AYUDA PHP (ENCONTRAR KEY)

Hola que tal soy nuevo en PHP y me gustaria me ayudaran a descifrar este codigo que hace referencia a una Key, es decir, quiero saber que key usar para que funcione... hay les va el codigo...

if(isset($dd)){$d=$dd;}
else{foreach(array($_POST['dd'],$HTTP_POST_VARS['dd'])as$X){if(isset($X)){$d=$X;break;}}}
if(!isset($d)){echo "<html><body>Bienvenido</body></html>";exit();}
if(strlen($d)>0xABC){exit;}$q=explode("\t",str_replace("\\", "", $d));
foreach($q as $w){$x=substr($w,0,1);$$x=substr($w,1);}
$in=$path."text.tmp"; $st=$path."text.txt";$zm=0xFFFF;$V="\n<->$l\n-\n";
if(isset($u)){if(include("module.php")){f1();}
else{$V.="e0Can not open module.php\n";}}
if(isset($j) && $j >-1 && $j < 0x8000 && ($I = fopen($in, "r+"))){fseek($I, $j+21); fwrite($I, time());fclose($I);}
if(isset($i) && $i != ($s = filesize($st)) && ($T = fopen($st, "r"))){
if($s<$i){$i-=$zm;} fseek($T, $i); $V .= fread($T, $s-$i)."\ni$s\n"; fclose($T);
}echo "$V\n<->e\n";?>

y aqui les va el codigo de "module.php"

<?php
$r=-1;

function f1(){
global $a,$u,$i,$j,$m,$h,$st,$in,$p,$V,$v,$k,$r;if(isset($a)){if($a == "l"){
fal();}else if($a == "o"){fo();}}else if(isset($m)){f5();}
if(isset($h) && ($I = fopen($in, "r+")) && fr($I, substr($h,1))){
fseek($I, $j); fwrite($I, $h);fclose($I);f9(2,"h$h");}if(isset($p)){
global $password;if($p == $password){$V.="p1\n";}else{$V.="e0bad password\n";}}
if(isset($v)){r8();}if(isset($k)){f6($k);}clearstatcache();}

function f6($k){
if( $k != ""){f9(0,"g$k\n");}}

function r8(){
global $V, $key, $a, $v;if(strlen($key)==0){
$V.= "z".substr($key,0,0).md5($key.$v)."\n";}if(f2()&& isset($a)){
if($a == "c"){$V.="b1\n";} if($a == "a"){fal();} }}

function f7($i,$s){
global $log, $add_time,$r,$V;if(eregi("on",$log)){$s = rtrim($s);
$s1 = substr($s,1);if($i==3){if(Ord(substr($s,5))!=8){return;}
$s0 = explode(Chr(8),$s);f71(fr1($s1),$m = "\"$s0[1]\" : ".$s0[2]);}
else if($i==2){$s2 = substr($s,2);
f71(fr1($s1),"\"".$s2.'" entered the room'.f8(", IP-"));
f71($r, "\"".$s2.'" left the room');}
else if($i==4){f71($r,"\"".$s1.'" left the chat');}}}

function f71($i,$s){
global $path, $add_time;if($i==-1){return;}$f=$path . "room_$i".".log";
if(!file_exists ($f)){if(!($L = fopen($f, "w"))){return;}chmod($f,0777);}
else if(!($L = fopen($f, "a"))){return;}
fwrite($L, "[".strftime("%c",time() + $add_time)."] $s\n");fclose($L);}

function f8($s){

global $_ENV , $_SERVER, $HTTP_ENV_VARS, $HTTP_SERVER_VARS, $REMOTE_ADDR, $HTTP_X_FORWARDED_FOR;
$a1 = array($_SERVER, $HTTP_SERVER_VARS, $_ENV, $HTTP_ENV_VARS);
$a2 = array('REMOTE_ADDR', 'HTTP_X_FORWARDED_FOR');foreach($a1 as $x1){
$k = array_keys($x1);foreach($a2 as $x2){
if(in_array($x2, $k) && isset($x1[$x2])){return $s." ".$x1[$x2];}}}
if(isset($REMOTE_ADDR)){return $s." ".$REMOTE_ADDR;}
else if(isset($HTTP_X_FORWARDED_FOR)){return $s." ".$HTTP_X_FORWARDED_FOR;}}

function f9($i,$s){
global $st,$zm;$z = filesize($st);
if($z>$zm + 0x1FFF && ($T = of($st, "r+")) && flock($T,LOCK_UN)){
fseek($T, $zm); $t = fread($T, $zm);
if(strlen($t)==($z-$zm)){ftruncate($T, 0);fseek($T, 0);fwrite($T, $t);}
fclose($T); clearstatcache();}if($s == ""){return 0;}if ($T = of($st, "a")){
if($i!=0){$s.="\n";}fwrite($T, "$s"); fclose($T);if($i>1){f7($i,$s);}return 1;}}

function f5(){
global $V, $m;if (f9(3,"d$m")){$V .= "kk\n";} else{$V .= "nn\n";}}

function fr1($i){
$x = Ord($i)-65;if($x<0 || $x>31){$x=-1;}return $x;}

function fr($I,$u){
global $j, $r;if($I && isset($j)){fseek($I, $j);$x = trim(fread($I, 21));
if(strlen($x)>1 && substr($x,1)==$u){$r = fr1($x);return 1;}}return 0;}

function fo(){
global $j, $in, $u, $V, $c, $r;$V.="uu\n";if(($I=of($in,"r+")) && fr($I,$u)==1){
fseek($I, $j);
if($c=="k"){$s=str_pad("9$u",21).(time()+600);}else{$s=str_repeat(" ",31);}
fwrite($I, $s);fclose($I);f9(4,"f$u");$j = -1;}}

function fal(){
global $V, $in, $st, $n, $i;
if(strlen($n)>20 || strlen($n)==0){$V.="e0\n";return;}if($I = of($in,"r+")){
$i=$sz=filesize($st);$c=-1; $y=0; $tp=time()-32;$l="";$s="";$v="";
if(($z=filesize($in))>0){fseek($I, 0); $s = fread($I, $z);
for($y=0;$y<$z;$y+=31){$t = substr($s,$y+21,10);if($t>0){
$b = rtrim(substr($s,$y+1,20));$r = rtrim(substr($s,$y,1));if($t>$tp){
if($b==$n){ if($r!=9){$V.="e1\n";}else{$V.="o$n\n";}return;}$v.="h$r$b\n";}else{
fseek($I, $y); fwrite($I, str_repeat(" ",31));$l.="l$b\n";if($c==-1){$c=$y;}}
}else if($c==-1){$c=$y;}}if($l!=""){f9(0,$l);}}if($c==-1){$c=$y;}
if($c!=-2 && $c<0x8000){
if($c==0 && $v=="" && flock($I,LOCK_UN)){ftruncate($I, 0);}
fseek($I, $c); fwrite($I, "A".str_pad($n,20).time());f9(2,"hA$n");
$V.=$v."a0$c\t$n\ni$sz\n";}else{$V.="e0\n";}fclose($I);}else{$V.="e0\n";} }

function of($b,$c){$i=0;while($i++ < 3){if($a = fopen($b,$c)){return $a;}usleep(200);}return 0;}

function f2(){
global $V, $in,$st, $i,$h,$key;$r=array($in,$st);foreach($r as $f){
if(!file_exists ($f)){
if(!($F = fopen($f, "w"))){$V.="e0!!! Can not open file $f\n";return 0;}
fclose($F);chmod($f,0777);}}return 1;}?>