$b) { $key = pack("H*",md5($key)); } $key = str_pad($key, $b, chr(0x00)); $ipad = str_pad('', $b, chr(0x36)); $opad = str_pad('', $b, chr(0x5c)); $k_ipad = $key ^ $ipad ; $k_opad = $key ^ $opad; return md5($k_opad . pack("H*",md5($k_ipad . $data))); } }