 722 55790
>| siemens ag.....................fax  : +49 89 722 47713
>| icn m sr 3                     mailto:[email-masked]
>|                                mailto:[email-masked]
>| hofmannstr. 51                 intranet:
>http://intranet.icn.siemens.de/marketing/cs27/topics/security/
>| d-81359 muenchen               internet: http://www.siemens.de/
>| __________________
>| germany
>-----------------------------------------------------------------------
>
>
>_______________________________________________
>audio/video transport working group
>[email-masked]
>https://www1.ietf.org/mailman/listinfo/avt

_______________________________________________
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