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Add a note regarding HRT precision #57

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Feb 28, 2018
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Add a note regarding HRT precision #57

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Add a note regarding HRT precision
plehegar Feb 27, 2018
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Todd's feedback
plehegar Feb 27, 2018
c5f5407
Ilya's comment
plehegar Feb 28, 2018
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7 changes: 5 additions & 2 deletions index.html
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Expand Up @@ -266,7 +266,7 @@ <h3>The <dfn>DOMHighResTimeStamp</dfn> Type</h3>
typedef double DOMHighResTimeStamp;
</pre>
<p>A <a>DOMHighResTimeStamp</a> SHOULD represent a time in milliseconds
accurate to 5 microseconds - see <a href="#sec-privacy-security"></a>.</p>
accurate to some microseconds - see <a href="#clock-resolution"></a> for additional considerations.</p>
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'accurate enough to allow measurement and inaccurate enough to prevent attack'

<p class='note'>If the User Agent is unable to provide a time value
accurate to 5 microseconds due to hardware or software constraints, the
User Agent can represent a <a>DOMHighResTimeStamp</a> as a time in
Expand Down Expand Up @@ -350,8 +350,11 @@ <h3>Clock resolution</h3>
this new API an attacker may be able to obtain high-resolution estimates
through repeat execution and statistical analysis. To ensure that the new
API does not significantly improve the accuracy or speed of such attacks,
the recommended minimum resolution of the <a>Performance</a> interface
the recommended minimum resolution of the <a>DOMHighResTimeStamp</a> type
should be set to 5 microseconds.</p>
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Please change from 'should be set to 5 microseconds' to 'should be inaccurate enough to prevent attack'.

<div class="issue" data-number="56">
The recommended minimum resolution of the <a>DOMHighResTimeStamp</a> is likely to increase in the upcoming future.
</div>
<p>Mitigating such timing side-channel attacks entirely is practically
not possible: either all operations would have to execute in a time that
does not vary based on the value of any confidential information, or, the
Expand Down