Re: [rtcweb] Let's define the purpose of WebRTC

Jonathan Lennox <jonathan@vidyo.com> Mon, 07 November 2011 16:16 UTC

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From: Jonathan Lennox <jonathan@vidyo.com>
To: Eric Rescorla <ekr@rtfm.com>, Cameron Byrne <cb.list6@gmail.com>
Date: Mon, 7 Nov 2011 11:16:03 -0500
Thread-Topic: [rtcweb] Let's define the purpose of WebRTC
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Subject: Re: [rtcweb] Let's define the purpose of WebRTC
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Eric Rescorla wrote:

> Good point. Also, of course (unless you use the SRTP header encryption
> extension) the SRTP header is in the clear, so you mostly just don't get the media itself.

The extension (assuming you're talking about draft-ietf-avtcore-srtp-encrypted-header-ext) is header extension encryption, not a header encryption extension ... the base RTP header remains in the clear in SRTP, even with this draft. 

SRTP forms its per-packet IVs based on the SSRC and sequence number, so those fundamentally have to be sent in the clear.  I suppose in theory you could encrypt some of the other fields of the RTP header, but I don't see much point in it. (At some point, if things are this sensitive, you're better off just using IPSec.)

-- 
Jonathan Lennox
jonathan@vidyo.com