[tbb-bugs] #18279 [Tor Browser]: Javascript setTimeout can be used for high resolution clock

Mon Feb 8 15:11:48 UTC 2016

#18279: Javascript setTimeout can be used for high resolution clock
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     Reporter:  cypherpunks  |      Owner:  tbb-team
         Type:  defect       |     Status:  new
     Priority:  Medium       |  Milestone:
    Component:  Tor Browser  |    Version:
     Severity:  Normal       |   Keywords:
Actual Points:               |  Parent ID:  #16110
       Points:               |    Sponsor:
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 Using Javascript setTimeout, around 20ms timer resolution can be achieved.
 This is likely sufficient for input fingerprinting.

 Simple demo that logs a counter to the console.

 {{{
 <html>
 <body onload="logTime()">
 <p>Test</p>

 <script>
 var counter = 0;

 function logTime() {
   counter += 1;
   var today = new Date();
   console.log(today.getSeconds() + "." + today.getMilliseconds() + " " +
 counter);
   var t = setTimeout(logTime, 1);
 }
 </script>

 </body>
 </html>
 }}}

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/18279>
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