jdavis/twofactorauth — pull request #599 by landakram (2014-06-23 21:12:32+00:00)
Title: Add Clef as a 2FA provider

[Clef](https://getclef.com) is a two-factor replacement for passwords. We use possession of the phone and knowledge of a PIN as the two factors. Authentication is done by verifying digital signatures generated by a private key stored in the smartphone app.