XXXVIII. Mcrypt Encryption Functions

These functions work using mcrypt.

This is an interface to the mcrypt library, which supports a wide variety of block algorithms such as DES, TripleDES, Blowfish (default), 3-WAY, SAFER-SK64, SAFER-SK128, TWOFISH, TEA, RC2 and GOST in CBC, OFB, CFB and ECB cipher modes. Additionally, it supports RC6 and IDEA which are considered "non-free".

If you linked against libmcrypt 2.4.x, the following additional block algorithms are supported: CAST, LOKI97, RIJNDAEL, SAFERPLUS, SERPENT and the following stream ciphers: ENIGMA (crypt), PANAMA, RC4 and WAKE. With libmcrypt 2.4.x another cipher mode is also available; nOFB.

To use it, download libmcrypt-x.x.tar.gz from here and follow the included installation instructions. You need to compile PHP with the --with-mcrypt parameter to enable this extension. Make sure you compile libmcrypt with the option --disable-posix-threads.

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.

Example 1. Encrypt an input value with TripleDES under 2.2.x in ECB mode <?php $key = "this is a very secret key"; $input = "Let us meet at 9 o'clock at the secret place."; $encrypted_data = mcrypt_ecb (MCRYPT_3DES, $key, $input, MCRYPT_ENCRYPT); ?>

This example will give you the encrypted data as a string in $encrypted_data.

If you linked against libmcrypt 2.4.x, these functions are still available, but it is recommended that you use the advanced functions.

Example 2. Encrypt an input value with Triple