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.

akay

افزونه مکمل دیجیتس آکای یک ابزار حرفه‌ای و پیشرفته برای ارتقای عملکرد افزونه اورجینال Digits است که با اکثر سامانه‌های پیامکی ایرانی کاملاً سازگار بوده و امکانات بیشتری را برای مدیریت ثبت‌نام و ورود با شماره موبایل در سایت‌های وردپرسی فراهم می‌کند. این افزونه نه‌تنها از قابلیت‌های ارسال پیامک ساده پشتیبانی می‌کند، بلکه با امکان ارسال پیامک با پترن (Pattern) نیز کاملاً سازگار است، که این ویژگی باعث افزایش سرعت ارسال پیامک‌ها و کاهش هزینه‌ها می‌شود. با تنظیمات ساده و پشتیبانی از زبان فارسی
<h4>درگاه های پیامک</h4>
<ul>
<li>MeliPayamak.com</li>
<li>IPPANEL.com</li>
</ul>
<h3>External Services</h3>
<h3>IPPanel API</h3>
This plugin connects to the “IPPanel” API to send SMS messages. 
Data sent: 
– Phone numbers (recipient) 
– Message content (pattern or text)
When data is sent: 
– When sending OTPs or transactional SMS messages.
Service provided by “IPPanel”: 
– <a href="https://ippanel.com/" rel="nofollow ugc">Terms of Use</a> 
– <a href="https://ippanel.com/" rel="nofollow ugc">Privacy Policy</a>
<h3>MeliPayamak API</h3>
This plugin connects to the “MeliPayamak” API to send SMS messages. 
Data sent: 
– Phone numbers (recipient) 
– Message content (pattern or text)
When data is sent: 
– When sending OTPs or transactional SMS messages.
Service provided by “MeliPayamak.com”: 
– <a href="https://www.melipayamak.com/rules/" rel="nofollow ugc">Terms of Use</a> 
– <a href="https://www.melipayamak.com/rules/" rel="nofollow ugc">Privacy Policy</a>
<h3>License</h3>
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program. If not, see <a href="https://www.gnu.org/licenses/gpl-2.0.html" rel="nofollow ugc">https://www.gnu.org/licenses/gpl-2.0.html</a>.

Akay Digits Add-on

افزونه مکمل دیجیتس آکای برای استفاده با افزونه اورجینال دیجیتس سازگاری با سامانه های پیامکی

Google Authenticator vs Akay Digits Add-on