My PHP MCRYPT extension for Ubuntu is installed properly by I getting this message from PHPMYADMIN.
The mcrypt extension is missing. Please check your PHP configuration.
Here's how I configured it:
$ sudo apt-get install php5-mcrypt
Reading package lists... Done
Building dependency tree
Reading state information... Done
php5-mcrypt is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.