Hi everyone, Here is my status report for March 2025.

At the beginning of the month, I continued from where I left last month. First, I finished my proposal about integrating the Lox crate in the browser [tor-browser!1300]. I don't think it'll be merged as it is, but it already contains a lot of new code, so I prefer getting feedback before continuing this task. Then, I continued the rebase on Firefox 132 [tor-browser#43413].

Over the month, I worked on several issues related to Go and pluggable transports. I started by updating Go to 1.23.6 on alpha [tor-browser-build#41386]. Previously, we were on 1.22, but it went EOL, so we decided to update. However, we had to keep the old version for macOS since we still want to support macOS 10.15. We used to bootstrap Go starting from 1.4, the last version written in C. However, 1.23 required an additional version in the bootstrap chain, so I took the occasion to investigate the toolchain reproducibility. It's amazing: the 1.23.6 built with our chain matches bit-by-bit the official release from Google. Therefore, we switched to the official binaries as bootstrappers [tor-browser-build#41121]. Also about PTs, I created an automation to keep their license files updated [tor-browser-build#41411], and, in general,  I reworked the way we include licenses for Tor and its dependencies [tor-browser-build!1188] (however, this MR hasn't been merged yet).

I also worked a little bit on fingerprinting and screen size protection. First, I finalized the patch to spoof screen size differently from what we're currently doing [tor-browser#41747]. Even though it doesn't reduce entropy, it should help with some basic fingerprinting scripts and bot detection. However, we preferred to push the fix to 15.0 since we would like it to be tested for some time before shipping it to stable, and 14.5 is too close according to our plans. Then, I fixed an issue about letterboxing visible albeit disabled in some cases [tor-browser#42670]. I also investigated the upstream patches for window.devicePixelRatio in RFP, as Thorin found a problem with them [tor-browser#43239]. Eventually, I opened an upstream Bug [Bug 1954493] and sent a patch there first.

I also worked on a few smaller issues, like adding string files with branding on Android [tor-browser#43464], adding a "What's new" link to the About dialog [tor-browser#42720], and more.

Best, Pier

[tor-browser#41747] https://gitlab.torproject.org/tpo/applications/tor-browser/-/issues/41747 [tor-browser#42670] https://gitlab.torproject.org/tpo/applications/tor-browser/-/issues/42670 [tor-browser#42720] https://gitlab.torproject.org/tpo/applications/tor-browser/-/issues/42720 [tor-browser#43239] https://gitlab.torproject.org/tpo/applications/tor-browser/-/issues/43239 [tor-browser#43413] https://gitlab.torproject.org/tpo/applications/tor-browser/-/issues/43413 [tor-browser#43464] https://gitlab.torproject.org/tpo/applications/tor-browser/-/issues/43464 [tor-browser!1300] https://gitlab.torproject.org/tpo/applications/tor-browser/-/merge_requests/... [tor-browser-build#41121] https://gitlab.torproject.org/tpo/applications/tor-browser-build/-/issues/41... [tor-browser-build#41386] https://gitlab.torproject.org/tpo/applications/tor-browser-build/-/issues/41... [tor-browser-build#41411] https://gitlab.torproject.org/tpo/applications/tor-browser-build/-/issues/41... [tor-browser-build!1188] https://gitlab.torproject.org/tpo/applications/tor-browser-build/-/merge_req... [Bug 1954493] https://bugzilla.mozilla.org/show_bug.cgi?id=1954493