title: Using UDID to create unique user identity
body: <p>I am working on an iPhone App which communicates with a Server to store and exchange data. Since I would like to make it as simple as possible, I want to avoid registration (or mybe also the using of a password) for the user account. Is it possible (and allowed?) to get the UDID of the iPhone device and make eg. an MD5-hash of it, which I transfer to the server and use it for authentification? Since this ID is unique I could simply use it to login and get the user specified data from the server, without any need of creating login data.</p>
  
  <p>Is it allowed to access the UDID, make an MD5-hash of it and store it in a database?</p>
  
  <p>Second question is: how do I get the UDID? ;-)</p>