libmcrypt (encryption functions for MCrypt)

mcrypt is a program for encrypting files or streams. It is intended
to be a replacement for the old UNIX crypt. It uses well-known and
well-tested algorithms like BLOWFISH, AES, ARCFOUR, CAST-128, and
more in several modes or operation.

This package is configured with --disable-posix-threads. Using the worker
or event MPM with apache can lead to instability when using mod_php and
non-thread-safe extensions. The flag can be safely removed from the
slackbuild when the prefork MPM is used, or when apache will not be installed
or running on the target machine.

See http://php.net/manual/en/mcrypt.installation.php for more details.