title: Door unlocking with NFC on iOS and Android smartphones; Reading UID of NFC chip
body: <p>I came across this discussion <a href="https://stackoverflow.com/questions/27239473/get-static-nfc-tag-id-with-hce-mode">Get Static NFC Tag Id with HCE mode</a> and I have some questions on how NFC technology works in card emulation mode on smartphones, particularly when it comes to unlocking doors.</p>
  <p>How do iPhone devices differ from Samsung devices in this regard? The phone models I am mostly interested in are iPhone 13, Samsung Galaxy S21 and Samsung Galaxy A32.</p>
  <ol>
  <li>Does an NFC-enabled smartphone need an application in order to emulate a card that opens a door?</li>
  <li>Is the UID of the secure element of the NFC chip in the phone static or dynamic?</li>
  <li>When using an application that emulates a card, is the UID read by the reader an UID specific for that card or is it the same as the UID of the NFC chip in the smartphone?</li>
  <li>If “the device generates a new random UID whenever it is turned on” does that mean that we can emulate more than one card with the same UID?</li>
  <li>Can a smartphone copy the content of a tag (key) and then emulate it?</li>
  <li>What security measures need to be added to a door-unlocking system relying on the UID of an NFC chip?</li>
  </ol>