I just got mcrypt support for my PHP:

    // Open the cipher
    $td = mcrypt_module_open ('rijndael-256', '', 'ofb', '');

     // Create the IV and determine the keysize length
    $iv = mcrypt_create_iv (mcrypt_enc_get_iv_size($td), MCRYPT_DEV_RANDOM);
    $ks = mcrypt_enc_get_key_size ($td);

     // Create key
    $key = substr (md5 ('very secret key'), 0, $ks);

     // Intialize encryption
    mcrypt_generic_init ($td, $key, $iv);

     // Encrypt data
    $encrypted = mcrypt_generic ($td, 'This is very important data');


     // Show string
    echo trim ($encrypted)."\n";

     // Terminate encryption handler
    mcrypt_generic_deinit ($td);

     // Initialize encryption module for decryption
    mcrypt_generic_init ($td, $key, $iv);

     // Decrypt encrypted string
    $decrypted = mdecrypt_generic ($td, $encrypted);

     // Terminate decryption handle and close module
    mcrypt_generic_deinit ($td);
    mcrypt_module_close ($td);

     // Show string
    echo trim ($decrypted)."\n";