Ivan

The Google Authenticator plugin for WordPress gives you two-factor authentication using the Google Authenticator app for Android/iPhone/Blackberry.
If you are security aware, you may already have the Google Authenticator app installed on your smartphone, using it for two-factor authentication on Gmail/Dropbox/Lastpass/Amazon etc.
The two-factor authentication requirement can be enabled on a per-user basis. You could enable it for your administrator account, but log in as usual with less privileged accounts.
If You need to maintain your blog using an Android/iPhone app, or any other software using the XMLRPC interface, you can enable the App password feature in this plugin, 
but please note that enabling the App password feature will make your blog less secure.
<h3>Credits</h3>
Thanks to:
<a href="https://profiles.wordpress.org/evinak/" rel="nofollow ugc">Oleksiy</a> for a bugfix in multisite.
<a href="https://github.com/pancek" rel="nofollow ugc">Paweł Nowacki</a> for the Polish translation
<a href="https://github.com/FabioZumbi12" rel="nofollow ugc">Fabio Zumbi</a> for the Portuguese translation
<a href="https://www.guidoschalkx.com/" rel="nofollow ugc">Guido Schalkx</a> for the Dutch translation.
<a href="https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=henrik%40schack%2edk&lc=US&item_name=Google%20Authenticator&item_number=Google%20Authenticator&no_shipping=0&no_note=1&tax=0&bn=PP%2dDonationsBF&charset=UTF%2d8" rel="nofollow ugc">Henrik.Schack</a> for writing/maintaining versions 0.20 through 0.48
<a href="http://tobias.baethge.com/" rel="nofollow ugc">Tobias Bäthge</a> for his code rewrite and German translation.
<a href="http://blog.pcode.nl/" rel="nofollow ugc">Pascal de Bruijn</a> for his “relaxed mode” idea.
<a href="http://technobabbl.es/" rel="nofollow ugc">Daniel Werl</a> for his usability tips.
<a href="http://dd32.id.au/" rel="nofollow ugc">Dion Hulse</a> for his bugfixes.
<a href="https://profiles.wordpress.org/users/aldolat/" rel="nofollow ugc">Aldo Latino</a> for his Italian translation.
<a href="http://www.kaijia.me/" rel="nofollow ugc">Kaijia Feng</a> for his Simplified Chinese translation.
<a href="http://www.buayacorp.com/" rel="nofollow ugc">Alex Concha</a> for his security tips.
<a href="http://jetienne.com/" rel="nofollow ugc">Jerome Etienne</a> for his jquery-qrcode plugin.
<a href="http://orizhial.com/" rel="nofollow ugc">Sébastien Prunier</a> for his Spanish and French translation.

Google Authenticator

Personally I feel 2FA should be a part of WordPress core. But since it isn't, plugins like this one are a must-have to secure your sites.

The configuration interface is clearly layed out and the login page fits in perfectly with the default WP login page styling.

This plugin is light-weight, unobtrusive, free and adds that extra layer of security. Should your admin credentials ever be compromised, 2FA will keep your site secure.

Must-have security plugin

Awesome plugin, which is almost always in first group of plugin I've install on new website. Thank you for create and maintain it.

One on few my first-to-install plugin

Google Authenticator for your WordPress blog.

Kieran O'Shea

Henrik Schack

This plugin dramatically enhances the security of your WordPress website by adding Multi Factor Authentication (MFA) in the form of One Time Passwords (OTP) 
using <a href="https://www.yubico.com/" rel="nofollow ugc">Yubikey USB Tokens</a>. In addition to providing your username and password to login, this plugin requests an OTP code 
generated by a Yubikey, validates this via an API and only grants access if this check passes. The requirement to use an OTP can be set on a user by user 
basis and there is also a feature to require users above a certain privilege level to always use OTP.
<h3>External services</h3>
This plugin connects to an API to validate the OTP tokens generated by your security key. This is required because storing the private keys 
on the same web server as the site you wish to protect would be a security risk.
By default Yubico’s own validation server is employed, although you may setup your own server and use this instead
The default Yubico API only collects the one time password (OTP) data as provided by your security key when you login. The service validates this 
and then stores this token as “used” so it may not be replayed as part of an attack. It does not collect any other data (such as what URL is being 
authenticated using the key etc.)
This service is provided by “Yubico AB”: <a href="https://www.yubico.com/support/terms-conditions/privacy-notice/" rel="nofollow ugc">Privacy Policy</a>, <a href="https://www.yubico.com/support/terms-conditions/yubico-website-terms-conditions/" rel="nofollow ugc">Terms of Use</a>

Yubikey


Calling all regular Yubikey users! If you haven’t done so already, please take the time to review the plugin here



If you have a problem, issue or question, please post in the forums first before rating the plugin negatively – most things can be sorted out either through communication or a new release!


Reviews welcome

Enhanced login security for WordPress by requiring the presentation of a One Time Password (OTP) from a registered Yubikey

Google Authenticator vs Yubikey