[tor-bugs] #28942 [Circumvention/Snowflake]: Evaluate pion WebRTC

Tor Bug Tracker & Wiki blackhole at torproject.org
Wed Jun 19 20:03:49 UTC 2019


#28942: Evaluate pion WebRTC
-------------------------------------+-------------------------------
 Reporter:  backkem                  |          Owner:  cohosh
     Type:  enhancement              |         Status:  assigned
 Priority:  Medium                   |      Milestone:
Component:  Circumvention/Snowflake  |        Version:
 Severity:  Normal                   |     Resolution:
 Keywords:  ex-sponsor-19            |  Actual Points:
Parent ID:                           |         Points:
 Reviewer:                           |        Sponsor:  Sponsor28-can
-------------------------------------+-------------------------------

Comment (by Sean-Der):

 Replying to [comment:19 dcf]:
 > Replying to [comment:17 cmm323]:
 > > Great! One concern I have is that if there are specific features in
 `pion` implementation that are different from the native implementation,
 which make it easy to block.
 >
 > I am not too worried about that at this point, because what little
 research we did using libwebrtc ([[doc/Snowflake/Fingerprinting]]) showed
 that even with the native library, Snowflake did not match other
 applications. I don't think swapping one library for another costs much at
 this point, in that respect.
 >
 > Replying to [comment:18 Sean-Der]:
 > > We *should* have zero differences
 >
 > I would be surprised if this is the case--unless pion has paid
 extraordinary attention to matching externally visible protocol
 implementation details, which goes farther than interoperability. What
 about the order of ciphersuites in the DTLS handshake, or the metadata
 inside STUN messages? One of the things we found is that there's no single
 "WebRTC" fingerprint, nor even a single "Chrome WebRTC" fingerprint--it
 depends on the specific application. That said, I'm glad that you are
 involved, and I am hopeful that pion will be easier to adapt if and when
 needed.

 Oh yes you are 100% right about that. I haven't paid any attention to
 that, I have only been concerned about interoperability.

 This hasn't been a concern for me, but I would love to make this work for
 you. Maybe we can write some sort of test suite that does ICE/DTLS/SCTP
 and compares libwebrtc/Pion nightly and brings down the drift.

 Would it also be helpful to 'randomize' Pion? We could add features that
 helps make Snowflake more resistant to fingerprinting. I am not up to date
 on concepts/needs around censorship circumvention

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/28942#comment:23>
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