What is mcrypt?
MCrypt is a replacement for the old crypt() package and crypt(1) command, with extensions. It allows developers to use a wide range of encryption functions, without making drastic changes to their code. It allows users to encrypt files or data streams without having to be cryptographers.
Why is this important?
1. PHPmyAdmin will show this error "Cannot load mcrypt extension. Please check your PHP configuration". Although error can be ignored, it is annoying.
2. When compliling PHP code you may require encryption and your pages will not display correctly on your testing server when encryption is used without mcrypt. eg login pages
NOTE: This install was completed on Windows 7 Ultimate 64 bit and works for 32 bit systems.
Open Control Panel
Open Programs and Features
Scroll down to PHP 5.X.XX
Highlight PHP 5.X.XX and click Change
Then Click Next
Select option IIS FastCGI then Next
Click on the '+' to view Extensions
Scroll down to Mcrypt
Click Mcrypt and select 'Will be installed on local hard drive'
You will see this window briefly
Congratulations! - you have now Installed mcrypt extension for PHP.
The error in PHPMyAdim "Cannot load mcrypt extension. Please check your PHP configuration" has gone.
A new file 'libmcrypt.dll' has been placed into you PHP program file and your Ext folder in PHP.
The following will also appear uncommented in your PHP.ini configuration, usually at the bottom.
This is the only method that should be used to install mcrypt as it will install the correct version for your PHP version.
DO NOT download and intall it from the internet as it is unlikely to work.