That&#x27;s already part of the EME standard, implemented in the browser (so as open source as the browser is).<p><a href="https:&#x2F;&#x2F;w3c.github.io&#x2F;encrypted-media&#x2F;#clear-key" rel="nofollow">https:&#x2F;&#x2F;w3c.github.io&#x2F;encrypted-media&#x2F;#clear-key</a>