title: How can I encrypt an URL (or rather the GET parameter part of it) using PHP?
body: <p>I'm working on a function to send links to forms, en masse, trough our aplication's built-in email sender, and I'm planning to just send an url that contains the id and type of the entity it's been sent to, the id of the form and an identifier telling me in which database to look in (we have more than one databases with client data). I'm looking for a simple way to encode this information. </p>
  
  <p>I thought about just sending an Id and keeping everything in the database, but since these emails will probably be sent en masse for marketting or loyalisation campaigns I think it's not a good idea. </p>
  
  <p>I googled some encryption functions but the ones I tried sometimes returned results with illegal characters like "?" and "&amp;" which wreck my link.</p>