[Masque] MASQUE and Tor "pluggable transports"

Philipp Winter <phw@torproject.org> Tue, 06 August 2019 16:20 UTC

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Date: Tue, 6 Aug 2019 09:20:44 -0700
From: Philipp Winter <phw@torproject.org>
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Subject: [Masque] MASQUE and Tor "pluggable transports"
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Hi everyone,

I read the most recent MASQUE draft that I found here:
<https://davidschinazi.github.io/masque-drafts/draft-schinazi-masque.html>
It's great work, thanks for this!

Section 2.4 suggests onion routing on top of MASQUE servers to add
anonymity.  There may be an easier way to accomplish this: one could
turn MASQUE into a "pluggable transport" protocol.  Originally developed
by Tor, pluggable transports are a traffic obfuscation mechanism that
puts a proxy in front of both a client and a server.  These proxies
disguise the traffic that's exchanged between client and server as shown
in the following diagram:
<https://gitweb.torproject.org/torspec.git/tree/pt-spec.txt#n61>

Turning MASQUE into a pluggable transport would make it easy-ish to
integrate for systems that support the pluggable transport specification
including Tor, Psiphon, and Lantern.  MASQUE would also benefit from
security properties offered by its "host" system -- in Tor's case this
would be anonymity.

Practically speaking, a user would start Tor Browser with the MASQUE
pluggable transport (which would be included in Tor Browser).  A
rendez-vous mechanism would inform the user about MASQUE servers that
she could use.  Once a MASQUE server receives the user's HTTPS data, the
server extracts the content and shoves it into a Tor bridge that's
running on the same (or potentially a different) machine.  All of this
could be implemented as part of a new module for the obfs4proxy system,
which is the pluggable transport proxy that the Tor project uses:
<https://gitlab.com/yawning/obfs4>

Is there interest in pursuing support for pluggable transports?

Cheers,
Philipp