Re: [rtcweb] Asking TLS for help with media isolation

Dan Wing <dwing@cisco.com> Tue, 08 April 2014 19:41 UTC

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From: Dan Wing <dwing@cisco.com>
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Date: Tue, 8 Apr 2014 12:41:19 -0700
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To: Martin Thomson <martin.thomson@gmail.com>
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Subject: Re: [rtcweb] Asking TLS for help with media isolation
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On Apr 8, 2014, at 11:24 AM, Martin Thomson <martin.thomson@gmail.com> wrote:

> On 8 April 2014 09:50, Bernard Aboba <bernard.aboba@gmail.com> wrote:
>> [BA] I'm not sure that the concept of "isolation" makes sense for those
>> intermediaries (or to voicemail or an audio/video conference, for that
>> matter).   While in a point-to-point call it might be useful, in a
>> conference the whole point is to have audio/video sent to multiple parties,
>> and recording is commonplace.  The problem is that from a protocol point of
>> view the cases are not easily distinguishable -- and so if the browser
>> insists on "isolation" then one wonders what will happen if the conference
>> bridge/video MCU/voicemail system refuses to negotiate it.   Refusing to
>> send media would not be a desirable outcome.
> 
> I think that for this, it's perfectly reasonable to use identity, but
> not stream isolation.  With isolation, if the peer does not agree to
> comply, then the session fails to complete.
> 
> The authenticated party here is an MCU (or bridge, or voicemail,
> etc...).  Rather than sending to "anindividual@example.org".org", media is
> sent to "mcu@example.com".com".  Is it reasonable for that MCU to forward
> media to other, unspecified entities?  Clearly it can, but should it?
> 
> (Not having thought it through completely, a voicemail box could
> conceivably work.  I think that I'd want to use a different identity
> for it though.)

For voicemail, there was a proposal in 2009 for doing what amounted to object security, http://tools.ietf.org/html/draft-naslund-srtp-saf.  That document's last update was in 2011 but I don't know if it evolved into a product or died out or what.

-d