Key application?

<?php
function RandomKeyGen($length=10)
{
   $key = '';
   list($usec, $sec) = explode(' ', microtime());
   mt_srand((float) $sec + ((float) $usec * 100000));
   
      $inputs = array_merge(range('z','a'),range(0,9),range('A','Z'));

      for($i=0; $i<$length; $i++)
   {
          $key .= $inputs{mt_rand(0,61)};
   }
   return $key;
}


 echo RandomKeyGen(40);  

?>

<?php
$fp = fopen('data.txt', 'w');
fwrite($fp, '23');
fclose($fp);
?>

<?php
$read = file_get_contents('http://www.example.com/data.txt');
echo $read;
?>

<?php
$read = file_get_contents('http://www.example.com/data.txt');
echo $read;
?>

<?php
$myFile = "keys.txt";
$fh = fopen($myFile, 'r');
$theData = fgets($fh);
fclose($fh);
echo $theData;
?>