Add Authy two-factor authentication to WordPress. Users opt in for an added level of security that relies on random codes from their mobile devices.
Enable the plugin, enter your Authy API keys, and your users can enable Authy on their accounts.
Once users configure Authy through their WordPress user profiles, any login attempts will require an Authy token in addition to the account username and password.
This plugin is compatible with WordPress 3.5 and higher. I haven’t tested it with earlier versions, but it might work.
This plugin is available in the WordPress plugins directory at http://wordpress.org/extend/plugins/authy-for-wp/, and via your WordPress dashboard.
Donations are gladly accepted via PayPal and are used solely to support development of this and future plugins.