[tor-project] Anti-censorship team meeting notes, 2025-09-11

[onyinyang via tor-project]

Hey everyone!

Here are our meeting logs:
http://meetbot.debian.net/tor-meeting/2025/tor-meeting.2025-09-11-16.00.html

And our meeting pad:

Anti-censorship work meeting pad
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Anti-censorship
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Next meeting: Thursday, Sep 18 16:00 UTC
Facilitator:shelikhoo

^^^(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:onyinyang

== Goal of this meeting ==

Weekly check-in about the status of anti-censorship work at Tor.



== Links to Useful documents ==
    * Our anti-censorship roadmap:

Coordinate collaboration between people/teams on anti-censorship at the Tor Project and Tor community.         * Roadmap:https://gitlab.torproject.org/groups/tpo/anti-censorship/-/boards

    * The anti-censorship team's wiki page:

        * https://gitlab.torproject.org/tpo/anti-censorship/team/-/wikis/home

    * Past meeting notes can be found at:
        * https://lists.torproject.org/pipermail/tor-project/
    * Tickets that need reviews: from projects, we are working on:
        * All needs review tickets:

            * https://gitlab.torproject.org/groups/tpo/anti-censorship/-/merge_requests?scope=all&utf8=%E2%9C%93&state=opened&assignee_id=None

        * Project 158 <-- meskio working on it

            * https://gitlab.torproject.org/groups/tpo/anti-censorship/-/issues/?label_name%5B%5D=Project%20158

== Announcements ==


== Discussion ==
(Sep 11 New)
    * Rechecked webtunnel bridge extra info intensity(before=3011):

        * 3041

        * 3023

        * 3014
    * tor#7349 and proposed changes for bridges
        * https://gitlab.torproject.org/tpo/core/tor/-/issues/7349

        * $ tar -O -xf bridge-extra-infos-2025-09.tar.xz | grep -B3 '^transport webtunnel' | grep '^published '|grep 2025-09-10|wc -l         * $ tar -O -xf bridge-extra-infos-2025-09.tar.xz | grep -B3 '^transport webtunnel' | grep '^published '|grep 2025-09-09|wc -l         * $ tar -O -xf bridge-extra-infos-2025-09.tar.xz | grep -B3 '^transport webtunnel' | grep '^published '|grep 2025-09-08|wc -l         * https://gitlab.torproject.org/tpo/network-health/team/-/issues/318#note_3254888             * tldr: should onionoo only get the Running flag for bridges from bridgestrap and ignore Serge's reachability check?         * recommend not exposing ORPort: https://gitlab.torproject.org/tpo/anti-censorship/team/-/issues/129

== Actions ==



== Interesting links ==

    * Remove webtunnel setuid script in 5 weeks.(decrease this by one every week)     * https://opencollective.com/censorship-circumvention/projects/snowflake-daily-operations/updates/2025-august-update     * https://interseclab.org/wp-content/uploads/2025/09/The-Internet-Coup_September2025.pdf#page=61         * "Blocking online privacy and circumvention tools" section of InterSecLab report on Geedge Networks, mentions Tor, Snowflake, WebTunnel

    * https://www.amnesty.org/en/documents/asa33/0206/2025/en/

    * https://github.com/net4people/bbs/issues/519


== Reading group ==


        * https://www.usenix.org/system/files/usenixsecurity25-tai.pdf

        * Pakistan: Shadows of Control: Censorship and mass surveillance in Pakistan         * Leak of Geedge Networks internal documents (100,000+ from Jira, Confluence, GitLab     * (Protests in Nepal turned deadly after thousands of youngsters marched against the blocking of social media platforms.)     * We will discuss "IRBlock: A Large-Scale Measurement Study of the Great Firewall of Iran" on September 11         * https://irblock.org/ is supposed to have public data according to Section 8, but it shows a "Cloudflare Tunnel error"         * https://zenodo.org/records/15572895 has limited data from November 2024 to January 2025, not raw data, but already aggregated

        * 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?

