Closed Bug 1945296 Opened 14 days ago Closed 11 days ago

Collect DPR of the window that rendered user characteristic canvases

Categories

(Core :: Privacy: Anti-Tracking, enhancement)

enhancement

Tracking

()

RESOLVED FIXED
137 Branch
Tracking Status
firefox137 --- fixed

People

(Reporter: fkilic, Assigned: fkilic)

References

(Blocks 1 open bug)

Details

Attachments

(1 file)

Set text is dpr sensitive. We collect DPR and scalings, but that doesn't tell us with what dpr value the canvas was rendered with. Collect DPR of the window/page that renders the page.

DATA REVIEW REQUEST

  1. What questions will you answer with this data?

Help us understand how canvas data change with dpr.

More generally: What is the most productive use of engineering time to make fingerprinting an ineffective method of tracking users? As detailed in https://bugzilla.mozilla.org/show_bug.cgi?id=1879151

  1. Why does Mozilla need to answer these questions? Are there benefits for users?
    Do we need this information to address product or business requirements?

We want to improve our fingerprinting defenses. We don't want to guess at what will make an improvement, so we want to make a decision based on data. We also want to know how much of an improvement we have made, so we can state it and know how much further we have to go.

  1. What alternative methods did you consider to answer these questions?
    Why were they not sufficient?

We considered privacy preserving metric collection (DAP), collecting it indirectly (e.g. via hashes of the data), using exisiting (lmited) data we currently collect, not collecting the data at all and using academic literature. These options are detailed in https://docs.google.com/document/d/1m_j0BQEprQleRHZ7tVT7mG-krc8UA171GD5Vl6gZbL0/edit

  1. Can current instrumentation answer these questions?

As detailed in https://docs.google.com/document/d/1m_j0BQEprQleRHZ7tVT7mG-krc8UA171GD5Vl6gZbL0/edit - some attributes are collected by current instrumentation. However, using this data (and not using the other data we don't collect) will give an incomplete picture that may mislead us into choosing a task that does not make an appreciable change for users. We will also be unable to accurately state the improvement we have made.

  1. List all proposed measurements and indicate the category of data collection for each
    measurement, using the Firefox data collection categories found on the Mozilla wiki.
Measurement Name Measurement Description Data Collection Category Tracking Bug
characteristics.canvas_dpr The device pixel ratio of the canvas rendering context technical https://bugzilla.mozilla.org/show_bug.cgi?id=1945296
  1. Please provide a link to the documentation for this data collection which
    describes the ultimate data set in a public, complete, and accurate way.

This collection is Glean so is documented in the Glean Dictionary.

  1. How long will this data be collected?

This collection will be collected permanently.
tom@mozilla.com will be responsible for the permanent collections.

  1. What populations will you measure?

All channels, countries, and locales. No filters.

  1. If this data collection is default on, what is the opt-out mechanism for users?

These collections are Glean. The opt-out can be found in the product's preferences.

  1. Please provide a general description of how you will analyze this data.

The general question is "What engineering tasks should we do". To determine that, we will answer sub-questions like:

  • How many users are uniquely identifiable via fingerprinting?
  • For the users who are not, how large a cohort are they bucketed into?
  • What attributes contribute the most to making users unique, or placing them in small buckets
  • What attributes correlate with each other, such that we would need to address them in tandem
  1. Where do you intend to share the results of your analysis?

We hope to publish an academic paper, actually, as this is a significant contribution to the topic of browser fingerprinting. We can also expect to do a blog post. The decisions about what engineering tasks we choose to do to decrease the uniqueness of our users will be filed as Bugzilla Bugs that will contain descriptions of why this is the engineering task to do.

  1. Is there a third-party tool (i.e. not Glean or Telemetry) that you
    are proposing to use for this data collection?

No.

Pushed by fkilic@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/5d90950f3a33 Collect DPR of the window that rendered user characteristic canvases. r=tjr
Status: ASSIGNED → RESOLVED
Closed: 11 days ago
Resolution: --- → FIXED
Target Milestone: --- → 137 Branch
Blocks: fpdata
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