Implement Two Factor Authentication plugin using DuoWeb

For security reasons, it could be interesting to provide a new authentication plugin with Two Factor Authentication mechanism.

The goal is to integrate an external service that provides a 2 factor authentication system.
The target Service is DuoWeb : https://www.duosecurity.com/docs/duoweb

see : https://www.duosecurity.com/api

• the flow is rather simple
• they provide both JS and Java client (https://github.com/duosecurity/duo_java)

The integration probably requires :

• a custom login page to handle the 2nd factor
• a custom login plugin that call a WebService to validate a token