Mcrypt can be used to encrypt and decrypt using the above
mentioned ciphers. If you linked against libmcrypt-2.2.x, the
four important mcrypt commands (mcrypt_cfb(),
mcrypt_cbc(), mcrypt_ecb(),
and mcrypt_ofb()) can operate in both modes
which are named MCRYPT_ENCRYPT and
MCRYPT_DECRYPT, respectively.
If you linked against libmcrypt 2.4.x or 2.5.x, these functions are still available, but it is recommended that you use the advanced functions.
Example #1 Encrypt an input value with AES with a 256-bit key under 2.4.x and higher in CBC mode
<?php
$key = hash('sha256', 'this is a secret key', true);
$input = "Let us meet at 9 o'clock at the secret place.";
$td = mcrypt_module_open('rijndael-128', '', 'cbc', '');
$iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_DEV_URANDOM);
mcrypt_generic_init($td, $key, $iv);
$encrypted_data = mcrypt_generic($td, $input);
mcrypt_generic_deinit($td);
mcrypt_module_close($td);
?>