Not sure whether it’s just a gimmick or something useful, but recently we saw some online examples (e.g. by Google) of authentication by delegating the authentication to your smart-phone using a QR code (the odd thing which your mother in law just recently asked you what it was, since it started appearing in all kinds of magazines).
In any case, it sounded like a good test (to us and to you) for the extensibility of the authentication framework we added to Wt in 3.2.0.
The idea of logging in using QR Codes is that you keep yourself logged in on your phone (using a remember-me cookie, for example) and delegate the authentication from any other (desktop) to your phone by scanning a QR code. In this way you avoid retyping your credentials on a computer which you just happen to run across.
The example is deployed here. You’ll need a mobile phone which can scan QR codes to try it for yourself (you’ll need to register first).
The source code is available in git and will thus be part of the next release. It defines a new authentication service (QRAuthService) which implements the logic, and in QRAuthWidget we specialize the Wt::Auth::AuthWidget to add the option of logging in using a QR code.
All in all, this method integrates nicely with the Wt::Auth framework and will work regardless of how you authenticate on your smart phone, or how you integrate the authentication widget in your application.