#17046: Event.timeStamp reveals startup time
-----------------------------+--------------------------
Reporter: arthuredelstein | Owner: tbb-team
Type: defect | Status: new
Priority: normal | Milestone:
Component: Tor Browser | Version:
Keywords: tbb-linkability | Actual Points:
Parent ID: | Points:
-----------------------------+--------------------------
Experimenting with JS Events, I noticed the following:
If I open a web page's console in standard Firefox and enter
`new Event("asdf").timeStamp`
it returns a number like
`1442000361118206`.
This corresponds to the number of microseconds since the epoch. I confimed
this result by entering:
{{{
window.setInterval(() => console.log(new Event("asdf").timeStamp), 1000)
}}}
and it prints out
{{{
1442000426991504
1442000427990600
1442000428989561
1442000429989980
1442000430990465
1442000431990790
1442000432989823
1442000433989783
...
}}}
This violates the web standard, which specifies ''milliseconds'' since the
epoch: http://www.w3.org/TR/2000/REC-DOM-
Level-2-Events-20001113/events.html#Events-Event-timeStamp
Tor Browser gives similar result, but rounded to the nearest 100
microseconds, because of TBB's #1517 patch.
In any case, that's not the usual way to use Events. A more typical usage
is:
`window.addEventListener("mousedown", e => console.log(e.timeStamp))`
If I click the mouse once per second (by listening to a clock) I get:
{{{
1028609
1029641
1030609
1031641
1032617
1033609
1034601
1035601
...
}}}
which indicates that the results are expressed in milliseconds. The epoch,
however, is defined differently. In this case it reveals the system
startup time, which is a linkability issue.
--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17046>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
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