Re: [rtcweb] draft-ietf-rtcweb-rtp-usage-12 Client-to-Mixer Audio Level

"Cullen Jennings (fluffy)" <fluffy@cisco.com> Wed, 05 March 2014 14:35 UTC

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From: "Cullen Jennings (fluffy)" <fluffy@cisco.com>
To: tim panton <tim@phonefromhere.com>
Thread-Topic: [rtcweb] draft-ietf-rtcweb-rtp-usage-12 Client-to-Mixer Audio Level
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Date: Wed, 5 Mar 2014 14:35:41 +0000
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Subject: Re: [rtcweb] draft-ietf-rtcweb-rtp-usage-12 Client-to-Mixer Audio Level
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On Mar 5, 2014, at 2:33 PM, tim panton <tim@phonefromhere.com> wrote:

> 
> On 5 Mar 2014, at 14:25, Justin Uberti <juberti@google.com> wrote:
> 
>> So there are three things here:
>> 1) MUST the implementation offer encrypted header extensions? (i.e. mandatory-to-implement)
>> 2) MUST the implementation use encrypted header extensions? (i.e. mandatory-to-use)
>> 3) MUST the implementation expose an API to control this? (i.e. no SDP munging needed)
>> 
>> I think we want yes for #1, no for #2, and #3 is potentially interesting but out of scope for 1.0.
>> That gives encrypted headers for audio on by default, but remote parties can negotiate this off using RFC 6904 mechanisms.
>> 
> 
> In order to agree with that I’d need to be persuaded that there isn’t a known-plaintext attack risk there
> (e.g. detecting a muted mic therefore knowing the ulaw content of a packet), since
> any weakening  in DTLS also impacts the data channel and video channels - assuming bundle.
> 
> Like I say, I’m not enough of a cryptographer to know.

No - it does not weaken DTLS to know the plaintext (and if it did, DTLS would have series security problems )