Re: [csswg-drafts] [css-fonts] incorporate mitigations for font based fingerprinting (#4055)

The CSS Working Group just discussed `mitigations for font based fingerprinting`.

<details><summary>The full IRC log of that discussion</summary>
&lt;emilio> Topic: mitigations for font based fingerprinting<br>
&lt;emilio> github: https://github.com/w3c/csswg-drafts/issues/4055<br>
&lt;emilio> TabAtkins: [introduces the issue]<br>
&lt;emilio> TabAtkins: we expose a lot of PI data on the web<br>
&lt;emilio> ... even if you plug fonts we're probably not below the level where you cannot identify a single user<br>
&lt;emilio> ... to do that you probably need to do software rendering on canvas for example<br>
&lt;emilio> ... so unless somebody comes up with a list of stuff and data<br>
&lt;emilio> ... I think we shouldn't do that<br>
&lt;emilio> ... a bit annoying from a PR standpoint to argue why it doesn't really matter but...<br>
&lt;emilio> myles: our goal is to remove all the sources of fingerprinting on the web<br>
&lt;emilio> ... we should reduce as much as possible<br>
&lt;emilio> TabAtkins: you cannot remove all of them<br>
&lt;emilio> ... no media queries, etc..<br>
&lt;emilio> TabAtkins: unless you could reduce it to 20 you haven't done anything<br>
&lt;emilio> myles: well you're closer to the goal<br>
&lt;emilio> [funny methafores]<br>
&lt;emilio> metaphors*<br>
&lt;Rossen_> q?<br>
&lt;emilio> TabAtkins: going from "individually identify someone" to "individually identify someone" does nothing<br>
&lt;emilio> ... there's a specific threshold we need to reach to do anything<br>
&lt;emilio> ... and nobody can<br>
&lt;emilio> myles: we'll try<br>
&lt;emilio> dino: I really believe we should ask the question for each feature of what the cost is<br>
&lt;emilio> ... I accept what TabAtkins says about the number of bits<br>
&lt;emilio> ... but it's this group's duty to do the cost of the feature vs. the privacy impact<br>
&lt;emilio> florian: cost is breaking the web for minority languages, benefit is not clear yet<br>
&lt;emilio> TabAtkins: w3c has the privacy interest group working on this, if their conclusion is that we can hit this range by doing this<br>
&lt;emilio> ... then happy to<br>
&lt;emilio> plinss: every time we add a bit we make it that much harder, if we throw our hands up in the air then sure, let's add identifiers<br>
&lt;emilio> thomas: There's also ways to alert the user it's being fingerprinted<br>
&lt;Rossen_> q?<br>
&lt;emilio> nmccully: I'm hearing mostly that it's not the right fix. We shouldn't make it worse but...<br>
&lt;leaverou> q+<br>
&lt;emilio> myles: our job is to design CSS APIs and we have to weight pros and cons. We found that font-based fingerprinting is one of the most unique ways users are fingerprinted. We also found that it doesn't affect most users' experience<br>
&lt;Rossen_> ack leaverou<br>
&lt;emilio> ... so pros and cons seem clear here<br>
&lt;dino> emilio: I agree with myles<br>
&lt;emilio> leaverou: Lots of old sites rely on common fonts like Calibri or Cambria installed<br>
&lt;florian> q?<br>
&lt;florian> q+<br>
&lt;emilio> ... also there's a perf impact of always downloading the font since sites tend to use `local()`<br>
&lt;emilio> ???: Are we getting ahead of the game between standards and impls<br>
&lt;fantasai> s/???/glenn/<br>
&lt;dino> s/???/Glenn/<br>
&lt;emilio> myles: the spec can't do much here<br>
&lt;Rossen_> ack flackr<br>
&lt;emilio> myles: we are an standardization, we can't do more that saying in the spec that should have privacy considerations<br>
&lt;Rossen_> ack florian<br>
&lt;emilio> ... but browsers like Safari can and have gone further<br>
&lt;emilio> florian: so you mentioned that you investigated the amount of sites<br>
&lt;emilio> ... that broke or not<br>
&lt;emilio> ... if you're removing language support minority users can't use the web<br>
&lt;emilio> ... also bandwidth may be a concern<br>
&lt;emilio> ... I don't care if sites are slowly slower for californians<br>
&lt;emilio> myles: having philosophical discussions is not particularly useful<br>
&lt;emilio> ... we need a concrete proposal<br>
&lt;emilio> ... and there's nothing to resolve on until there's one<br>
&lt;emilio> ... the spec already says that a UA may or not scan al fonts in the system<br>
&lt;emilio> Rossen_: out of time<br>
</details>


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Received on Tuesday, 17 September 2019 07:51:07 UTC