[tor-project] Anti-censorship team meeting notes, 2025-07-10

Shelikhoo · July 13, 2025, 7:37pm

Hey everyone!

Here are our meeting logs:

And our meeting pad:

Anti-censorship work meeting pad

···

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Anti-censorship
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Next meeting: Thursday, July 17 16:00 UTC
Facilitator: meskio

^^^(See Facilitator Queue at tail)

Weekly meetings, every Thursday at 16:00 UTC, in #tor-meeting at OFTC
(channel is logged while meetings are in progress)

This week's Facilitator: shelikhoo

== Goal of this meeting ==

Weekly check-in about the status of anti-censorship work at Tor.
Coordinate collaboration between people/teams on anti-censorship at the Tor Project and Tor community.

== Links to Useful documents ==
* Our anti-censorship roadmap:
* Roadmap:Issue Boards · Development · Boards · Anti-censorship · GitLab
* The anti-censorship team's wiki page:
* Home · Wiki · The Tor Project / Anti-censorship / Team · GitLab
* Past meeting notes can be found at:
* The tor-project Archives
* Tickets that need reviews: from projects, we are working on:
* All needs review tickets:
* Merge requests · Anti-censorship · GitLab
* Project 158 <-- meskio working on it
* Issues · Anti-censorship · GitLab

== Announcements ==

\*

== Discussion ==
(July 10 New:)
== Actions ==

== Interesting links ==
(July 10 New:)
* GitHub · Where software is built TLSMirror: Looks like TLS Censorship Resistant Transport Protocol is Looking for Developer Feedback
== Reading group ==

 \* We will discuss &quot;&quot; on
     \*
     \* Questions to ask and goals to have:
         \* What aspects of the paper are questionable?
         \* Are there immediate actions we can take based on this work?
         \* Are there long\-term actions we can take based on this work?
         \* Is there future work that we want to call out in hopes that others will pick it up?

== Updates ==
Name:
This week:
- What you worked on this week.
Next week:
- What you are planning to work on next week.
Help with:
- Something you need help with.

cecylia (cohosh): 2025-07-10
Last week:
- found and fixed regression in snowflake prometheus stats (snowflake#40470)
- met with new conjure bridge operator (conjure#46)
- added June Snowflake SQS costs

- added a clarification to the broker metrics spec (snowflake!577)
- updated discussion on client rendezvous errors (snowflake#40447)
- fixed up client-polls merge request in snowflake-graphs
- Generate CSV of client rendezvous polls by country (!1) · Merge requests · David Fifield / snowflake-graphs · GitLab
- opened issue to follow up on reports of short-lived client connections (snowflake#40471)
This week:
- snowflake-webext version bump and deployment
- follow-up on new conjure bridge set up(conjure#46)
- start work around snowflake enumeration attacks
- O3.1, Develop and implement plans around snowflake enumeration attacks (#40397) · Tasks · The Tor Project / Anti-censorship / Pluggable Transports / Snowflake · GitLab
- follow up on snowflake rendezvous failures
- take a look at potential snowflake orbot bug
- [BUG] 20% CPU overhead in kindness mode · Issue #1183 · guardianproject/orbot-android · GitHub

meskio: 2024-06-26
Last week:
- merge the contaners of rdsys and bridgestrap, the staging server is life...
- investigate the changes in webtunnel used in russia to bypass censors (censorship-analisys#40064)
- test snowflake proxy patch for Iran (snowflake#40465)
- support grant writting
Next week:
- AFK

Shelikhoo: 2024-07-10
Last Week:
- [Testing] Unreliable+unordered WebRTC data channel transport for Snowflake rev2 (cont.)( Draft: Unreliable+unordered WebRTC data channel transport for Snowflake rev2 (!315) · Merge requests · The Tor Project / Anti-censorship / Pluggable Transports / Snowflake · GitLab ) testing environment setup/research
- [Invesgate, Deployment] Meek Bridge Offline, we should consider switching to anther hosting provider(Meek Bridge Offline, we should consider switching to anther hosting provider (#162) · Issues · The Tor Project / Anti-censorship / Team · GitLab)
- [Merge Request] Bug 41508: Switch built-in meek bridge to meek-unredacted (Draft: Bug 41508: Switch built-in meek bridge to meek-unredacted (!1252) · Merge requests · The Tor Project / Applications / tor-browser-build · GitLab)
- Vantge point maintaince
- Merge request reviews
Next (working) Week/TODO:
- Merge request reviews
- Support the Testing of domain fronting sites ( Support the Testing of domain fronting sites (#6) · Issues · The Tor Project / Anti-censorship / Connectivity Measurement / logcollector · GitLab ) (cont.)

