Inspired by Github and Google, here is a Bukkit plugin to use two factor authentication. Your Mojang/Minecraft account is protected by a single password or login token. What happens if your account gets stolen? Therefore this plugin exists.
The password is time based and generated by your smartphone completely independent from your Mojang account and your computer. This makes your account safer, because other hackers would have to hack your account and your smartphone. This method is also known as 2FA.
Please leave a star on Github here: https:github.com/TuxCoding/SecureMyAccount

You don't have to decompile the plugin. You can find there the source code with comments and building utilities.
SecureMyAccount is open source and hosted on GitHub; feel free to fork, star, or contribute by making pull requests and opening issues.
Only a 2 Factor App on your smartphone For example->
Google Authenticator
Duo Mobile
Authy
Microsoft Authenticator