title: Hide time by MD5 or similar in PHP file
body: <p>My client want to give a user access to a certain page only for a couple of days. After that the client has to contact him again. For this I created the following code. </p>
  
  <pre><code>&lt;head&gt;
  &lt;style&gt;
  body {height: 100%;width: 100%;overflow: hidden;padding: 0px;margin: 0px;}
  iframe {border: 0px;width: 100%;height: 100%;}
  &lt;/style&gt;
  &lt;/head&gt;
  &lt;html&gt;
  &lt;body&gt;
  &lt;?php
  $today = strtotime(date("Y-m-d"));
  $expireDate = strtotime("2013-12-01");
  if ($today &lt; $expireDate) {
  echo "&lt;iframe src='http://www.domain.eu/active'&gt;";
  } else {
  echo "&lt;iframe src='http://www.domain.eu/deactive'&gt;";
  }
  ?&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>So basically when the time of today is less than the date in <code>$expireDate = strtotime("2013-12-01");</code> it shows the deactive page. But the code above is located into an index.php file that the client has to upload to its server. Now when the client is a little bit smart he/she can change the date to whatever they want and have access all the time. How can I make this part <code>$expireDate = strtotime("2013-12-01");</code> use MD5 or something similar.</p>
  
  <p>Thanks for the help in advance.</p>