Install PHP mcrypt Extension on Linux

In order to use encryption and decryption in PHP, we need to inatall PHP extension mcrypt.

php_mcrypt installation on CentOS

# First Install Extended Repository 
yum install epel-release
# Then simply install mcrypt
yum -y install php-mcrypt
# Restart apache
systemctl restart httpd

php_mcrypt installation on Ubuntu

sudo apt-get install mcrypt php5-mcrypt
sudo php5enmod mcrypt
sudo service apache2 restart