    * Next:

            * Is there future work that we want to call out in hopes that others will pick it up?         * https://interseclab.org/wp-content/uploads/2025/09/The-Internet-Coup_September2025.pdf#page=61         * "Blocking online privacy and circumvention tools" section of InterSecLab report on Geedge Networks, mentions Tor, Snowflake, WebTunnel

== 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): 2025-09-11
    Last week:
        - fixed snowflake extension translation bug (snowflake-webext#120)
        - updated wiki page for integrating new PTs into Tor Browser

            - https://gitlab.torproject.org/tpo/anti-censorship/team/-/wikis/Tor-Browser-Integration-Guide-for-New-Pluggable

    -Transports

        - met with Rob to discuss proteus integration steps
        - updated analysis of snowflake proxy timeouts (snowflake#40447)
    Next week:
        - follow up on snowflake rendezvous failures
        - deploy new snowflake webextension with translation fixes
        - take a look at potential snowflake orbot bug
            - https://github.com/guardianproject/orbot-android/issues/1183


dcf: 2025-09-11
    Last week:
    Next week:

        - implemented and deployed new prometheus metrics to track proxy answers by implementation         - open issue to have snowflake-client log whenever KCPInErrors is nonzero https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/40262#note_2886018             - parent: https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/40267

Help with:

meskio: 2024-09-11
    Last week:
        - brainstorm on dual stack bridges (tor!786)
        - catch up with emails and fail
    Next week:


Shelikhoo: 2024-09-11
    Last Week:

         - [Testing] Unreliable+unordered WebRTC data channel transport for Snowflake rev2 (cont.)( https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/merge_requests/315 ) testing environment setup/research

         - [Deploy Over] Add Domain Fronting Test Support to probeobserver

         - Support the Testing of domain fronting sites ( https://gitlab.torproject.org/tpo/anti-censorship/connectivity-measurement/logcollector/-/issues/6 ) (Done)

         - (Many merge reviews)
    Next (working) Week/TODO:
        - Merge request reviews
        - Choosing domain fronting targets for domain fronting tests
        - invesgate russian vantage point issues


onyinyang: 2025-09-11
    Last week(s):

        -Deployed and merged https://gitlab.torproject.org/tpo/anti-censorship/rdsys/-/merge_requests/562         - Confirmed that we are still distributing malfunctioning webtunnel bridges https://gitlab.torproject.org/tpo/anti-censorship/bridgestrap/-/issues/47

        - Looking into why ^

        - Looking into a solution for distributing a proportion of webtunnel bridges to telegram users with new accounts https://gitlab.torproject.org/tpo/anti-censorship/rdsys/-/issues/283

Next week:
        - Continue looking into bridgestrap#47
        - Continue looking into rdsys#283

      Switch back to some of these:
          As time allows:

        - Lox still seems to be filling up the disk on the rdsys-test server despite changes made to delete old entries, look into what's going wrong                Blog post for conjure: https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/conjure/-/issues/46               - review Tor browser Lox integration https://gitlab.torproject.org/tpo/applications/tor-browser/-/merge_requests/1300

              - add TTL cache to lox MR for duplicate responses:
https://gitlab.torproject.org/tpo/anti-censorship/lox/-/merge_requests/305

        - 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:
https://gitlab.torproject.org/tpo/applications/tor-browser/-/issues/42974

        - sketch out Lox blog post/usage notes for forum

    (long term things were discussed at the meeting!):


theodorsm: 2025-06-12
        Last weeks:

        - improve metrics collection/think about how to show Lox is working/valuable         - 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'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'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?             - 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:

                * Chrome randomizes the order of extension list.
                * Firefox uses DTLS 1.3 by default in WebRTC.

        Next weeks:
            - Getting paper camera ready.

                * 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.                 * 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.             - Fix merge conflicts in MR (https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/merge_requests/448).

        Help with:
            - Should we do user testing of covert-dtls?



Facilitator Queue:
        onyinyang shelikhoo meskio


--
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onyinyang

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