<?php
$key = 'Welcome to the monkey house'
$s   = 'cc-number-goes-here';
$alg = MCRYPT_BLOWFISH;
$mode = MCRYPT_MODE_CBC;

$iv = mcrypt_create_iv(
    mcrypt_get_iv_size($alg, $mode), 
    MCRYPT_DEV_URANDOM
);
$data = mcrypt_encrypt($alg, $key, $s,  $mode, $iv);

mysql_query(
    sprintf("INSERT INTO customers (iv, data) ('%s', '%s')", 
        mysql_escape_string($iv), mysql_escape_string($data)
    ), 
    $dbh
);
?>