PHP Cryptographic Decryption class

<?PHPclassMypass {Static functionEncrypt$data,$key){        $key=MD5($key); $x= 0; $len=strlen($data); $l=strlen($key);  for($i= 0;$i<$len;$i++){            if($x==$l){                $x= 0; }            $char.=$key{$x}; $x++; }         for($i= 0;$i<$len;$i++){            $str.=CHR(Ord($data{$i}) + (Ord($char{$i}))% 256); }        return Base64_encode($str); }    Static functionDecrypt$data,$key){     $key=MD5($key); $x= 0; $data=Base64_decode($data); $len=strlen($data); $l=strlen($key);  for($i= 0;$i<$len;$i++)        {            if($x==$l)             {             $x= 0; }            $char.=substr($key,$x, 1); $x++; }         for($i= 0;$i<$len;$i++)        {            if(Ord(substr($data,$i, 1)) <Ord(substr($char,$i, 1)))            {                $str.=CHR((Ord(substr($data,$i, 1)) + 256)-Ord(substr($char,$i, 1))); }            Else            {                $str.=CHR(Ord(substr($data,$i, 1))-Ord(substr($char,$i, 1))); }        }        return $str; }}/*$data = ' PHP encryption and decryption algorithm ';     Encrypted information $key = ' 123 '; Key $encrypt = Encrypt ($data, $key); $decrypt = Decrypt ($encrypt, $key); Echo $encrypt, "n", $decrypt;*/?>

PHP Cryptographic Decryption class