Re: [rtcweb] SDP Security Descriptions (RFC 4568) and RTCWeb

[Randell Jesup <[e-mail]>]

On 4/25/2013 7:19 PM, Eric Rescorla wrote:
> On Thu, Apr 25, 2013 at 4:01 PM, Martin Thomson 
> <[e-mail] <mailto:[e-mail]>> wrote:
> [snip]
>
>     The default mode of operation for getUserMedia is to return media that
>     is accessible to the web site.  The same for RTCPeerConnection.  That
>     means that the site can see and modify your media in your browser,
>     even if it can't tamper with it on the network.
>
>
> It's certainly true that the site has access to the media with DTLS if you
> don't use identity assertions/isolated streams. However, what it doesn't
> have is *invisible* access. I.e., it must do something that is user 
> visible,
> which allows for the detection of cheating by the site. By contrast, 
> if SDES is used
> then the site can simply passively monitor all your traffic, or at least
> any that goes through its network and you can't detect it.
>

Or they can simply store off the key to be used to offline-decrypt raw 
traffic captured at an ISP, at their leisure.  SDES is basically 
"protect against WiFi sniffers" encryption.  Ironically, Apple's 
messaging stuff apparently uses strong end-to-end encryption (the 
wonders of not caring about legacy interop).

-- 
Randell Jesup
[e-mail]