[tor-bugs] #5578 [Flashproxy]: Investigate WebRTC for flash proxy NAT punching

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#5578: Investigate WebRTC for flash proxy NAT punching
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     Reporter:  dcf         |      Owner:  dcf
         Type:  task        |     Status:  new
     Priority:  normal      |  Milestone:
    Component:  Flashproxy  |    Version:
   Resolution:              |   Keywords:
Actual Points:              |  Parent ID:
       Points:              |
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Comment (by infinity0):

 Continuing from the above, the following option probably would not require
 any changes to the ICE authentication code, nor the facilitator to have
 another certification key (nor to use the existing encryption key for
 certification) - but it does assume the existence of a fully-known
 confidential channel between the facilitator and the browser proxy (i.e.
 not SSL with x509).

 1. the client, L, generates a secret key K(R) and sends it to the
 facilitator in an encrypted client registration. this means only the
 facilitator can read K(R).
 2. when the facilitator picks a proxy, R, to serve L, it gives it K(R) via
 the confidential channel. now only the facilitator and the proxy can read
 K(R).
 3. R then uses K(R) as the authentication key for ICE as normal. no
 changes to normal ICE authentication are needed.
 4. L assumes that the facilitator works honestly, and that no-one else can
 read K(R) in transit, due to the confidential channel.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/5578#comment:24>
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