srand((double)microtime( )*1000000 );
$td = mcrypt_module_open(MCRYPT_RIJNDAEL_256, '', MCRYPT_MODE_CFB, '');
$iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
$ks = mcrypt_enc_get_key_size($td);
$key = substr(sha1('Your Secret Key Here'), 0, $ks);
mcrypt_generic_init($td, $key, $iv);
$ciphertext = mcrypt_generic($td, 'This is very important data');
mcrypt_generic_deinit($td);
mcrypt_generic_init($td, $key, $iv);
$plaintext = mdecrypt_generic($td, $ciphertext);
mcrypt_generic_deinit($td);
mcrypt_module_close($td);
print $iv . "\n";
print trim($ciphertext) . "\n";
print trim($plaintext) . "\n";
?>