title: Two-way encryption in PHP
body: <p>My application (obviously) uses a unique ID to distinguish records.  This UID is passed in URLs (e.g. <code>./examplepage.php?UID=$example_int</code>), among other things.</p>
  
  <p>While I obviously have server-side validation in place to make sure clients don't access other clients' data, is there a two-way encryption method I can use in PHP to only pass encrypted UIDs (e.g. <code>./examplepage.php?EUID=$encrypted_int</code>), to further reduce the chance of anyone thinking "hey, what happens if I increment this integer?"</p>
  
  <p>TIA.</p>