On linux:
sudo apt-get install php5-mcrypt
sudo php5enmod mcrypt
sudo service apache2 restart
这些函数需要使用 » mcrypt 库。 请从 » http://mcrypt.sourceforge.net/ 下载 libmcrypt-x.x.tar.gz， 并按以下指导完成安装。
从 PHP 5.0.0 开始，你需要使用 libcrypt 2.5.6 或更高版本。
PHP 5.2 的 Windows 二进制发行版中已经包含了本库。 PHP 5.3 的 Windows 二进制发行版中开始使用 MCrypt 静态库， 所以不再需要 DLL。
如果使用 libmcrypt 2.4.x 或更高版本链接编译 PHP，支持以下附加的分组加密算法： CAST，LOKI97，RIJNDAEL，SAFERPLUS，SERPENT， 以及以下流密码：ENIGMA（加密）， PANAMA，RC4 和 WAKE。 如果使用 libmcrypt 2.4.x 或更高版本，那么还支持 nOFB 密码模式。
On linux:
sudo apt-get install php5-mcrypt
sudo php5enmod mcrypt
sudo service apache2 restart
there are no instructions included with the sourceforge download.
After php 5.3 mcrypt is automatically included and enabled.
(i was looking to enable an extension)
Both mcrypt and libmcrypt are available through the linked website. You simply have to click the "Browse all files" or similar link once on the "development site" and not just look for the default Sourceforge download button.
mcrypt is built in for PHP 5.3.x on windows, you don't need to do anything with a dll anymore.
If installing libmcrypt from RPM, you need both libmcrypt*.rpm and libmcrypt-devel*.rpm. I found RPMs for both were available for most platforms on this page:
http://rpmforge.net/user/packages/libmcrypt/
Also files.edin.dk does not seem to carry the win32 files anymore.