title: Encoding URL $_GET variables
body: <p>I am passing $_GET[]; variables in a link but want to encrypt the values in the url. I would normally use sessions but since I am not using a form and just a url what are my options. I am sure there is someway to exploit this method so I am trying to make it as secure as possible.</p>
  
  <p>Below is my code:</p>
  
  <pre><code>$cost = "152.00";
  &lt;a href="registration.php?class=Spanish&amp;age=4-6&amp;time=3pm&amp;cost=&lt;?echo $cost; ?&gt;"&gt;
  </code></pre>
  
  <p>and registration.php looks like</p>
  
  <pre><code>&lt;?
  $class = $_GET[class];
  $age = $_GET[age];
  $time = $_GET[time];
  $cost = $_GET[cost];
  ?&gt;
  </code></pre>
  
  <p>If I could use something like md5 to encode the values and then decode them on registration.php that would be good or if there is a way to pass $_session variables using <code>&lt;a&gt;</code> that would be good.</p>