The mcrypt extension is an interface to the mcrypt cryptography library. This extension is useful for allowing PHP code using mcrypt to run on PHP 7.2+.
The main problem with mcrypt extension is that it is based on libmcrypt that hasn’t been developped since its upstream in 2007. Thus, it has been already 10 years, even though the library has been still used. However, without the proper developement and maintenance library has become security alert for many system administrators.
Because of the end of the mcrypt extension’s development, the extention was also removed from PHP 7.2 and moved to an unofficial PECL repository. However, you can still find the mcrypt extention in PHP 5.4 through PHP 7.1. The arrival of PHP 7.2 has been announced but it won’t contain mcrypt extention. For PHP 7.2+, PHP instead uses libsodium as a cryptography library.
To install this extension on PHP 7.2, run the following commands as your server’s root user:
php -v
pecl version
If your php isn’t 7.2 then use /usr/bin/php7.2 instead php command.
Mcrypt PECL extenstion
sudo apt-get -y install gcc make autoconf libc-dev pkg-config
sudo apt-get -y install libmcrypt-dev
sudo pecl install mcrypt-1.0.1
When you are shown the prompt
libmcrypt prefix? [autodetect] :
Press [Enter] to autodetect.
After success installing mcrypt trought pecl, you should add mcrypt.so extension to php.ini.
The output will look like this:
...
Build process completed successfully
Installing '/usr/lib/php/20170718/mcrypt.so' ----> this is our path to mcrypt extension lib
install ok: channel://pecl.php.net/mcrypt-1.0.1
configuration option "php_ini" is not set to php.ini location
You should add "extension=mcrypt.so" to php.ini
Grab installing path and add to cli and apache2 php.ini configuration.
sudo bash -c "echo extension=/usr/lib/php/20170718/mcrypt.so > /etc/php/7.2/cli/conf.d/mcrypt.ini"
sudo bash -c "echo extension=/usr/lib/php/20170718/mcrypt.so > /etc/php/7.2/apache2/conf.d/mcrypt.ini"
Run command:
php -i | grep "mcrypt"
The output will look like this:
/etc/php/7.2/cli/conf.d/mcrypt.ini
Registered Stream Filters => zlib.*, string.rot13, string.toupper, string.tolower, string.strip_tags, convert.*, consumed, dechunk, convert.iconv.*, mcrypt.*, mdecrypt.*
mcrypt
mcrypt support => enabled
mcrypt_filter support => enabled
mcrypt.algorithms_dir => no value => no value
mcrypt.modes_dir => no value => no value
Q: I see error message: ERROR: 'phpize' failed
A: You can install php7.2-dev apt-get install php7.2-dev
Q: What is the solution for installing on a PHP 7.1 and highet setup on MacOS / OSX?
A: You can use macports, after then you can install sudo port install php71-mcrypt