Re: [rtcweb] No Interim on SDES at this juncture

Martin Thomson <martin.thomson@gmail.com> Thu, 20 June 2013 23:41 UTC

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Date: Thu, 20 Jun 2013 16:41:07 -0700
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From: Martin Thomson <martin.thomson@gmail.com>
To: Richard Barnes <rlb@ipv.sx>
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Cc: "rtcweb@ietf.org" <rtcweb@ietf.org>
Subject: Re: [rtcweb] No Interim on SDES at this juncture
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On 20 June 2013 16:09, Richard Barnes <rlb@ipv.sx> wrote:
> If, in addition, the browser does not expose media keys to JS (as is
> required for SDES), then even an active attacker who hijacks the HTTP
> connection to inject scripts cannot access the media keys.

That's only true if that attacker were not able to also set the keys.
I haven't had anyone explain what the API for EKT would look like, but
one possibility would permit that attacker to set keys (i.e., keying
would be write-only).  That possibility would be attractive from a
symmetry perspective - the non-browser can insert new keying, why
should the browser be prevented from doing so - but I can see how
implementation of EKT does not strictly require that possibility.
That would preclude some interesting browser-API-based scenarios
though.