Subject: Re: [clue] Last Call: <draft-ietf-clue-rtp-mapping-10.txt> (Mapping RTP streams to CLUE Media Captures) to Proposed Standard

From: Magnus Westerlund <[email-masked]>
Date: Fri, 13 Jan 2017 13:22:21 +0100

Hi,

As one of IANA's expert reviewers for the two registries that this 
document attempts to register in, I want to provide some feedback on 
individual basis and directly.

The SDES item registration of the CaptureID is fine with the exception 
that it isn't clear on the security consideration for the CaptureID 
field as SDES item. I fail to find any limitations or even 
recommendations for how the value is created by the implementation. Nor 
does the security considerations discuss the potential risk that the 
capture ID is privacy sensitive, like "Adrian's Mic" rather than AC0 as 
in the example in the data model document. The data model document is 
fairly clear on the need for confidentiality and authorization for the 
whole data model document. However, this thinking has not been raised 
and clarified in this specific move of the information into the RTP 
protocol.

So, I would recommend a discussion in general if the field should have 
anonymous labels, that do not contain privacy information. Then one 
needs to be clear on what requirements that puts on transporting this 
field in RTP. And that depends on how certain one can be that it is 
anonymous or that it may contain sensitive information and therefore 
should be confidentiality protected. In all cases this field needs 
integrity and source authentication. Which should be made explicit in 
the security consideration. The clue mapping require implementation of 
SRTP with DTLS-SRTP keying, however, it fails to be specific on which 
protection profiles that are to be supported, both for the SRTP as well 
as the crypto functions for the key handshakes in DTLS-SRTP. Thus, I 
can't be certain if the CaptureID will be confidentiality protected or 
not even in RTCP.

When it comes to the RTP Header Extension case, the RFC 7941 is very 
explicit about the requirement on doing this security consideration. And 
I note that with the above analysis of what requirements to put, one can 
ensure that the right requirements on the CLUE system to protect any RTP 
header extension with the CaptureID is done. I do note that if 
confidentiality protection is needed, this means additional 
implementation requirement. Such needs to be defined in this or 
referenced document if that is the case.

This should be fairly straight forward to fix, but needs to be done.

Cheers

Magnus

Den 2016-12-22 kl. 22:18, skrev The IESG:
>
> The IESG has received a request from the ControLling mUltiple streams for
> tElepresence WG (clue) to consider the following document:
> - 'Mapping RTP streams to CLUE Media Captures'
>   <draft-ietf-clue-rtp-mapping-10.txt> as Proposed Standard
>
> The IESG plans to make a decision in the next few weeks, and solicits
> final comments on this action. Please send substantive comments to the
> [email-masked] mailing lists by 2017-01-12. Exceptionally, comments may be
> sent to [email-masked] instead. In either case, please retain the
> beginning of the Subject line to allow automated sorting.
>
> Abstract
>
>
>    This document describes how the Real Time transport Protocol (RTP) is
>    used in the context of the CLUE protocol.  It also describes the
>    mechanisms and recommended practice for mapping RTP media streams
>    defined in SDP to CLUE Media Captures.
>
>
>
>
> The file can be obtained via
> https://datatracker.ietf.org/doc/draft-ietf-clue-rtp-mapping/
>
> IESG discussion can be tracked via
> https://datatracker.ietf.org/doc/draft-ietf-clue-rtp-mapping/ballot/
>
>
> No IPR declarations have been submitted directly on this I-D.
>
>
>
>
>

-- 

Magnus Westerlund

----------------------------------------------------------------------
Services, Media and Network features, Ericsson Research EAB/TXM
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Ericsson AB                 | Phone  +46 10 7148287
Färögatan 6                 | Mobile +46 73 0949079
SE-164 80 Stockholm, Sweden | mailto: [email-masked]
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---

From: Paul Kyzivat <[email-masked]>
Date: Fri, 13 Jan 2017 15:27:46 -0500

Roni?

