evp.md

<form action="signup.php" method="POST">
  <input type="email" name="email" autocomplete="email" nonce="1234">
  <input type="hidden" name="token" autocomplete="email-verification">
</form>

<form action="signup.php" method="POST">
  <input type="tel" name="tel" autocomplete="tel" >
  <input type="verification" for="tel" nonce="1234" name="token">
</form>

<form action="signup.php" method="POST">
  <input type="email" name="email" autocomplete="email">
  <!-- one neat property of this is that this is a one-liner that developers can copy/paste on their forms -->
  <input type="hidden" name="token" nonce="1234" autocomplete="email-verification-token">
</form>

<form action="/register" method="POST" verify-identity="email" identity-nonce="xyz123">
  <input type="email" name="user_email">
  <button type="submit">Register</button>
</form>

And the proof is returned in a special HTTP Header