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joue-quroi / canvas-fingerprint-blocker

Block HTML canvas element from being used for fingerprinting purposes
http://add0n.com/canvas-fingerprint-blocker.html
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Identify Wordpress emoji canvas check and not flag as fingerprinting #8

Open mylittleplaceholder opened 3 years ago

mylittleplaceholder commented 3 years ago

Wordpress inserts a bit of JavaScript and canvas detection to find out which emojis are supported by the browser so it knows when to use the native character and when to use the replacement image. While this is fingerprinting-like, this is very prevalent due to the number of wordpress sites out there. It would be nice if Canvas Fingerprint Blocker would ignore this method if it's this function (whether or not it alters the image).

Wordpress has their own ticket regarding this https://core.trac.wordpress.org/ticket/42428 Mozilla also has a ticket regarding their own canvas fingerprinting detection https://bugzilla.mozilla.org/show_bug.cgi?id=1437472

An example of the bit of code is below (just latest site I've run into this).

<link rel='dns-prefetch' href='//s.w.org' />
<link rel="alternate" type="application/rss+xml" title="RaMMicHaeL&#039;s Blog &raquo; 7+ Taskbar Tweaker Comments Feed" href="https://rammichael.com/7-taskbar-tweaker/feed" />
        <script type="text/javascript">
            window._wpemojiSettings = {"baseUrl":"https:\/\/s.w.org\/images\/core\/emoji\/13.0.1\/72x72\/","ext":".png","svgUrl":"https:\/\/s.w.org\/images\/core\/emoji\/13.0.1\/svg\/","svgExt":".svg","source":{"concatemoji":"https:\/\/rammichael.com\/wp-includes\/js\/wp-emoji-release.min.js?ver=5.7"}};
            !function(e,a,t){var n,r,o,i=a.createElement("canvas"),p=i.getContext&&i.getContext("2d");function s(e,t){var a=String.fromCharCode;p.clearRect(0,0,i.width,i.height),p.fillText(a.apply(this,e),0,0);e=i.toDataURL();return p.clearRect(0,0,i.width,i.height),p.fillText(a.apply(this,t),0,0),e===i.toDataURL()}function c(e){var t=a.createElement("script");t.src=e,t.defer=t.type="text/javascript",a.getElementsByTagName("head")[0].appendChild(t)}for(o=Array("flag","emoji"),t.supports={everything:!0,everythingExceptFlag:!0},r=0;r<o.length;r++)t.supports[o[r]]=function(e){if(!p||!p.fillText)return!1;switch(p.textBaseline="top",p.font="600 32px Arial",e){case"flag":return s([127987,65039,8205,9895,65039],[127987,65039,8203,9895,65039])?!1:!s([55356,56826,55356,56819],[55356,56826,8203,55356,56819])&&!s([55356,57332,56128,56423,56128,56418,56128,56421,56128,56430,56128,56423,56128,56447],[55356,57332,8203,56128,56423,8203,56128,56418,8203,56128,56421,8203,56128,56430,8203,56128,56423,8203,56128,56447]);case"emoji":return!s([55357,56424,8205,55356,57212],[55357,56424,8203,55356,57212])}return!1}(o[r]),t.supports.everything=t.supports.everything&&t.supports[o[r]],"flag"!==o[r]&&(t.supports.everythingExceptFlag=t.supports.everythingExceptFlag&&t.supports[o[r]]);t.supports.everythingExceptFlag=t.supports.everythingExceptFlag&&!t.supports.flag,t.DOMReady=!1,t.readyCallback=function(){t.DOMReady=!0},t.supports.everything||(n=function(){t.readyCallback()},a.addEventListener?(a.addEventListener("DOMContentLoaded",n,!1),e.addEventListener("load",n,!1)):(e.attachEvent("onload",n),a.attachEvent("onreadystatechange",function(){"complete"===a.readyState&&t.readyCallback()})),(n=t.source||{}).concatemoji?c(n.concatemoji):n.wpemoji&&n.twemoji&&(c(n.twemoji),c(n.wpemoji)))}(window,document,window._wpemojiSettings);
        </script>
        <style type="text/css">
img.wp-smiley,
img.emoji {
    display: inline !important;
    border: none !important;
    box-shadow: none !important;
    height: 1em !important;
    width: 1em !important;
    margin: 0 .07em !important;
    vertical-align: -0.1em !important;
    background: none !important;
    padding: 0 !important;
}
</style>