onyinyang: 2025-07-10
Last week(s):
- Mid-year break
- Finished up work on webtunnel distribution through telegram:
- Distribute WebTunnel bridges via Telegram bot? (#158) · Issues · The Tor Project / Anti-censorship / Team · GitLab
- Webtunnel button for Telegram (!534) · Merge requests · The Tor Project / Anti-censorship / rdsys · GitLab
- Looking into bridge distribution issues: bridges function test last ran on 2025-06-28 (webtunnel & obfs4) (#267) · Issues · The Tor Project / Anti-censorship / rdsys · GitLab
- Related to rdsys-admin update on 06/26?
- restarted rdsys to see if that helps
- Next is looking into this mystery: Bridges website hitting a error while fetching bridges with WebTunnel pluggable transport (#262) · Issues · The Tor Project / Anti-censorship / rdsys · GitLab

Next week:
Finish up webtunnel work on rdsys
Blog post for conjure: Set up a more permanent Conjure bridge (#46) · Issues · The Tor Project / Anti-censorship / Pluggable Transports / conjure · GitLab
Switch back to some of these:
As time allows:
- review Tor browser Lox integration Bug 43096: Move to Rust for the Lox integration (!1300) · Merge requests · The Tor Project / Applications / Tor Browser · GitLab
- add TTL cache to lox MR for duplicate responses:
Enable repeat responses to successful Lox requests (!305) · Merge requests · The Tor Project / Anti-censorship / lox · GitLab

     \- Work on outstanding milestone issues:
         \- key rotation automation

     Later:
     pending decision on abandoning lox wasm in favour of some kind of FFI? https://gitlab.torproject.org/tpo/applications/tor-browser/-/issues/43096):
         \- add pref to handle timing for pubkey checks in Tor browser
         \- add trusted invitation logic to tor browser integration:

- improve metrics collection/think about how to show Lox is working/valuable
- sketch out Lox blog post/usage notes for forum

 \(long term things were discussed at the meeting\!\):
     \- brainstorming grouping strategies for Lox buckets \(of bridges\) and gathering context on how types of bridges are distributed/use in practice
         Question: What makes a bridge usable for a given user, and how can we encode that to best ensure we&#39;re getting the most appropriate resources to people?
             1\. Are there some obvious grouping strategies that we can already consider?
                 e\.g\., by PT, by bandwidth \(lower bandwidth bridges sacrificed to open\-invitation buckets?\), by locale \(to be matched with a requesting user&#39;s geoip or something?\)
             2\. Does it make sense to group 3 bridges/bucket, so trusted users have access to 3 bridges \(and untrusted users have access to 1\)? More? Less?

theodorsm: 2025-06-12
Last weeks:
- Applying for funding from NLnet to implement DTLS 1.3 in Pion. Got through the first round.
- Writing paper for FOCI: continuation of master thesis about reducing distinguishability of DTLS in Snowflake by implementing covert-dtls, further analysis of collected browser fingerprint and stability test of covert-dtls in snowflake proxies. Draft: https://theodorsm.net/FOCI25
- Key takeaways:
* covert-dtls is stable when mimicking DTLS 1.2 handshakes, while the randomization approach— though more resistant to fingerprinting — tends to be less stable.
* Chrome webextensions are more unstable than standalone proxies
* covert-dtls should be integrated in Snowflake proxies as they produce the ClientHello messages during the DTLS handshake.
* Chrome randomizes the order of extension list.
* Firefox uses DTLS 1.3 by default in WebRTC.
* A prompt adoption of DTLS 1.3 in both Snowflake and our fingerprint-resistant library is needed to keep up with browsers
* The evolution of browsers’ fingerprints had no noticeable effect on Snowflake’s number of daily users over the last year.
* Even with a sharp drop in the amount of proxies, it does not seem to affect the number of Snowflake users.
* Browser extensions make Snowflake resistant to ClientHello fingerprinting.
* Standalone proxies can serve more Snowflake clients per volunteer than webextensions.
* We need metrics on which types of proxies are actually being matched and successfully used by clients.
Next weeks:
- Getting paper camera ready.
- Fix merge conflicts in MR (Add covert-dtls to proxy and client (!448) · Merge requests · The Tor Project / Anti-censorship / Pluggable Transports / Snowflake · GitLab).
Help with:
- Should we do user testing of covert-dtls?

Facilitator Queue:
meskio onyinyang shelikhoo
1. First available staff in the Facilitator Queue will be the facilitator for the meeting
2. After facilitating the meeting, the facilitator will be moved to the tail of the queue