- substr: documentation ( source)
- chr: documentation ( source)
- octdec: documentation ( source)
- strrev: documentation ( source)
- hexdec: documentation ( source)
- strtolower: documentation ( source)
- define: documentation ( source)
<?php
function decrypt($a)
{
$a1 = strtolower(strrev($a));
$a2 = hexdec(substr($a1,0,4)) ^ hexdec('BFF') ^ hexdec('D77D');
$a3 = substr($a1,4);
$a5 = 0;
unset($ans);
for($a5=0;$a5<strlen($a3);$a5+=6){
++$a6;
$mul=$a6 * $a6;
$a7=$mul ^ hexdec('6E');
$ans = $ans . chr(octdec(hexdec(substr($a3,$a5,6))) ^ hexdec('AFE43') ^ hexdec('399AA3') ^ $a7 ^ octdec(hexdec(substr($a3,$a5,6))));
}
return $ans;
}
define('__FLAG__', 'flag{hidden_flag}');
if(decrypt("DEFBFD2EFBFDBCFBFD58FBFD56FBFD31FBFDDFEBFD3BEBFD48EBFD16EBFD83EBFD2DDBFDDFDBFDBCDBFDCBDBFD87DBFDB9DBFDB5DBFD76DBFDF6DBFDF5DBFDD5DBFD82ED") == 'pwning_the_phpreverse!')
{
echo __FLAG__;
}
?>