[tor-project] Anti-censorship team monthly report: August 2020

[Philipp Winter]

Hi all,

Here's what we accomplished in August 2020:

Snowflake
---------

* We set up an anonymous bug-reporting pad for the team.  Take a look at
  our reporting instructions:
  https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/wikis/home#reporting-bugs
  https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake-webext/-/issues/14

* NAT type matching in Snowflake browser proxies.  Released version
  0.4.1 of the browser extension.
  https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/34129

* Perform a test for symmetric NATs on startup.
  https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake-webext/-/issues/13

* Implemented a fix so Snowflake stops using the client's network when
  Tor isn't making reqests.
  https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/21314

* Hashik Donthineni, our GSoC 2020 student, successfully finished his
  Android proxy app project!  It needs more UI improvements and testing
  before being ready for use.
  https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake-mobile/-/wikis/home

* Made progress on allowing clients to split traffic across multiple
  proxies.
  https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/25723

* Updated Snowflake stats to include counts of restricted, unrestricted,
  and unknown proxies.
  https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/40008

BridgeDB
--------

* Inspected several months worth of BridgeDB's HTTPS distributor logs
  and distilled a few insights.
  https://gitlab.torproject.org/tpo/anti-censorship/bridgedb/-/issues/31871

* Took a closer look at bot scraping attempts.
  https://gitlab.torproject.org/tpo/anti-censorship/bridgedb/-/issues/32117

Rdsys
-----

* Decided to call our BridgeDB redesign rdsys, which is short for
  "resource distribution system."  Do you have a better name?  If so,
  let us know!

* Created a GitLab repository for rdsys.  The code is a messy
  construction site and will continue to be in the foreseeable future.
  https://gitlab.torproject.org/tpo/anti-censorship/rdsys

* Improved the way rdsys talks to bridgestrap to verify that bridges are
  working.

* Built an HTTP streaming interface between rdsys's backend and its
  distributors.  This interface allows the backend to stream resource
  updates to the distributors without delay.  The goal is that resources
  (i.e. bridges) are distributed to users immediately after they are
  added to the system.

Salmon
------

* Implemented a crude prototype of the Salmon bridge distribution
  mechanism.  Brainstormed a handful of privacy-preserving features that
  would improve the original design.
  https://gitlab.torproject.org/tpo/anti-censorship/rdsys/-/issues/1

Bridgestrap
-----------

* Improved the service's shutdown procedure, caching mechanism, its
  documentation, and its HTTP API.  Added a command line flag to print
  bridgestrap's cache.
  https://gitlab.torproject.org/tpo/anti-censorship/bridgestrap

* Added a token bucket mechanism to limit the number of requests that
  the service accepts.

Emma
----

* Updated the resources that emma tries to connect to (replaced a guard
  relay and removed the default bridge "frosty").  Changed trac links to
  GitLab links.
  https://gitlab.torproject.org/tpo/anti-censorship/emma

Miscellaneous
-------------

* Retired the default bridge "frosty" because the colocation site where
  the bridge was running will be shut down.
  https://gitlab.torproject.org/tpo/applications/tor-browser-build/-/issues/40066

Outreach
--------

* Published a blog post on our challenges, priorities, and progress.
  https://blog.torproject.org/anti-censorship-challenges-priorities-progress

* Published our July 2020 report as blog post.
  https://blog.torproject.org/anti-censorship-july-2020

* David presented his Turbo Tunnel paper at FOCI'2020.  His talk is
  available online:
  https://www.usenix.org/conference/foci20/presentation/fifield

* Roger participated in a FOCI'2020 panel on "Internet Freedom in the
  Domestic Arena."

* Cecylia was a panelist at Tor's latest PrivChat iteration, called "the
  Good, the Bad, and the Ugly of Censorship Circumvention."  The
  recording is available online:
  https://www.youtube.com/watch?v=aOOChyMCZH4