[tbb-dev] Tor Browser Friendliness Scanner: Seeking Feedback

Sanketh Menda sgmenda at uwaterloo.ca
Fri Apr 9 15:49:34 UTC 2021

Hi Kevin,

This is a great idea!

I have a few optional nitpicks:

  1.  Rather than check if the website supports HTTPS or if it loads JS over HTTPS, it might be worth considering just checking if it works in HTTPS-only mode (in other words, if there was *any* non-HTTPS content.) This seems more timely with Firefox and other browsers slowing rolling out HTTPS-only modes.
  2.  I am not sure if auto-play is necessarily a bad thing. IRCC even non-tbb browsers like brave stop auto-play and make certain media click-to-play.
  3.  It may not be the case that the APIs blocked or fuzzed by Tor Browser are necessarily bad, for instance, people may use the canvas for good (like cropping images or converting formats) so it may be worth emphasizing that in the wording (compared to say the HTTPS test where you could be more forceful).
  4.  Also, as usual, this list is subject to change, so it might be valuable to have an update mechanism in place from the start.

Thanks again for sharing your idea here.

From: tbb-dev <tbb-dev-bounces at lists.torproject.org> On Behalf Of Kevun
Sent: Friday, April 09, 2021 11:19 AM
To: tbb-dev at lists.torproject.org; ux at lists.torproject.org
Subject: [tbb-dev] Tor Browser Friendliness Scanner: Seeking Feedback

Hello all!

After a year away from my Tor related research, I'm finally back at it. As I've introduced in the past [1] I wanted to build a Tor Browser Friendliness scanner that would scan the web and rate the Tor Browser friendliness of web pages. Unfortunately time got away from me for personal reasons, but I finally got the chance to work on the scanner and I feel it's close to being ready to run.

To re-introduce the concept: the scanner checks a web page for evidence of some activity that would likely cause the site to not render or run properly on the Tor Browser. This includes the tests listed below, which are motivated by the Tor Browser Design Document [2] and our own experiences analyzing what broke on the Tor Browser during analysis of some randomly selected websites.


1. Checks to see if the site supports HTTPS. If not, there's a problem.
2. Checks to see if the site serves JavaScript over HTTP. If not, there could be a problem on the Safer setting of the Tor Browser Security Slider,
3. Checks to see if there is auto-played media or hidden media. This could cause issues on the Safer setting of the Tor Browser Security Slider.
4. Checks to see if there is any evidence of usage of the following JavaScript libraries/functionalities. These were taken from the draft of the Tor Browser Design Document.
    01. asm
    02. battery status
    03. game pad
    04. graphite
    05. media devices
    06. navigator online
    07. sensor
    08. network connection
    09. touch
    10. web audio
    11. webgl
    12. webrtc
    13. web speech
    14. HTML canvas
5. Checks to see if the page contains JAR files or Flash files.
6. Checks to see if the page contains chrome:// or resource:// links.

Given this information, I have a few questions.

1. What other tests should I add, if any?
2. Is there any other feedback on this idea that you'd like to provide?

Please keep in mind that I intend on releasing the source code soon. At the moment it's in an "academic code" state, and I want to clean it up before release.




[1] https://lists.torproject.org/pipermail/tor-dev/2019-March/013731.html

[2] https://2019.www.torproject.org/projects/torbrowser/design/
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