title: Web based login using ssl public/private key?
body: <p>Is it possible to create a login process that requires a public/private key through a web browser? The public key would be stored on the server and the private key would be kept (and encrypted) by the user.</p>
  
  <p>I basically want to do something similar to what SSH does, but through the web. Perhaps a custom method of HTTP Authentication (other than "Digest").</p>
  
  <p>I know that it may not be possible to do this with a stock browser, so extensions to make this work are acceptable (Chrome/Firefox).</p>
  
  <p>The keys would ideally be encrypted on a USB Stick. When the USB stick is unplugged in has to be impossible to login (don't want the browser to cache it).</p>
  
  <p>This would be used internally.</p>
  
  <p><strong>Edit:</strong> Client certificates would be what I'm looking for, but how do I store these certificates on a USB stick? Also, is there information on how to authenticate a user using PHP?</p>