---

From: "Roni Even" <[email-masked]>
Date: Sun, 15 Jan 2017 08:05:22 +0200

Hi Magnus,
CaptureID here is just conveying the value defined in the CLUE data model
and CLUE protocol defines the security consideration for conveying the
adertized and configured values.
So any security on creating is done in the protocol document

As for the header extension, I will add some text
Roni

> -----Original Message-----
> From: clue [mailto:[email-masked]] On Behalf Of Magnus Westerlund
> Sent: Friday, January 13, 2017 2:22 PM
> To: [email-masked]
> Cc: [email-masked]; [email-masked];
[email-masked]
> Subject: Re: [clue] Last Call: <draft-ietf-clue-rtp-mapping-10.txt>
(Mapping RTP
> streams to CLUE Media Captures) to Proposed Standard
> 
> Hi,
> 
document
> attempts to register in, I want to provide some feedback on individual
basis and
> directly.
that it isn't
> clear on the security consideration for the CaptureID field as SDES item.
I fail to
> find any limitations or even recommendations for how the value is created
by
> the implementation. Nor does the security considerations discuss the
potential
> risk that the capture ID is privacy sensitive, like "Adrian's Mic" rather
than AC0
> as in the example in the data model document. The data model document is
whole data
> model document. However, this thinking has not been raised and clarified
in this
> specific move of the information into the RTP protocol.
> 
> anonymous labels, that do not contain privacy information. Then one needs
to
> be clear on what requirements that puts on transporting this field in RTP.
And
> that depends on how certain one can be that it is anonymous or that it may
> contain sensitive information and therefore should be confidentiality
protected.
> In all cases this field needs integrity and source authentication. Which
should be
> made explicit in the security consideration. The clue mapping require
> implementation of SRTP with DTLS-SRTP keying, however, it fails to be
specific
> on which protection profiles that are to be supported, both for the SRTP
as well
> as the crypto functions for the key handshakes in DTLS-SRTP. Thus, I can't
be
> certain if the CaptureID will be confidentiality protected or not even in
RTCP.
> When it comes to the RTP Header Extension case, the RFC 7941 is very
explicit
> about the requirement on doing this security consideration. And I note
that with
> the above analysis of what requirements to put, one can ensure that the
right
> requirements on the CLUE system to protect any RTP header extension with
the
> CaptureID is done. I do note that if confidentiality protection is needed,
this
> means additional implementation requirement. Such needs to be defined in
this
> or referenced document if that is the case.
> 
> > The IESG has received a request from the ControLling mUltiple streams
> > for tElepresence WG (clue) to consider the following document:
> > [email-masked] mailing lists by 2017-01-12. Exceptionally, comments may
> > be sent to [email-masked] instead. In either case, please retain the
> _______________________________________________
> clue mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/clue

---

From: Magnus Westerlund <[email-masked]>
Date: Mon, 16 Jan 2017 14:56:42 +0100

> So any security on creating is done in the protocol document

Yes, it is containing a value. And the data model and protocol documents 
defines the protocol level security requirements and solution. However, 
as the CaptureID is taken out of the context of the CLUE protocol, and 
put into RTP/RTCP there needs to be consideration for the implications 
of that action.

As I don't find any recommendation for how an implementation generates 
CaptureIDs I could not determine the security sensitivity of the field. 
That is why I am asking about that aspect. Please provide an analysis of 
what it may contain, i.e. worst case, and the appropriate recommendation 
for appropriately securing that field.

> As for the header extension, I will add some text

And I think this is relevant also for SDES items in general, not only 
for the header extension. The security risks and fundamental 
requirements are shared anyway.

Cheers

Magnus

-- 

Magnus Westerlund

---

From: Paul Kyzivat <[email-masked]>
Date: Mon, 16 Jan 2017 15:01:29 -0500

> put into RTP/RTCP there needs to be consideration for the implications

Good point. When used within the CLUE protocol the captureID is 
protected by DTLS. RTP/RTCP presents new concerns.

	Thanks,
	Paul

>>> needs
>>> can't