Subject: [AVT] TLS-SRTP internet draft as a WG item in AVT

From: David McGrew <[email-masked]>
Date: Wed, 20 Jun 2007 13:54:49 -0700

Hi Colin, Roni, and Tom,

I would like to ask that draft-mcgrew-tls-srtp be taken up as a  
working group action item in AVT, as part the plan for carrying  
forward the RTPSEC work (as per Cullen's email of May 11 to the  
rtpsec list).   I would like to continue on as an author of this  
work, and Eric as agreed to do the same.  There are a small number of  
minor open issues which I expect can be wrapped up quickly:

1.  The draft needs to be clarified so that, in the Symmetric RTP  
case, only one handshake is needed.

2.  Section 3.6.2.1 needs to be resolved to either decide on a  
"symmetry breaking" rule or not.  It may be desirable to have such a  
rule to handle cases in which the signaling system can't tell a  
device which should act as client and which should act as server.    
This would allow opportunistic probing, i.e. a TLS-SRTP  
implementation could attempt to find out whether another RTP  
implementation supports TLS-SRTP, absent any help from signaling.

3.  The "single DTLS session per SRTP session" issue needs to be  
decided, and Appendix A should then be removed from the draft.

4.  It should be decided to use, or not to use the "TLS Extractor",  
and Section 3.3 should be rewritten accordingly.

5.  The duplicate list of srtp profiles needs to be eliminated.

Best regards,

David

--

p.s. - here's the AVT-specific part of Cullen note, so that you don't  
need to dig it out of your mailbox: "AVT - Describe how DTLS is used  
to key SRTP and how SRTP is used in combination with DTLS. This  
includes the issues of multiplexing DTLS and SRTP on one port. draft- 
mcgrew-tls-srtp will be the starting draft for this."

_______________________________________________
Audio/Video Transport Working Group
[email-masked]
https://www1.ietf.org/mailman/listinfo/avt

---

From: Colin Perkins <[email-masked]>
Date: Tue, 26 Jun 2007 12:00:47 +0100

Hi David,

What milestone(s) do you see this work adding to the AVT charter, if  
accepted?

Colin

On 20 Jun 2007, at 21:54, David McGrew wrote:
> work, and Eric as agreed to do the same.  There are a small number  
> of minor open issues which I expect can be wrapped up quickly:
>
> "symmetry breaking" rule or not.  It may be desirable to have such  
> a rule to handle cases in which the signaling system can't tell a  
> p.s. - here's the AVT-specific part of Cullen note, so that you  
> don't need to dig it out of your mailbox: "AVT - Describe how DTLS  
> is used to key SRTP and how SRTP is used in combination with DTLS.  
> This includes the issues of multiplexing DTLS and SRTP on one port.  
> draft-mcgrew-tls-srtp will be the starting draft for this."

-- 
Colin Perkins
http://csperkins.org/

---

From: David McGrew <[email-masked]>
Date: Tue, 26 Jun 2007 14:05:27 -0700

Hi Colin,

how does this milestone sound?  "December 2007 Submit TLS-SRTP for  
Proposed Standard"   Perhaps I'm aggressive in expecting us to have  
the draft ready before the Vancouver meeting; we could push it back  
to March 2008.

David

On Jun 26, 2007, at 4:00 AM, Colin Perkins wrote:

> Hi David,
>
> What milestone(s) do you see this work adding to the AVT charter,  
> if accepted?
>
> Colin
>
>
>
>
>> device which should act as client and which should act as  
>> server.   This would allow opportunistic probing, i.e. a TLS-SRTP  
>> 4.  It should be decided to use, or not to use the "TLS  
>> Extractor", and Section 3.3 should be rewritten accordingly.
>>
>> This includes the issues of multiplexing DTLS and SRTP on one  
>> port. draft-mcgrew-tls-srtp will be the starting draft for this."
>
>
>
> -- 
> Colin Perkins
> http://csperkins.org/

---

From: Cullen Jennings <[email-masked]>
Date: Tue, 26 Jun 2007 15:13:59 -0700

I have no problem with that milestone if that is what you decide on ...

One question about it - would calling it "DTLS-SRTP" be better than  
"TLS-SRTP"? I don't care but if we were going to change the name,  
this would be the right time to do that.

Cullen <with my AD hat on>

---

From: David McGrew <[email-masked]>
Date: Tue, 26 Jun 2007 16:34:34 -0700

Hi Cullen,

> this would be the right time to do that.

I'm name agnostic.  Whatever Eric and/or the TLS folks say is the  
right TLS terminology.   I said TLS-SRTP here because that's the name  
of the current draft, though lots of people (including me) have used  
the other name.

