Thanks. Note that I tried to write an accurate roadmap based on the discussion, but it was not the only roadmap I could&#x27;ve written – early stage, goals still to define.<p>&gt; <i>There have been Persona extensions before for at least Firefox. It will probably be important to learn from them, even if I&#x27;m sure hardly anyone tried to use them.</i><p>Do you know some? I only found <a href="https:&#x2F;&#x2F;addons.mozilla.org&#x2F;en-US&#x2F;firefox&#x2F;addon&#x2F;browser-sign-in&#x2F;" rel="nofollow">https:&#x2F;&#x2F;addons.mozilla.org&#x2F;en-US&#x2F;firefox&#x2F;addon&#x2F;browser-sign-...</a>, which is old (but new to me) and it seems defunct. I&#x27;m not sure whether the source code is accessible. <a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=um0Ym-Yma8Y" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=um0Ym-Yma8Y</a> looks nice though.<p>Thanks for the hint to passwordless.net. A simpler fallback-provider might be exactly right, maybe even something for stage 1.5.<p>The BrowserID protocol actually has a user certificate as endpoint. I&#x27;m not sure how and whether that is stored.