Install the PHP mcrypt extension

The mcrypt extension provides PHP functions for using the mcrypt cryptography library.

For PHP 5.6 through PHP 7.1, the mcrypt extension is installed by default. You do not need to install the mcrypt extension for these PHP versions.

Starting with PHP 7.2, the mcrypt extension was removed from PHP and must be installed as a third-party extension using the instructions below.

Install the mcrypt extension

Installing the extension involves the following steps:

Install build dependencies (packages that are required to build the extension).
Build the extension’s library file.
Enable the extension in the PHP configuration.

Install build dependencies

Set environment variables for the package manager.

export DEBIAN_FRONTEND=noninteractive

Install a compiler and other packages that are required for building PHP extensions.

sudo apt-get -y install gcc g++ make autoconf libc-dev pkg-config

Install additional packages that are required to build the mcrypt extension.

sudo apt-get -y install libmcrypt-dev

Build the extension

The PECL install command compiles the extension’s .so library file.

sudo yes '' | pecl8.4-sp install --nodeps mcrypt-snapshot

sudo yes '' | pecl8.3-sp install --nodeps mcrypt-snapshot

sudo yes '' | pecl8.2-sp install --nodeps mcrypt-snapshot

sudo yes '' | pecl8.1-sp install --nodeps mcrypt-snapshot

sudo yes '' | pecl8.0-sp install --nodeps mcrypt-snapshot

sudo yes '' | pecl7.4-sp install --nodeps mcrypt-snapshot

sudo yes '' | pecl7.3-sp install --nodeps mcrypt-snapshot

sudo yes '' | pecl7.2-sp install --nodeps mcrypt-snapshot

Enable the extension

Configure PHP to load the extension.

sudo bash -c "echo extension=mcrypt.so > /etc/php8.4-sp/conf.d/mcrypt.ini"

sudo bash -c "echo extension=mcrypt.so > /etc/php8.3-sp/conf.d/mcrypt.ini"

sudo bash -c "echo extension=mcrypt.so > /etc/php8.2-sp/conf.d/mcrypt.ini"

sudo bash -c "echo extension=mcrypt.so > /etc/php8.1-sp/conf.d/mcrypt.ini"

sudo bash -c "echo extension=mcrypt.so > /etc/php8.0-sp/conf.d/mcrypt.ini"

sudo bash -c "echo extension=mcrypt.so > /etc/php7.4-sp/conf.d/mcrypt.ini"

sudo bash -c "echo extension=mcrypt.so > /etc/php7.3-sp/conf.d/mcrypt.ini"

sudo bash -c "echo extension=mcrypt.so > /etc/php7.2-sp/conf.d/mcrypt.ini"

Restart PHP-FPM.

sudo service php8.4-fpm-sp restart

sudo service php8.3-fpm-sp restart

sudo service php8.2-fpm-sp restart

sudo service php8.1-fpm-sp restart

sudo service php8.0-fpm-sp restart

sudo service php7.4-fpm-sp restart

sudo service php7.3-fpm-sp restart

sudo service php7.2-fpm-sp restart

Verify the extension is enabled in PHP.

php8.4-sp -i | grep mcrypt

php8.3-sp -i | grep mcrypt

php8.2-sp -i | grep mcrypt

php8.1-sp -i | grep mcrypt

php8.0-sp -i | grep mcrypt

php7.4-sp -i | grep mcrypt

php7.3-sp -i | grep mcrypt

php7.2-sp -i | grep mcrypt

If the extension is enabled, you will see output like the following.

/etc/phpX.Y-sp/conf.d/mcrypt.ini,
Registered Stream Filters => zlib.*, convert.iconv.*, bzip2.*, string.rot13, string.toupper, string.tolower, string.strip_tags, convert.*, consumed, dechunk, mcrypt.*, mdecrypt.*
mcrypt
mcrypt support => enabled
mcrypt_filter support => enabled
mcrypt.algorithms_dir => no value => no value
mcrypt.modes_dir => no value => no value

Uninstall the mcrypt extension

Uninstalling the extension involves the following steps:

Disable the extension in the PHP configuration.
Remove the extension’s library file.

Disable the extension

Remove the extension’s configuration from PHP.

sudo rm /etc/php8.4-sp/conf.d/mcrypt.ini

sudo rm /etc/php8.3-sp/conf.d/mcrypt.ini

sudo rm /etc/php8.2-sp/conf.d/mcrypt.ini

sudo rm /etc/php8.1-sp/conf.d/mcrypt.ini

sudo rm /etc/php8.0-sp/conf.d/mcrypt.ini

sudo rm /etc/php7.4-sp/conf.d/mcrypt.ini

sudo rm /etc/php7.3-sp/conf.d/mcrypt.ini

sudo rm /etc/php7.2-sp/conf.d/mcrypt.ini

Restart PHP-FPM.

sudo service php8.4-fpm-sp restart

sudo service php8.3-fpm-sp restart

sudo service php8.2-fpm-sp restart

sudo service php8.1-fpm-sp restart

sudo service php8.0-fpm-sp restart

sudo service php7.4-fpm-sp restart

sudo service php7.3-fpm-sp restart

sudo service php7.2-fpm-sp restart

Remove the extension

The PECL uninstall command removes the extension’s .so library file.

sudo pecl8.4-sp uninstall mcrypt

sudo pecl8.3-sp uninstall mcrypt

sudo pecl8.2-sp uninstall mcrypt

sudo pecl8.1-sp uninstall mcrypt

sudo pecl8.0-sp uninstall mcrypt

sudo pecl7.4-sp uninstall mcrypt

sudo pecl7.3-sp uninstall mcrypt

sudo pecl7.2-sp uninstall mcrypt