title: Implementing Copy Protection in a Desktop Mac App
body: <p>I'm looking for an easy to use serial-number registration system for a small Mac App I've created. Frankly, I'm not overly concerned about pirates, but I do want a way to have a screen show up with 'Register/buy' options, and have a serial number that is related to the username/email. So, perhaps some sort of MD5 with salt? I've always heard that lots of programmers use some sort of RPN to do it, but, frankly, I have no idea how to create a serial number that would be related to registration information.</p>
  
  <p>Anyways, I'd really prefer a plugin module (kinda like sparkle :) ) that would handle the registration for me, but, in lieu of that, I'd happily take some nice documentation that will lead the way to creating something like this.</p>
  
  <p>Thanks much!</p>