David

---

From: "Dan Wing" <[email-masked]>
Date: Tue, 26 Jun 2007 23:42:29 -0700

If we're taking votes, I would also prefer DTLS-SRTP.  For all we know, we
might want or need TLS (over TCP) with SRTP later (streaming video,
perhaps?).

-d

> -----Original Message-----
> From: Cullen Jennings [mailto:[email-masked]] 
> Sent: Tuesday, June 26, 2007 3:14 PM
> To: David McGrew ((mcgrew))
> Cc: Colin Perkins; Roni Even; [email-masked]; AVT; Dan 
> Wing (dwing); Eric Rescorla
> Subject: Re: TLS-SRTP internet draft as a WG item in AVT
> 
>

---

From: Colin Perkins <[email-masked]>
Date: Wed, 27 Jun 2007 10:59:52 +0100

David, All,

That's fine. We therefore propose to accept this draft as an AVT work  
item, with the milestone listed. If there are any objections to this  
plan, please state them by 29th June 2007.

Colin

On 26 Jun 2007, at 22:05, David McGrew wrote:
>>> work, and Eric as agreed to do the same.  There are a small  
>>> number of minor open issues which I expect can be wrapped up  
>>> quickly:
>>>
>>> "symmetry breaking" rule or not.  It may be desirable to have  
>>> such a rule to handle cases in which the signaling system can't  
>>> tell a device which should act as client and which should act as  
>>> don't need to dig it out of your mailbox: "AVT - Describe how  
>>> DTLS is used to key SRTP and how SRTP is used in combination with  
>>> DTLS. This includes the issues of multiplexing DTLS and SRTP on  
>>> one port. draft-mcgrew-tls-srtp will be the starting draft for  
>>> this."
>>
>>
>>
>> -- 
>> Colin Perkins
>> http://csperkins.org/
>

-- 
Colin Perkins
http://csperkins.org/

---

From: Magnus Westerlund <[email-masked]>
Date: Wed, 27 Jun 2007 16:01:32 +0200

> plan, please state them by 29th June 2007.

Hi,

Are you of the opinion that the following item in the charter covers this?

- to maintain and enhance the SRTP Profile, with review and input from
the Security Area

Cheers

Magnus Westerlund

IETF Transport Area Director & TSVWG Chair
----------------------------------------------------------------------
Multimedia Technologies, Ericsson Research EAB/TVM/M
----------------------------------------------------------------------
Ericsson AB                | Phone +46 8 4048287
Torshamsgatan 23           | Fax   +46 8 7575550
S-164 80 Stockholm, Sweden | mailto: [email-masked]
----------------------------------------------------------------------

---

From: Colin Perkins <[email-masked]>
Date: Wed, 27 Jun 2007 15:57:47 +0100

On 27 Jun 2007, at 15:01, Magnus Westerlund wrote:
> Colin Perkins skrev:
>> That's fine. We therefore propose to accept this draft as an AVT  
>> work item, with the milestone listed. If there are any objections  
>> to this plan, please state them by 29th June 2007.
>> Colin
>

That, and the charter item "to provide a framing mechanism for RTP  
over TCP and TLS", and an explicit request from our area director to  
take this draft... If that's not sufficient, we can propose  
additional text (since a charter update will be needed to add the new  
milestone anyway).

-- 
Colin Perkins
http://csperkins.org/

---

From: Colin Perkins <[email-masked]>
Date: Fri, 29 Jun 2007 16:48:24 +0100

There were no objections, therefore this draft is accepted as an AVT  
work item.
Colin

On 27 Jun 2007, at 10:59, Colin Perkins wrote:
>> Proposed Standard"   Perhaps I'm aggressive in expecting us to  
>> have the draft ready before the Vancouver meeting; we could push  
>> it back to March 2008.
>>
>> David
>>
>>>> 1.  The draft needs to be clarified so that, in the Symmetric  
>>>> RTP case, only one handshake is needed.
>>>>
>>>> server.   This would allow opportunistic probing, i.e. a TLS- 
>>>> SRTP implementation could attempt to find out whether another  
>>>> RTP implementation supports TLS-SRTP, absent any help from  
>>>> signaling.
>>>>
>>>> DTLS is used to key SRTP and how SRTP is used in combination  
>>>> with DTLS. This includes the issues of multiplexing DTLS and  
>>>> SRTP on one port. draft-mcgrew-tls-srtp will be the starting  
>>>> draft for this."
>>>
>>>
>>>
>>> -- 
>>> Colin Perkins
>>> http://csperkins.org/
>>

-- 
Colin Perkins
http://csperkins.org/