[tor-bugs] #19478 [Applications/Tor Browser]: File API leaks ms-resolution time

Mon Jun 27 15:55:10 UTC 2016

#19478: File API leaks ms-resolution time
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 Reporter:  arthuredelstein                      |          Owner:
     Type:  defect                               |  arthuredelstein
 Priority:  Medium                               |         Status:
Component:  Applications/Tor Browser             |  needs_review
 Severity:  Normal                               |      Milestone:
 Keywords:  tbb-fingerprinting,                  |        Version:
  TorBrowserTeam201606R                          |     Resolution:
Parent ID:                                       |  Actual Points:
 Reviewer:                                       |         Points:
                                                 |        Sponsor:
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Comment (by mcs):

 Replying to [comment:4 gk]:
 > Hm. `new Date.getTime()` gives me something like 1467036079100 and
 `Math.floor(new File([], "").lastModified / 100000) * 100000)`
 1467036100000 or 1467036400000 or something similar. It seems your code is
 not rounding to 100ms?

 The units for mLastModificationDate are microseconds, so part of the patch
 will need to be changed.

 I am not sure how to fix the tests to detect when values are rounded too
 much. Maybe by using a real file with a known modified date?

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/19478#comment:6>
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