[tbb-bugs] #13018 [Tor Browser]: Determine if high-precision Math routines are fingerprintable

[Tor Bug Tracker & Wiki]

#13018: Determine if high-precision Math routines are fingerprintable
-------------------------+-------------------------------------------------
     Reporter:           |      Owner:  tbb-team
  mikeperry              |     Status:  new
         Type:  task     |  Milestone:
     Priority:  normal   |    Version:
    Component:  Tor      |   Keywords:  tbb-fingerprinting, tbb-easy,
  Browser                |  ff31-esr, TorBrowserTeam201410Easy
   Resolution:           |  Parent ID:
Actual Points:           |
       Points:           |
-------------------------+-------------------------------------------------

Comment (by cypherpunks):

 Values computed using standard algebraic expression:
 {{{
     asinh(1) = 0.8813735870195429
     acosh(1e300) = NaN
     atanh(0.5) = 0.5493061443340549
     expm1(1) = 1.718281828459045
     log1p(10) = 2.3978952727983707
     sinh(1) = 1.1752011936438014
     cosh(10) = 11013.232920103324
     tanh(1) = 0.7615941559557649
 }}}
 Using code:
 {{{
 function asinh(x) {
   if (x === -Infinity) {
     return x;
   } else {
     return Math.log(x + Math.sqrt(x * x + 1));
   }
 }
 function acosh(x) {
   return Math.log(x + Math.sqrt(x * x - 1));
 }
 function atanh(x) {
   return Math.log((1+x)/(1-x)) / 2;
 }
 function cbrt(x) {
     var y = Math.pow(Math.abs(x), 1/3);
     return x < 0 ? -y : y;
 }
 function cosh(x) {
     var y = Math.exp(x);
     return (y + 1 / y) / 2;
 }
 function expm1(x) {
     return Math.exp(x) - 1;
 }
 function log1p(x) {
   return Math.log(1 + x);
 }
 function sinh(x){
     var y = Math.exp(x);
     return (y - 1/y) / 2;
 }
 function tanh(x) {
   if(x === Infinity) {
     return 1;
   } else if(x === -Infinity) {
     return -1;
   } else {
     var y = Math.exp(2 * x);
     return (y - 1) / (y + 1);
   }
 }
 }}}

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/13018#comment:9>
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