Re: [tor-bugs] #23104 [Applications/Tor Browser]: CSS line-height reveals the platform Tor Browser is running on

["Tor Bug Tracker & Wiki" <blackhole@xxxxxxxxxxxxxx>]

#23104: CSS line-height reveals the platform Tor Browser is running on
--------------------------------------+--------------------------
 Reporter:  gk                        |          Owner:  igt0
     Type:  defect                    |         Status:  accepted
 Priority:  Medium                    |      Milestone:
Component:  Applications/Tor Browser  |        Version:
 Severity:  Normal                    |     Resolution:
 Keywords:  tbb-fingerprinting-os     |  Actual Points:
Parent ID:                            |         Points:
 Reviewer:  gk                        |        Sponsor:
--------------------------------------+--------------------------
Changes (by igt0):

 * cc: igt0 (added)
 * reviewer:   => gk


Comment:

 Many fonts have issues with their vertical metrics. they
 are used to influence the height of ascenders and depth
 of descenders. Gecko uses it to calculate the line height
 (font height + ascender + descender), however because of
 that idiosyncratic behavior across multiple operating
 systems, it can be used to identify the user's OS.

 The solution proposed in the patch(see attached patch) is to use a default
 factor
 to be multiplied as ascender and descender. This way all operating
 systems will have the same line height.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/23104#comment:3>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
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