ActiveAuth

ActiveAuth is a powerful yet easy to use solution which enables two-factor authentication for your wordpress site.
The plugin can increase your online security and will protect your privacy by adding a second layer of identity verification to prevent access to your site by password hacking.
The two-step verification (two-factor authentication) sends a second request, after you enter your ID and password on the website to your mobile device.
Even if you are using are using the strongest password ever, you never can be sure if you are not a subject of password sniffing or hacker attack on the password database.
By adding the 2nd layer of authentication, you remain secure even in the event your password for the first step is lost or stolen.
Simple and efficient you can use Mobile Push (over data) SMS, or even a phone call for the 2nd step.