## Runtime Configuration

The behaviour of these functions is affected by settings in php.ini.

Mcrypt configuration options
Name | Default | Changeable | Changelog
--- | --- | --- | ---
mcrypt.algorithms_dir | `NULL` | PHP_INI_ALL |
mcrypt.modes_dir | `NULL` | PHP_INI_ALL |

For further details and definitions of the PHP_INI_* modes, see the Where a configuration setting may be set.

Here's a short explanation of the configuration directives.

`mcrypt.algorithms_dir` string

  The directory that contains the algorithms. Defaults to the directories compiled within libmcrypt, which is typically /usr/local/lib/libmcrypt. See mcrypt_list_algorithms() for additional details.

`mcrypt.modes_dir` string

  The directory that contains the modes. Defaults to the directories compiled within libmcrypt, which is typically /usr/local/lib/libmcrypt. See mcrypt_list_modes() for additional details.