title: Duplication of NTAG203 tags
body: <p>I'm creating a system that uses NTAG203 tags to identify accounts. The tags are formatted in the following way:</p>
  
  <p>An Android app reads the tag's unique id.</p>
  
  <p>The tag id is sent to a web server.</p>
  
  <p>The web server creates a new account record, create a hash and salt from a combination of the new account id and the tag id and stores the hash and salt with the new account record.</p>
  
  <p>The hash is returned to the Android app which then writes it on the tag.</p>
  
  <p>When the tag is then scanned in future, the hash and tag id is sent to the web server for authentication.</p>
  
  <p>My question is, how easy would it be to duplicate a tag like this? This would involve creating a tag with the same unique id, is this possible or can only NXP create the chips?</p>