PHP Encrypt and Decrypt function

/*you can chage the key as your wish*/
$key = "+OmENio4F8/8895tSQXaS13hire3FjXAQ5EfRfgHseI=";

function encrypt( $string )
{
return base64_encode(mcrypt_encrypt(MCRYPT_RIJNDAEL_256, md5($key), $string, MCRYPT_MODE_CBC, md5(md5($key))));
}

function decrypt( $encrypt_string )
{
return trim(mcrypt_decrypt(MCRYPT_RIJNDAEL_256, md5($key), base64_decode($encrypt_string), MCRYPT_MODE_CBC, md5(md5($key))));
}

$srt ='malinda';
$en = encrypt( $srt );
$de = decrypt( $en );

echo "String - " . $srt.'<br/>';

echo "Encrypt String - " . $en.'<br/>';

echo "Decrypt String - " . $de.'<br/>';


Credits -  http://ideone.com/yQIAX