title: How to have End to End Encryption in Flutter chat app?
body: <p>I have made a chatting app using flutter and my own server as a backend for the database.
  <br>
  I want to add end to end encryption, similar to other chat apps like WhatsApp, but I am not having complete knowledge about it.
  <br>
  So What I wanna ask is :<br></p>
  <ol>
  <li>Work for an end to end encryption has to be done on client-side or at the backend?</li>
  <li>How can this be achieved</li>
  <li>is there any third-party provider for such thing, compatible with flutter</li>
  <li>And How one can even do it own there own without 3rd party Provider?</li>
  </ol>