I have authentication implemented with this API. How I did it:
- first specify an api path in the plugin options, mine was /api
- make a folder in the document root of your site, in this case a folder named "api"
- now place a .htaccess file in this directory (and nothing else)
- the contents of the .htaccess file:
AuthName "This is a protected area"
- Now go to your terminal and make a file called 'users' in /etc
- to add users follow this tutorial: http://www.htaccesstools.com/htpasswd-generator/