Ported from http://code.google.com/p/google-authenticator/

• Fixes an error in the library with the timestamp format.
• Removes original demo app.
• Adds own demo app (auth-demo.php, style.css, dump.sql).
• Adds totp.php to help understand the TOTP algorithm.

This script is discussed in c't Magazin issue 11/2016.

Issues:

The demo app's user interface is in German. If there's interest I might translate it.