HTOP

GoogleAuthHTOP.php

<?php

function base32_decode($data) {
  $base = array_flip(array_merge(range("A","Z"), range("2", "7")));
  
  $array = str_split(strtoupper($data));
  $n      = 0;
  $j      = 0;
  $binary = "";

  foreach($array as $c) {
    $n = $n << 5;
    $n = $n + $base[$c];
    $j = $j + 5;
    
    if ($j >= 8) {
      $j = $j - 8;
      $binary .= chr(($n & (0xFF << $j)) >> $j);
    }
  }
  
  return $binary;  
}

function GetTop($key, $counter, $length) {
  
  $cur_counter = array(0, 0, 0, 0, 0, 0, 0, 0);
  for($i = 7; $i >= 0; $i--) {
    $cur_counter[$i] = pack ('C*', $counter);
    $counter = $counter >> 8;
  }
  $bin_counter = implode($cur_counter);

  if (strlen($bin_counter) < 8) {
    $bin_counter = str_repeat (chr(0), 8 - strlen ($bin_counter)) . $bin_counter;
  }

  $hash = hash_hmac('sha1', $bin_counter, $key);

  $hmac_result = array();
  
  foreach(str_split($hash,2) as $hex) {
    $hmac_result[] = hexdec($hex);
  }
  
  $offset = $hmac_result[19] & 0xf;
  
  $decimal = ((($hmac_result[$offset+0] & 0x7f) << 24 ) |
              (($hmac_result[$offset+1] & 0xff) << 16 ) |
              (($hmac_result[$offset+2] & 0xff) << 8 ) |
               ($hmac_result[$offset+3] & 0xff));

  $str = str_pad($decimal, $length, "0", STR_PAD_LEFT);
  $str = substr($str, (-1 * $length));
  return $str;  

}

$pass = "PEHMPSDNLXIOG65U";
$seed = base32_decode($pass);
var_dump(GetTop($seed, (time()/30), 6));