PHP 7.2 includes support for a new password hashing algorithm Argon2. Argon2 was the winner of the Password Hashing Competition (PHC) in July 2015. Note that the Argon2 module is only available for PHP 7.2 and therefore doesn’t support PHP 7.1 and below.
To benefit from the update you don’t have to do anything inside your server, because it has been taken care of by Servermeister.
If you want to use Argon2 inside PHP 7.0 and PHP 7.1, you can manually compile it from PHP Argon2 Ext. The Argon2 library is available inside our repository. You just have to download them to compile your own Argon2 module.
sudo apt-get install libargon2-1-dev