<?php
  // tutorial
  // coloque o código criptografado dentro do arquivo xxx.txt
  // agora execute este arquivo ex: http://localhost/zen.php
  //siga as instruções

  $xxx = "xxx.txt";
  if(file_exists($xxx)) $code = @file_get_contents($xxx);
  $x = gzinflate(base64_decode(strrev($code)));
  $x = explode(';',$x);
  $x = explode('val($',$x[5]);

  if($x[0] == 'e') {
   eval(gzinflate(base64_decode(strrev($code))));
   echo $i;
   $code = gzinflate(base64_decode(strrev($code)));
   $code = explode(';',$code);
   $code = str_replace(array('eval($',')'),'',$code[5]);
   $code = "${$code}";
   $code = str_replace(array('eval(gzinflate(base64_decode(strrev($','))));'),'',$code);
   file_put_contents($xxx,"${$code}");
   echo 'press F5 again';
  } else {
    highlight_string(gzinflate(base64_decode(strrev($code))));
  }