title: Device identification without device ID and on Nougat
body: <p>I am interested to how I can identify user with some alternative way:</p>
  
  <ul>
  <li><p>I don't want to use device ID because it demands permission and ask user, it ruins my app</p></li>
  <li><p>I cannot use MAC address because from Nugat its not allowed</p></li>
  <li><p>Other authentication things are not unique</p></li>
  </ul>
  
  <p>I need some unique device identifier what I can use without permissions to assign user in database to his device.</p>